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Multiphase boride layers consisting of (CoFe)2B, (Fe0.4Mn0.6)B, Cr2Ni3B6 and (Cr0.4Mn0.6)B were formed on the surface of Co1.21Cr1.82Fe1.44Mn1.32Ni1.12Al0.08B0.01 high entropy alloy by powder-pack boronizing at 900 °C, 950 °C and 1000 °C for 4 h. The nanohardness (H), modulus of elasticity (E) and fracture toughness (KC) of the multiphase boride layers were determined based on the load–displacement (P-h) curves obtained in the nanoindentation tests. Three distinct regions were identified on the cross-sections of the produced layers: an outer layer consisting of MeB-type borides, an inner layer consisting of Me2B-type borides and the transition zone. The microstructural aspects of the layers were investigated using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Detailed analysis of the influence of the chemical composition on hardness, elastic modulus and fracture toughness in the three regions indicated that the most critical factor influencing the mechanical properties was the presence of chromium, iron and cobalt borides in the microstructure. Especially the formation of chromium borides reduced the fracture toughness of the transition zone.

In machine learning models, one of the most popular models is artificial neural networks. The activation function is one of the important parameters of neural networks. In this paper, the sigmoid function is used as an activation function with a fractional derivative approach to minimize the convergence error in backpropagation and to maximize the generalization performance of neural networks. The proportional Caputo definition is considered a fractional derivative. We evaluated three neural network models on the usage of the proportional Caputo derivative. The results show that the proportional Caputo derivative approach has higher classification accuracy than traditional derivative models in backpropagation for neural networks with and without L2 regularization.

Refractory high entropy alloys (RHEAs) with multiple principal elements constitute a new paradigm in alloy design and have gained recent interest for advanced technical applications due to their unique properties and mechanical stability at high temperatures. However, the refractory metals that make up these alloys are pretty expensive, and they cause RHEAs to exhibit low plasticity behaviour at room temperature. The high stability properties of RHEAs from room temperature to high temperatures limit their machinability with traditional cutting methods. Therefore, it is vitally important to economically machine these alloys while preserving their mechanical properties and minimising waste. For this purpose, in this study, the machinability of a HfTaTiVZr RHEA was evaluated with wire electric discharge machining (WEDM). The surface morphology, crack formation, and mechanical characteristics of the surface layer were investigated as a function of three different cutting conditions: rough cutting, semi-finishing, and finishing. The RHEA was precision cut in three passes by reducing the volume of material in each pass, resulting in better surface quality with the optimal cutting speed and metal removal rate. However, rough cutting gave better results than semi-finish and finished cutting processes in preserving mechanical properties.

Refractory high entropy alloys (RHEAs) have shown great promise for a multitude of advanced engineering applications due to their high mechanical stability from cryogenic temperatures to 1600 °C. However, the low ductility they exhibit at room temperature limits their machinability when traditional machining techniques are used. Studies on the nontraditional machining of RHEAs, on the other hand, are very limited. In the present work, MoNbTaTiZr RHEAs subjected to wire electrical discharge machining (WEDM) were examined using electron microscopy, contact profilometry, and nanoindentation. Voids, microcracks, and recast material were observed on the machined surfaces. A transition from roughing to finishing decreased the amount of recast material, but the density of observable voids and microcracks on the surface increased. Optimal results were obtained by finishing, where the surface quality was improved by the removal of recast material remaining from prior passes. The brass wire electrode provided a smoother surface while the copper-core electrode provided minor heat-affected zone in the MoNbTaTiZr samples. In the roughing cuts, a 7.00% improvement in surface roughness was achieved using the copper-core electrode compared to the brass electrode. In the semi-finishing and finishing cuts, the brass wire electrode provided improvements of 13.68% and 22.68%, respectively, compared to the copper-core electrode. On the other hand, the wear of the brass electrode was as much as 20.98% higher than that of the copper-core electrode.

Antimony triselenide (Sb2Se3) is one of the most promising absorber material choices among the inorganic semiconductors that has attracted much attention today. However, highest recorded efficiencies for Sb2Se3 solar cells are still lower than ideal. Exploring antimony selenosulfide (Sb-2(SxSe1-x)(3)) to increase device performance is one option because some features of alloyed Sb-2(SxSe1-x)(3) depend on composition such as bandgap and band position. In this study, two-step process was used to grow Sb-2(SxSe1-x)(3) thin films. In the first stage, Sb2Se3 thin films were deposited on soda lime glass substrates using direct current magnetron sputtering technique. In the second stage, Sb2Se3 thin films were exposed to sulfurization process in a quartz ampoule to obtain Sb-2(SxSe1-x)(3) thin films. Characterization results showed that morphological, optical, and structural properties of Sb-2(SxSe1-x)(3) thin films grown by presented method were highly dependent on amount of sulfur in the films. By the adjustment of the S/S + Se atomic ratio, Sb-2(SxSe1-x)(3) absorber materials with suitable bandgap, favorable orientation and compact morphology can be obtained for photovoltaic applications.

This study focused on chromium addition (0 wt%, 3 wt%, 6 wt%, 9 wt% and 12 wt%) on the boride layer formation, microhardness, fracture toughness and elevated temperature friction and wear behaviour of alloys formed by powder metallurgy (P/M). The boride layers obtained on P/M alloys were characterized by examining density, porosity, surface roughness, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray difraction, surface proflometry, microhardness, and fracture toughness. The addition of Cr has a signifcant efect on both boride layer formation and friction-wear behaviour of P/M alloys. Increasing the Cr addition up to 6 wt% has an improving efect on the microhardness, fracture toughness and wear resistance of the P/M alloys, whereas in the case of 9–12 wt% Cr addition causes exfoliation in the boride layer and low fracture toughness, thus reducing wear resistance. Coefcients of friction and wear volume losses at elevated temperatures are higher than room temperature. The best wear resistance at room temperature was obtained in the sample containing 3 wt% Cr with the highest fracture toughness, while the best wear resistance at 250 °C and 500 °C was obtained in the sample containing 6 wt% Cr, where the highest hardness value was obtained.

In this study, it is aimed to improving core material by using eloxal sludge for production B2 composite panel. The calcination study of eloxal sludge which arises from anodic oxidation process has a highest Al2O3 percentage by weight was performed with different temperature and time. It was focused how will be used the eloxal sludge such as relative humidity, dried or calcine because of tend to agglomerate structure. Optimal calcine eloxal sludge form was obtained at heat treatment regime with 700 C-0 and 270 minutes. The milling process with a different time was performed for obtaining fine grain size distribution. Also it was aimed to investigate possible agglomerate form in the polyurethane. The X-Ray Diffraction (XRD) and particle size analysis were performed to understand detailed structural analysis. Grain size distribution was obtained 306 mu m, 247 mu m and 203 mu m for different milling time. The eloxal sludge was respectively doped with different percentage with 15 % and 6 % in the polyurethane for obtaining core material. . B2 composite panels were produced as 1250-1500 mm as a standard. The mechanical properties were measurement for different doped of eloxal sludge. The highest mechanical properties was obtained by using 15 % eloxal sludge has a 247 mu m when it was observed that surface defects such as air bubbles. Also the thickness of the composite panel was measurement for all samples with 3.8 mm-4.2 mm.

In this work, single crystals of superconducting Fe1-xPbxTe0.5Se0.5 (x = 0.0, 0.01, 0.05, and 0.1) were grown by self-flux method. The structural, electrical, and mechanical properties of prepared samples were investigated. Structurally, it was determined that as the Pb ratio increased, the a- parameter of the crystal structure increased and the c-parameter decreased. SEM analysis showed that there was no significant microstructural change in Pb substituted FeSeTe material compared with the unsubstituted sample. There was a growth in the form of single-crystal sheets with thicknesses between 700 nm and 2 mu m. It was observed that the Pb substitution was not shown any positive change in the electrical properties compared to the unsubstituted FeSeTe system, and superconductivity deteriorated as the Pb concentration was increased. Similar trends were obtained both for the upper critical field, H-c2(T), and a characteristic length, xi(c). Relation between the mechanical properties and substitution ratio was also investigated. The hardness profiles value was found in the range of 0.90-0.49 GPa, while the elastic modulus was obtained between 19.4 and 7.84 GPa depending on the Pb substitution. It was seen that these values were slightly lower than the results obtained for unsubstituted FeSeTe material. This shows that Pb substitution has an effect on the elasticity of FeSeTe material.

Surfaces of cam shafts made of AISI 8620 steels were hardened by boriding processes in both solid and liquid mediums. Various chemical agents were used to achieve boride layers on the surfaces of the cam shafts in these processes. It was aimed to examine effects of the chemical agents on microhardness and thickness of the boride layers obtained. It was concluded that a bath composition of 5% B4C-90% SiC-5% KBF4 was appropriate for the hardest and thickest boride layer achieved in the solid medium, and a composition of 70% Na2B4O7-30% B4C in the liquid medium.

Different weight ratios of cerium (0.5, 1 and 2 wt.%) were produced in a controlled atmosphere by High Pressure Die Cast method to Mg-6Al-0.3Mn-1Sn alloy. The influence of cerium on microstructure and high-temperature mechanical properties was investigated. The microstructure study revealed that the main alloy contains intermetallic phases such as alpha-Mg, beta- Mg17Al12, Mg2Sn and Al11Ce3. The hardness values of the alloys were increased with the addition of 0.5%, 1 and 2 cerium. With the addition of 0.5 wt.% Ce, the yield strength increased to 145 MPa. With the addition of 2 wt.% of Ce, it was found to be 160 MPa with an increase of 14%. Tensile strength was obtained as 190 MPa. Elevated temperature tensile test was carried out at 120 degrees C, 180 degrees C and 240 degrees C, to all the alloys. It was found that increased Ce ratio increased the high-temperature mechanical strength. At 120 degrees C, the highest tensile and yield strength values were obtained with 159 MPa and 147 MPa, respectively, in the alloy with 2% wt. cerium added. In the tensile test performed at 180 degrees C, the highest tensile and yield strength were measured as 91 MPa and 77 MPa, respectively. The operating temperature of Mg alloys produced industrially by HPDC has a significant effect on mechanical properties. High operating temperatures reduce mechanical properties. However, the mechanical properties at high test temperatures were increased by the addition of Ce metal to the AM60-1Sn-XCe alloy produced with HPDC.

The synthesis and extensive characterization of newly developed boron nitride nanosheet (BNNSs)-reinforced WNiCoFeCr high-entropy alloys (HEAs) are presented. The influence of B4C on the structural, physical, mechanical, and nuclear shielding characteristics of synthesized HEAs has been widely examined in terms of its monotonic effects on the behavior changes. The internal morphology and structural characteristics of the fabricated composites are first investigated using X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. Wear testing is used to determine the coefficient of friction as a function of sliding distance. Experimental gamma ray and neutron setups are created to determine their shielding characteristics against nuclear radiation. Finally, the shielding characteristics of nuclear radiation for gamma ray and fast neutrons are compared extensively to those of many existing and new-generation shielding materials. Among the examined samples, the S2 sample with B4C and BNNSs reinforcement had the greatest mechanical characteristics. Our findings imply that increasing B4C directly contributes to the shielding qualities of nuclear radiation. The B4C created in the structure of BNNSs contributes to the overall properties of HEAs, which are crucial for nuclear applications, since HEAs are being examined as a component of future nuclear reactors. Additionally, B4C is a very versatile material that may be used in circumstances where mechanical and nuclear shielding properties need to be enhanced for a variety of radiation energies. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature. 2-s2.0-85134366577

In the present study, the effect of an La alloying element with different quantities (1, 3 and 5 wt.-%) on the microstructure, mechanical and dry sliding wear properties of Mg- 3Al-3Sn-3Sb alloy was investigated. The wear tests were done on the alloys using pin on-disk equipment against a 4140 steel disc as counterpart under three different sliding velocities of 0.3, 0.6 and 1.2 ms-1 and four different loads of 5, 10, 20 and 40 N. The microstructural results showed that the new intermetallic phases (La5Sn3 and LaSnSb2) were formed with addition of La to the main alloy. Also, it was observed that the hardness of the Mg-3Al-3Sn-3Sb alloy was raised with increasing La addition. Furthermore, the tensile properties of the Mg-3Al-3Sn-3Sb alloy improved with rising La content at room and elevated temperature. The wear rates of the alloys increase with increasing of the sliding speed and load. In addition to this, the wear rate of the Mg-3Al-3Sn-3Sb alloy was found to be higher than that of the La content alloys for all test conditions.

Distaloy SA is a sponge iron powder (nominal composition: Fe-1.75Ni-1.5Cu-0.5Mo) widely used in the production of powder metallurgy (P/M) parts in the automotive industry. In this study, Distaloy SA powders were sintered in two different atmospheres, one consisting of pure Ar gas (traditional sintering) and the other consisting of a mixture of 90 wt.% B4C and 10 wt.% NaBF(4)powders (borosintering). To investigate the effects of the different sintering atmospheres, the P/M samples were characterized using density measurements, surface roughness tests, scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, microhardness measurements, nanoindentation experiments, wear tests and corrosion tests. On the surface of the borosintered samples, a 160-325 mu m thick double-phase FeB + Fe2B boride layer was formed. The hardness (1405-1688 HV) and elastic modulus (122.21-162.42 GPa) of the surface were significantly improved with the borosintering treatment compared to conventional sintering (215-250 HV, 63.28-94.86 GPa). Borosintering also provided low friction coefficient values and an increased wear resistance compared to conventional sintering. A significant increase in corrosion resistance was also observed with the borosintering treatment in three different solutions. The corrosion rates of both sintered and borosintered samples were ranked as NaCl < HCl < H2SO4. The borosintered samples displayed superior corrosion resistance compared to the sintered samples, especially in the acid solutions. The results of this study show that significant cost savings can be achieved by combining the boriding and sintering treatments in a single borosintering process.

International Conference on Photovoltaic Technologies (PVCon) -- JUL 04-06, 2018 -- Middle E Tech Univ, Culture & Convent Ctr, Ankara, Turkey, WOS: 000499762300011, In the present study, using a large area roll-to-roll DC magnetron sputtering system deposition of ITO thin films on polyethylene terephthalate (PET) substrates were achieved. In order to investigate the effect of growth conditions on the film properties all through the deposition process, optical emission spectroscopy (OES) analysis have been accomplished in a governable way. The consequences of Oxygen partial pressure and film thickness on electrical, and optical properties of the films were determined. It was shown that the intensity of optical emission peaks are subjected to the discharge power and as well as the O-2/Ar flow ratio. Large area, uniform ITO films with relatively high transparency and low electrical resistivity (R(2)(

Laser-clad AlCrFeCoNi high entropy alloy (HEA) coatings, produced on the surface of AISI 316 L stainless steel, were pack-borided at 1000 °C for 4 h in open air, high-purity Ar and vacuum environments. The HEA, which had an initial hardness of 6.14 ± 2.06 GPa, formed a complex boride layer consisting of (CoFe)B2, (CrFe)B2 and Cr2Ni3B6 phases on its surface, with hardness ranging from 15.95 ± 0.7 to 20.15 ± 4.50 GPa as a result of the boriding process. While the greatest boride layer thickness was obtained in the sample borided in vacuum, the highest surface hardness was obtained in the sample borided in air. The borided coatings showed improved wear resistance and lower friction values compared to the untreated control samples, both at 25 °C and 650 °C. The borided coatings also showed reduced coefficients of friction at 650 °C. The wear losses at 650 °C significantly exceeded those at 25 °C.

The effects of diferent heat and cryogenic (sub-zero) treatment parameters such as temperature and holding time on the microstructure (amount of retained austenite) and hardness of extrusion molds produced from the 21NiCrMo2 and 100Cr6 steels were investigated. The 21NiCrMo2 grade extrusion die was carburized for 22.5 h in an endogas (25% CO, 35% N-2 40% H2) atmosphere at 920 degrees C. At the end of the carburization process, the temperature was kept at 850 degrees C, which is the austenitization temperature, for 2 h, followed by cooling in oil at 80 degrees C and remaining in oil for 45 minutes. The carburizing process was not performed for the extrusion molds made of 100Cr6 steel grade. Only the austenitizing heat treatment at 850 degrees C (holding for 2 h) was carried out in this steel. The steel molds which were produced with 21NiCrMo2 and 100Cr6 steels were cryogenically treated at -120 degrees C for 2 h and subsequently tempered at 150 degrees C for 1.5 h. As a result of the cryogenic treatment, the hardness of 21NiCrMo2 steel increased to 840 Hv and the wear resistance of the extrusion die surface was improved. The amount of residual austenite decreased from 20% to 6% after the cryogenic treatment. Due to the effect of the cryogenic process, the surface hardness of the 100Cr6 steel sample increased to similar to 870 Hv, which implies an increase of 4.5%, due to the transformation of residual austenite to martensite. The mass loss, during the wear tests, of the hardened extrusion dies was reduced from 0.1420 mg to 0.0221 mg. The notch impact strength value measured in this condition was 20 J. The 100Cr6 steel after the cryogenic treatment was used to extrude 12 tons of Al alloy in an industrial press. This amount of material is 30% lower than for hot work tool steel. On the other hand, the 100Cr6 steel is more economical and heat treatment is more practical. The extrusion performance of 21NiCrMo2 steel was 50% lower than the hot work tool steel.

This study comparatively investigated how the metallographic and mechanical properties of Armox 500T armor steel plates joined with Hybrid Plasma Arc Welding (HPAW), Gas Metal Arc Welding (GMAW), and Cold Metal Transfer Arc Welding (CMTW) methods were affected by welding methods. In this context, the Armox 500T welded specimens were examined by radiographic test, optical microscope (OM), Scanning Electron Microscope-Energy distribution spectroscopy (SEM-EDS), hardness, tensile, bending and notched impact tests. OM and SEM microscopy investigations showed that while sufficient fusion occurred between the weld metal and the substrate material in HPAW and GMAW methods. It was determined that the microstructures of the specimens welded with HPAW and GMAW were mostly composed of bainitic structure, in addition to a small amount of martensitic structure while, the microstructure of CMTW welded specimen consist of austenitic, martensitic and partially δ-ferrite structure. Choosing a carbide-forming wire, it was ensured that the hardness values of the weld metal and heat affected zone (HAZ) regions of the specimens combined with all three welding methods were higher than the base metal. The highest tensile strength was obtained in the HPAW welded specimen, while the highest impact notch strength was obtained in the CMTW welded specimen. All of the welded specimens failed within the HAZ and the fracture type is similar to the intergranular fracture type. The mechanical properties results of the specimens combined with three different welding methods have shown that HPAW is the most suitable welding method for joining Armox 500T armor steel.

The thermodynamics of nanosystems is interesting, as they constitute the transition between the atomistic and solid states. This is empowered by the development of tools to manipulate individual atoms and perform atomistic simulations and fundamental thermos-science, such as microscopic time-symmetry and macroscopic time-asymmetry, the origin of time’s arrow, and photo-cryo-refrigeration. We examine here the photo-thermo and time dynamics in 1-nm silicon nanoparticles with tetrahedral-molecular core–shell structure prepared ex situ and suspended in solvents or re-constituted in films. We examined the temperature dependence of the quantum efficiency and time-dynamics of the Stokes luminescence and its energy dependence across the band. With temperature, we get flat lifetimes but with delay in the onset in agreement with a model calculation of above barrier emission. Our atomistic time-dependent density functional theory shows that Stokes heating takes place in the molecular-like shell where the lifetime is in the nanosecond regime, whereas anti-Stokes cooling takes place in the tetrahedral core where the lifetime is in the ms regime. Unlike doped glasses, we observed a 2-order of magnitude increase in the quantum efficiency of the Stokes luminescence at 10° K. The increase in the quantum efficiency at low temperature, the high quantum efficiency of stimulated anti-Stokes scattering and its anti-correlation with the luminescence, and the visible transparency/blindness due to quantum confinement are requirements for solid state photo-cooling, which may afford an all-silicon photo-cryo-refrigeration, with potential full integration into the CMOS silicon industry.

Organophosphorus pesticides are widely utilized in agricultural fertility. However, their long-term accumulations result in serious damage to human health and ecological balance. Paraoxon (PAR) can block acetylcholinesterase in the human body, resulting in death. Thus, in this study, a molecularly imprinted electrochemical PAR sensor based on multiwalled carbon nanotubes (MWCNTs)/molybdenum disulfide nanoparticles (MoS(2)NPs) nanocomposite (MoS(2)NPs@MWCNTs) was proposed for selective tap water determination. A hydrothermal fabrication approach was firstly implemented to prepare MoS(2)NPs@MWCNTs nanocomposite. Afterwards, the formation of PAR imprinted electrochemical electrode was performed on nanocomposite modified glassy carbon electrode (GCE) in presence of PAR as template and pyrrole (Py) as a monomer by cyclic voltammetry (CV) technique. Just after determining the physicochemical features of as-fabricated nanostructures by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), Raman spectros-copy, and atomic force microscopy (AFM), the electrochemical behavior of the fabricated sensors was deter-mined through CV, differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The suggested imprinted electrode provided the acceptable limit of quantification (LOQ) and limit of detection (LOD) values of 1.0 x 10(-11) M, and 2.0 x 10(-12) M, respectively. As a consequence, the proposed PAR imprinted electrochemical sensor can be offered for the determining safe tap water and its utility.

This study is dedicated to the detailed investigation of boronization kinetic, microstructural, mechanical, and wear properties of high entropy alloys (HEAs) considering their sluggish diffusion effect properties. A CoCrFeNiAl0.5Nb0.5 HEA was powder-pack boronized in the interval of 850–1050 °C for 2, 4, and 6 h in the boronizing medium containing 90 wt% of boron carbide and 10 wt% of sodium tetrafluoroborate. Boronizing of CoCrFeNiAl0.5Nb0.5 HEA was successfully produced. The obtained multi-phase boronized layers were characterized by compactness and flatness showing up inside its typical dendritic zones. The X-Ray Diffraction (XRD) studies showed the presence of ternary phases inside the boronized layers having a thickness of 4.38–92.16 µm. The nano and microhardness values were also determined and the adhesion force was analyzed through the Rockwell indentation tests. In addition, the Vickers fracture toughness values (0.46–1.83 MPa m−1/2) of the treated samples were found to be very dependent on the boronizing temperature. The wear losses have decreased due to the increase in hardness and an improvement of up to 99% has been achieved. The average diffusion coefficient model was implemented to deduce the boron activation energy in the CoCrFeNiAl0.5Nb0.5 HEAs. Finally, the predicted layers’ thicknesses were coincident with the experimental data.

The early diagnosis of major diseases such as cancer is typically a major issue for humanity. Human ?-fetoprotein (AFP) as a sialylated glycoprotein is of approximately 68 kD molecular weight and is considered to be a key biomarker, and an increase in its level indicates the presence of liver, testicular, or gastric cancer. In this study, an electrochemical AFP immunosensor based on Fe3O4NPs@covalent organic framework decorated gold nanoparticles (Fe3O4 NPs@COF/AuNPs) for the electrode platform and double-coated magnetic nanoparticles (MNPs) based on SiO2@TiO2 (MNPs@SiO2@TiO2) nanocomposites for the signal amplification was fabricated. The immobilization of anti-AFP capture antibody was successfully performed on Fe3O4 NPs@COF/AuNPs modified electrode surface by amino-gold affinity, while the conjugation of anti-AFP secondary antibody on MNPs@SiO2@TiO2 was achieved by the electrostatic/ionic interactions. Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) analysis, cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) techniques were used to characterize the nanostructures in terms of physical and electrochemical features. The limit of detection (LOD) was 3.30 fg mL?1. The findings revealed that the proposed electrochemical AFP immunosensor can be effectively used to diagnose cancer. Graphical abstract: [Figure not available: see fulltext.] © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.

Monel 400 was pack-borided in the temperature range of 1173-1273 K for exposure times of 2-6 h. The boride layers produced on the surface of the alloy were examined by scanning electron microscopy and phase identification was carried out by X-ray diffraction. The topmost layer on the borided Monel 400 was compact and contained the Ni2B phase while the diffusion zone contained grain boundary precipitates of borides. Boride layers of 35-290 mu m thickness and 1002-1476 HV0.025 hardness were obtained. SEM observations revealed a smooth interface between the boride layer and the diffusion zone. A kinetic model based on the integral method was applied to investigate the kinetics of Ni2B layer. The boron activation energy in the Ni2B layer was estimated as equal to 300.7 kJ mol(-1). An experimental validation of the model was made by comparing the experimental layer thicknesses obtained, after boriding at 1198 K for 1 and 3 h, with predicted values.

Each year, unwanted plant pests and diseases, such as Hendel or potato soft rot, cause damage to crops and ecosystems all over the world. To continue to feed the growing population and protect the global ecosystems, the surveillance and management of the spread of these pests and diseases are crucial. Traditional methods of detection are often expensive, bulky and require expertise and training. Therefore, inexpensive, portable, and user-friendly methods are required. These include the use of different gas-sensing technologies to exploit volatile organic compounds released by plants under stress. These methods often meet these requirements, although they come with their own set of advantages and disadvantages, including the sheer number of variables that affect the profile of volatile organic compounds released, such as sensitivity to environmental factors and availability of soil nutrients or water, and sensor drift. Furthermore, most of these methods lack research on their use under field conditions. More research is needed to overcome these disadvantages and further understand the feasibility of the use of these methods under field conditions. This paper focuses on applications of different gas-sensing technologies from over the past decade to detect plant pests and diseases more efficiently.

Purpose: In this study, it was produced with HPDC by adding Cerium rare element to Mg-4Sb-2Al alloy. The effect of Ce on mechanical properties was explained by the theories of microstructural transformation and new phase formation. Theory and Methods: Mg-4Sb-2Al alloy, which is a new generation alloy in Mg alloys, was developed and the existing properties were further improved by adding the alloy RE (Rare Element). In the selection of additive elements of the basic alloying element, Mg-4Sb-2Al alloy, its suitability to pressure casting (HPDC) technique, which is one of the most important production techniques especially for light metal casting industry, has been taken into consideration. Sb and Al elements as the alloying element were added to the Mg alloy and the main alloying element was produced. In the selection of these elements, approaches such as basic material science criteria, favorable flow and porosity properties for casting, compliance with strength enhancement criteria were taken as basis. 0.5wt.% -2wt.% Ce was added to the alloy and metallurgical investigations were carried out. Results: The addition of Ce was chosen between wt. 0.5% and wt. 2% and the optimum Ce ratio was determined. It was understood that the added Ce also acts as a grain refiner and a new intermetallic CeSb was formed at the grain boundaries. wt. 1% Ce added alloy had a tensile strength of 164-168 MPa and an elongation of 13%. In the amount of 2% Ce added, the tensile strength of the alloy produced was found to be 16%, measured at values between 163-167 MPa. Conclusion: It has been concluded that if the elongation criteria of Mg-4Sb-2Al alloys produced with HPDC are 12%, the alloy with 1% Ce addition will be an ideal engineering alloy on the basis of tensile strength, hardness and economy., Bu çalışmada Mg-4Sb-2Al alaşımına, ağırlıkça% 0,5, 1, 2 oranlarında Ce (seryum) elementi ilavesinin etkisi incelenmiştir. Döküm prosesi olarak yüksek basınçlı kokil kalıba döküm yöntemi kullanılmıştır. Üretilmesi planlanan ürünler direk olarak çekme ve darbe numunesi şeklinde üretilmiştir ve çekme numuneleri yarı endüstriyel pilot ölçekli numuneleri temsil etmektedir. Üretilen numunelerin mekanik özelliklerini tespit etmek için çekme deneyleri, sertlik deneyleri, metalurjik ilişkiyi tespit etmek için ise metalografik inceleme, SEM ve XRD incelemeleri yapılmıştır. İlave edilen Ce oranına bağlı olarak mekanik özellikler artmıştır. Bu sonuçlara göre Mg3Sb2, Mg12Ce, CeSb ve Mg fazlarının varlığı tespit edilmiştir. İlave edilen Ce oranının artmasına bağlı olarak yeni bir faz olan CeSb fazının şiddeti artmıştır. CeSb ve Mg3Sb3 intermetalik fazlarının tane sınırlarında biriktiği anlaşılmıştır. Tane sınırlarında çubuğumsu bir şekilde birikim gösteren bu yapılar, dislokasyon hareketini engellemek ve ince taneli bir yapı oluşturmak sureti ile çekme mukavemetini ve sertlik değerlerini artırmıştır. Çekme mukavemeti değerleri %0,5 Ce, %1 Ce, %2 Ce ilave edilen alaşımlar için sırası ile 145-148 MPa, 164-168 MPa, 163-167 MPa aralığında, uzama yüzdeleri ise sırası ile %12,%13 ve %16 olarak tespit edilmiştir. Ce ilavesi ile sertlik değeri 48 BHN’den 54 BHNe’ye artmıştır.

This paper presents tables of key thermoelectric properties, which define thermoelectric conversion efficiency, for a wide range of inorganic materials. The twelve families of materials included in these tables are primarily selected on the basis of well established, internationally-recognized performance and promise for current and future applications: tellurides, skutterudites, half Heuslers, Zintls, Mg-Sb antimonides, clathrates, FeGa3-type materials, actinides and lanthanides, oxides, sulfides, selenides, silicides, borides and carbides. As thermoelectric properties vary with temperature, data are presented at room temperature to enable ready comparison, and also at a higher temperature appropriate to peak performance. An individual table of data and commentary are provided for each family of materials plus source references for all the data., National Science Foundation; UK Engineering and Physical Sciences Research Council (EPSRC)

Iron-based superalloys are alloys produced for use in corrosive environments as an alternative to high-cost nickel-based superalloys. However, their average strength and hardness, attributed to their austenitic structures, limit their use in tribological applications. In an attempt to counter these drawbacks, boriding was applied to an iron-based A286 superalloy having an initial surface hardness of 320 HV. Boriding kinetics, some mechanical properties, and tribo-wear (ambient air and 3.5 NaCl environment) behaviors of the formed boride layers were investigated. Multicomponent boride layers (consist of FeB, Fe2B, CrB, NiB, Ni4B3) were formed on the surface of the alloy, with hardness and thickness values of 1498-1961 HV and 20-130 mu m, respectively, depending on the boriding temperature and the treatment time. The integral diffusion model was adopted to deal with the kinetics of monoboride and hemiboride layers formed on the surface. The boron activation energies of FeB, Fe2B, and DZ layer were estimated as equal to 175.86, 198.7, and 205.73 kJ mol- 1, respectively. As a result of increased surface hardness, all of the borided samples displayed reduced friction coefficients and higher wear resistance compared to the untreated alloy, in both ambient air and 3.5% NaCl. However, the increase in wear resistance was not proportional to the increase in hardness; while the best wear resistance was obtained in samples borided at 850-950 degrees C for 6 h, the lowest wear resistance was obtained in samples borided for 4-6 h at 1050 degrees C. This situation was caused by the Kirkendall effect and residual stresses in the structure of alloying elements with different diffusion rates due to the high-temperature effect of the boriding process.

Electrolytic Plasma Technology has been used to improve the surface properties of AISI-316L Steel. Electrolytes were selected from water-soluble inorganic salts containing interstitial elements such as N and C. High energy cathodic plasma was created by applying from 300V to 600V at the electrolyte/316L interface. N and C elements ionized in high energy plasma diffused to 316L surface. Diffusion time was between 5 seconds and 30 minutes. As a result, it was observed that the surfaces consist of phases containing N, C and O, and the diffusion distance and hardness increased depending on the increasing time. Using H2N-CO-NH2 electrolyte, magnetite in the chemical form of Fe3O4 and non-cytochiometric ironnitride and chromiumnitride were formed on the surface. The hardness increased from 187 HV to 536 HV. Using NH4NO3 electrolyte, the highest hardness increased up to 550 HV. As a result of XRD analysis, thin film magnetite in the chemical form of Fe3O4 and non-cytochiometric ironnitride (FeN0.076), chromiumnitride phases were formed on the surface. There is diffusion of oxygen and nitrogen elements on the surface, and the nitrogen concentration has reached 1% by weight. After electrolytic plasma diffusion process, wear loss decreased significantly. Wear resistance increased up to 6 times after plasma diffusion., AISI 316L Çeliğinin yüzey özelliklerinin iyileştirilmesi için Elektrolitik Plazma Teknolojisi kullanılmıştır. Elektrolitler suda çözünebilen N (azot) ve C (karbon) gibi ara-yer elementi içeren inorganik tuzlardan seçilmiştir. Elektrolit/316 L ara yüzeyinde 300 V ve 600 V arağındaki gerilimler uygulanarak yüksek enerjili katodik plazma oluşturulmuştur. Yüksek enerjili plazma içinde iyonize olan N ve C elementleri 316 L yüzeyine difüze olmuştur. Elektrolitik Plazma difüzyon süresi katodik olarak 5 saniye ile 30 dakika arasında farklı sürelerde uygulanmıştır. İşlemler sonucunda katot yüzeyinin N, C ve O içeren fazlardan oluştuğu, artan süreye bağlı olarak difüzyon derinliğinin ve ara-yer elementi ile doplanan yüzeyin sertliğinin arttığı gözlenmiştir. H2N-CO-NH2 elektrolit ile yapılan deneylerde, yüzeyde Fe3O4 kimyasal formunda magnetit yapıda demiroksit ve sitokiometrik olmayan demir nitrür ve krom nitrür gibi fazlar oluşmuştur. Sertlik değeri 187 HV den 536 HV ye yükselmiştir. NH4NO3 elektrolit ile yapılan deneylerde, en yüksek sertlik 550 HV değerine kadar yükselmiştir. XRD analizleri neticesinde yüzeyde Fe3O4 kimyasal formunda ince film magnetit ve sitokiometrik olmayan demir nitrür (FeN0,076), krom nitrür fazları oluşmuştur. Yüzeyde oksijen ve azot elementlerinin difüzyonu söz konusu olup, azot konsantrasyonu ağırlıkça %1 seviyesine ulaşmıştır. Elektrolitik plazma difüzyon işlemi sonrası aşınma kaybı önemli ölçüde azalmıştır Difüzyon sonrası aşınma dayanımı 6 kata kadar artış göstermiştir.

In this study, synthesis of two multifunctional acetic acid functionalized carbazole bearing monomers; 243,6-bis(2,3-dihydrothieno [3,4-b] [1,4]dioxin-5-yl)-9H-carbazol-9-yl)acetic acid (Ml) and 3,6-dithien-2-yl-9H car bazol-9-ylaceticacid (M2) via Stille cross-coupling reaction was reported. Obtained monomers were electro-chemically polymerized in 0.1 M TBAPF(6)/DCM/ACN (5:95, v:v) solution and characterized in terms of electrochemical, spectroelectrochemical and electrochromic switching behaviors. When poly-2-(3,6-bis(2,3-dihydrothieno[3,4-b] [1,4]dioxin-5-yl)-9H-carbazol-9-ypacetic acid (P1) and poly-3,6-dithien-2-yl-9H car bazol-9-ylaceticacid (P2) were compared in terms of electrochemical behaviors, by virtue of the electron-rich EDOT units in the P1 chains, the polymer film exhibited lower monomer oxidation potential at around 1.05 V. Both polymers exhibited neutral state yellow color with similar optical band gaps and multi-electrochromic behaviors under different applied potentials. Insertion of thiophene unit instead of ethylene dioxythiophene (EDOT) unit on the polymer backbone enhanced the electrochromic and optical contrast properties and P2 showed the higher optical contrast then P1. Furthermore, owing to the promising electrochromic properties of P2 like red shifted absorption and higher optical contrast, a prototype P2 and PEDOT bearing solid state electrochromic devices (ECDs) were constructed and characterized. P2 and PEDOT comprising ECD works between yellow and blue colors at - 2.0 V and at 2.0 V respectively, with 41% optical contrast and 1.3 s switching time at 580 nm. Furthermore, P2 was used for energy storage applications before and in the present study it was used for ECD applications with promising results which make acetic acid functionalized carbazole derivatives mull-purpose new generation materials.

In this study, Ni-based Inconel 718 coatings were additively manufactured on the surface of AISI H13 work tool steel by electro-spark deposition (ESD). Some of the electro-spark deposited samples were boronized at 1000 ? for 5 h to evaluate the effects of boronizing on microstructure, high-temperature wear, and corrosion resistance. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), 2D pro-filometry, wear and electrochemical corrosion testing was used to characterize the surfaces, microstructures, microhardness, some mechanical properties, high-temperature wear, and corrosion resistance of the applied coatings. Wear tests were performed at room temperature and 650 ?, and corrosion tests were performed in 3.5% NaCl at room temperature, considering the applications of AISI H13 and Inconel 718 alloys. The characterization studies showed evidence of microcracking and oxidation in the as-deposited Inconel 178 coatings. In the boronized Inconel 718 coatings, the oxides and microcracks were slightly reduced. The hardness of the boronized Inconel 718 coating was increased to about four times the hardness of the as-deposited Inconel 718 coating, and this significantly improved its wear resistance. The highest wear resistance was achieved with the boronized coating, while the best corrosion resistance was obtained with the as-deposited coating. The improvements in wear resistance provided by boronizing have the potential for expanding the applications of Inconel 718 coatings in machine components.

In this study, we developed fast and highly sensitive, label-free Ca-doped cupric oxide (CuO) based che-miresistive biosensors to detect C-reactive protein (CRP). The Successive Ionic Layer Adsorption and Reaction (SILAR) method was used to deposit pure and Ca-doped CuO thin films on interdigitated gold electrodes. Film surfaces were functionalized with monoclonal anti-C-reactive protein antibody (anti-CRP) by random physisorption method. Sensor fabrication steps were monitored using the linear sweep vol-tammetry method. Scanning electron microscopy was used to investigate the surface morphology. Energy-dispersive X-ray spectroscopy was used to determine the elemental composition. The structure of the films was investigated by the powder X-ray diffractometry method. Sensor parameters were determined by the change in sensor resistance over time. The sensors showed a good response to CRP with a linear detection range of 0.1-5.0 pg/ml, which was within the clinically significant range. Detection limits of 49.61 and 48.81 ng/ml were estimated using the standard deviation of the y-intercept and the standard deviation of the regression line, respectively. Dynamic response times of all fabricated sensors were found to be less than 30 s (c) 2022 Elsevier B.V. All rights reserved.

WOS: 000520134000010, Remelted NiCrBSi coatings were examined using optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, x-ray diffraction analysis, microhardness and wear testing. After wear tests, the surfaces of the worn samples were examined by 3D profilometry and scanning electron microscopy to investigate the effects of load and temperature on the coefficient of friction and wear resistance. In all the wear experiments, there was a momentary increase in the wear volume and a momentary decrease in the average coefficient of friction values at the elevated test temperatures. This behavior was caused by the stable oxide layer formed on the surface as a consequence of the elevated test temperature. Three dominant wear mechanisms were observed with the NiCrBSi coatings: delamination at room temperature, spalling and adhesion at 250 degrees C, and oxidation at 450 degrees C, whereas in the uncoated samples there was delamination at room temperature, and micro-cracking and oxidation, both at 250 degrees C and 450 degrees C. Remelted NiCrBSi coatings provided better wear resistance and lower coefficient of friction than uncoated STKM-13A steel, especially at higher temperatures.

0000-0002-7719-6051, WOS: 000486217900001, The performance of cutting tools was examined, involving synthesis of a 10 nm thin film of Aluminum oxide using atomic layer deposition. Characterization of coated and uncoated cutting tools was done by several methods. scanning electron microscopy was used and the images were compared with each other. Chemical characterization was performed by X-ray diffraction and X-ray photoelectron spectroscopy. Coated and uncoated cutting tools were tested with steel material in turning tests. After turning, it was observed that the adhesion effect was reduced to a large extent in turning with coated tool. It was observed that the coating showed stability at high temperatures during cutting and the cutting performance was increased. The main advantage of the coating was that the tools produced were more environmentally friendly, with a longer useful life and they were easier to recycle.

WOS: 000451757200009, Research on sustainable concrete has drawn scientist's attentions on industrial by-products and wastes. Thus, consumption of raw materials would be diminished. In this study alkali activation of electric arc furnace slag (EAFS) was studied with a comprehensive test program. Different silicate modulus, sodium concentrations, curing conditions, curing temperatures and relative humidity condition variables were selected. Their effects on mechanical and micro structural behaviors of the mortar were investigated through SEM - XRD analyses. Result of this study, EAFS was activated with sodium hydroxide and sodium silicate solutions. Test results also revealed that increase in relative humidity, curing temperature and curing time had positive effects on strength parameters due to diminishing micro cracks and altering hydration reactions. With the current study utilization of EAFS is thought to be successfully disposed.

Multiband absorption is the interest of the microwave communities due to several applications in sensing, filtering, and stealth. Usually, the stacking of metal and dielectric multilayered structures form a multiband absorber which makes the device bulky and costly. In this paper, we investigate a multiband absorber based on a single-layered fractal metasurface for the 5G applications. The unit cell of the fractal metasurface is comprised of six ring-shaped symmetric split-ring resonators (SRRs) connected back-to-back with each other. The absorptivity is investigated in the 5G microwave regime (22-36 GHz) for various obliquities at different substrate thicknesses. Simulation results show that the proposed fractal metasurface has several absorption peaks in different 5G bands. Furthermore, measured results agree well with the simulation results. The proposed absorber can play an important role in 5G applications wherein sensing the angle of incidence and polarization of the incoming electromagnetic waves is desired.

Indium tin oxide/silver/indium tin oxide (ITO/Ag/ITO) multilayers have attracted much attention to fulfill the growing need for high-performance transparent conducting oxide electrodes. To make these transparent multilayers work better, electro-annealing, which is a method of self-heating by electric current, can be effective. Moreover, the effect of current on ITO/Ag/ITO multilayers should be investigated to make sure that electronic devices will be reliable over their lifetime. In this study, ITO/Ag/ITO multilayer electrodes with varying Ag thicknesses were grown by DC magnetron sputtering at room temperature. Structural, optical, and electrical properties of these multilayers were investigated before and after electro-annealing. Measurement results revealed that improved optical transmittance and sheet resistance can be obtained by the optimization of Ag thickness for the as-grown ITO/Ag/ITO layers. The highest figure of merit (FoM) value of 17.37 × 10−3 Ω−1 with optical transmittance of 85.15% in the visible region and sheet resistance of 11.54 Ω/□ was obtained for the Ag thickness of 16.5 nm for as-grown samples. The electro-annealing of as-grown ITO/Ag/ITO multilayers led to improved optical behavior of the multilayer structure over a wide spectral range, especially in the near-infrared range. Electro-annealing also provided an improvement in the crystallinity and sheet resistance of the electrodes. The improvement of the electrical and optical properties of the structure enabled a FoM of 23.07 × 10−3 Ω−1 with the optical transmittance of 86.80% in the visible region and sheet resistance of 10.52 Ω/□. The findings of this work provide proper knowledge of the properties of ITO/Ag/ITO multilayers under electrical current and suggest that the overall performance of the multilayers can be improved by the electro-annealing process.

In cast alloys with a long freezing range such as ZA-27, casting defects like porosity and shrinkage may occur in case of failure to control casting variables. In this study, the role of casting variables in the formation of shrinkage and micro-porosity defects in ZA-27 was investigated. The defects of casting were predicted using Artificial Neural Network (ANN) algorithms. To this end, cooling rate, solidification time, temperature, liquid phase, initial mold temperature, and %shrinkage were obtained from a series of simulation-experimental tests. The heat transfer coefficient of ZA-27 and graphite die was calculated as 2000 W/(m2K). In the samples poured into the mold heated at 350°C, the minimum feeder shrinkage volume was observed. Locations of the chronic hotspot and shrinkage problem were determined and evaluated. It was observed that the casting heated to 150_C caused deep shrinkage on the upper and lateral surfaces of the feeder. A good correlation was obtained between the modeling results of the ANN and the experimental results. Optimum ANNs were designed, trained, and tested to predict the shrinkage rate at different initial mold temperatures and in various physical conditions. Thanks to the sigmoid (sigmoaxon) function training, the most systematic modeling ANN set was revealed with 99% (vol. 7.65%shrinkage) prediction.

Boride layers were grown on the surface of a Co1.19Cr1.86Fe1.30Mn1.39Ni1.05Al0.17B0.04 high-entropy alloy (HEA) by boronizing at temperatures of 900, 950 and 1000 °C for 4 h using nanosized boronizing powders. Characterizations were carried out by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), microhardness measurements, nanoindentation tests, surface profilometry and ball-on-disc type wear tests. The tribocorrosion behavior of the boronized HEAs and the untreated alloy were investigated in air and in 5% HCl. Microstructural examinations revealed complex metal boride layers on the surfaces of the boronized HEAs, consisting mainly of Cr2Ni3B6, Fe0.4Mn0.6B, Cr0.4Mn0.6B and CrFeB2 phases. The boride layers were silicide-free, with thickness and hardness values of 31.95–64.36 μm and 23.49–28.09 GPa, respectively. The boronized HEAs exhibited reduced friction coefficients and low wear losses in both ambient air and 5% HCl compared to the untreated HEA. Due in part to the lubricating and cooling effect of the solution, the untreated HEA and the boronized HEAs showed reduced wear losses in 5% HCl compared to air. In air, the wear mechanism of the boronized HEAs was abrasive wear combined with polishing, while in the as-cast HEA the wear mechanism was abrasive wear accompanied by plastic deformation. In 5% HCl, the wear mechanism of the boronized HEAs was abrasive wear accompanied by oxidation and pitting, while in the as-cast HEA the wear mechanism was abrasive wear combined with pitting.

A new approach is brought to diamond recovery from waste cutting segments. Unlike the commonly used hydrometallurgical processes, this approach offers the simultaneous recovery of copper with diamond. Besides, instead of strong acids, this work involves use of a dilute acid solution, reducing the evolution of toxic vapors. Copper base segments of waste diamond tools were used as anode, which were dissolved by applying potentials above the dissociation voltage of Cu. Simultaneously, the diamond grits detached from the segments and gathered at the bottom of the cell. Then, the dissolved Cu2+ cations were reduced, and Cu powders were electrodeposited at cathode without affecting the accumulated diamond particles. Eventually, the diamond particles could be collected from the bottom of the cell, providing the simultaneous recovery. In this work, the effect of individual process parameters on the outcome of presented approach is studied. The process parameters were then optimized, and mathematical models were developed for response variables by response surface methodology. Also, a mini-prototype was designed and operated at the optimized conditions to check the possibility of converging the proposed approach to industrial applications. Prototype tests show that all detached diamond could be recovered in 3 h and simultaneously with Cu powders., This study was funded by The Scientific and Technological Research Council of Turkey (TUBITAK) under the Grant No. 116M406.

The grain refining effect of Zirconium (Zr) is known, nevertheless the effect of Zr amount and its effect on solidification and wear behavior of modified Mg-Zn alloys has not been adequately studied. Mg-4Zn-(x)Zr alloys alloyed with the addition of 0.5 wt.% to 4 wt.% Zr element are melted and poured into two different casting molds and thermal analyzes were performed. Casting microstructure, solidification behavior, phase transformations, grain size, thermal analysis curves and wear properties were examined. The microstructure was modified by the addition of Zr and the grain size was reduced for both graphite and ceramic mold materials. Maximum tensile strength was obtained by adding 1% Zr (170 MPa) and 4Zr (105-110 HRB) using graphite mold, respectively. The maximum room temperature tensile strength was achieved on the Mg-4Zn-1Zr alloy the elongation was 4.9 percent and the tensile strength was 138 MPa. The max hot tensile value was achieved on the 2 wt% Zr added alloys. The wear rate of Mg-4Zn alloy decreased with increasing Zr element up to 2 wt% Zr. Addition of more than 2% by weight of Zr caused an increase in microporosity in the microstructure. Due to the microporosity caused by the Zr addition, the wear rate was slightly reduced.

Purpose The purpose of this paper is to investigate the effect of doping element on the microwave absorption performance of hexagonal nano boron nitride (h-nBN)-reinforced basalt fabric (BF)/epoxy composites. A new type of hybrid composite that will be produced by the use of boron nitride as an additive that leads to increased radar absorption capability will be developed and a new material that can be used in aeronautical radar applications. Design/methodology/approach This study is focused on the microwave absorption properties of h-nBN doped basalt fabric-reinforced epoxy composites. Basalt fabric (BF)/epoxy composites (pure composites) and the BF/h-nBN (1 Wt.% h-nBN doped composites) hybrid composites were fabricated by vacuum infusion method. Phase identification of the composites were performed using X-ray diffraction (XRD), the 2θ scan range was from 10 to 60 with the scanning speed of 3°/min and surface morphologies of the composites were investigated using scanning electron microscopy (SEM). Microwave properties of samples were investigated through transmission/reflection measurements in Agilent brand 2-Port PNA-L Network Analyzer in the frequency range of 3–18 GHz. The prepared sample is positioned between two horn antennas with and without metal plate. Findings Experimental results show that h-nBN doped composite was synthesized successfully and the produced hexagonal nano boron nitride-added fiber laminated composite material has good absorption behavior when they are used with metallic sheets and good for isolation applications at many points in the 3–18 GHz band. Originality/value This paper will contribute to the literature on the use of basalt fabric, which are new types of fibers, and hexagonal nano boron nitride and the effects of boron nitride on radar absorption properties of composite material. It presents detail characterization of each composite by using XRD and scanning electron microscopy.

Surface enhanced Raman scattering (SERS), in which sample molecules are placed in the proximity of conducting nanostructures, subjects the molecules to intense electron oscillation (plasmon) field. The intense field, however, may cause heavy distortion and thermal damage to the molecule as well as non-separable and heavy convolution with the metal electronic structure. We utilized 3-nm red luminescent Si nanoparticles decorating the DNA molecules (drawn electrostatically) to enhance Raman scattering in solution at 532 nm. We demonstrated that the nanoparticles enhance the spectral resolution and intensity of vibrations of DNA by two orders of magnitude and reveal vibrations that are otherwise weak or forbidden. Theoretically, we conducted calculations of Mie scattering and three-dimensional finite-difference time-domain scattering and obtained the wavelength dependence of the near-field distribution from single or dimer Si particles. The simulations show moderate intensity enhancement (25–40-fold) and exciton resonances. Moreover, it shows that the near field is highly confined, extending only to 3–5 A from the Si particle (atomic scale) compared to several nanometers for metal nanoparticles. The observed SERS-type characteristics are understood in terms of polarization-based light scattering, which is possible by the use of Si of highly reduced size for which the polarizability and exciton processes are strong. However, multilayers contribute to metal SERS, and monolayers/single molecules dominate the Si case. Weaker but highly confined, ultra-short range polarization-based scattering provides an alternative to plasmon and Mie scattering, while providing practical, straightforward interpretation of vibration printing of bio-medical species without compromising the molecular structure.

The thermal fatigue behavior of chromium vanadium carbide (Cr − V − C) coatings and the wear of the coatings after thermal fatigue cycling was studied. The Cr − V − C coatings were grown on the surface of a ductile iron using thermo-reactive diffusion (TRD) and subjected to thermal fatigue in the temperature range of 25 to 750 °C for up to 500 cycles. Characterizations were made using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, microhardness measurements and wear tests. The Cr − V − C coated samples displayed superior thermal fatigue and wear resistance compared to the untreated ductile iron, mainly due to the dissolution of graphite nodules in the vicinity of the surface during TRD. The dissolution of graphite reduced the possibility of failure initiating from graphite nodules and graphite-matrix interfaces. Increasing the number of cycles resulted in increased flaking and decreased wear resistance in both the Cr − V − C coatings as well as the untreated ductile iron. Although much of the Cr − V − C coating was lost (due to flaking) after thermal cycling, the absence of graphite near the surface still provided improved resistance to wear in the TRD-treated samples. The results of this study indicate that TRD coatings hold great promise for use in the industrial applications.

Sinter is a blast furnace input material obtained by heating to 900-1200 oC without full melting and adhering to each other with superficial melting. It is considered as a multi-phase material with its sinter heterogeneous microstructure. In general, the main mineral phases are hematite, magnetite, silicoferrite of calcium and aluminium (SFCA) and silicates. By determining the SFCA structure in the sinter material, the sintering process will be made more stable and important parameters affecting the quality in the sintering process will be examined. Sinter material obtained from iron ore, iron and steel industry by products and auxiliary materials. The scope of this project is the determination of the amount of SFCA formed by bonding SiO2, CaO, Fe2O3, Al2O3 and MgO compounds and monitoring this value as a parameter by the enterprise. Sinter samples having different characteristic features will be made ready for X-ray diffraction (XRD) and optical microscopy inspections by polishing, etching and freezing in epoxy for mineralogical researches. Before raw data obtained from the analysis is evaluated at Autoquan, they will be converted into Autoquan format and then, they will be read in XRD device and mineralogical composition of the sinter will be revealed by XRD analyses. Detailed view of mineralogical compounds will be investigated so as to complete scanning electron microscope (SEM) analyses and XRD analyses; elemental composition of the compounds and valence conditions of the elements will be researched by energy dispersive spectroscopy (EDS) method. Hematite, magnetite, calcium ferrite phase structures in different formations will be studied subject to melting and temperature during optical microscopy studies conducted on sinter samples. Furthermore, it will be researched variations of SFCA, SFCA-I and SFCA-II phase structures within the sinter matrix subject to different raw material input and process parameters. It will be ensured to interpret the results through rietveld method.

Stabilization of clayey soil has been studied by mixing different additives to the soil to increase its strength and durability. Recently, there has been an increasing interest in the stabilization of soils with natural pozzolans. Nevertheless, very few articles have investigated the impact of basic oxygen furnace (BOF) slag additives under freeze–thaw cycling. This study presents the results of an experimental research study on the durability behavior of clayey soils treated with BOF slag. In this study, the effects of clay soils on the bearing value were investigated by adding 3%, 6%, 9%, 12%, 15%, and 20% BOF slag to the clay mineral sample within the scope of ASTM D-5918 tests. California bearing ratio (CBR) tests were then applied before and after freezing–thawing processes to the samples prepared at these optimum conditions. The relationship between the determined freezing and swelling speeds and the strength losses of the soil samples after freeze–thawing processes were investigated. For this purpose, eight mixtures with different geotechnical properties were subjected to freeze–thaw experiments on a total of 24 soil samples, each of which was repeated three times. Results show that the addition of steel-making slag to clay soils lead to favorable effects on freezing–thawing behavior. The effects of BOF slag on the clay sample after the freezing and thawing cycle were investigated and interpreted by considering their macro and micro phase structure. The findings indicate that using BOF slag has positive effects on strength and durability of clayey soil.

a bstract In this study, different types of waste aluminum produced in daily life and their pure equivalents were evaluated and compared in terms of their hydrogen generation performance through the water-splitting reaction. An experimental system was designed for the production process that consisted of electrodes, DC power supply, alkaline solution, and various waste aluminum products. The hydrogen generation rate of the aluminum source was then measured to determine the optimum conditions for hydrogen production with different types of pure and waste aluminum, normality of the aqueous solution, and applied DC voltage. The best results for micro-hydrogen generation were obtained using pure powder Aluminum, which was attributed to the increased active surface area for the reaction. For beverage can waste (and its powder form), the maximum hydrogen generation rate (cm3/g.min) was achieved using the powder form of the waste aluminum at 2 N alkaline solution. However, the total amount of hydrogen generation (cm3/g) yielded different results compared to the maximum hydrogen generation rate where, when the amount of hydrogen generation volume per mass was considered, the beverage can pieces achieved the best result under constant voltage. This result was attributed to a longer total reaction time.

CoCrFeNiAl0.25Ti0.5 high entropy alloy alloys (HEA), produced by powder metallurgy were subjected to boriding to improve their mechanical properties. Sintering was carried out at 1200 degrees C for 2 h in Ar, and boriding was performed at 900, 1000 and 1100 degrees C for 2 h using a 90 wt% B4C + 10 wt% NaBF4 boriding powder mixture. Microstructures, densities, surface roughnesses, and mechanical properties (hardness, fracture toughness and nanoindentation responses) of the samples were investigated. FCC, BCC and sigma phases had been observed after sintering, whereas complex metal borides were formed on the surfaces after boriding. Relative density values were between 85% and 90%. Significant increases in surface hardness were observed after boriding due to formation of hard, silicide-free boride layers. The boride layer thickness and hardness increased with increasing boriding temperature. The elastic modulus of the surface of the sintered sample (47.07 GPa) increased with the boriding process to values in the range of 140-151 GPa. Fracture toughness values between 3.57 and 4.25 MPa m(1/2) were obtained in borided samples, and increasing the boriding temperature reduced the fracture toughness.

Bi2Sr2−xCsxCo2Oy materials with 0 ≤ x ≤ 0.15, have been fabricated via the classical ceramic technique. XRD results have indicated that undoped and Cs-substituted samples are composed of Bi2Sr2Co2Oy phase as the major one. Microstructural studies have demonstrated the formation of a liquid phase, which allows a drastic grain growth. This factor is responsible for a drastic improvement of relative density, reaching about 95% of the theoretical one for 0.125 Cs content. On the other hand, electrical resistivity has been reduced up to 14 mΩ cm at 650 °C for 0.125 Cs content, around 40% lower than the obtained in undoped samples. As a consequence, Seebeck coefficient has been decreased due to the raise in charge carrier concentration. The highest power factor at 650 °C (0.21 mW/K2 m) has been found for 0.125 Cs substituted sample, about 40% larger than the obtained in undoped samples, and very similar to the notified in single crystals (0.26 mW/K2 m). Magnetisation with respect to temperature results have demonstrated that measured samples have a paramagnetic property above 50 K, except 0.10 Cs. Magnetic hysteresis curves have shown that the slopes and the magnitudes have increased with decreasing temperature., This study was carried out within the scope of Cukurova University Scientific Research Projects Unit FBA-2020-13007 and FBA-2020-12784. The authors wish to thank the Spanish MINECO-FEDER (MAT2017-82183-C3-1-R), and Gobierno de Aragón (Research Group T 54-17 R) for funding. The authors wish to acknowledge the use of Servicio General de Apoyo a la Investigación-SAI, Universidad de Zaragoza.

The aim of this work is to investigate the effect of the hexagonal nano boron nitride (h-BN) doped epoxy on the mechanical performances and machinability behaviors of basalt fiber (BF) composites. The h-BN has used as a dopant with a weight rate of 1 wt. %. The polymer composites were prepared by the vacuum bagging method and specimens were processed with abrasive water jet machining (AWJM) to analyze the machinability of the material. A circular hole with an 8 mm size was machined by abrasive water jet (AWJ) on the composite plate with a thickness of 2.3 ± 0.1 mm using the garnet size of 80 µm as an abrasive. Taper angle and circularity of machined hole, the entry-exit hole diameter, delamination, splintering, burring, thickness, and hardness were measured. Results indicate that cutting speed has a high influence on the taper angle and circularity respectively.

Nickel-based superalloy Nimonic 80A was pack-borided in a solid medium at temperatures of 850 degrees C and 950 degrees C for 2 h and 4 h using silicon-free boriding powders. To investigate the effects of the boriding treatments on mechanical properties (hardness, modulus of elasticity, fracture toughness) and high temperature oxidation resistance, the layers grown on the surfaces were characterized using optical and scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffractometry, and evaluated using microhardness, nanoindentation, wear and oxidation tests. Wear tests were performed on untreated and borided Nimonic 80A alloys using a ball-on-disc tribometer at room temperature and at 500 degrees C under dry sliding conditions. Oxidation tests were carried out in air at 1000 degrees C for 5 h, 25 h and 75 h. Characterization studies revealed a smooth, 22 to 86 mu m thick crack-free boride layer consisting mainly of Ni2B and minor quantities of CrB, Cr2B and Cr5B3 in the borided samples. The hardness and elastic modulus of the boride layer was measured as 15.57-18.95 GPa and 142-217 GPa, respectively. Increasing the boriding temperature and time increased the concentrations of chromium in the boride layer. The hardness and elastic modulus of the boride layer increased with chromium content while its fracture toughness decreased. The boriding treatments improved the dry sliding wear resistance. Increasing boriding time and temperature generally led to a higher wear resistance values. However, the treatments had no significant effect on oxidation resistance. The results of this study show that boriding can significantly improve the wear resistance of Nimonic 80A without compromising its oxidation resistance.

Modulation of the grain boundary properties in thermoelectric materials that have thermally activated electrical conductivity is crucial in order to achieve high performance at low temperatures. In this work, we show directly that the modulation of the potential barrier at the grain boundaries in perovskite SrTiO3 changes the low-temperature dependency of the bulk material's electrical conductivity. By sintering samples in a reducing environment of increasing strength, we produced La0.08Sr0.9TiO3 (LSTO) ceramics that gradually change their electrical conductivity behavior from thermally activated to single-crystal-like, with only minor variations in the Seebeck coefficient. Imaging of the surface potential by Kelvin probe force microscopy found lower potential barriers at the grain boundaries in the LSTO samples that had been processed in the more reducing environments. A theoretical model using the band offset at the grain boundary to represent the potential barrier agreed well with the measured grain boundary potential dependency of conductivity. The present work showed an order of magnitude enhancement in electrical conductivity (from 85 to 1287 S cm(-1)) and power factor (from 143 to 1745 mu W m(-1) K-2) at 330 K by this modulation of charge transport at grain boundaries. This significant reduction in the impact of grain boundaries on charge transport in SrTiO3 provides an opportunity to achieve the ultimate "phonon glass electron crystal" by appropriate experimental design and processing.