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Additive Manufacturing (AM) is an appropriate name to describe the technologies that erect 3D objects by enumerating layer-upon-layer of material, hence the name additive, whether the material is thermoplastic, metal, concrete, exclusive materials such as ceramics, carbon fibre or even human tissues. A 3D Slicing programme (to slice the 3D model into successive layers), machine equipment configuration, and material layering are all popular AM technologies. The Slicing programme decodes data from the CAD file, slices it into successive layers, and converts it to G-codes after it is created. When we run this G-code in the AM System, the computer builds a 3D component by layering liquid resin, powder, or solid filaments on top of each other. Rapid prototyping (RP) is one of the quickest-growing automated manufacturing innovations, with the ability to go from CAD models to finished products. Powder Bed Fusion (PBF) and Direct Energy Deposition (DED) are two kinds of metal additive manufacturing techniques. The metal additive manufacturing method can also be classified by material type, energy source, build scale, and so on. This paper discusses the relevance of metal additive manufacturing and provides detailed information on the processes of Selective Laser Melting, Selective Laser Sintering, Direct Metal Deposition, and Laser Metal Deposition.

Duplex stainless steels contain ferrite and austenite phases in balanced proportions. They exhibit good corrosion resistance in numerous environments and are resistant to pitting corrosion and stress corrosion cracking. DSS are employed in the process industries due to their ability to withstand erosive and aggressive environments and high pressure. Characteristic strength of DSS is twice that of the austenitic stainless steel. They are difficult to machine due to high toughness and low thermal conductivity. Conventional methods deteriorate machined surface and irregular wear that creates a negative impact on the efficacy of the material and productivity. The powder metallurgy is a prominent solution to produce DSS and is possible to control the chemical and phase composition, by eliminating number of difficulties present during the production of DSS by conventional methods. SPS is an advanced sintering technique used to fabricate poorly sinterable materials. SPS has a major advantage in the processing of high temperature materials with poor deformability. The ultra-fine grain structure obtained by SPS allows increase of strength and hardness in various stainless steel grades. In this review, nano structured DSS powders of composition Fe-25Cr-7Ni (wt. %) were prepared by dual drive planetary ball mill. The nano structured DSS powders consolidated by SPS technique were studied and characterized by X-Ray diffraction while morphology of DSS powders were studied by Scanning Electron Microscope.

Among all the metal oxide nanoparticles, CuO and ZnO nanomaterials are very popular and showcase the tremendous properties. They can be prepared from various physical, mechanical, biological, and chemical methods. But, a biological method like the green synthesis of metal oxide nanoparticle by plant or flower extract has become more popular due to its simplicity, low cost, feasibility, and eco-friendly impact. In the present paper, we have prepared both CuO and ZnO nanoparticles by Crocus Sativus (Saffron) flower extract followed by calcination at 400 °C for 15 min. The prepared metal oxide nanoparticles were characterized by UV–visible spectroscopy to study the bandgap energy, and the value was found to be 3.52 eV for CuO and 3.4 eV for ZnO nanoparticles, respectively. The morphology of the prepared metal oxide nanoparticles was studied by scanning electron microscopy, and phase, strain, and crystallite size were investigated by using X-ray diffraction. The investigation of the thermal properties of the CuO and ZnO nanoparticles was performed by thermogravimetric and differential thermal analysis. We determined the percentage weight loss, enthalpy change, and activation energy at 6, 8, and 10 °C/min heating rates. The activation energy of CuO and ZnO nanoparticles was calculated by the Kissinger method and was found to be 13.34 and 8.86 kJ/moles, respectively. The particle size of CuO and ZnO nanoparticles was found to be 300 and 450 nm, respectively. The Fourier-transform infrared spectroscopy was performed to study the functional groups present in both the nanoparticles.

Copper oxide nanoparticles (CuO) were electro-generated and electro-deposited simultaneously on the glassy carbon electrode (GCE) using cyclic voltammetry at a reduction potential of − 1.4 V to − 0.2 V in 0.1 M NaOH and 1.67 mM CuCl solution. The electrodeposited CuO nanoparticles show an excellent electro-catalytic activity towards the detection of potassium ferricyanide. The scan rate, concentration of the analyte and pH of the solution were varied accordingly to study the stability of the copper oxide deposited glassy carbon electrode (CuO/GCE). The CuO/GCE electrode shows amazing stability, charge transfer and reproducibility even at low concentration of the analyte. The cyclic voltammetry is proved to be one of the convenient methods to reduce the precursors into metal oxide nanoparticles just by applying suitable current. The main advantage of this method is uniform deposition of CuO nanoparticles on GCE and thus increases the number of active sites, surface area and electro-catalytic properties. Scanning electron microscopy (SEM) was used to study the morphology of the electro-generated CuO nanoparticles. The zeta-potential analysis was carried out to study the surface potential of charged CuO nanoparticles and it was found to be + 58.29 mV. Further, CuO nanoparticles were characterized by X-ray diffraction to study the phases. UV–visible spectroscopy depicts the absorption peak at 288 nm confirms the formation of CuO nanoparticles. This absorption is attributed by the electronic transition from valence band to conduction band due to the quantum size of the particles.

In the present study, we report on the synthesis of ZnO nanoparticles using Tilia Tomentosa (Ihlamur) leaves extract followed by calcination at 400 °C for 15 min. The prepared ZnO nanoparticles were characterized by XRD and SEM to study the phase and microstructure, respectively. The XRD analysis showed the absence of impurity peaks and the SEM image confirmed the spherical nature of the prepared ZnO nanoparticles with an average particle size of 80 nm. UV-Visible spectroscopy was used to study the optical properties, and the bandgap was calculated to be 3.55 eV. This large bandgap is attributed to the property of the semiconductor, which can be explored for solar cell applications. Therefore, we used green synthesized ZnO nanoparticles to fabricate dye-sensitized solar cells (DSSC). From the J-V curves, we calculated the DSSC parameters such as open-circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF) and efficiency (η), and their values were 0.65 V, 6.26 mA, 48.5%, and 1.97%, respectively, at 100 mW/cm2.

The nonlubricated sliding wear behavior of nano-yttria-dispersed and yttria-free duplex and ferritic stainless steel against a diamond tip was studied. The stainless steel samples were fabricated by a conventional powder metallurgy route in which nano-yttria-dispersed and yttria-free duplex and ferritic stainless steel powders were cold compacted and then conventionally sintered at either 1000, 1200, or 1400°C in an argon atmosphere. For comparison, another set of samples was sintered at 1000°C in a nitrogen atmosphere. The wear behavior of sintered stainless steel samples against a diamond indenter was investigated using a pin-on-disc apparatus at 10 and 20 N loads and at a constant speed of 0.0041 m/s. It is proposed that yttria-dispersed stainless steels showed higher wear resistance compared to yttria-free stainless steel due to their improved hardness and density. Stainless steel sintered in a nitrogen atmosphere exhibited better wear resistance than those sintered in an argon atmosphere due ...

Here we report the effects of nano-Y2O3 addition, sintering atmosphere and time during on the fabrication of PM duplex and ferritic stainless steels composites by dual-drive planetary milling of elemental Fe, Cr and Ni powders followed by conventional pressureless sintering. Yttria-free and yttria-dispersed duplex and ferritic stainless steels are fabricated by conventional sintering at 1000, 1200 and 1400 °C temperatures under argon atmosphere. In another set of experiment, yttria-free and yttria-dispersed duplex and ferritic stainless steels are consolidated at 1000 °C for 1 h under nitrogen atmosphere to study the effect of sintering atmosphere. It has been found that densities of duplex and yttria-dispersed duplex stainless steel increase from 71% to 91% and 78% to 94%, respectively, with the increase in sintering temperature. Similarly, hardness value increases from 257 to 567 HV25 in case of duplex, and from 332 to 576 HV25 in yttria-dispersed duplex stainless steel. X-ray diffraction analysis shows the domination of more intense austenite phase than ferrite at higher sintering temperature and also in nitrogen atmosphere. It is also evident that addition of yttria enhances phase transformation from α-Fe to γ-Fe. Duplex and yttria-dispersed duplex stainless steels exhibit the maximum compressive yield strength of 360 and 312 MPa, respectively.

Nano-structured duplex and ferritic stainless steel powders were prepared by high energy planetary milling of elemental Fe, Cr and Ni powders. Here, we have studied the effect of process control agent (PCA) such as stearic acid (SA), effect of ball to powder weight ratio (BPR 6:1and 12:1) and milling speed (64% and 75% critical speed) during planetary milling of elemental Fe–18Cr–13Ni (duplex) and Fe–17Cr–1Ni (ferritic) powders for 10 h in a dual drive planetary mill (DDPM). We have found that all these milling parameters have great influence in tuning the final particle morphology, size and phase evolution during milling. It was found that addition of PCA, a BPR of 12:1 and 75% critical speed is more effective in reducing particle size and formation of duplex and ferritic stainless steel after 10 h milling of elemental powder compositions than their counterparts. The particle size of duplex and ferritic stainless steel milled in the presence of SA for 10 h is found to be 13 and 14 μm, whereas the particle size is 20 and 16 μm without SA respectively. The particle size of powder milled at 12:1 BPR is lower than powder milled at 6:1 BPR because of more impact energy induced by balls on powders and it is found to be 10 and 12 μm respectively for duplex and ferrite in presence of SA. The median particle size of duplex and ferritic stainless steel milled at 75% critical speed is found to be 3.5 and 2.4 μm respectively.

In this present investigation, elemental powders of duplex stainless steel composition (Fe-18Cr-13Ni) with 1 wt. % nano yittria and tungsten were milled separately in dual drive planetary mill (DDPM) for 10 h to fabricate yittria dispersed and tungsten dispersed duplex stainless steel powders. The milled powder samples were characterized by X-Ray diffraction and scanning electron microscopy (SEM) to study the size, morphology and phase evolution during milling. The gradual transformation from ferrite to austenite is evident from XRD spectra during milling. The crystallite size and lattice strain of yittria dispersed duplex stainless steel after 10 h milling were found to be 7 nm and 1.1% respectively. The crystallite size of tungsten dispersed duplex stainless steel was 5 nm. It has been observed from SEM analysis that particles size has been reduced from 40 to 5 μm in both cases. Annealing of 10 h milled powder was performed at 750°C for 1 h under argon atmosphere to study phase transformation in both yittria and tungsten dispersed duplex stainless steel. The XRD analysis of annealed stainless steel depicts the phase transformation from α-Fe to γ-Fe with the formation of oxides of Y,Fe and Cr. The differential scanning calorimetry analysis was conducted by heating the milled powder from room temperature to 1200°C under argon atmosphere to investigate the thermal analysis of both the stainless steel powders.

The incidence of malignant melanoma appears to be increasing at an alarming rate throughout the world over the past 30–40 years and continues to increase in the United States, Canada, Australia, Asia, and Europe. The behavior of head and neck melanoma is aggressive, and it has an overall poorer prognosis than that of other skin sites. The authors review the published literature and text books, intending to give an overall picture of malignant melanomas of the head and neck and a special emphasis on treatment considerations with controversies in treatment including biopsy, radiation therapy, sentinel node biopsy, and nodal dissection.

Nano-structured duplex and ferritic stainless steel powders were prepared by planetary milling of elemental Fe, Ni and Cr powder compositions (duplex: 69Fe-18Cr-13Ni and ferritic:82Fe-17Cr-1Ni) in a dual drive planetary mill for 10 hours. The feasibility for solid solution formation of Cr and Ni in Fe matrix were studied. The samples were collected at regular time intervals and characterized for their morphological and phase analysis using X- Ray diffraction (XRD) and scanning electron microscopy (SEM). It has been observed that as the milling time increases crystallite size decreases and lattice strain increases. Thermodynamic aspects of milled stainless steel powders were performed using Miedema model. The theoretical values ΔH,ΔS and ΔG of and were calculated and were found to be -14.32kJ/mol, 6.93J/mol and -16.39 kJ/mol for duplex stainless steel and -2.81kJmol, 4.35Jmol and -4.11 kJ/mol for ferritic stainless steel respectively.