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In this study, based on different element configurations within constant atomic ratio of elements, (Ti 0.93 W 0.07 Mo 0.07)C–20%Ni and (Ti 0.93 W 0.07 Mo 0.07)CN 0.3 -20%Ni derived cermets have been synthesized. The basis for the difference in the production route was whether the carbides were formed by carbothermic reaction from the metal oxide together or separately, or in the case of Mo 2 C, the carbide is added to the mixture together with the binder after reduction and just before consolidation. Another basis for the difference was whether the cermet was a carbide or a carbonitride. To investigate the influence of the different production routes, the crystal structure, microstructure, and mechanical properties of the cermets produced were examined using XRD, FESEM, STEM, and Vickers indentation. The XRD spectra of all the cermets were found to be very similar to those of TiC-based cermets, indicating that the additive carbides in the TiC or Ti(CN) phases of the cermets dissolve perfectly during the high vacuum sintering process at 1510 °C. The highest toughness (14.65 MPa m1/2) was obtained in (Ti 0.93 W 0.07) C–8%Mo 2 C–20Ni cermets with a core-rim structure. In addition, the use of nitrogen leads to a dramatic reduction in particle size. The use of molybdenum and tungsten in the form of separate carbides had little effect on limiting the expansion of crystal size and grain size compared to the scenario where the dissolution of these elements took place within the primary core-rim structure. However, in terms of hardness and toughness, it was found that, in addition to grain size, the route taken in the addition of molybdenum and tungsten was also important. [ABSTRACT FROM AUTHOR]

Aluminum dross (AD) and red mud (RM) are waste discharged from aluminum industry. AD and RM contain 5-15 wt% of hazardous aluminum nitride (AlN) and 20–50 wt% of iron oxide, respectively. In this work, alumina-based cermet was in-situ prepared from AD and RM, after reduction of iron oxide with AlN by pyrometallurgy. Cermet was consisted of metal reinforcement phase about 1 μm, alumina matrix phase and low-melting aluminosilicate binder. Mechanism of in-situ preparation was studied after exploring phase composition of the cermet powder. Iron, silicon and titanium oxide from RM was reduced into Fe 3 Si and TiN, which acted metal reinforcement phase in cermet. Reaction was consisted of two steps, Fe 2 O 3 , TiO 2 and AlN dissolving into low-melting aluminosilicate and electron transferring from AlN to Fe 2 O 3 , SiO 2 and TiO 2. Content of Fe in ceramic phase was decreased from 6 at.% to 1 at.% after reduction reaction. Low-melting aluminosilicate acted both reaction solvent for reduction reaction, and binder for metal reinforcement phase and alumina matrix phase. More low-melting aluminosilicate was formed when temperature was increased from 1200 °C to 1400 °C, which made more metal balls be formed. The metal ball and alumina were bonded by low-melting aluminosilicate, which increased the bond strength between reinforcement phase and ceramic phase in cermet. This work achieved a total recycle of AD and RM into cermet. It was proposed a novel idea of in-situ preparing cermet, which was generating metal reinforcement phase in ceramic matrix phase. [Display omitted] [ABSTRACT FROM AUTHOR]

Combining with the advantages from mature technologies of fused deposition modelling and powder injection molding, 3D NiFe 2 O 4 -based cermet with weight over 1.3 kg and relative density of 95.8 % were fabricated by composite extrusion modelling using polyoxymethylene-based feedstock. Microstructure and rheological properties of the feedstock, roles of printing parameters on the morphology green samples and related catalytic debinding, sintering properties of cermets were investigated in detail. Uniformly dispersed cermet powders in feedstock were confirmed, due to the good wettability between the powders and binders. The feedstock with high solid loading of 58 vol% exhibited shear-thinning behavior and contained high storage modulus for reliable shape retention. With optimized printing parameters, a high compression ratio (layer height/nozzle diameter) over 2.5 tended to shrink the size of stacking pores, resulting in dense green samples. Catalytic debinding was proved to be defect-free and efficient debinding route, which was successfully used to deal with dense cubic samples with thickness of 30 mm. Sintered samples showed uniform microstructure with interconnected FeCuNi and Ni(Fe)Fe 2 O 4 phases. Except for partial stacking pores in the fracture section, polished cermets exhibited mirror-like surfaces, indicating the good controlling of the final microstructure and performance of 3D cermets. [ABSTRACT FROM AUTHOR]

In this paper, by adding Co, Mo, and Ni metal binder and using spark plasma coupling high-frequency induction (SP–HF) sintering technology, high-entropy (W,Nb,Mo,Ta,Ti)C cermet with good performance was successfully prepared at 1350 °C. The sintering temperature was much lower than that of the solid-state sintering temperature adopted for high-entropy carbide ceramics (about 2000 °C) while maintaining high hardness and fracture toughness. The effects of sintering temperature, holding time and sintering pressure on the mechanical properties of high-entropy (W,Nb,Mo,Ta,Ti)C cermet were investigated. The experimental results show that the SP-HF sintering can promote the liquid phase flow inside the high-entropy (W,Nb,Mo,Ta,Ti)C cermet and improve the density. The high-frequency induction sintering effect of the high-intensity magnetic metal binder phase (Co, Ni) promotes the rapid diffusion of the constituent phases using the vacancy mechanism and the metal liquid phase, which helps to form a high-entropy cermet solid solution at a lower temperature. The different high-entropy effects of the inner and outer layers of high-entropy (W,Nb,Mo,Ta,Ti)C cermet materials play a role in strengthening and toughening the materials, and effective solid solution strengthening is the main reason for improving mechanical properties. The mechanical properties of high-entropy (W,Nb,Mo,Ta,Ti)C cermet are the optimized at 1350 °C, holding time of 8 min, and sintering pressure of 35 MPa. The Vickers hardness, fracture toughness, and flexural strength are 18.38 ± 0.19 GPa, 9.65 ± 0.25 MPa · m1/2 and 970 ± 30 MPa, Vickers hardness was measured at 49 N load. [ABSTRACT FROM AUTHOR]

High Velocity Oxygen Fuel (HVOF) process enables superior properties and is foreseen as a suitable candidate for deposition of hard chromium alternative coatings over the other surface hardening techniques like cladding/deposition through electrolysis/CVD methods, owing to the widespread adaptability and preference in aerospace industry, in particular landing gear mechanism and associated modules that operating in severe environments encountering abrasion, erosion, sliding and fretting wear. Cermet coatings are very often utilised to intensify the wear and corrosion resistance of a wide range of engineering components. The objective of this work is to develop thermally sprayable oxides, nitrides and carbides of WC and Cr3C2 cermet coatings on AISI 4340 steel by HVOF technique. The modified surface is characterised by SEM/EDAX study, followed by the evaluation of Porosity and Microhardness of the modified different speeds and loads. The study unveiled that of all the stated coatings, the blend of WC-Co-VC matrix yields superior hardness, Coefficient of friction and lower order of porosity. The observation forefronts the enhancement of wear properties in terms of surpassing wear resistance and declining trend in volume loss compared to other compositions. [ABSTRACT FROM AUTHOR]

Biomimetic micro-laminated structures are gaining traction for their potential to enhance the mechanical properties of composites. A salient challenge lies in fabricating this intricate layered construct with good interfacial adhesion. In this research, we developed a micro-laminated metal/ceramic composite utilizing CoCrCuFeNi as the infiltration layers. However, after CoCrCuFeNi infiltration, the metal layer phase of cermet transforms into FCC + BCC, which belongs to the category of medium entropy alloy. The mechanical properties displayed a direct relationship with the TiC skeleton's content. Notably, cermet with a TiC volume fraction of 65% exhibited bending strength of 770 MPa, crack-initiation toughness (K IC) of 10.31 MPa•m1/2, crack-propagation toughness (K JC) of 35.1 MPa•m1/2. Mechanisms such as crack deflection and branching acted at the crack tip, significantly reducing peak stress. Contrasting prior studies marked by pronounced interface delamination, the robust adhesion between CoCrCuFeNi and TiC in this study facilitated the congruence of strength and toughness. Our findings introduce a pioneering methodology for designing laminated metal/ceramic composites with CoCrCuFeNi infiltration layers, aiming to achieve superior strength and toughness. [ABSTRACT FROM AUTHOR]

The objects of the study were TiN-Mo cermet, as the final product of the reaction. Thermogravimetric study of cermets of the TiN + Mo and 2TiN + Mo systems revealed two exothermic peaks at temperatures of 560 °C and 700 °C, which may be related to the oxidation of dissolved and of titanium. The increase in mass after a complete heating-cooling cycle at the maximum temperature of 950 °C was 5%. [ABSTRACT FROM AUTHOR]

Thermal spraying by flame is one of the methods employed in the treatment of cracks and pores that occur in materials subjected to elevated temperatures or varying climatic conditions. Nickel was used as a base material and reinforced with two ceramic materials, nickel oxide, NiO, at a fixed rate of 5%, and chromium oxide as the second material. The study involved using Triple Cr2O3 with varying reinforcement percentages (10%, 20%, 30%, 40%, and 50%). The materials were mixed for a duration of two hours, following the specified ratios. The coating process was carried out on a base of out-of-service turbine blades cut into coupons. The coating was subjected to a heat treatment at a temperature of 1000 °C for a duration of two hours. Various structural and physical tests were conducted on the resulting system to examine its crystalline structure. The scanning electron microscope analysis revealed a consistent pattern of regularity, with the most optimal outcome observed at 50%Cr2O3. Under optimal conditions and with a sintering rate of 50%, the material achieved a real density of 7.4 g/cm3, a real porosity of 18%, a water absorption rate of 0.893%, a Brinell hardness value of 770 Kg/mm2, and a wear rate of 1.31 × 10−8 g/cm of travel. [ABSTRACT FROM AUTHOR]

Material extrusion (MEX) allows for the production of advanced cutting tools with new internal cooling systems, which are suitable for new machining equipment. To produce cutting tools via this process, hardmetal and cermet feedstock must be prepared for the extrusion of 3D printing filaments. After shaping the 3D object (green), debinding and sintering must be performed to achieve densification. Defects and microstructural heterogeneities were studied according to the powder material. The present study shows that, although MEX is a viable solution for hardmetals, it needs to produce homogeneous filaments for cermets. The WC-Co bulk microstructures versus hardness were similar to the ones that were measured with pressing and sintering. While cermet (Ti(CN)/WC-Ni/Co) microstructures were heterogeneous, their hardness, when compared with that from the pressing and sintering manufacturing process, decreased significantly. [ABSTRACT FROM AUTHOR]

Nuclear Thermal Propulsion (NTP) systems hold promise in reducing transit times for exploration of the solar system by both crewed and uncrewed missions. NTP systems currently under investigation include a once-through high-temperature gas-cooled fission reactor to provide thermal energy to heat the coolant, which also serves as the propellant. The fuel system consists of angular UN fuel particles dispersed in a matrix of W/Re, creating a ceramic and metallic composite or cermet, which has been irradiated in Idaho National Laboratory's (INL) Transient Reactor Test Facility (TREAT). This enabled evaluation of these materials under representative nuclear heating rates (∼95 K/s) and peak surface temperatures (∼2527 K). These surface conditions were indicative of achievement of the target peak internal temperature of approximately 2850 K. These tests named Sirius-1 (UN–W/Re), have been irradiated and this paper will present post-irradiation examination results. The Sirius-1 test produced minor, stable cracks in the fuel specimen and spalling of surface material. Volatilized uranium 'soot' was found deposited on the inner wall of the irradiation capsule indicating loss of some fissile material from the fuel specimen. Spalling from the surfaces was also noted upon visual inspection. Uranium diffusion from the fuel particles resulted in the formation of U/Re phases and the production of a laminar microstructure on the edge of the fuel system. Overall, the specimen was stable and remained within a coolable geometry upon conclusion of multiple thermal cycles to prototypical operating temperatures. • A cermet nuclear fuel of UN particles in a W/Re matrix was irradiated and examined. • The sample material is a candidate for a nuclear thermal propulsion system. • The irradiation used prototypic heating rates and peak temperatures. • Post examination revealed that the fuel specimen remained largely intact. • Some localized zones of intermetallic W–Re sigma phase existed. [ABSTRACT FROM AUTHOR]

Mo2FeB2 based cermets with different w（Fe）/w（Ni）（10∶0, 7∶3, 5∶5, 3∶7） were prepared by the vacuum liquid phase sintering with MoB, Fe, Ni, and Cr powders as raw materials. The effects of w（Fe）/w（Ni） on the phase compositions, microstructures and mechanical properties of cermets were investigated. The results showed that the compositions of hard and binder phases of boride-based cermet with different w（Fe）/w（Ni） were different. When w（Fe）/w（Ni） of 3∶7, the hard phase was composed of Mo2NiB2 and Mo2FeB2; while in the cases of other w（Fe）/w（Ni）, the hard phase was Mo2FeB2. At 1 350 ℃, the microstructure of cermets was uniform and the size of pore is minimized, with the increase of sintering temperature, the hard-phase particles aggregated and the microstructure was not homogeneous, which led to the decrease of mechanical properties. After sintering at 1350 ℃ for 2 h, the hardness and bending strength of the obtained cermet（w（Fe）/w（Ni）=10∶0） reached the maximum, which were 82.1 HRA and 1 498.7 MPa respectively. Meanwhile, the analysis of fracture morphology revealed that a large number of dimples and rich tearing edges are closely related to the improvement of the bending strength of cermets. [ABSTRACT FROM AUTHOR]

The influence of microstructure and processing route on the small-scale mechanical response as well as on the deformation and failure mechanisms of Ti(C,N)-FeNi cermets were investigated by uniaxial compression of micropillars milled by focused ion beam with different sizes. Stress-strain curves were determined and associated deformation mechanisms were observed in-situ using scanning electron microscopy. The appropriate micropillars dimension was assessed, based on the microstructural characteristics of studied cermets, to overcome scale effect issues. A direct relationship was observed between yield strength and ceramic/metal ratio for colloidal samples. Meanwhile, deformation of metallic binder and glide between Ti(C,N)/Ti(C,N) particles were evidenced as dominant mechanisms during the compression for colloidal cermets with 70 and 80 vol% of ceramic phase, respectively. The obtained results illustrate that samples processed from powder attained by colloidal route provide superior mechanical behavior, as compared to that exhibited by specimens shaped following a conventional powder metallurgy one (wet ball-milling/drying). [Display omitted] [ABSTRACT FROM AUTHOR]

MoCoB–Co cermets with different Mn contents were synthesized using an in-situ sintering reaction, and the effect of Mn addition on the microstructure, interfaces, and mechanical properties was investigated. The addition of Mn inhibited the transition of the binder phase from fcc to hcp. Adding an appropriate Mn can increase the density of the material and refine the hard phase grain. With increasing Mn content, the hardness decreased marginally and then gradually increased, and the transverse rupture strength (TRS) and fracture toughness (K IC) gradually decreased. The cermet with 6 wt% Mn addition had the smallest grain size and lower porosity. The hardness of the cermet increased from HRA 89.0 to HRA 91.7. The interface bonding strength of MoCoB/hcp-Co is higher than that of MoCoB/fcc-Co. After isothermal aging treatment, the content of hcp-Co in the binder phase increased markedly; thus, the K IC and TRS increased from 11.3 MPa m1/2 and 1200 MPa–13.3 MPa m1/2 and 1750 MPa, respectively. [ABSTRACT FROM AUTHOR]

The effects of representative sintering techniques on the residual thermal stress (RTS) in the as-prepared cermets were investigated using the WC-Co composites as an example. The real processing parameters of the spark plasma sintering (SPS) and sinter-hot isostatic pressing (Sinter-HIP) techniques were introduced to quantify RTS and its mechanisms. The real microstructures of cermets were used in the models for evaluation of RTS distributions in different phases. The macro-mesoscale coupled calculations indicated that during the cooling of both the SPS and Sinter-HIP processes, the WC phase of the sintered cermets has a state of compressive stress, while Co phase has a tensile stress state. The internal stress magnitude of both phases increases linearly with the decrease of temperature. There are larger temperature and displacement fields in the SPSed cermets compared to those prepared by Sinter-HIP. The stress accumulation in the SPS process is faster than that in the Sinter-HIP by 30%. The RTS in the SPSed cermets is highly concentrated at the acute dihedral angles of WC/Co interfaces, which tends to promote the face-centred cubic (fcc) to hexagonal close-packed (hcp) martensitic transformation of the Co phase. [ABSTRACT FROM AUTHOR]

Using pre-synthesized high-entropy (Ta 0.2 W 0.2 Nb 0.2 Mo 0.2 V 0.2)C carbide as the reinforcing phase, Ti(C 0.7 N 0.3)-based cermets were prepared by pressureless sintering at 1600 °C. The results revealed that due to the solid solution reaction between the mono-carbide and (Ta 0.2 W 0.2 Nb 0.2 Mo 0.2 V 0.2)C, only one set of face-centered-cubic diffraction peaks in XRD was detected in the as-sintered cermets, alongside the typical core-rim structure. Compared to the Ti(C 0.7 N 0.3)-based cermets without high-entropy reinforcing phase, the Vickers hardness was increased from 17.06 ± 0.09 GPa to 18.42 ± 0.33 GPa and the fracture toughness was increased from 9.21 ± 0.31 MPa m1/2 to 12.56 ± 0.23 MPa m1/2 by adding 10 wt% (Ta 0.2 W 0.2 Nb 0.2 Mo 0.2 V 0.2)C. The wear resistance of the cermet was enhanced significantly with increasing (Ta 0.2 W 0.2 Nb 0.2 Mo 0.2 V 0.2)C content. This work provided a potential that the high-entropy carbide can be applied as an effective reinforcing phase in the preparation of high-performance Ti(C 0.7 N 0.3)-based cermets. [ABSTRACT FROM AUTHOR]

The possibilities of obtaining Al2O3–Al cermet materials by means of liquid-phase oxidation of aluminum by blowing oxygen through the melt are considered. The ease-of-processing makes it possible to avoid the use of powder materials, which effects large variability in the shaping of the phase components of the materials obtained and cost reduction of their production as compared with the methods of powder metallurgy. It found that by controlling the oxidation process by changing the speed and supply of the gas mixture it is possible to obtain metal-ceramic composites with different geometric configurations of the ceramic phase and its amount. An algorithm, taking into account different aspects of the thermophysical process, for calculating the kinetics of aluminum oxidation during the preparation of the ceramic phase of the cermet is proposed [ABSTRACT FROM AUTHOR]

Geothermal is one of the least utilized renewable energy sources due to high investment costs and long development cycle. A major cost for geothermal operations is drilling, where the cost is dependent on drilling depth, tripping times, environments, etc. These costs can increase significantly for greater drilling depths, harsher environments, component failures, etc. During drilling, hammers break the rock through repetitive impact and cuttings are removed via a high-velocity stream. Component lifetime can be extended by selecting appropriate coatings resulting in reduced lost time and improved drilling efficiency. High-velocity oxygen fuel (HVOF) spraying is one of the most popular technique to deposit thick, dense and highly adherent coatings. This paper discusses the characteristics of cermet and alloy coatings using liquid-fueled HVOF spraying technique and their performance in simulated geothermal drilling environment. Properties of the deposited cermet (WC-CoCr, CrC-NiCr) and alloy (Ni self-fluxing, Fe-based amorphous) coatings in terms of surface roughness, thickness, porosity, hardness, adhesion strength, and erosion–corrosion resistance have been studied, and their performance are compared with selected benchmarking steel used in geothermal drilling. Based on the findings of this study, recommendations are made on the type of HVOF coatings that can potentially be used in geothermal applications. [ABSTRACT FROM AUTHOR]

For the first time, the formation of coatings by detonation spraying (DS) of a binder-free tungsten carbide, WC, was studied. The coating phase composition was shown to depend on the O/C molar ratio in the oxygen-acetylene mixture used for the spraying. Along with WC, cubic carbide/oxycarbide WC1-xOy, tungsten semicarbide W2C and metallic W were present in the coatings formed at O/C = 0.9 and O/C = 1.0, indicating the formation of cermet composite coatings. When O/C was greater than 1.1, WC almost fully transformed into metallic tungsten in the coatings. The hardness of the cermet coatings was higher than that of the metallic tungsten-based coatings. During the coating formation, noticeable compression stresses accumulated in the deposited layers. These stresses do not lead to coating detachment or cracking: coatings with thicknesses of up to 500 μm retain their integrity. [ABSTRACT FROM AUTHOR]

A novel one-pot synthesis route leading to the formation of a wormhole-like structure was developed for the successful fabrication of porous YSZ and Ni-YSZ systems. This method involved co-precipitation in the presence of the micelle-forming agents CTAB/Pluronic P123 and crystallising NaCl. The obtained skeletons were mechanically stable and presented almost 50% uniform, open porosity without using any additional pore-formers. The fabricated 0.3 M CTAB/NaCl Ni-YSZ showed better long-term electrical stability in hydrogen than a traditional Ni-YSZ cermet. It resulted from the suppression of Ni structural changes throughout the anode scaffold. Moreover, higher electrochemical activity of this novel anode is expected due to the smaller particle sizes of Ni/YSZ, high homogeneity, highly developed TPB, and better interfacial interaction between the Ni and YSZ. Therefore, the novel soft-hard templating method is recognised as a promising route for the fabrication of the YSZ or Ni-YSZ with a highly developed microstructure and improved stability. [ABSTRACT FROM AUTHOR]

AlN and equimolar ratio of gas atomized CoCrFeMnNi HEA powders were used to prepare AlN–CoCrFeMnNi cermets by ball milling followed by hot pressing sintering at 1240 °C for 2 h. The microstructure characteristics and electrical properties of the cermets were investigated. The sintered cermet bulks were composed of a FCC-structured CoCrFeMnNi solid solution binder phase, AlN phase, and a small amount of Cr 7 C 3 type carbide. No obvious interfacial reaction occurred between AlN and CoCrFeMnNi HEA. The resistivity of AlN–CoCrFeMnNi cermets nonlinearly increased with increasing AlN content and temperature. A conductivity model of AlN–CoCrFeMnNi cermets at room temperature and 600 oC was established based on the generalized effective medium (GEM) equation. Results indicated that AlN–CoCrFeMnNi cermets had a typical percolation threshold phenomenon, which allowed to continuously regulate their resistivity between 102 μΩ cm to 103 μΩ cm as AlN was in the range of 10–50 wt% under room temperature. Therefore, the AlN–CoCrFeMnNi cermets are promising materials for applications in the e-cigarette field. [ABSTRACT FROM AUTHOR]

Additive Manufacturing is experiencing an upswing in many sectors of industry for a broad variety of materials. Processes are mainly developed for polymers and metals. For ceramics, hardmetals and especially cermets there are only a few additive processes suitable. The powder-based technique Binder-Jetting is one of these suitable processes with high productivity and relatively low green density. Within this study, TiCN-based cermets are printed by Binder-Jetting for the first time. The complexity of influences of the morphology and composition of cermet powders are discussed in regard to bulk density and material properties of printed and sintered parts. Studied TiCN-based cermet compositions represent different Ni and Mo2C contents. Main points of this investigation are further the adjustment of ratio of the raw materials for good sintering behaviour and their influence on the microstructures and as a function of varied sintering temperatures. [ABSTRACT FROM AUTHOR]

It is very challenging for 3D printing based on the selective laser melting (SLM) technology to obtain cermet bulk materials with high density and homogeneous microstructures. In this work, the SLM process of the cermet powders was studied by both simulations and experiments using the WC-Co cemented carbides as an example. The results indicated that the evolution of the ceramic and metallic phases in the cermet particle during the heating, melting and solidification processes were all significantly inhomogeneous from atomic scale to mesoscale microstructures. As a consequence, the microstructural defects were caused intrinsically in the printed bulk material. The formation and growth of the bonding necks between the particles were mainly completed at the later stage of laser heating and the early stage of solidification. Both simulations and experiments demonstrated that thin amorphous layers formed at the ceramics/metal interfaces. This work disclosed the mechanisms for the evolution from the atomic scale to microstructure during the SLM printing of cermet powders, and discovered the origin of the defects in the printed cermet bulk materials. [ABSTRACT FROM AUTHOR]

In the present work, turning performance of Inconel 825 superalloy is studied under Nanofluid Minimum Quantity Lubrication (NFMQL). Nanofluid used is nano-Al2O3 dispersed distilled water. The tool insert used in this study is PVD multi-layered (TiN/ TiCN/ TiN) coated cermet. The following machining performance indicators: tangential cutting force, tool-tip temperature, wear morphologies of the tool insert, macro/ micro-morphologies of chips produced, etc. are studied. It is observed that dry machining environment causes vibration signals of random nature whose frequency and amplitude of acceleration are highly time-variant. On the contrary, periodic vibration signal with lower amplitude of acceleration is detected in case of NFMQL machining. Consequently, NFMQL exhibits lower cutting force, reduced tool-tip temperature, and less severe tool wear than that of dry machining. NFMQL produces thinner chips with shorter segmentation spacing and wider shear angle than dry machining. [ABSTRACT FROM AUTHOR]

To improve the tool wear during micro-milling Ti‐6Al‐4V, Ti(C 0.7 N 0.3)-based cermet was used as the cutting tool material, and its grinding damage mechanisms and wear mechanisms were investigated. The structures of the cermet micro-milling cutters were designed and optimized using a 3D milling simulation model. The grinding force model was proposed to adjust grinding parameters. The grinding damage mechanism of the cutting edge was mainly the brittle removal mechanism, while the grinding damage mechanism of the helix flute included the plastic removal mechanism. The wear morphology of the cermet micro-milling cutters was flank wear, its wear mechanism was mainly adhesive wear, and no tip fracture occurred. The cermet micro-milling cutters had a better cutting performance than the WC micro-milling cutters. [Display omitted] • The Ti(C 0.7 N 0.3)-based cermet micro-milling cutters were designed and manufactured for micro-milling Ti-6Al-4V. • The grinding damage mechanism of the helix flute included the plastic removal mechanism. • The damage morphology was flank wear, and the damage mechanism was mainly adhesive wear, and no tip fracture occurred. • The cermet micro-milling cutters had a better cutting performance than the WC micro-milling cutters. [ABSTRACT FROM AUTHOR]

Evaluating the static and dynamic properties of different multilayer coatings on cermet is helpful to guide the coating design of cermet tools. The radar chart method is used to systematically evaluate the static and dynamic performance of the three multilayer coatings. The results show that the presence or absence of the Al 2 O 3 coating in the coating system will affect the friction and cutting properties of the coating-substrate system. In addition, the growth texture of each layer of coating will also affect the performance of the coating-substrate system. The static properties of TiN/TiCN/α-Al 2 O 3 /TiN (A1) coating are better than TiN/TiCN/TiC/TiN (A0) and TiN/TiCN/κ-Al 2 O 3 /TiN (A2). Compared with A0 and A2, the morphology of the A1 coating has larger undulations and the largest roughness. However, the average friction coefficient of A1 is the smallest at 25 °C. Especially at 750 °C, the particle size of the coating surface will affect the friction performance. The order of the friction coefficient of three multilayer coatings at 25 °C is A1

Although ceramic particle‐metal matrix materials (i.e., cermets) can offer superior performance, manufacturing these materials via conventional means is difficult compared to the manufacturing of metal alloys. This study leverages the laser powder bed fusion (LPBF) process to additively manufacture dense tungsten carbide (WC)‐17 wt.% nickel (Ni) composite specimens using novel spherical, sintered‐agglomerated composite powder. A range of processing parameters yielding high‐density specimens was discovered using a sequential series of experiments comprised of single bead, multi‐layer, and cylindrical builds. Cylinders with a relative density >99% were fabricated and characterized in terms of microstructure, chemical composition, and hardness. Scanning electron microscopy images show favorable wetting between the Ni binder and carbide particles without any phase segregation and laser processing increased the average carbide particle size. Energy dispersive X‐ray and X‐ray diffraction analyses detected traces of secondary products after laser processing. For samples processed at high energy densities, complex carbides and carbon agglomerate phases were detected. The maximum hardness of 60.38 Rockwell C is achieved in the printed samples. The successful builds in this study open the way for LPBF of dense WC‐Ni parts with a large workable laser power‐laser velocity processing window. [ABSTRACT FROM AUTHOR]

The demand for materials with an unusual combination of properties has increased tremendously at a level that cannot be attained through the use of conventional materials. This is especially true for materials used in aircraft, automotive and power generation applications. The microstructure and mechanical properties of Al7075 - 6, 9 and 12 wt.% WCCo particles reinforced composites are shown in this study. Liquid metallurgy is used to create the composites. The planetary ball milling method is utilized to turn the WC-Co mixtures into cermets, and the particles with a size range of 30-40 µm are employed as reinforcement. SEM and EDS analyses were used to characterize the microstructure. ASTM standards are used to test the mechanical characteristics of both as cast Al7075 and Al7075-6, 9 and 12 wt.% WC-Co composites. SEM was used to perform fractography study on the prepared composite. [ABSTRACT FROM AUTHOR]

Iron-based (Fe-based) cermets with silicon carbide particles (SiCP) as abrasive were prepared by vacuum hot pressing sintering. The influence of SiCP content on the microstructure and grinding performance of Fe-based cermets was studied. The microstructure, mechanical properties, and grinding performance of the prepared cermets were tested and analyzed to explore the grinding mechanism of Fe-SiC cermets. It was shown that the grinding mechanism changed due to the reduction of SiCP content. And the grinding behavior was related to the bonding force between SiCP and matrix. Through experiments and finite element analysis, the source/distribution of grinding heat and heat flow were verified, and the mechanism of material removal was revealed. The results showed that with the decrease of SiCP content, the grinding behavior of cermet changed from cutting and plowing to friction. [ABSTRACT FROM AUTHOR]

This paper reports the development of TiCN - Co - Cr 3 C 2 - Si 3 N 4 cermets modified with the addition of B 4 C. Cermets of three different compositions with varying B 4 C in TiCN - Co - Cr 3 C 2 - Si 3 N 4 were fabricated. The TiCN, Co, Cr 3 C 2 , Si 3 N 4 and B 4 C powders in the combinations 80%TiCN-5%Co-5%Cr 3 C 2 –5%Si 3 N 4 –5%B 4 C; 75%TiCN-5%Co-5%Cr 3 C 2 –5%Si 3 N 4 –10%B 4 C; 70%TiCN-5%Co-5%Cr 3 C 2 –5%Si 3 N 4 –15%B 4 C were ground in a ball milling unit for six hours at a speed of 300 rpm at a ball-to-powder ratio of 10:1. The powders were then sintered in a vacuum hot press at a temperature of 1600 °C and a pressure of 50 MPa with soaking time of 90 min. For comparison purpose, 90%TiCN-5%Co-5%Cr 3 C 2 cermet was prepared. The microstructure of the sintered cermets revealed the core-rim structure. The Vickers hardness test was done with a load of 10 Kg and for duration of 10 s. Fracture toughness was measured using the crack length data obtained from the hardness test using scanning electron microscopy. The cermet with a composition 75% TiCN-5%Co-5% Cr 3 C 2 –5% Si 3 N 4 –10% B 4 C produced higher hardness of 26.53 ± 0.56 GPa and fracture toughness of 10.29 ± 0.18 MPa m and 70% TiCN-5%Co-5% Cr 3 C 2 –5% Si 3 N 4 –15% B 4 C showed high fracture toughness value of 11.23 ± 0.09 MPa m with hardness value of 21.05 ± 0.10 GPa. The cermet composition 75% TiCN-5%Co-5% Cr 3 C 2 –5% Si 3 N 4 –10% B 4 C retained the hardness of 16.85 GPa even after annealing at 600 °C. The sintered cermets tend to form TiO 2 which determines the hardness of the annealed cermets at a range of 600 °C – 1000 °C. The presence of these oxides tends to decrease the hardness. The wear test was performed taking the cermet as the pin material. The abrasive and adhesive wear mechanisms were dominant in the cermets. The harder precipitates formed tend to increase wear resistance by reducing the wear rate. The harder precipitates (TiN and TiB 2) formed mainly due to the addition of Si 3 N 4 and B 4 C, this addition promotes adhesive wear by a tribolayer formation. • Developed 75% TiCN-5%Co-5% Cr 3 C 2 –5% Si 3 N 4 –10% B 4 C cermet with hardness of 26.53 ± 0.56 GPa and K 1c of 10.29 ± 0.18 MPa m. • 75% TiCN-5%Co-5% Cr 3 C 2 –5% Si 3 N 4 –10% B 4 C retained the hardness of 14 GPa even after annealing at 1000 °C. • 75% TiCN-5%Co-5% Cr 3 C 2 –5% Si 3 N 4 –10% B 4 C cermet showed high wear resistance. [ABSTRACT FROM AUTHOR]

Understanding the formation mechanism of core-rim structure in TiC-based cermets is essential for optimizing their mechanical properties, such as strength and toughness. In this work, the formation process of core-rim structure in TiC-WC-Ni cermet at the early sintering stage was investigated by means of the multiphase and phase-concentration modeling framework coupled with CALPHAD (CALculation of PHAse Diagrams) databases. The effect of W content in the Ni binder phase on the rim thickness was examined. The results reveal that W in the Ni binder phase diffuses into the undissolved TiC particles at the early sintering stage, leading to the formation of (Ti,W)C solid solution phase on the particle surface. This solid solution phase serves as the rim which constitutes the core-rim structure together with TiC particles. Furthermore, there is a positive correlation between the rim thickness and the W content in the Ni binder phase. Phase-field simulation exhibits a good agreement with the scanning electron microscopy (SEM) observations of the annealed WC-Ni/TiC–Ni cermet diffusion couple. This study offers a novel approach for exploring the formation mechanism of core-rim structure in TiC-based cermets. [ABSTRACT FROM AUTHOR]

In this study, TiC–50 wt% W, TiN–50 wt% W, TiC 0.7 N 0.3 –50 wt% W, Ti 0.55 C 0.13 N 0.32 –50 wt% W, TiC 0.5 N 0.5 –50 wt% W and TiC 0.5 N 0.5 –70 wt% W cermet specimens with grain sizes smaller than 1 μm were prepared by blending TiC, TiN, TiC 0.5 N 0.5 , W and Ti powders followed by the spark plasma sintering of the blended powders. Under Ar gas flow conditions at 1973 K, the TiC 0.5 N 0.5 –50 wt% W and TiC-50 wt% W cermet specimens exhibited the first and second highest strengths, respectively, whereas the TiN–50 wt% W and Ti 0.55 C 0.13 N 0.32 –50 wt% W cermet specimens exhibited the lowest strength among all the cermet specimens prepared in this study. In contrast, the Ti 0.55 C 0.13 N 0.32 –50 wt% W and TiC 0.5 N 0.5 –50 wt% W cermet specimens exhibited the first and second highest strengths, respectively, at room temperature in laboratory air. Coherent interfaces, whose type differed from those of the TiC 0.5 N 0.5 –50 wt% W and TiC 0.5 N 0.5 –70 wt% W cermet specimens, were found in (Ti, W)C grains in the TiC–50 wt% W cermet specimen. The coherent interfaces in the TiC–50 wt% W cermet specimen were considered to suppress the grain growth because these interfaces normally suppress the interdiffusion of Ti, W and C atoms. Moreover, the grain growth seemed to be suppressed in the TiC 0.7 N 0.3 –50 wt% W, Ti 0.55 C 0.13 N 0.32 –50 wt% W, TiC 0.5 N 0.5 –50 wt% W and TiC 0.5 N 0.5 –70 wt% W cermet specimens owing to the core–rim structures with coherent interfaces in the cermet specimens. The coherent interfaces and core–rim structures are thus considered to contribute to improving the high-temperature strength of all the cermet specimens except for the TiN–50 wt% W cermet specimen, which contained neither core–rim structures nor coherent interfaces. • TiC–W cermet has a different type of coherent interface from TiC 0.5 N 0.5 –W cermet. • TiC 0.5 N 0.5 –W cermet shows higher strength at 1973 K than TiC-W and TiN-W cermets. • Ti 0.55 C 0.13 N 0.32 –W cermet showed lower strength than TiC 0.5 N 0.5 –W cermet at 1973 K. [ABSTRACT FROM AUTHOR]

Processing route is a determining factor that affects the properties of hard materials. Although processing routes are well defined for WC-Co hardmetals, a complete study is needed to understand the factors influencing the properties when alternative compositions are developed. In this investigation, Ti(C,N)-Fe15Ni10Cr cermets were produced following conventional powder metallurgy routes. Two types of milling – attritor and planetary, using different vessel/ball materials – and of sintering regimes – sinter-HIP and high-vacuum – were used to process the specimens and compare their final properties. Carbon content was also included in the study as experimental variable. Density, porosity, microstructure, mechanical and magnetic properties, and corrosion behaviour of the resulting cermets were determined by using a wide range of characterization techniques. Optimization of their production led to materials with a competitive hardness-toughness combination, comparable to those exhibited by plain WC-Co grades. Evaluation of corrosion confirmed the improved resistance when Cr is included as alloying element and also compared to cobalt, as well as the superior corrosion response of Ti(C,N) with respect to WC. [ABSTRACT FROM AUTHOR]

The present work investigated the microstructure and mechanical properties of TiC x -Cu cermets before and after thermal shock tests. Thermal shock temperature was from 800 °C to 1200 °C and number of cycles was from 1 to 20. The results indicated that TiC x -Cu cermets with co-continuous structure exhibited a stable and excellent thermal shock resistance. When quenched at 1000 °C for 1 cycle, the residual flexural strength of the cermet increased to 882 MPa, which was 10.1% higher than that without thermal shock. After 20 cycles of thermal shock, the residual flexural strength still maintain 760 MPa. When quenched at 800 °C and 1200 °C, the strengths of cermet decreased correspondingly, which were caused by the thermal mismatch between metal and ceramics and effusion of Cu or collapses of oxide layer, respectively. Herein, the recrystallization and refinement of metal phase grains caused during the thermal shock process, resulting in the superior thermal shock performance of cermet. [Display omitted] [ABSTRACT FROM AUTHOR]

We report on a novel polymer‐derived synthesis approach that yields boron carbide monoliths and metal‐reinforced B4C cermets. This single‐step approach relies on a preceramic powder blend of boron and an acetylenic resin with a high char yield. At low temperatures below 1500°C and without applied pressures, preceramic precursor reaction bond together and form nanocrystalline refractory B4C matrices. Resulting near net shape boron, carbide monoliths exhibit small crystal grain sizes, maintain chemical purity, and exhibit morphological homogeneity. We reinforce the refractory carbide with five different metals and demonstrate the influence of each on the density, hardness, oxidation stability, and electronic conductivity of resulting cermet composites. We assess the optimal synthesis and reinforcement strategies that tailor these nanostructured materials for inexpensive and high‐performing engineering applications. [ABSTRACT FROM AUTHOR]

EDS, SEM, and TEM were utilized to investigate the effects of various Cr doping amounts on the microstructure and properties of Mo 2 FeB 2 -based cermets. The mechanism behind Cr doping and its influence on the biphase interfaces were elucidated by first-principle and EET theories, respectively. The results show that a moderate amount of Cr doped into Mo 2 FeB 2 -based cermets is preferentially solid-solved in the Mo 2 FeB 2 hard phase, which leads to an enhancement in the wettability of the system, as well as an increase in the fracture toughness and transverse rupture strength (TRS) of the cermets. Excessive Cr addition leads to a decrease in mechanical properties due to coarser aggregation of hard phase particles and a decrease in the volume fraction of the binder phase. With increased Cr addition, a significant amount of Cr starts to solid-solve in the Fe-based binder phase when the saturation point for solid-solved Cr in the hard phase is approached. However, Cr solid-solved in the hard phase has the most pronounced effect on the mechanical properties of cermets. Combined with the first principle calculation, it can be seen that Cr tends to occupy the position of iron atoms when solid-solved in the hard phase, thus enhancing the covalent bonding in the system. Analysis of the valence electron structure at the interface reveals that adding a moderate amount of Cr increases the electron density and the number of atomic state groups at the interface. At this point, the interfacial stability and bond strength between the two phases are increased, which positively affects the mechanical properties of the cermets. Nevertheless, an excess of Cr is detrimental as it leads to a decrease in the ρ ' and σ N , thus affecting the bond strength at the interface. • Systematic study of the effect of Cr doping on the mechanical properties of Mo 2 FeB 2 -based cermets. • The strengthening mechanism of Cr doping on Mo 2 FeB 2 -based cermets was explained. • From the level of electrons, the effect of Cr doping on the biphase interface has been explained for the first time. [ABSTRACT FROM AUTHOR]

The oxidation-wear properties of WC-Co cermet at high temperatures were remarkably enhanced by Ru addition for increasing life expectancy of cermet tools in high-speed cutting processes. The oxidation-resistant mechanisms of Co with substitutional Ru were disclosed by calculating the energy barrier for oxygen adsorption and diffusion in Co with and without Ru doping. Particularly, the oxidation of WC was effectively inhibited due to the suppression of reactions between cobalt oxides and WO 3. Thus less cracking occurred in the Ru-containing cermet as its tribolayer contained fewer oxides with low shear resistance, which in turn protected the subsurface materials from further oxidation. • High-temperature wear resistance of WC-Co cermets was remarkably enhanced by Ru addition. • Simultaneous anti-oxidation mechanisms of Ru-doped Co and WC were discovered. • Suppressed interactions between oxidation and friction of cermets were demonstrated. [ABSTRACT FROM AUTHOR]

The mechanical properties degradation of cermets under high temperatures greatly limits their applications. In this paper, the compressive yield strength of WC-Co based cermets at high temperatures was significantly improved by the addition of Ru. Based on the detailed microstructure analyses, the contribution of Ru to the plastic deformation of the cermets was disclosed. The addition of Ru would stabilize the fcc-Co structure, leading to an increase in the proportion of the coherent WC/Co phase boundaries. The coherent phase boundaries are beneficial to avoid stress concentration across the interface and premature crack initiation, inducing higher dislocation densities and larger plastic deformation in both Co and WC phases. The solid solution strengthening effect of Ru and the Ru cluster in the Co phase can inhibit the softening of the binder phase at high temperatures. The synergy of solid solution strengthening and dislocation strengthening is responsible for the higher yield strength of WC-Co cermets with Ru at high temperatures. • The addition of Ru enhanced the yield strength of WC-Co cermets at room and high temperatures. • The increased strength of Ru doped WC-Co cermets was from solid solution strengthening and dislocation strengthening. • The addition of Ru stabilized the fcc-Co structure and facilitated formation of coherent WC/Co phase boundaries. • Ru doping induced a high dislocation density hence larger plastic deformation in Co and WC phases. • The formed Ru clusters in the Co phase inhibited softening of the binder phase at high temperatures. [ABSTRACT FROM AUTHOR]

More efficient transportation, structural energy storage systems, active sensing, and self-diagnosis are examples where disruptive materials are necessary for driving technological innovation forwards. Unprecedented combinations of properties can be achieved when materials of dissimilar nature and contrasting properties like metals and ceramics are merged. For multimaterial systems, the key challenge is to develop suitable manufacturing processes as to be able to, first, successfully produce the material and, second, to achieve the desired behavior without compromising the integrity of the combined materials. A particular interesting class of material is what are defined in this work as structural electroactive cermets: composite materials constituted by conductive ductile metallic particles dispersed within and used as reinforcement for an insulating dielectric matrix. Specifically, chemically unreactive conductive second-phase reinforcing metallic particles such as Ag or Pt are added to piezoelectric ceramics aiming to enhance their brittle mechanical behavior. As analyzed in the present review, the quest for better mechanical properties results in the enhancement of the dielectric properties in general and of the dielectric constant in particular via the percolation effect for which the percolation theory and other alternative models are discussed. Finally, challenges are identified and potential areas of scientific interest for further developments proposed. [ABSTRACT FROM AUTHOR]

Low-cost ceramic--metal composite (cermet) membrane supports have been elaborated and characterized. A plastic paste was prepared from kaolin (K), feldspar (F), sand (S), and two types of aluminum (i.e., waste aluminum alloy (WA) and commercial aluminum (CA)) mixed with water. This was followed by the preparation of a ceramic porous tube by extrusion and sintering at a temperature of 1350 °C for 2 h. The sampleswere then characterized using porosity, permeability, scanning electron microscopy (SEM), and chemical and mechanical properties to evaluate the effects of the addition of aluminum to the porcelain matrix on the mixture (50% K, 25% F, and 25% S). The microfiltration active layer was added on the support by a slip casting method using 63 m kaolin powder, water, and polyvinyl alcohol solution (PVA); after drying at room temperature for 24 h, the microfiltration layer was heated to 650 °C for consolidation. SEM observation showed homogeneous layers without crackswith 5 mand 9 mthick layers for the two membranes prepared. Application of the membrane for the treatment of textile wastewater showed a turbidity removal of more than 98% and a chemical oxygen demand of more than 85%. This was a much better separation performance when compared to other membranes. [ABSTRACT FROM AUTHOR]

Thin and porous anodes need three important properties, high porosity, moderate catalytic ability, and no carbon deposition, when using hydrocarbon fuels for the operation of solid oxide fuel cells (SOFCs). Nickel-based (Ni/YSZ) cermets might perform serious carbon deposition using hydrocarbon fuels. Instead, many researches select Cu-based cermets to extend the application period. This study chose half replaced cermet (50%Cu–Ni in Y-doped ZrO 2), and verified the effects of H 2 formation and carbon deposition comparing to other two series, i.e. Ni-YSZ and Cu-YSZ. Three ingredients were homogeneously mixed and reduced, then sintered to the porosity of 54 ± 3%. The re-dox properties under various atmospheres and the permeability of made cermets have been investigated. The results showed that 50%Cu–Ni with 8YSZ performed moderate catalytic ability, low cracking rate for CH 4 , and good electric conductivity of 1503 S cm−1 at 650 °C. The sample is suitable for using CH 4 fuel for SOFCs. • Porous Cu–Ni-8YSZ anodes are made by reducing under 20%H 2 –N 2 atmosphere. • 50%Cu–50%Ni in 8YSZ anode slowly cracks CH 4 and hardly induces carbon deposition in 2 h. • The anode of good permeability and electric conductivity is suitable for solid oxide fuel cell. [ABSTRACT FROM AUTHOR]

MoCoB–Co cermets with varying Mo/B atomic ratios (AR Mo/B) and Co contents were fabricated, and their microstructure, mechanical properties, and corrosion behavior were investigated. The MoCoB hard phase exhibited the maximum grain size and anisotropy when the AR Mo/B was 0.84, which degraded the mechanical properties. For AR Mo/B ≥ 1.08, a third phase, Co 7 Mo 6 , and dense three-dimensional networks composed of stacking faults and ε-martensite plates were observed. These three-dimensional networks limited the dislocation slip in face-centered cubic γ-Co and ε-martensite, improving the hardness of the cermet and decreasing the transverse fracture strength (TRS). The corrosion resistance of the cermets was influenced by the MoCoB particle size, the Mo content of the binder phase, and the ε-martensite content. With an increase in the AR Mo/B , the corrosion resistance of cermets initially decreased and then increased. Additionally, as the Co content increased, the hardness gradually increased, whereas the TRS and fracture toughness steadily decreased. For AR Mo/B = 0.92 and a Co content of 45 at.%, the cermet displayed the best overall performance, with hardness, TRS, and fracture toughness values of HRA 89, 1720 MPa, and 13.2 MPa m1/2, respectively. [ABSTRACT FROM AUTHOR]

A new technique for producing complex-shaped items from wear-resistant TiC-(Ni-alloy) cermets is described. Cermets are produced by infiltration of TiC-preforms with Ni-alloy, which combines the advantages of powder metallurgy and casting. A special vacuum induction furnace is designed to effectively implement the new technique, which enhances the production capacity and quality of a cermet item against other known technologies. The structure of new cermets is characterized by a uniform distribution of TiC grains in the Ni matrix. During infiltration, a considerable part of tungsten and some part of molybdenum migrate in TiC grains forming solid solution shells on them. The shell ensures the connection between TiC and Ni-alloy and high physical and mechanical properties of the cermet. The physical and mechanical properties of the TiC-(Ni-alloy) cermet at temperatures up to 1100 °С and the results of practical use of items from cermets in production are presented. The shop tests showed the increase of the durability of a cermet ball valve by more than 6 times as compared with conventional wedge valves. [ABSTRACT FROM AUTHOR]

It is well known the interest of the scientific community in substituting the traditional cemented carbides (WC–Co) by alternative ceramic-metal systems. In this regard, Ti(C,N)-based cermets arise as excellent candidates due to their exceptional mechanical, tribological and thermal properties. In this work, microstructurally different Ti(C,N)–FeNi cermets were processed using a combination of colloidal and powder metallurgy techniques. Three distinct ceramic/metal phase ratios were used: 85/15, 80/20 and 70/30 (volume fraction) of Ti(C,N) and FeNi respectively. Microstructural parameters and micromechanical properties (hardness and stiffness) of the three composite systems and their constitutive phases were assessed. Small-scale hardness was evaluated by means of massive nanoindentation testing and statistical analysis of the gathered data, under the consideration of three mechanically different phases: Ti(C,N) particles, metallic binder and a composite-like one, corresponding to probing regions containing both constitutive phases. It is found that values of local hardness for both composite-like and metallic phases increase as the ceramic/metal phase ratio rises. In particular, local hardness values are determined to be significantly distinct for the metallic binder in the three cermets investigated. Results are discussed and rationalized on the basis of the constrained deformation imposed for the harder phase to the softer and more ductile one. Estimated effective flow stress values for the metallic binder as well as detailed inspection of crack-microstructure interaction and fractographic features point out the effectiveness of FeNi as reinforcement phase and toughening agent for Ti(C,N)-base cermets. [ABSTRACT FROM AUTHOR]

The article shows new designed cermets and processes concerning primary to applications as thermal insulation materials with low emissivity. A new projected microstructure was obtained where dense regions (micropellets) rest inside the main porous pellet. The feature resembles a frozen hypercube, therefore such architecture is called hyper-pellet/ cermet. The processing method to obtain the hyper-cermet is based on sequential tape castings and sintering techniques. Ni-zirconia lamellae were prepared by a special mechanochemical process followed by sintering, which remain inside the main pellets as a dense region. The whole pellet is turned to be porous by employing pore-forming additives. All the constituents and porosity shapes are aligned along the disc/ flake planes. Thermal conductivity is estimated for the materials up to 800 °C by a flash diffusivimeter. Ceramographic analyses show graded density regions with directional constituents and pores. Applications of such materials are foreseen as temperature insulation materials and thermal radiation shields. [ABSTRACT FROM AUTHOR]

The dense TiC-316 L stainless steel cermets with different TiC content were fabricated via conventional powder metallurgy (PM) process. The effects of TiC content on the microstructure and mechanical properties of TiC-316 L stainless steel cermets are studied. Scanning electron microscopy (SEM) is employed to observe the microstructure, fracture morphology, and crack propagation of cermets. The binder mean free path (MFP) and hard phase contiguity are analyzed based on the stereological principles. The relative density, hardness and transverse rupture strength (TRS) of the cermets are measured by the Archimedes' principle, Rockwell scale hardness tester and three-point flexural test, respectively. The average TiC grain size decreases first and then increases with the increase of hard phase content. At a content of 80 wt%, the maximum relative density (99.1%), hardness (88.9 HRA) and TRS (1373 MPa) are obtained. During crack propagation, both intergranular and transgranular fractures exist, of which the intergranular fracture prevail and coarse grains are more prone to transgranular fracture. • Dense and low cost TiC-316 L stainless steel cermet was fabricated. • The effect of TiC content on the microstructure and mechanical properties of the cermets were investigated. • Both intergranular and transgranular model exist in the cermets during the crack propagation. [ABSTRACT FROM AUTHOR]

Niobium carbide (NbC) based cermets are emerging as strong contenders to replace conventional tungsten carbide (WC) based cermets for applications involving abrasion and wear resistance due to their superior mechanical, physical, and chemical properties. NbC cermets with various binders have been explored in literature and nickel has emerged as a promising candidate binder material. Mechanical mixing (MM) followed by spark plasma sintering (SPS) has been shown to be one of the effective methods to synthesize NbC-Ni cermets. However, the effect of certain crucial process parameters during the MM + SPS process on the end product have not been established. To address this, the present study reports the effect of ball milling time and the effect of sintering temperature on the microstructure, binder distribution, hardness, and indentation fracture toughness of NbC – 16 vol% Ni cermets synthesized using MM + SPS. Insufficient milling time resulted in inhomogeneous binder distribution in the consolidated cermets and sintering above a certain temperature resulted in complete loss of binder. Therefore, the combination of sufficient milling time and an appropriate sintering temperature was essential to obtain a consolidated cermet with homogeneous microstructure and uniform mechanical properties. [Display omitted] • Spark plasma sintering (SPS) of NbC-Ni cermets beyond a threshold temperature resulted in loss of binder. • Mechanical mixing (MM) for a shorter duration led to an inhomogeneous binder distribution in the consolidated cermet. • A combination of appropriate mixing time & sintering temperature was needed to retain and distribute the binder uniformly. • MM + SPS processed NbC-16 vol% Ni cermet had a hardness of 1208 ± 20 HV 30 and a fracture toughness of 7.16 ± 0.42 (30 kgf). [ABSTRACT FROM AUTHOR]

Cermet based-coatings, made of a ceramic matrix and metallic nanoparticles, have attracted a lot of attention in applications such as solar absorbers in a solar concentrating system since they allow a strong solar absorptance, a low IR emittance, and present good thermal stability. It has been shown that many parameters impact the performances of the cermet-based solar absorber such as the thickness, composition, and features of the metallic nanoparticles. In this study, we report on the synthesis of a Al 2 O 3 -Ag cermet by reactive co-sputtering of Ag and aluminum in Ar/O 2 gas mixtures. The influence of important experimental parameters (i.e. sputtering power on the Ag target, deposition time, and O 2 content) on the chemistry, morphology, and optical properties of the cermet coating is studied while the photothermal property of the cermet has been evaluated by measuring the surface elevation temperature of the coating under 1 sun irradiation. Our data reveal that by optimizing the features of the cermet, an absorbance of 0.92 and a surface temperature elevation up to 9.1 K can be reached after 30 min of illumination. • Al2O3/Ag NPs cermet coating properties at ambient temperature • The chemistry of the matrix influence the photothermal properties. • Highest absorbance obtained for a fraction of Ag NPs of 0.15 • A solar absorbance of 0.92 is achieved by optimizing the deposition conditions. • Surface temperature elevation reaches 9.1 K under 1 sun illumination during 30 min. [ABSTRACT FROM AUTHOR]

To find high-performance ternary borides as the hard phase of the cermets, first-principles calculation was applied to systematically investigate the structure, mechanical, electronic and thermal properties of 26 ternary borides MⅠ x MⅡB x (x = 1 or 2). The phase stability and mechanical properties were evaluated by formation enthalpy and elastic constants. Debye temperatures were calculated to study the thermal conductivity, and the hardnesses of the candidates were predicted via the overlap populations calculation and hardness model. The results show that all the candidates possess thermodynamic and mechanical stability. Most of the MⅠ x MⅡB x (x = 1 or 2) exhibit a better ductility than WC, except Ta 2 FeB 2 , Mo 2 MnB 2 , Nb 2 CrB 2 , Nb 2 FeB 2 and Ti 2 ReB 2. Moreover, sorted from high to low, Nb 2 CrB 2 , Mo 2 CoB 2 , W 2 MnB 2 , Mo 2 FeB 2 , Ti 2 ReB 2 , NbFeB, MoCoB, Mo 2 NiB 2 , Nb 2 FeB 2 , and Mo 2 NbB 2 have a larger Debye temperature than WC. All the candidate ternary borides exhibit a lower hardness than WC, with the maximum hardness of 26.3 GPa for MoCoB. The analysis of electronic properties indicates that all the MⅠ x MⅡB x (x = 1 or 2) exhibit metallic, ionic and covalent hybrid properties. The calculated results are expected to provide guideline for developing ternary boride-based cermets or coating materials that may replace WC-Co cermet. • Ternary boride-based cermets may replace WC-Co. • The mechanical and thermal properties of 26 MⅠ x MⅡB x (x = 1,2) were investigated. • A novel high hardness and thermal conductivity MoCoB-Co cermet was proposed. • A scientific foundation for accelerated design of tungsten substitutable cermets. [ABSTRACT FROM AUTHOR]

Abstract Due to the renewed interest in alternative binders for cemented carbides it is important to understand how the binder composition influences not only mechanical properties but also the microstructure and related measurements for quality control. Microstructure and chemical composition of WC-Co is often evaluated by magnetic measurements. However, when the binder composition deviates significantly from conventional Co-based binders it should not be assumed that the standard measurements can be used to directly evaluate the same parameters. In this paper we investigate the influence of relative C-content on the microstructure and magnetic properties of an alternative binder cemented carbide. It is shown that the saturation magnetization is related to the relative C-content and the magnetic coercivity is related to the microstructure, more specifically to the binder phase distribution, but could not be directly linked to the carbide grain size in the same manner as for standard WC-Co. Furthermore, a direct correlation between Curie temperature and saturation magnetization is observed for this system which means that the Curie temperature potentially could be used for calibration of empirical relations or as a method to accurately determine the binder volume fraction. Highlights • Cemented carbides with a NiFe alternative binder were produced and characterized. • Increasing C-content gives larger grain size and homogeneous binder distribution. • Magnetic properties are sensitive to the binder composition and the microstructure. • Empirical models for magnetic quality control of WC-Co are not directly useable. • Curie temperature is shown to be a useful complement for calibration of the models. [ABSTRACT FROM AUTHOR]

Abstract Cemented carbides cover a wide range of applications in many relevant industries, i.e. as cutting tools (turning, milling, drilling) for machining of metal components in the automotive and/or aerospace industry, as components of drill bits or road headers in the rock tools and mining area or as wear parts in wire drawing dies or punch tools. In this review selected cemented carbide and cermet microstructures are presented. The focus is on microstructures, both those that are already established in the cemented carbide industry and those which have drawn scientific attention due to new potential applications. Cemented carbides are here divided in four groups based on microstructure and chemistry: WC morphology and chemistry, cubic carbide containing cemented carbide and cermets, functionally graded cemented carbides, and binder design of cemented carbides. Furthermore, this review covers some historical background that motivated the microstructure design as well as the status of each class of materials nowadays. The paper aims at categorising cemented carbides in a structured way and to serve as an introduction to cemented carbide microstructures for engineers, researchers and scientists. Graphical abstract Unlabelled Image Highlights • Mapping of relevant cemented carbide microstructures. • Cemented carbides classified based on microstructure and chemistry. • Microstructure linked to properties and applications. • Review covers historical background and current and future trend for each class of materials. [ABSTRACT FROM AUTHOR]