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This study explored the feasibility of fabricating a ZrO 2 -Zr 2 Cu ceramic-metal (CERMET) fuel through additive manufacturing (AM) followed by melt infiltration. ZrO 2 was selected as a surrogate for UO 2 owing to its similar properties, and Zr 2 Cu was selected owing to its low melting point and neutron absorption cross-section to explore the feasibility of forming a uniform distribution of ceramic particles within a metal matrix. The binder jetting (BJ) AM technique was employed to fabricate preforms with precise control over the particle distribution, addressing the challenges associated with particle agglomeration and ensuring preform shape integrity. Subsequently, spontaneous melt infiltration was employed to achieve a dense and homogeneous CERMET structure. This study emphasized the significance of controlling wettability and surface energies for successful melt infiltration, focusing on the interfacial reactions between Zr 2 Cu and ZrO 2. These results indicate that this novel approach can significantly enhance the thermal and irradiation performance of CERMET fuels. [ABSTRACT FROM AUTHOR]

Traditional studies on boride cermet have rarely considered the effects of the synergistic interactions among their multiple components on their microstructure and properties. In this study, FeCrNiCo-boride cermet is prepared for the first time via hot-press sintering. The microstructure evolution and corrosion resistance of the cermet are investigated for sintering temperatures in the range of 1000–1300 °C. The results show that the phase comprises Mo 2 FeB 2 , MoB 2 , and FCC phases (including that of FeCrNiCo or various intermetallic solid solutions formed by FeCrNiCo decomposition). Owing to its low Gibbs free energy, Mo 2 FeB 2 occurs in the hard phase. Cr atoms dissolve into the crystal lattice and stabilise the Mo 2 FeB 2 crystals. A certain amount of MoB 2 is also present in the hard phase. The bond phase is formed by alloying elements and solid solutions. The cermet sintered at 1100 °C exhibits the least structural defects, highest cermet content, and best corrosion resistance; the porosity is 9.94 % and phase ratio of cermet is 48.9 %. The cermet phase has the smallest grain size of 5.96 μm. The equilibrium potential (E corr) is −0.52 V, corrosion current density (I corr) is 2.07 × 10−6 A/cm2, and open-circuit potential (OCP) in a 3.5 % NaCl solution is −0.34 V. [ABSTRACT FROM AUTHOR]

The effects of carbon content on microstructure and mechanical properties of the (TiTaNbZrMo)C-Co cermets were investigated in details. Uniform high-entropy carbide powders with different carbon contents were obtained through carbothermal reduction and mixed with a Co binder phase via ball milling for fabricating cermets at the elevated temperature. The increased carbon content makes the hardness of cermets initially rose and then decreased, while the fracture toughness demonstrates an overall decline. Among all high-entropy ceramic based cermets, (TiTaNbZrMo)C 0.9 -Co cermet (C1) exhibited the optimal combination of hardness and fracture toughness properties, with a Vickers hardness (HV 30) of 15.83 GPa and a fracture toughness of 7.74 MPa m1/2. Furthermore, the presence of graphite phases accompanied by the excess carbon content could enhance the wear resistance of cermets. (Ti,Ta,Nb,Zr,Mo)C-Co high-entropy ceramic based cermets have potential applications in the fields of cutting tools and wear-resistant components. [ABSTRACT FROM AUTHOR]

Stainless steel is used throughout the world as a structural material. However, it undergoes corrosion damage when exposed to extremely corrosive media, such as the marine environment. An alternative to solve this problem lies in the development of coatings that can withstand extreme conditions but also be easily deposited with inherently corrosion-resistant materials such as silicon carbide (SiC). The present study shows a simple method to produce Al/SiC cermet powders by attrition milling. The resulting cermet powders with a metallic matrix and hemispherical morphology, were employed as fillers in polycarbosilane (PCS) solutions that were sprayed on A304 stainless steel substrates. Al/SiC composite coatings were produced after heating the sprayed suspensions at 700 °C for 1 h in Ar atmosphere. The resulting composite coatings exhibited low surface energies (< 35 mN/m), water contact angles of 53°, and adhesion strength of up to 30 MPa. Finally, corrosion tests were performed in a cyclic corrosion test chamber, showing that these coatings effectively reduced the corrosion rate of stainless steel by 87%, reaching corrosion rate values of 0.007 g/cm2 year. [ABSTRACT FROM AUTHOR]

The present study focuses on the effect of molybdenum and nitrogen on the microstructure and mechanical properties of VC x O y -Fe cermets. Samples with 0–23 at% Mo were fabricated using a wet synthesis route and heat treatment under Ar and N 2 atmospheres. Phase transformations during heating were investigated by TGA-DSC in combination with XRD, and the resulting materials were analyzed by SEM/EDX. A doping level of 6–12 at% was found to be optimal, as it lowered the melting point of the metallic binder to 1320–1360 °C. Replacing argon with nitrogen further decreased the melting point to 1210–1240 °C and reduced the grain size. Depending on the sintering temperature, gas environment, and molybdenum content, the produced cermets were characterized by 92–97 % density, 17–29 vol% binder phase, 8–14 GPa hardness, and 6–9 MPa m0.5 fracture toughness. The average size of oxycarbide grains, their stoichiometry, and the amount of dissolved vanadium in the iron binder demonstrated a strong correlation with changes in mechanical properties. [Display omitted] [ABSTRACT FROM AUTHOR]

During the hot dip aluminum plating process, components such as sinking rollers, pulling rollers, and guide plates will come into long-term contact with high-temperature liquid aluminum and be corroded by the aluminum liquid, greatly reducing their service life. Therefore, the development of a material with excellent corrosion resistance to molten aluminum is used to prepare parts for the dipping and plating equipment and protect the equipment from erosion, which can effectively improve the production efficiency of the factory and strengthen the quality of aluminum-plated materials, which is of great significance for the growth of corporate profits. With AlFeNiCoCr as the binder phase and ZrB2 as the hard phase, ZrB2-based ceramic composites were prepared by spark plasma sintering (SPS). SEM, EDS and XRD were used to characterize the microstructure and properties of the sintered, corroded, and abraded material samples. The density, fracture toughness, corrosion rate and wear amount of the composite material were measured. The results show that ZrB2-AlFeNiCoCr ceramics have compact structure and excellent mechanical properties, and the density, hardness and fracture toughness of ZrB2-AlFeNiCoCr increase with the increase in sintering temperature. However, when the composite material is at 1600 °C, the relative density of the sintering at 1600 °C decreases due to the overflow of the bonding phase. Therefore, when the sintering temperature is 1500 °C, the high entropy alloy has the best performance. The average corrosion rate of ZrB2-1500 at 700 °C liquid aluminum is 1.225 × 10−3 mm/h, and the wear amount in the friction and wear test is 0.104 mm3. [ABSTRACT FROM AUTHOR]

Iron-based cermet has the advantages of high-temperature resistance, low price, good performance, and so on. At present, most of the studies on cermets are focused on the measurement of macroscopic properties and optical microscopic characterization, while there are few microscopic studies on the interface structure. In this paper, based on density functional theory (DFT), the stability of the Fe/Al2O3 interface is studied, and the stability difference and interface formation mechanism of different end combinations are investigated. By calculating the surface energy, adhesion work, interface energy, density of states, charge density, differential charge density, and so on, it was concluded that the stability of the O-terminal interface was greater than that of the Al interface. It has a certain guiding role in the preparation of Fe/Al2O3 cermet materials. [ABSTRACT FROM AUTHOR]

Cermets generally exhibit a trade-off between strength and energy dissipation capacity. By applying a dual design strategy combining bioinspired architecting and metastability engineering, we developed a transforming interpenetrating-phase cermet made from zirconia ceramic preform infiltrated with an Al-Zn-Mg-Cu alloy. The cermet micro-pillars possessed compressive yield strengths of 773 ± 62 MPa and energy dissipation densities of 110 ± 8 MJ·m−3, 50% and 45% higher than those of the monolithic Al alloy, respectively. These results are attributed to the interpenetrating-phase architecture, stress-induced martensitic transformation in the ceramics, robust interfacial bonding, and high-density dislocations near the interfaces.

This study is about the electrodeposition of Ni-SiC composite coatings at various ultrasonic agitation temperatures (50, 55, and 60°C). The coatings were characterised by a scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Vickers microhardness test and immersion test were used to determine the hardness and corrosion behaviour of the composite coating respectively. The immersion test was conducted in 0.5M sulphuric acid to analyse the coating corrosion rate. The results demonstrate that increasing the ultrasonic agitation temperature increase the corrosion resistance of the composite coating. Furthermore, the hardness of the Ni-SiC shows higher hardness values at the highest agitation temperature, 60°C. This shows that Ni-SiC composite coating sample S.60 had the best hardness and corrosion behaviour.

In this study, TiC0.5N0.5–60 wt% W and TiC0.5N0.5–70 wt% W cermet cutting tool specimens consisting of Ti(C, N) core, W-rich Ti(C, N) rim, and W-based alloy phases with much higher strengths than conventional heat-resistant tool materials at temperatures above 1673 K were fabricated by spark plasma sintering, electric discharging, and polishing. The cutting performance characteristics of the cermet cutting tool specimens were then examined and compared with those of commercially available NX2525, JX1, and HTi10 cutting tool specimens when cutting S32750 super-duplex stainless steel round bars under dry condition at a cutting speed of 800 m/min. The NX2525, JX1, and HTi10 specimens were TiC–Ni-based cermet containing Mo, Nb, and Co, WC–Al2O3-based composites, and WC–Co cemented carbide, respectively. The TiC0.5N0.5–70 wt% W and TiC0.5N0.5–60 wt% W cermet cutting tool specimens exhibited the first and second longest lifetimes among all the noncoated cutting tool specimens. The lifetime of the TiC0.5N0.5–70 wt% W cermet cutting tool specimen was extended by coating it with TiAlN film by physical vapor deposition. In contrast, the TiC0.5N0.5–60 wt% W and TiC0.5N0.5–70 wt% W cermet specimens exhibited compressive strengths much higher than those of the NX2525, JX1, and HTi10 specimens at 1973 K, whereas all the specimens exhibited similar compressive strengths at room temperature.

In this study, the application of physical vapor deposition (PVD) coatings on various cermet substrates for the machining of nodular cast iron was investigated, given that cermet materials are traditionally not the primary choice for such applications. Through the evaluation of key parameters including wear on the flank face and surface roughness, and with vibration analysis serving as a supplementary measurement, it was discovered that machining stability is compromised by the inherent brittleness of cermet and the adhesion of material on the rake face. While the application of coatings was found to extend tool life, the cermet-coating combinations did not surpass the performance of other materials such as cemented carbide with multi-layer coatings. Notably, the stability of surface roughness across various stages of tool wear was observed. [ABSTRACT FROM AUTHOR]

This study is about the electrodeposition of Ni-SiC composite coatings at various ultrasonic agitation temperatures (50, 55, and 60°C). The coatings were characterised by a scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Vickers microhardness test and immersion test were used to determine the hardness and corrosion behaviour of the composite coating respectively. The immersion test was conducted in 0.5M sulphuric acid to analyse the coating corrosion rate. The results demonstrate that increasing the ultrasonic agitation temperature increase the corrosion resistance of the composite coating. Further-more, the hardness of the Ni-SiC shows higher hardness values at the highest agitation temperature, 60°C. This shows that Ni-SiC composite coating sample S.60 had the best hardness and corrosion behaviour. [ABSTRACT FROM AUTHOR]

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]

In this study, a TiC-Ti composite has been synthesized as a novel cermet without using rare elements like W, Co, and Ni. The mechanical properties of the prepared TiC-Ti composite are improved by utilizing Ti and C powders as raw materials in the mechanical alloying process. The effects of the non-equilibrium state during mechanical alloying on the characteristics of the composite have been analyzed. The results indicate that for short milling times, the addition of 25 mol% of C results in the Ti phase size in the sintered compact typically being on the order of several tens of micrometers, and unreacted C remains in the sample. A milling time of ≤21.6 ks affords a TiC-Ti composite containing approximately 80% fine TiC phase with an average size of 1–2 µm. As the milling progresses, the crystalline size of the Ti phase decreases, while the lattice strain increases. Prolonged milling improves the diffusion of C into Ti; a milling time of 36 ks at a low temperature of ~700 K results in the formation of TiC as well as uniform diffusion of C throughout the Ti phase. Sintering the composite powder milled for 36 ks affords a Vickers hardness of approximately 700 Hv, which is similar to that of a TiC-35% Ni cermet. [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]

Nickel oxide reduction kinetics and formation of the electric potential of anode-supported solid oxide fuel cell (SOFC) were studied using in situ Raman spectroscopy (RS) and conventional electrochemical techniques. It was shown that the time dependence of the electric potential and the intensity of the Raman spectra during anode substrate reduction can be conditionally divided into two stages. At the initial stage, in the first seconds after hydrogen supply, the open circuit voltage (OCV) quickly rises and stabilizes at a value of about 0.85 V. This stage is not accompanied by noticeable changes in RS. Then, there is a more gradual rise, requiring tens of minutes, to the OCV equilibrium value. The beginning of the second stage of the increase in the OCV coincides with a sharp change in the intensity of the specific spectral line in the Raman spectrum. An increase of the OCV in the first seconds after hydrogen supply is explained by an increase in the hydrogen concentration at the outer boundary of the SOFC anode. The sharp change in the intensity of the Raman spectrum, in turn, can be explained by the reduction of NiO to the metallic state in the near electrolyte region. In this work, a detailed reduction model of the NiO-YSZ (yttria-stabilized zirconia) cermet composite supporting substrate of an anode-supported SOFC was constructed. The model was developed on the assumption that the rate of the nickel oxide reduction reaction at each point of the sample depends only on the partial pressure of hydrogen, the fraction of oxidized nickel, and temperature. In the case of repeated reduction and at high temperatures, it can be assumed that the reaction has first-order kinetics, i.e., reaction rate is proportional to the fraction of oxidized nickel. At primary reduction and temperatures of 400–600 °C, the reaction is described by Avrami-Erofeev kinetics. [ABSTRACT FROM AUTHOR]

Magnesium alloys are very interesting engineering materials because of their high strength-to-density ratio. On the other hand, they are characterized by low hardness as well as low erosion resistance. Because of these reasons, their applications in the industry are very limited. The article presents the results of the high velocity oxy-fuel (HVOF) spraying of the hard cermet coatings onto AZ31 magnesium alloy substrate. Three feedstock powders were used in the process with composition (wt.%): WC-12Co, WC-10Co-4Cr and WC-20Cr3C2Ni. The spray distance (SD) was selected as a variable parameter with values equal to 320 and 400 mm. Observations carried out under a scanning electron microscope (SEM) revealed a typical HVOF-sprayed microstructure with a compact structure and low porosity (below 3 vol.%). The hardness of the manufactured coatings, ranging from 912 HV0.2 to 1328 HV0.2, what was significantly higher than the substrate. The solid particle erosion tests were carried out according to the ASTM G76-04 standard. Erosive experiments were done for 30°, 60° and 90° inclination angles of the nozzle using Al2O3 abrasive. Erosion tests confirm that cermets exhibit substantial erosion resistance better than the substrate. The highest erosion resistance was noted for WC-10Co-4Cr coatings. The erosion rate for cermet coatings was mostly below 0.9 mg/min, whereas for the AZ31 it was more than 1.5 mg/min. In the case of the average erosion value, it was between 12 and 22 times lower than for the substrate. Results analysis reveal that shorter spray distance decreases porosity, increases hardness, and finally supports erosion resistance of the cermets.

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]

AbstractCeramic uranium mononitride (UN) is being considered as a reactor fuel for nuclear thermal propulsion. To avoid or reduce the dissociation of UN at the high temperatures needed, embedding it in a metallic matrix (cermet) has been proposed. To assess the viability of this concept, hot hydrogen testing of tungsten-coated UN kernels embedded in a Mo-30 wt% W (Mo30W) alloy matrix has been performed at temperatures from 1800°C to 2300°C. Both the isolated kernels and kernels consolidated by spark plasma sintering in the Mo30W matrix were tested.In addition to direct observations and mass loss measurements, the samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS) after each run. The decomposition of UN started at 1800°C despite the coating and matrix, and increased at 2000°C. Uranium seeped through the tungsten grain boundaries of the coating at all temperatures. The consolidated sample expanded irregularly at 2000°C through the formation of voids, and SEM/EDS analysis showed uranium-containing veins in the matrix consisting of U2Mo according to the XRD data. The observed pore generation at 2000°C was explained by the formation of water vapor from residual oxides and diffused hydrogen. At 2200°C and above, both the kernels and the consolidated samples melted through the formation of uranium or low–melting point uranium-molybdenum alloys. [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]

We introduce a groundbreaking plasmonic metamaterial, the Nano-Hemisphere on Hyperbolic Metamaterial (NHoHMM), which involves the fabrication of Ag nano-hemispheres on a multilayered Ag/SiO2 structure, achieved solely through sputtering and heat treatment. Finite Difference Time Domain (FDTD) simulations unveil the intriguing slow propagation of the localized electric field, where light travels at only 1/40th of its usual speed within this structure. These simulations reveal distinctive sharp absorption peaks in the visible spectrum, attributed to surface plasmon resonance. In practical experiments, the NHoHMM structure, characterized by random Ag nano-hemispheres, exhibits broad absorption peaks spanning the visible range, rendering it a versatile broadband optical absorber. For comparison, the optical properties of the Ag nano-hemispheres on a nanocermet (NHoNC) structure were analyzed through simultaneous sputtering of Ag and SiO2 followed by heat treatment. Simulations employing effective medium theory and the transfer matrix method demonstrate variable optical properties dependent on the Ag filling ratio in the nanocermet structure. The results obtained differ from the spectra of the NHoHMM structure; thus, it is concluded that in the NHoHMM structure, the calculated multi-peaks are broadened due to the inhomogeneity of the nano-hemispherical structure's size, rather than the metal/dielectric multilayer structure being altered by the heat treatment. [ABSTRACT FROM AUTHOR]

Layered composite materials based on niobium and cermet are produced via the self-propagating high-temperature synthesis of preliminarily structured samples using metal foils (Ti, Nb, Ta, Ni) and reaction tapes (Ti + 1.7B) and (5Ti + 3Si). The reaction tapes for synthesis are produced by rolling powder mixtures. The microstructure, and elemental and phase compositions of the synthesized multilayer composite materials are studied by scanning electron microscopy and X-ray phase analysis. Particular attention is paid to the formation of intermediate layers and surface modification occurring during combustion. The strength characteristics of the synthesized materials are determined according to the three-point loading scheme at temperatures of 1100°C. Analysis of the obtained materials shows that joining in the combustion mode of metal foils and reaction tapes is provided due to reaction diffusion, mutual impregnation, and chemical reactions occurring in the reaction tapes and on the surface of the metal foils. The formation of thin intermediate layers in the form of cermet and eutectic solutions provides the synthesized multilayer materials with good strength properties up to 87 MPa at 1100°C. These results are of interest for the development of structural materials operating under extreme conditions. [ABSTRACT FROM AUTHOR]

Magnesium alloys are very interesting engineering materials because of their high strength-to-density ratio. On the other hand, they are characterized by low hardness as well as low erosion resistance. Because of these reasons, their applications in the industry are very limited. The article presents the results of the high velocity oxy-fuel (HVOF) spraying of the hard cermet coatings onto AZ31 magnesium alloy substrate. Three feedstock powders were used in the process with composition (wt.%): WC-12Co, WC-10Co-4Cr and WC-20Cr3C2Ni. The spray distance (SD) was selected as a variable parameter with values equal to 320 and 400 mm. Observations carried out under a scanning electron microscope (SEM) revealed a typical HVOF-sprayed microstructure with a compact structure and low porosity (below 3 vol.%). The hardness of the manufactured coatings, ranging from 912 HV0.2 to 1328 HV0.2, what was significantly higher than the substrate. The solid particle erosion tests were carried out according to the ASTM G76-04 standard. Erosive experiments were done for 30°, 60° and 90° inclination angles of the nozzle using Al2O3 abrasive. Erosion tests confirm that cermets exhibit substantial erosion resistance better than the substrate. The highest erosion resistance was noted for WC-10Co-4Cr coatings. The erosion rate for cermet coatings was mostly below 0.9 mg/min, whereas for the AZ31 it was more than 1.5 mg/min. In the case of the average erosion value, it was between 12 and 22 times lower than for the substrate. Results analysis reveal that shorter spray distance decreases porosity, increases hardness, and finally supports erosion resistance of the cermets. [ABSTRACT FROM AUTHOR]

This study has developed a surface modified titanium carbide (TiC)–titanium (Ti) composite for application in dry press working. This material was synthesized through mechanical alloying using Ti and graphite powder, followed by spark plasma sintering, and subsequently surface-modified via oxidation/carburization treatment. The oxidation/carburization behavior was investigated to determine the treatment conditions that formed a hard coating layer, and its wear resistance was evaluated. The activation energy for the isothermal oxidation of this composite material was 271 kJ/mol, with the rate primarily determined by the O and Ti diffusion in titanium dioxide (TiO2). In contrast, the activation energy for the growth of the carburized layer growth was 261 kJ/mol, with the rate determined by the carbon diffusion in TiC. The oxide film of the TiC–Ti composite material, oxidized by holding at 1073 K for 300 s, exhibited porous rutile TiO2 with a thickness of approximately 1.7 µm and hardness of 11 GPa. The carburized layer of the TiC–Ti composite material, carburized at 1073 K and held for 2400 s, had a thickness of approximately 3 µm and hardness of 20 GPa. During a wear test utilizing a stainless-steel pin as the mating material, stainless steel adhered to the surface of the unmodified sample. The oxidized sample experienced wear due to the peeling of the oxide film. However, the carbonized sample neither adhered to nor wore the mating material, suggesting that the carbonization treatment helps to improve the wear characteristics. This study offers valuable insights into the fabrication of TiC-based cermets as mold materials for realizing dry press working. [ABSTRACT FROM AUTHOR]

The main defect that occurs when using plows consists in the abrasive wear of ploughshares, whose highest wear level is observed in the toe part of a ploughshare. When restoring worn plowshares in order to increase their service life to a significant extent, it is worthwhile to use technical ceramics. A plowshare with soldered cermet plates has been chosen as the object for investigations. The proposed investigation methodology has involved the testing of plate adhesion, as well as bench and operational testing of experimental plowshares in comparison with serial ones. It has been established that the proposed type of joints between cermet plates and ploughshare has a high reliability level and can withstand a 3.8 to 4.9-fold excess with respect to design loads. As a result of the studies, a new resource-saving technology has been developed for the restoration and hardening of ploughshares by means of soldering with the use of a hydrogen-oxygen flame, which makes it possible to provide a 2 to 3-fold increase in the service life, as well as a 30–35% decrease in costs, instead of purchasing new serial ploughshares owing to applying a cheap hydrogen-oxygen gas mixture. [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%.

During the hot dip aluminum plating process, components such as sinking rollers, pulling rollers, and guide plates will come into long-term contact with high-temperature liquid aluminum and be corroded by the aluminum liquid, greatly reducing their service life. Therefore, the development of a material with excellent corrosion resistance to molten aluminum is used to prepare parts for the dipping and plating equipment and protect the equipment from erosion, which can effectively improve the production efficiency of the factory and strengthen the quality of aluminum-plated materials, which is of great significance for the growth of corporate profits. With AlFeNiCoCr as the binder phase and ZrB2 as the hard phase, ZrB2-based ceramic composites were prepared by spark plasma sintering (SPS). SEM, EDS and XRD were used to characterize the microstructure and properties of the sintered, corroded, and abraded material samples. The density, fracture toughness, corrosion rate and wear amount of the composite material were measured. The results show that ZrB2-AlFeNiCoCr ceramics have compact structure and excellent mechanical properties, and the density, hardness and fracture toughness of ZrB2-AlFeNiCoCr increase with the increase in sintering temperature. However, when the composite material is at 1600 °C, the relative density of the sintering at 1600 °C decreases due to the overflow of the bonding phase. Therefore, when the sintering temperature is 1500 °C, the high entropy alloy has the best performance. The average corrosion rate of ZrB2-1500 at 700 °C liquid aluminum is 1.225 × 10−3 mm/h, and the wear amount in the friction and wear test is 0.104 mm3.

This paper describes the compounds of refractory metal foils (Ti, Hf, Ta, and Ni) with ceramic layers formed as a result of combustion of reaction tapes rolled from Ti + 0.65C, Ti + 1.7B, and 5Ti + 3Si powder mixtures. Scanning electron microscopy and X-ray diffraction analysis are applied to study the microstructure, elemental composition, and phase composition of multilayer composites obtained by self-propagating high-temperature synthesis. The effect of synthesis conditions (initial temperature and applied pressure) and the initial structure of the samples on various parameters (combustion wave front propagation velocity, microstructure, phase composition, and strength properties) of the resulting layered materials is revealed. It is shown that compounds of metal foils and reaction tapes rolled from powder mixtures during combustion are ensured due to reaction diffusion, mutual impregnation, and chemical reactions occurring in the reaction tapes and on the surface of metal foils. The strength properties of the resulting materials (up to 275 MPa at 25°C and up to 72 MPa at 1100°C) are determined using a three-point loading scheme. The results of this study can contribute to the development of structural materials operating under extreme conditions. [ABSTRACT FROM AUTHOR]

The article assesses the effectiveness of turning polymeric materials with ceramic cutting tools. It is experimentally proven that turning caprolon and fluoropolymer using a cutting tool insert made of KNT16 cermet results in higher quality of the machined surface. The roughness parameters of a surface machined with a cermet cutting insert are lower than when turning with an insert made of VK8 tungsten–cobalt alloy, and the chips formed are of a different type. [ABSTRACT FROM AUTHOR]

The dependence of the heat resistance of tool materials on the melting point or the solid-state phase transition point is shown. The maximum permissible heating temperatures for these materials and the influence of these temperatures on the metal and ceramic phases are established and substantiated. High-potential compositions of metal phases of cermets are presented. [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]

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]

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]

The study reveals that the structure of Cr2O3–22 wt % Cr cermet, obtained from a mixture of chromium oxide and chromium by spark plasma sintering at a temperature of 1520°C and a pressure range of 40–300 MPa, consists of a chromium oxide matrix with globular 0.5- to 20-μm Cr inclusions, comparable in size to the particles of the initial mixture. At pressures ranging from 300 to 800 MPa, elongated inclusions appear in the structure, the concentration of which increases with the rise in pressure during spark plasma sintering, leading to a decrease in globular grain size. The cermet exhibits maximum Vickers hardness and crack resistance values, determined by the Palmqvist method at 20.2 GPa and 7.6 MPa m1/2, respectively. Its stability under intermittent dry cutting with 9Kh12F steel (HRC 58–60) is comparable to ceramics based on Al2O3–TiC from Sandvik Coromant (Sweden). [ABSTRACT FROM AUTHOR]

Fabrication of W- and Co-free wear-resistant cermets is a vital task in modern machinery due to the toxicity of Co-based products and poor availability of Co and W containing raw materials. In this paper, a TiC-NiMo coating produced by laser-directed energy deposition (L-DED) on a Ti-6Al-4V substrate was demonstrated. Mechanical alloying of TiC, Ni and Mo powders followed by spray-drying was proposed to fabricate a feedstock spherical composite powder suitable for an L-DED machine. It was shown that this method is more applicable in the case of a TiC-containing composition than gas atomization and plasma spheroidization methods. The size of the resulting particles was in the range of 10–100 μm while the size of the 70 vol.% was in the range of 45–75 μm. L-DED provided a good adhesion of the coating, though the presence of pores and transverse cracks was also observed. The coating's hardness was up to 1500 HV, which is not inferior to the hardness of known TiC-based cermets and is promising for obtaining a good wear resistance of the coating. It was shown that it depended on the thickness due to the mixing zone influence. The coating structure contained TiC- and Mo-based precipitates and a Ni-based binder. The weight loss of the coating samples after an abrasive wear test with 4000 revolutions of a testing wheel was 0.0464 g and that can be considered insignificant. The wear did not lead to the appearance of new defects and cleavage of the coating. Further optimization of the component ratio and L-DED parameters could help to improve the performance of the coating and make this technology rather promising to improve the wear resistance of machinery parts working in high-wear environments. [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]

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]

In order to improve the microstructure and mechanical properties, the hot compressive deformation with 50% height reduction at 1100·C was conducted on a Ti2C-Ti cermet. The results showed that the lamellar Ti precipitates in Ti2C grains were transformed to bimodal size distribution, which was approximately 290 nm and 5.8 μm in diameter, respectively, after the hot deformation. The bimodal Ti precipitates suppressed {011} cleavage surfaces of Ti2C during flexural fracture, which resulted in an 18.5% increment of strength. This phenomenon can be attributed to the bimodal Ti precipitates that decreased the average crack driving force due to their gentle variation in elastic modulus compared with the monolithic lamellar Ti precipitates. The present work can guide further deformation and mechanical property improvement of Ti2C cermets. [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]

Metamaterial absorbers over a broadband spectrum with high absorption, good angular tolerance, and easy configurations have essential importance for optical and optoelectronic devices. In this study, a hybrid metamaterial absorber comprising multilayered cermet thin films (multi-cermet) with tapered structure is designed and experimentally demonstrated. Combining optical interference of multi-cermet films and optical field localization of nano-cone structures, the average absorbance of both simulation and measurement are more than 98% in an ultrabroad bandwidth (300–3000 nm), and the proposed absorber shows a good angular tolerance as well. The composite process of two easy-operated and efficient methods, colloidal lithography, and magnetron sputtering, is employed for large-area fabrication. In addition, owing to flexible polyimide substrate, the proposed absorber also shows good bending and heating resistance, which reflects its potential in engineering application.

We introduce a groundbreaking plasmonic metamaterial, the Nano-Hemisphere on Hyperbolic Metamaterial (NHoHMM), which involves the fabrication of Ag nano-hemispheres on a multilayered Ag/SiO2 structure, achieved solely through sputtering and heat treatment. Finite Difference Time Domain (FDTD) simulations unveil the intriguing slow propagation of the localized electric field, where light travels at only 1/40th of its usual speed within this structure. These simulations reveal distinctive sharp absorption peaks in the visible spectrum, attributed to surface plasmon resonance. In practical experiments, the NHoHMM structure, characterized by random Ag nano-hemispheres, exhibits broad absorption peaks spanning the visible range, rendering it a versatile broadband optical absorber. For comparison, the optical properties of the Ag nano-hemispheres on a nanocermet (NHoNC) structure were analyzed through simultaneous sputtering of Ag and SiO2 followed by heat treatment. Simulations employing effective medium theory and the transfer matrix method demonstrate variable optical properties dependent on the Ag filling ratio in the nanocermet structure. The results obtained differ from the spectra of the NHoHMM structure; thus, it is concluded that in the NHoHMM structure, the calculated multi-peaks are broadened due to the inhomogeneity of the nano-hemispherical structure’s size, rather than the metal/dielectric multilayer structure being altered by the heat treatment.

A mathematical model was developed to determine the order of failure of layers in a two-layer ceramics composite and to determine the conditions for achieving the maximum limit load under three-point loading. The model was set in the space of three "bilayer parameters": the ratio of the thickness of the lower layer to the whole thickness of the beam, the ratio of Young's moduli of the lower layer to the upper layer, and the ratio of flexural strengths of the materials of the lower layer to the upper layer. The adequacy of the model obtained was confirmed by experimental results on the three-point bending of the experimental specimens. The experimental samples were two-layer composites consisting of a cermet layer TiB/Ti and a layer of α-Ti. The samples were obtained by free self-propagating high-temperature synthesis (SHS) compression and with varying their thickness. The results obtained make it possible to predict in advance which layer, based on the specific bilayer parameters, will trigger the brittle fracture mechanism as well as to set the maximum destructive load of bilayer composites. [ABSTRACT FROM AUTHOR]

In this paper, we propose a simple approach consisting in the use of a coating layer on a commercial SOFC in order to increase its fuel flexibility. Using the same CO 2 -laser-cut cell, we compared the I–V curves and impedance spectra (EIS) of four experiments. Three different ceramics (NiCu-CGO, NiFe-CGO, and NiCo-CGO) were evaluated as protective layers for cells fed with dry biogas or bioethanol, with the goal of determining which layer would be most promising. Electrochemical experiments revealed that an additional layer adds resistance to the cell, which negatively affects its performance. A slight decrease in maximum performance was observed when the coated cells were fed H 2. However, power density was not significantly different from the bare cell at potentials between 0.7 and 0.8 V, which provide a trade-off between performance and voltage efficiency. Additionally, such an approach improved the effectiveness of cells in using simulated biogas and ethanol as demonstrated by I–V curves and EIS analysis. As shown in the test results, NiCo-CGO provided the highest power density of 0.56 W cm−2 at 0.6 V. However, all the cells with protective layers performed significantly better than the bare cell in the dry biofuel tests. [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]

In parabolic trough technology, the development of thermally and structurally stable solar coatings plays a key role in determining the efficiency, durability, and economic feasibility of tube receivers. A cermet-based solar coating is typically constituted by a thin film stratification, where a multilayer graded cermet is placed between an infrared metallic reflector and an antireflection filter. This work reports the realization of materials based on Al2O3 and W characterized by high structural and chemical stability in vacuum at high temperature, obtained through the optimization of high-deposition-rate processes. Al2O3 material, employed as the antireflection layer, was deposited through a reactive magnetron sputtering process at a high deposition rate. Cermet materials based on W-Al2O3 were deposited and employed as absorber layers by implementing reactive magnetron co-sputtering processes. An investigation into the stability of the realized samples was carried out by means of several material characterization methods before and after the annealing process in vacuum (1 × 10−3 Pa) at high temperature (620 °C). The structural properties of the samples were evaluated using Raman spectroscopy and XRD measurements, revealing a negligible presence of oxides that can compromise the structural stability. Spectrophotometric analysis showed little variations between the deposited and annealed samples, clearly indicating the high structural stability.