Hard Matrix Research Articles

Strengthening cemented carbides by activated nano TaC

In this study, activated nano TaC was introduced into WC-Co cemented carbides to enhance their comprehensive performance properties. Changes of mechanical properties, elements distributions, phase constitutions and microstructures of the cemented carbides were examined as a function of TaC amount. It was found that due to the addition of activated nano TaC, nanoscale Co-rich particles and cubic-Ta4C3 precipitates were induced and dispersed within WC grains, which had good coherent interfacial relationship with the hard matrix. The combined strengthening effects of the nano precipitates and solid solution in WC resulted in excellent comprehensive mechanical properties of the cemented carbides. Particularly, the rupture strength has achieved the highest among those of the counterparts reported in the literature so far. This study opens a new perspective to use activated nano compound particles to modulate hard phases of cermet materials for high comprehensive performance.

Gas tungsten arc welding alloying of AISI 409 M steel with WC-10Co-4Cr powder to enhance the 3-body wear resistance

In order to improve the hardness and mechanical properties of AISI 409 M Martensitic stainless steel (MSS), WC-10Co-4Cr hard carbide matrix powder was deposited by gas tungsten arc welding (GTAW) alloying. The alloying was done by applying welding current of 200 Amp and welding speed of 9.68 mm/s. The heat input in the welding process was 111.57 J/mm. The characterization of the alloyed AISI 409 M steel and WC-10Co-4Cr powder was assessed by X-Ray Diffraction. The microstructure of AISI 409 M steel was investigated by optical microscope. The hardness of alloyed AISI 409 M and AISI 409 M steel was measured by Rockwell hardness tester and found to be 42 HRC and 6 HRC respectively. The wear studies of alloyed AISI 409 M and AISI 409 M steel was done on 3-body abrasive wear equipment. It was found that the cumulative weight loss of alloyed AISI 409 M is 43.26% less than by AISI 409 M steel, which is due to, enhanced hardness of alloyed AISI 409 M steel. The worn and bare surface was observed by scanning electron microscope and surface profile-meter.

The impact of high current pulses electron beam on the microstructure and surface properties of Sn/Al system

The purpose of this paper was to investigate surface alloying of Sn/Al system by high current pulses electron beam (HCPEB) irradiation. As a result, Sn covered on the surface and the formation of large size craters caused the increasing of surface roughness at the early stage of repeated pulsed irradiation. Subsequently, increasing pulsed irradiation led to the dissolution of Al and Sn together with elimination of craters forming a smooth allying layer with low surface roughness. On the topmost layer of alloying layer in Sn/Al system was the remelted layer with uniformly distributed ultrafine Sn particles. The beneath was diffused layer consisting of abundant structure defects, in the vicinity of which were separated out a large number of Sn particles. The microhardness was increased to about 0.82 GPa in the alloying layer after 35-pulsed samples. The tribological property was enhanced by HCPEB irradiation that induced the refinement of Sn particles and the formation of hard matrix.

Enhancement of tribological and thermo-mechanical properties of phenolic resin friction composites by improving interactions between elastomeric phase and matrix resin

New elastomer-modified brake friction composites with the identical composition, but differing in the type of rubber, were developed by altering polar/non-polar elastomeric phases into the phenolic resin matrix. Effect of dispersion and interaction of the polar/non-polar rubbers with the matrix resin on dry sliding wear characteristics of the friction composites was investigated using a laboratory-scale pin-on-disc tribometer. The composites were prepared by hot mixing followed by compression molding and post-curing at a high temperature. Coefficient of friction (COF) and specific wear rate of the composites sliding against a cast-iron disc were measured and analyzed. Polar acrylonitrile-butadiene rubber (NBR, both powder, and bale rubber), and non-polar styrene-butadiene rubber (SBR) and ethylene-propylene-diene monomer (EPDM) were used with the phenolic resin where rubber islands and its polarity played the key role in delayed stress dissipation, while the hard matrix phase contributed to the intrinsic strength of the composites. This work describes how the distribution and interaction of polar and non-polar rubbers with the matrix resin influence the performance of brake friction composites. NBR (powder)-phenolic composite showed the highest stable average COF of 0.52 as compared to 0.36 for EPDM-based composite. NBR (powder)-based composite also exhibited ~1.5 times better specific wear rate (4.9 × 10−3 mm3 N−1 m−1) than EPDM-based composite (7.2 × 10−3 mm3 N−1 m−1). However, EPDM rubber-based composite showed a significant enhancement in thermal conductivity (0.43 W/m K). Morphological analyses revealed that the dispersion of rubber phase in phenolic matrix played a significant role in transforming the wear mechanism from abrasive to adhesive.

Microstructure and fatigue crack growth behavior in welding joint of Al-Mg alloy

In this paper, the microstructure and fatigue crack growth behavior of Al-Mg alloy welding joint by metal inert-gas welding (MIG) were studied by means of metallographic microscope, scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). The results show that the welded joint is characterized by obvious heterogeneous microstructure. The weld zone is dominated by equiaxed cellular dendritic crystals, with a small amount of welding bubbles and microcracks. The position of welding joint with bubble, grain boundary, interface between hard phase particles and matrix, and hole of coarse impurity particles debonded tend to generate fatigue crack origins, and further develop into the main crack. Due to the influence of stress state, grain orientation, welding bubble and coarse phase particle, the fatigue crack propagation in the weld zone will appear deflection, bifurcation, convergence, bridging connection and other path choices, which will affect the direction and rate of fatigue crack propagation.

Multi-functional flexible 2D carbon nanostructured networks

Two-dimensional network-structured carbon nanoscale building blocks, going beyond graphene, are of fundamental importance, and creating such structures and developing their applications have broad implications in environment, electronics and energy. Here, we report a facile route, based on electro-spraying/netting, to self-assemble two-dimensional carbon nanostructured networks on a large scale. Manipulation of the dynamic ejection, deformation and assembly of charged droplets by control of Taylor cone instability and micro-electric field, enables the creation of networks with characteristics combining nanoscale diameters of one-dimensional carbon nanotube and lateral infinity of two-dimensional graphene. The macro-sized (meter-level) carbon nanostructured networks show extraordinary nanostructural properties, remarkable flexibility (soft polymeric mechanics having hard inorganic matrix), nanoscale-level conductivity, and outstanding performances in distinctly different areas like filters, separators, absorbents, and wearable electrodes, supercapacitors and cells. This work should make possible the innovative design of high-performance, multi-functional carbon nanomaterials for various applications.

Thermal conductivity and thermal shock resistance of TiB2-basedUHTCs enhanced by graphite platelets

TiB2-SiC-C and TiB2-TiC-C heteromodulus ceramics were sintered by reactive hot pressing of TiC-B4C-Si and TiC-B4C precursors at 1830 °C and 30 MPa. Sintering time at the maximum temperature was between 2 and 8 min. The reactions in TiC-B4C-Si green body create submicron (100–400 nm) TiB2 crystals inside silicon carbide grains as well as BxSiyCz nanofibers, which nucleate near SiC surfaces. Low hardness graphite platelets are formed within the hard matrix during the in-situ exothermic reaction. “Soft-hard” grain combination produces substantially improved fracture toughness (up to 9 MPa m1/2). The materials also demonstrate high thermal conductivity (up to 120 W/m∙K) and high thermal shock resistance. The thermal shock crack growth is arrested by the graphite platelets.

Development of models for estimating specific energy and specific wear rate of circular diamond saw blades based on properties of carbonate rocks

This paper presents an experimental study to assess the effects of physical and mechanical properties of carbonate rocks and diamond/metal matrix characteristics on performance and tool life of segmented circular sawblades. For this purpose, pertinent rock properties including strength, hardness, abrasivity, water absorption, porosity and unit weight were measured by laboratory tests and compiled into a database for subsequent analysis. The testing program including using six commercially available sawblades with different segment compositions in full scale tests. The related characteristics of the sawblades were diamond concentration, Vickers hardness of the hard facing matrix, mean diamond grain size, cobalt, tin, copper, and ferrous content. Thirteen different carbonate rocks including marble, limestone, and travertine samples from various sites in Turkey were used in the experimental program. The experimental data was analysed by multiple linear and nonlinear regression analysis to develop models for estimation of specific energy (SE) and specific wear (SW) rates using rock properties and sawblades segment parameters. The proposed models were validated by comparing the results of their prediction with those of actual test results and showed good agreements. The concept of optimum total (cutting) cost (OTC) estimation for natural stone cutting is also discussed in the context of estimating sawblade wear life.

PVD Coated Tools and Surface-Structured Workpieces in Dry Cold Forming of Steel

Cold forming, particularly forward impact extrusion, is used for mass production of steel components. To ensure robust forming processes, the workpieces are usually phosphated and then soaped as well as mineral oil-based lubricants are used. As these lubricants are often harmful to the environment and health, alternative approaches are to be investigated from an ecological, economic and legislative perspective. To achieve dry, lubricant-free cold forming of steel, two approaches are being pursued here. The tool-sided approach focuses on self-lubricating hard coatings, which are deposited on the forming tools by means of physical vapor deposition (PVD). The developed coating system CrAlN+Mo:S is synthesized in an industrial coating unit by a hybrid sputtering process, which combines direct current (DC) and high power pulsed magnetron sputtering (HPPMS) technology. The coating consists of a hard matrix CrAlN which is modified by Mo and S to provide friction reduction due to the in situ formation of MoS2 reaction layers under tribological load. The workpiece-sided approach focuses on the surface structuring by shot peening with various peening materials and particle shapes. In order to evaluate the influence of the self-lubricating tool coating CrAlN+Mo:S and the various workpiece topographies, dry full forward impact extrusion tests were carried out in an industrial scale with coated and uncoated tools. On the one hand, a one-shouldered die geometry and on the other hand a two-shouldered die geometry were tested. The field trials reveal that for both die geometries, the tool coating significantly reduces the punch force and the wear compared to the uncoated dies. Depending on the workpiece topography, it was shown that a smoother surface leads to reduced adhesive wear. Furthermore, it was proven that the dies with an opening diameter of D = 31.4 mm and an outlet diameter of d = 20.7 mm could be coated continuously over a length of l = 50 mm on the entire inner surface. After the dry field trials, the CrAlN+Mo:S coating remained completely intact. Hence, the developed coating system CrAlN+Mo:S exhibits great potential to conduct dry, lubricant-free cold forming of steel at industrial scale.

Mechanism of cementite decomposition in 100Cr6 bearing steels during high pressure torsion

Severe plastic deformation leads to cementite decomposition in pearlitic and martensitic alloys, resulting in high-strength nanocrystalline ferrite. This effect can be employed to strengthen pearlitic wires but it can also be associated with material failure by white etching cracks (WECs) that are primarily known to concern bearings or rails. We investigate the decomposition of spheroidal cementite in the martensitic bearing steel 100Cr6 with 62 Rockwell hardness during high pressure torsion at 9.5 GPa applied pressure. The hard martensitic matrix and the even harder spheroidal cementite precipitates behave plastically very differently. The enforced macroscopic plastic deformation is almost entirely carried by the matrix. Plastic material flow of the matrix around the spheroidal cementite leads to wear of the spheroidal cementite as indicated by continuously increasing levels of chromium in the matrix. Plastic deformation of spheroidal cementite via dislocation gliding supposedly accelerates this process as slip steps generated thereby are preferential sites of wear at the matrix/cementite interface. Larger spheroidal cementite precipitates are more prone to plastic deformation and to decomposition than smaller ones. The mechanism likely holds true in general for multiphase materials with large strain difference between phases subjected to high pressure torsion. Although the formation of WECs in 100Cr6 bearings might be slowed down by reducing the size of the spheroidal cementite precipitates, it is unlikely that this could entirely prevent this failure mechanism.

Optimized ion-conductive pathway in UV-cured solid polymer electrolytes for all-solid lithium/sodium ion batteries

Solid electrolyte-based lithium-ion batteries (LIBs) have enormous potential to replace conventional LIBs with flammable liquid electrolytes. However, most solid electrolytes show low ionic conductivity and poor interfacial properties with electrodes, preventing them from reaching the level of conventional liquid electrolyte systems with separators. Herein, we optimized the formation of an ion-conductive pathway in a UV-cured solid polymer electrolyte (USPE) via a semi-interpenetrating polymer network with a minimal liquid content. The USPE consists of a UV-curable hard matrix (trimethylolpropane ethoxylate triacrylate, ETPTA) as a backbone film with negligible ionic conductivity and an optimized ionic channel with an ion-solvated gel polymer (Li+/PVdF-HFP) with a minimal liquid content for boosting the Li+ conduction. The hybrid solid-state film provides high ionic conductivity (up to 85%) relative to commercial liquid electrolyte systems and a stable electrochemical window. We also applied the same USPE with Na+ for solid electrolyte-based sodium ion batteries, and similar positive effects were also observed. Going another step forward, both the PVdF-HFP/ETPTA ratio and the HFP content in the PVdF-HFP are critical gel polymer additives for generating reinforced Li+ ion pathways in USPE.

High temperature tribological properties of YSZ/AgTaO3 sol-gel nanocomposite coatings

Composite coatings whereby soft and lubricious phases were embedded in a hard matrix displayed considerable enhancement in their mechanical and tribological properties that include frictional response, wear resistance, and material toughness. In the current study, composite coatings of a yttria-stabilized zirconia (YSZ) matrix embedded with different contents of AgTaO3 particles (0–30 wt%) were prepared by a sol-gel process and subsequently deposited on Inconel 718 substrates using the spin coating technique. X-ray diffraction (XRD) measurements indicated the presence of YSZ in the cubic phase and of AgTaO3. The tribological properties of the coatings were evaluated at 25 and 650 °C against an alumina (Al2O3) ball using a 2 N load. AgTaO3 was found to significantly enhance the coatings’ wear and friction properties especially at 650 °C. The addition of this high temperature solid lubricant was found to decrease the steady state friction coefficient from 0.65 to 0.18 and the wear rate from 7 × 10−5 mm3/nm to 6 × 10−6 mm3/nm for YSZ-30 wt%AgTaO3. Scanning electron microscopy (SEM) provided information about the surface topography and the elemental composition of the coatings before and after wear testing. SEM images suggested that an increase in AgTaO3 content resulted in the formation of a continuous film of this solid lubricant over an underlying YSZ-based coating. This continuous film provided better wear protection to the composite coating. These observations provide insights useful for developing composite coatings using the sol gel method and that display tunable tribological properties depending on the intended applications.

Stage-specific expression patterns of ER stress-related molecules in mice molars: Implications for tooth development

The endoplasmic reticulum (ER) is a site where protein folding and posttranslational modifications occur, but when unfolded or misfolded proteins accumulate in the ER lumen, an unfolded protein response (UPR) occurs. A UPR activates ER-stress signalling genes, including inositol-requiring enzyme-1 (Ire1), activating transcription factor 6 (Atf6), and double-stranded RNA-activated protein kinase-like endoplasmic reticulum kinase (Perk), to maintain homeostasis. The involvement of ER stress molecules in metabolic disease and hard tissue matrix formation has been established; however, an understanding of the role of ER-stress signalling molecules in tooth development is lacking. The aims of this study are to define the stage-specific expression patterns of ER stress-related molecules and to elucidate their putative functions in the organogenesis of teeth. This study leverages knowledge of the tissue morphology and expression patterns of a range of signalling molecules during tooth development. RT-qPCR, in situ hybridization, and immunohistochemistry analyses were performed to determine the stage-specific expression patterns of ER-stress-related signalling molecules at important stages of tooth development. RT-qPCR analyses showed that Atf6 and Perk have similar expression levels during all stages of tooth development; however, the expression levels of Ire1 and its downstream target X-box binding protein (Xbp1) increased significantly from the cap to the secretory stage of tooth development. In situ hybridization results revealed that Atf6 and Xbp1 were expressed in cells that form the enamel knot at cap stage and ameloblasts and odontoblasts at secretory stage in stage-specific patterns. In addition, Atf6, Ire1, and Xbp1 expression exhibited distinct localization patterns in secretory odontoblasts and ameloblasts of PN0 molars. Overall, our results strongly suggest that ER-stress molecules are involved in tooth development in response to protein overload that occurs during signaling modulations from enamel knots at cap stage and extracellular matrix secretion at secretory stage.

An effort towards hard and tough coatings by cathodic arc deposition of Zr-Cr-O coating system

A new coating system of Zr-Cr-O in which tetragonal ZrO2 acts as toughening agent and Cr2O3 can act as stabilizer and hard matrix was proposed. The coatings were obtained by cathodic arc deposition of Zr and Cr in gas mixture of oxygen and argon. Pure ZrO2 coatings were also deposited as control group to verify the stabilizing effect of Cr in tetragonal ZrO2. Various substrate biases were applied to modify the properties of the coatings. The result showed that monoclinic phase dominated in pure ZrO2 coating, whereas only tetragonal phase can be detected in ZrO2 coating with low Cr content. Increasing of Cr content resulted in more and more amorphous phase until crystal Cr2O3 was obtained when Cr content was higher than 90.27%. The phase composition was also affected by substrate bias. It was found that tetragonal phase in pure ZrO2 was destroyed when substrate bias was applied, whereas tetragonal phase in Cr-doped ZrO2 was very stable, and the crystallinity of the co-deposited coatings was enhanced by substrate bias. The hardness of the coatings was affected by composition, substrate bias and crystallinity. It was regretful that Cr doped t-ZrO2 coatings showed relatively low hardness due to high amount of amorphous phase. However, a remarkable plastic deformation capability was found in all the co-deposited coatings, and the coating with high Cr content and high bias voltage exhibited relatively high hardness, H/E and plastic deformation.

High-performance CoSbS-based Na-ion battery anodes

CoSbS and its hard carbon-containing nanocomposite (CoSbS@hard-C) are prepared via simple solid-state reactions, and their potential as Na-ion battery (NIB) anode materials is investigated. The electrochemical phase change mechanism of CoSbS during Na insertion/extraction is thoroughly investigated using various ex situ analytical tools. During Na insertion, the CoSbS undergoes a topotactic transformation owing to the formation of a NaxCoSbS (x ≤ 1.6), and then, it is converted into Na3Sb, Na2S, and Co in the fully Na-inserted state via a conversion reaction. Conversely, during Na extraction, Na3Sb transforms to Sb, which alloys with Co to form CoSb. In the fully Na-extracted state, CoSb and S from Na2S are recombined into CoSbS. Owing to the interesting reaction mechanism of CoSbS, the electrochemical performance of the CoSbS and CoSbS@hard-C anodes is excellent. Specifically, when CoSbS is used as a NIB anode, the topotactic transformation between CoSbS and NaxCoSbS (x ≤ 1.6) leads to stable cycling behavior of the NIB and a volumetric capacity of ~480 mAh cm−3 is retained after 100 cycles. Additionally, the NIB with the CoSbS@hard-C anode presents highly reversible and stable capacity (~570 mAh cm−3 after 150 cycles) and fast rate capability (~500 and ~450 mAh cm−3 at 2C and 5C, respectively), which can be attributed to the presence of uniformly dispersed small (5–8 nm) CoSbS nanocrystallites in the hard carbon matrix. Therefore, CoSbS can be utilized as a new anode material for high-performance NIBs.

Research of Subsurface Damage Depth of Lithium Niobate Crystal by Fixed-Abrasive Lapping

The subsurface damage depth of optical material introduced by lapping determines the efficiency of lapping and polishing process. In order to explore the subsurface damage (SSD) of fixed-abrasive lapping process, angle polishing method was employed to evaluate the SSD depth and damage form of soft-brittle material lithium niobate (LN) crystal. The influences of the grit size, the applied load and the hardness of pad matrix on SSD were investigated experimentally. The results show that: with the grit size decreasing form W28 to W14, the damage depth decreases by 70%. With the applied load decreasing form 15 kPa to 7 kPa, the SSD decreases by 40%. The dense and deep subsurface micro-cracks are caused by the hard matrix pad during lapping processing, while the matrix with low hardness causes plastic scratches on the surface/subsurface of the workpiece without obvious micro-cracks around the scratches. This study affords effective method for SSD evaluation and control of soft brittle materials such as LN crystal.

Effect of microstructural damage on the mechanical properties of silica nanoparticle-reinforced silicone rubber composites

Many experiments have apparently shown that hard nanoparticle-reinforced elastomer matrix composites have not only an improved loading bearing capacity but also a good flexibility. The microscopic damage mechanism and its effect on the mechanical properties of such composites are systematically investigated in this paper by both tensile and tear experiments on nano-silica-particle reinforced silicone rubber composites, in which not only the case of surface unmodified nano-silica particles but also that of surface modified nano-silica particles is considered. It is found that both the ultimate strength and toughness of both composites increase monotonically with an increasing weight fraction of nanoparticles. The improved strength and toughness of silicone rubber composites reinforced by surface unmodified nanoparticles are attributed to the blocking effect of micro-sized agglomerations on crack propagation and the weak interface debonding between agglomerations and matrix, respectively. As for the composites with surface modified nanoparticles, not only the filler-blocking effect but also the strong interface between fillers and matrix is responsible for the remarkable strengthening, while the improved toughness is attributed to the crack-pinning and interface debonding around fillers. Another interesting finding is that, with the increase of nanoparticle fractions, formation of the main crack in both composites is firstly inhibited by the filler-blocking effect, and then re-activated by micro-crack coalescences. As a result, the final fracture elongation changes from increase to decrease when the nanoparticle fraction is beyond a critical value. The results in the present paper disclose different microscopic mechanisms that influence the strength and toughness of silicone rubber-based composites reinforced by surface unmodified and modified nanoparticles, which is helpful not only for the understanding of mechanical performance of nanoparticle-reinforced flexible elastomer composites, but also for the design of novel flexible composites with matching strength and toughness.

Dynamic self-stiffening in polyacrylonitrile/thermoplastic polyurethane composites

In this study, the self-stiffening under cyclic dynamic strain has been observed in polymeric blends containing polyacrylonitrile (PAN) and various contents of thermoplastic polyurethanes (TPU). The increase of the stiffness depends on the phase diagram of the blend, and it was found that the efficiency of self-stiffening decreases when phase separation occurs. Also, TPU containing alternative hard and soft blocks. When the hard block content in TPU increases, the self-stiffening becomes more effective. The interactions between PAN and TPU were investigated by different characterization methods. The soft and hard blocks of TPU plays different roles on the self-stiffening of the PAN/TPU blends, and the interface in between hard blocks and PAN matrix is crucial for the mechanical enhancement. These results indicate that the interface in between polymer chains with significant property difference could possibly lead to unique behaviors. Here, we observe that the fatigue life of PAN films under cyclic strains increases to more than 28 times, as well as the cyclization peak shifts to lower temperature and becomes broader with the addition of 0.5 wt % TPU. These interfaces induced unique behaviors, such as self-stiffening and longer fatigue life, would be valuable for the future developments of adaptable structural materials.

Synthesis of all equiatomic five-transition metals High Entropy Carbides of the IVB (Ti, Zr, Hf) and VB (V, Nb, Ta) groups by a low temperature route

The six possible equiatomic five-transition metal High Entropy Carbides (HECs) of the IVB (Ti, Zr, Hf) and VB (V, Nb, Ta) groups of the periodic table, i.e., TiZrHfVNbC5, TiZrHfVTaC5, TiZrHfNbTaC5, TiZrVNbTaC5, TiHfVNbTaC5 and ZrHfVNbTaC5, were successfully obtained via a powder metallurgy route at room temperature, specifically, by one-step diffusion mechanosynthesis starting from the elemental constituents (using graphite as the carbon source). Three of those HECs, TiZrHfVTaC5, TiZrVNbTaC5 and ZrHfVNbTaC5, were developed for the first time. Their development was possible without any subsequent thermal treatment, in contrast to the usual way (reactive sintering at 1800–2200 °C), and in a powder form, make them potential advanced raw ceramics for hard, refractory and oxidation resistance coatings or matrix phase composites.

Sintering and characterization of a hard-to-hard configured composite: Spark plasma sintered WC reinforced α−SiAlON

In this study, a composite comprising WC particulate-reinforced α−SiAlON was fabricated by spark plasma sintering (1750 °C/40 MPa/25 min) in order to develop a hard-to-hard phase configuration and to toughen the hard matrix through particulate reinforcement. Irrespective of the composition, the sintered samples were almost theoretically dense. The nature of the overall sintering process for the composite appeared to be guided by the liquid phase sintering of the SiAlON phase. Microstructural analyses using scanning and transmission electron microscopy indicated the presence of both equiaxed and elongated α−SiAlON grains. The WC grains principally appeared equiaxed in nature. A reaction product was not observed at the WC/α−SiAlON interface. High-angle annular dark-field scanning transmission electron microscopy imaging indicated the reasonable distribution of the elements within the constituent grains and grain boundary. The presence of an intergranular glassy phase was confirmed, which was principally rich in oxygen and yttrium, with some occasional tungsten in the case of triple junctions. The composite exhibited an acceptable combination of flexural strength, hardness, and fracture toughness with values around 489 MPa, 20 GPa, and 6 MPa-m0.5, respectively. In contrast to expectations, a decline in hardness was observed up to ≤30 wt% WC. Presumably, the WC grains acted as defects/inclusions with similar dimensions, which eventually resulted in inadequate interfacial performance and reduced hardness. Improvements in the Vickers hardness and fracture toughness were obtained at a WC loading of 40 wt%. The indentation size effect and load dependence of the fracture toughness were also determined for some selected specimens. Higher damage rates for the β−Si3N4 counterbody against the 40 wt% WC/α−SiAlON composite were observed up to 30 N under unlubricated conditions compared with those obtained against the monolithic constituent phases, i.e., α−SiAlON and WC. The formation of an adherent tribolayer was observed.