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International audience; In this work, two copper metal matrix composites (MMCs) reinforced with 20 wt.% of Ti(C,N) or Ti2AlN particles were studied. The reinforcement particles were synthesized by flash sintering under 2 bar nitrogen atmosphere causing an SHS reaction ignited by electrical current. This reaction led to produce TiC0.7N0.3 solid solution for the MMC1 reinforcement and Ti2AlN, TiN, and Ti3Al titanium aluminide for the MMC2 reinforcement. Both MMCs were densified by liquid phase sintering. The structural characterization was performed by XRD analysis while the morphology and chemical element distribution of both MMCs were analyzed by SEM and EDS. The structure of the two MMCs was relatively dense and showed good wettability. The mechanical and tribological behavior of MMCs evaluated by nanoindentation and wear testing reveals that the addition of 20 wt.% of reinforcement considerably improves the properties of copper matrix. Indeed, the MMC1 proved to be 3 times harder and 10 times more wear-resistant than the MMC2 composite.

Mechanical and tribological properties of nylon 6 and nylon 6/h-BN composites were investigated in this paper. Tensile, hardness, and impact tests were carried out for mechanical properties, while wear tests on pin-on-disc were carried out for tribological properties identification. Abrasion resistance tests were carried out on the TABER apparatus to analyze the abrasive wear of materials. SEM, XRD, and TGA were used to characterize the materials and to understand the distinctive features of nylon 6 and nylon 6/h-BN composites. Experimental results show that the mechanical properties and tribological behavior of nylon 6 got enhanced by the h-BN fillers. Tensile strength and modulus of elasticity were enhanced by 15.2% and 64.5%, respectively, while hardness and impact strength were enhanced by 3.45% and 6%, respectively. COF and wear rate of composites decreased up to 4 wt% filler reinforcement due to smooth transfer film formation. Coefficient of friction (COF) and wear resistance were improved by 10–15% and 8–10%, respectively, at various testing conditions. h-BN reinforcement in the matrix resulted in more weight loss due to abrasion and it reduced the abrasion resistance of nylon 6 by 5.5 times. Thermal stability was slightly increased, and crystallinity was little affected by the h-BN fillers.

As part of the tests, a two-phase NiAl/Ni3Al alloy and a composite based on this alloy with 4 vol% addition of TiB2 were produced by the reactive FAST/SPS (Field Assisted Sintering Technology/Spark Plasma Sintering) sintering method. The sintering process was carried out at 1273 K for 30 s under an argon atmosphere. The effect of reactive SPS on the density, microstructure, and mechanical and tribological properties of a dual-phase Ni-Al intermetallic compound and Ni-Al-TiB2 composite was investigated. Products obtained were characterized by a high degree of sintering (over 99% of the theoretical density). The microstructure of sinters was characterized by a large diversity, mainly in regard to the structure of the dual-phase alloy (matrix). Compression tests showed satisfactory plastic properties of the manufactured materials, especially at high temperature (1073 K). For both materials at room temperature, the compressive strength was over 3 GPa. The stress–strain curves were observed to assume a different course for the matrix material and composite material, including differences in the maximum plastic flow stress depending on the test temperature. The brittle-to-ductile transition temperature was determined to be above 873 K. The research has revealed differences in the physical, mechanical and tribological properties of the produced sinters. However, the differences favourable for the composite were mostly the result of the addition of TiB2 ceramic particles uniformly distributed on grain boundaries.

Рассмотрены процессы деформации и разрушения гальванических покрытий Au-Ni при трибологических испытаниях в условиях сухого трения. Показано, что изнашивание покрытий является результатом макроскопического контактного взаимодействия образца и контртела, а также абразивного действия микронеровностей на поверхности контртела и частиц износа. Исследованы механизмы формирования частиц износа и слоя переноса во время трения и продемонстрирована их роль в процессах изнашивания гальванических покрытий Au-Ni. Обоснована значимость сдвиговых напряжений, развивающихся на границе раздела покрытие/подслой, в разрушении покрытий., Deformation and fracture of electroplated Au-Ni coatings subjected to tribological testing under dry conditions were studied. Wear of the coatings is shown to result from macroscopic contact interaction of the specimen with the counterbody, and from abrasive action of microasperities on the counterbody surface and wear particles. The formation mechanisms of wear particles and a transfer layer were investigated, and their contribution to wear of the electroplated Au-Ni coatings was demonstrated. The significance of shear stresses arising at the coating/sublayer interface in coating fracture was substantiated.

TiAlBN films were produced by simultaneously sputtering from TiAl and TiB2 targets in Ar/N2 mixtures at a substrate temperature of 150 °C. The goal of this investigation was to study the influence of the nitrogen content (0-40 at.%) on two sets of four coatings with B/Al ratios of approximately 1 and 5. All coatings showed very dense structures and were mainly found to be only partially crystalline. Evidence of Al, AlN, Ti, TiB2, TiN and BN bonding was observed in the XPS spectra, and correlation of the compositional and mechanical data showed that film hardness and elastic modulus decreased with the presence of a 'soft' phase (Al, Ti or amorphous BN). Hardness and elastic modulus values of up to 25 and 250 GPa, respectively, were found for TiAl0.3B1.7 coatings. Coatings with a similar elastic modulus to that of the steel substrate showed the best adhesion. Friction coefficient values between approximately 0.5 and 0.7 were recorded in sliding wear experiments against SAE52100 and WC/6%Co balls. Although friction coefficients could not be correlated to the amorphous BN contents, it was noted that low combined ball and disc wear rates were found for coatings containing large amounts of BN. Coatings with B/Al 5 and elastic moduli of ≤290 GPa showed two orders of magnitude better sliding wear resistance against WC/6%Co balls compared to commercially available TiN. TiAlBN films were produced by simultaneously sputtering from TiAl and TiB2 targets in Ar/N2 mixtures at a substrate temperature of 150 °C. The goal of this investigation was to study the influence of the nitrogen content (0-40 at.%) on two sets of four coatings with B/Al ratios of approximately 1 and 5. All coatings showed very dense structures and were mainly found to be only partially crystalline. Evidence of Al, AlN, Ti, TiB2, TiN and BN bonding was observed in the XPS spectra, and correlation of the compositional and mechanical data showed that film hardness and elastic modulus decreased with the presence of a `soft' phase (Al, Ti or amorphous BN). Hardness and elastic modulus values of up to 25 and 250 GPa, respectively, were found for TiAl0.3B1.7 coatings. Coatings with a similar elastic modulus to that of the steel substrate showed the best adhesion. Friction coefficient values between approximately 0.5 and 0.7 were recorded in sliding wear experiments against SAE52100 and WC/6%Co balls. Although friction coefficients could not be correlated to the amorphous BN contents, it was noted that low combined ball and disc wear rates were found for coatings containing large amounts of BN. Coatings with B/Al approximately 5 and elastic moduli of ≤290 GPa showed two orders of magnitude better sliding wear resistance against WC/6%Co balls compared to commercially available TiN. 113 126 133 126-133

Using inorganic fullerene-like (IF) nanoparticles and inorganic nanotubes (INT) in organic-inorganic hybrid composite, materials provide the potential for improving thermal, mechanical, and tribological properties of conventional composites. The processing of such high-performance hybrid thermoplastic polymer nanocomposites is achieved via melt-blending without the aid of any modifier or compatibilizing agent. The incorporation of small quantities (0.1–4 wt.%) of IF/INTs (tungsten disulfide, IF-WS2 or molybdenum disulfide, MoS2) generates notable performance enhancements through reinforcement effects and excellent lubricating ability in comparison with promising carbon nanotubes or other inorganic nanoscale fillers. It was shown that these IF/INT nanocomposites can provide an effective balance between performance, cost effectiveness, and processability, which is of significant importance for extending the practical applications of diverse hierarchical thermoplastic-based composites., This work was supported by the Spanish Ministry Economy and Competitivity (MINECO), Project MAT-2010-21070-C02-01. Dr. M. Naffakh would like to acknowledge the Ministerio de Economía y Competitividad (MINECO) for a “Ramón y Cajal” Senior Research Fellowship and Ana Diez-Pascual wishes to acknowledge the CSIC for a JAE Postdoctoral Fellowship cofinanced by the EU., We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)

Investigated WC-Co cermets were produced via reactive sintering. In case of reactive sintering the elemental powders of tungsten, carbon black as graphite source and cobalt at first activated throw high energy milling and then the carbide synthesis is taking place in the same cycle with liquid phase sintering of the cermets. Because there is a lack of information about the influence of alloying additives on the reactive sintered WC-Co cermets, small amount of chromium carbide or vanadium carbide was added to the powders. To investigate the influence of carbon content in initial powder mixture on the microstructure and properties of reactive sintered WC-Co cermets alloyed with Cr3C2 and VC cermets with different carbon content were produced. The hardness, transverse rupture strength and erosion resistance of alloyed WC-Co cermets depending on carbon content in initial powder mixture is exhibited.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1347