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Mo2BC-TiC composites were fabricated by fast hot-pressing sintering method with Mo2BC powder as raw material and nano-TiC powder as sintering additive. The effect of nano-TiC additive (mass fraction of 5%) on microstructure and tribilogical behavior of Mo2BC composite was investigated. The results show that the addition of nano-TiC significantly improves the sintering properties, microstructure and mechanical properties of Mo2BC ceramic. The relative density, Vickers hardness, flexure strength, compressive strength and fracture toughness of Mo2BC composites are 98.9 %, 18.1 GPa, 480.5 MPa, 2.9 GPa and 4.1 MPa ⋅ m1/2, respectively. Transgranular fracture is the main fracture mode of Mo2BC-TiC composite. Mo2BC-TiC composite also exhibites a good tribological properites with the friction coefficient of 0.42 and wear rate of 0.6 x 10-5 mm³/ (N ⋅ m). [ABSTRACT FROM AUTHOR]

• Polycrystalline Mo 2 BC ceramic bulks were successfully prepared from elemental powders by SPS route. • The synthesized temperature of Mo 2 BC ceramic was confirmed to be as low as 1300 ºC. • The lattice parameters of as-prepared Mo 2 BC ceramic were determined by TEM characterization. • For the first time, the mechanical properties of Mo 2 BC ceramic bulks were investigated. Single-phase polycrystalline Mo 2 BC ceramic bulks were synthesized successfully from molybdenum, boron, and graphite powders using the spark plasma sintering method. Herein, it was established that the synthesis temperature of the Mo 2 BC ceramic could be as low as 1300 °C. Transmission electron microscopy (TEM) characterization confirmed that the crystal structure of the Mo 2 BC ceramic was comparable to that of the MoAlB ceramic. The Vickers hardness of the Mo 2 BC ceramic was measured to be 18.1 GPa. Additionally, the compressive strength, flexural strength, and fracture toughness were determined to be 1.74 GPa, 457.72 MPa, and 3.26 MPa· m1/2, respectively. The Mo 2 BC bulk exhibited typical brittle features, in which intergranular and transgranular fractures were the main failure modes. [ABSTRACT FROM AUTHOR]

Herein, in situ MoB particles reinforced Cu-Al matrix composites are prepared by sintering the Cu and MoAlB mixture. During the sintering process, Al atoms can diffuse out of the layered MoAlB and solid-dissolve into the Cu matrix, resulting in the formation of laminate MoB and Cu-Al alloy. The mechanical properties of as-prepared composites are significantly improved because of multiple strengthening mechanisms. Moreover, the two-body abrasive and adhesive wear effects are inhibited on account of the pinning effect of MoB particles. With the MoAlB content increasing up to 20 wt% and 30 wt%, a layer of tribo-film can be generated due to the tribo-oxidation reaction during the sliding, which can provide lubrication to reduce friction and wear. • In-situ MoB reinforced Cu-Al matrix composites are prepared for the first time. • The mechanical and tribological properties of as-prepared composites are improved. • Two-body abrasion and adhesive wear can be inhibited with MoAlB addition. • The generating tribo-film leads to the low friction coefficient and wear rate. [ABSTRACT FROM AUTHOR]

Tungsten carbide (WC) particles can be used as reinforcement to improve the mechanical and tribological properties of metal matrix. Herein, WC reinforced Cu-20Zn matrix composites were prepared. The mechanical and tribological properties of composites were also investigated. It was confirmed that the Cu 3 Zn solid solution was formed during the sintering process. Due to the solid solution and load transfer strengthening mechanism, the tensile and flexural strength were significantly improved. When the WC content was 30 wt%, the tensile and flexural strength were both increased by about two times compared with Cu-20Zn alloy. Additionally, the two-body abrasive and adhesive wear were gradually weakened with increasing WC content. When the WC content was 30 wt%, the composites showed low friction coefficient and wear rate. The formation of tribo-film, which was induced by tribo-oxidation reaction, was conceived to be responsible for the favorable lubricating properties. [Display omitted] • The mechanical and tribological properties of Cu-20Zn alloy were greatly improved with WC addition. • When the WC content was 30 wt%, the composites showed the best overall properties. • The strengthening mechanism was associated with dispersion strengthening. • The two-body abrasion and adhesion wear could be inhibited with WC addition. [ABSTRACT FROM AUTHOR]

Abstract: Ti–Al–C films were deposited on silicon (100) substrates using magnetron sputtering TiAl target and graphite target in argon atmosphere at various substrate negative bias voltages. The composition, surface morphology, hardness and friction coefficient of the resulting films were characterized using x-ray photoelectron spectroscope, energy dispersive spectrometry, atomic force microscopy, nanoindentation and tribological tester. Results show that the structure and properties of the deposited films strongly depend on the applied substrate negative bias voltage. The Ti–Al–C films deposited at high substrate negative bias voltage show high surface roughness, low hardness and short wear life. In contrast, the Ti–Al–C films deposited without negative bias voltage exhibit uniform and smooth surface, a high hardness of approximately 37 GPa and low friction coefficient and long wear life. Excellent friction and wear behaviors of the Ti–Al–C films deposited without negative bias may be attributed to the dense structure and high hardness. [Copyright &y& Elsevier]

In this study, Mo 0.9 Cr 0.1 AlB solid solution ceramic bulks were prepared from the element powder mixtures using hot pressing sintering method. Compared with MoAlB ceramics, the grains of as-prepared Mo 0.9 Cr 0.1 AlB were refined obviously. The lattice constants of Mo 0.9 Cr 0.1 AlB were confirmed to be a = 3.205 Å, b = 13.999 Å and c = 3.098 Å. The density of Mo 0.9 Cr 0.1 AlB was lower than that of MoAlB due to the incorporation of Cr element. In addition, the effect of doping Cr element on the comprehensive mechanical properties was studied as well. The hardness and compressive strength were improved significantly. In comparison with MoAlB ceramic, the improvement of mechanical properties could be attributed to solid solution strengthening and grain refinement. [ABSTRACT FROM AUTHOR]

Graphene-nickel (G-Ni) matrix composites were fabricated through in-situ growing graphene in bulk nickel matrix using a powder metallurgy method. Sucrose as precursor of graphene was dispersed into nickel powders to grow graphene, avoiding a traditional dispersion process of graphene in metal matrix. Multi-layer graphene was synthesized in-situ in nickel matrix, meanwhile nickel matrix was densified at high temperature. The nickel matrix acts as support and catalyst of graphene, and graphene grow in-situ in nickel matrix serving as reinforcement. This in-situ growth method offers a homogeneous dispersion of graphene and well-contacted interfaces between graphene and nickel matrix, which provides a guarantee for high load transfer from nickel matrix to graphene. [ABSTRACT FROM AUTHOR]