A C/C-TaB 2 -SiC composite was successfully prepared by high-solid-loading slurry impregnation combined with polymer infiltration and pyrolysis. The composite had a density of 3.46 g/cm 3 and consisted of pyrolyzed carbon, carbon fibers, TaB 2 particles, and precursor-derived SiC with their mass fractions of 7.8 %, 13.0 %, 58.6 %, and 20.6 %, respectively. The C/C-TaB 2 -SiC composite possessed a flexural strength of 248.2 ± 16.8 MPa and a fracture toughness of 13.7 ± 1.6 MPa·m 1/2 , and demonstrated a non-brittle fracture behavior . After exposure to oxyacetylene flame with a heat flux of 4.18 MW/m 2 for 120 s, the ablation temperature of the sample surface reached a maximum of 2263 °C, and the mass and line ablation rates were 2.24 mg/s and 12.92 µm/s, respectively. The ablation resistance mainly comes from the hindrance of oxygen diffusion by the oxide layer composed of tantalum oxide and a small amount of SiO 2 .
Yonghui Yu,Jie Wei,Xianghui Yan,Yuhong Chen,Biao Zhang,Yujin Wang,Feng Ye,Limeng Liu
TaB 2 –SiC composites with 0–20 wt% SiC contents were prepared by reaction hot pressing using Ta, B and SiC powders as starting materials. Densification, constituent phases, microstructure and mechanical properties, namely Vickers hardness, fracture toughness and flexure strength, were evaluated by means of inspection of sintering shrinkage, density measurement, XRD, SEM, TEM, HRTEM, EDS, SAED, indentation and three-point bending tests. Phase formation, including dominant (TaB 2 , SiC) and minor (TaC, glassy SiO 2 ) phases, was checked by thermodynamic assessment relevant with Ta 2 O 5 and B 2 O 3 impurities introduced into the reaction system by the starting powders. The results showed that mixtures of Ta, B and SiC powders would initiate self-propagating combustion synthesis (SPCS) at about 900 °C; a transient hold at 800 °C for 1 h could suppress this reaction. Volatilization of B 2 O 3 impurity in association with local high temperature due to SPCS helped reduce the TaC and glassy SiO 2 minor phase formation. TaB 2 –SiC composites could reach 99 % relative densities with 3 wt% SiC addition and above. Compositions with <7.5 wt% SiC additions showed uniform dispersion of SiC particles at multi-TaB 2 grain junctions while compositions with higher SiC content revealed SiC segregation. Bending strength of 503 MPa and fracture toughness of 6.69 MPa⋅m 1/2 could be reached with 7.5–20 wt% SiC addition.
It is well-known that a lower wear rate, favorable mechanical properties, and limited inflammatory response are critical factors in determining the long-term service of orthopedic implants. In this study, we prepare TaB 2 /PEEK coatings by electrophoretic deposition (EPD) of borated tantalum (TaB 2 ) and polyether-ether-ketone (PEEK) particles on a pure titanium plate (TA2). Nanoindenter, reciprocating ball-on-disc tester, and in vitro biological experiments were used to investigate the effects of TaB 2 particles on the mechanical properties, tribological properties, and biological properties of composite coatings. The results demonstrate that a small amount of TaB 2 particles were equally dispersed in the PEEK matrix, and the mechanical properties are improved, resulting in better tribological properties of the coating. In particular, the wear rate of P-TB-3 coating in the simulated body fluid (SBF) was 72% lower than that of the PEEK coating, with a friction coefficient (COF) of 0.164 and a wear rate of 1.45 × 10 −6 mm 3 ·N −1 m −1 , respectively. Furthermore, the P-TB-3 surface boosted Raw264.7 macrophage adherence and proliferation, with a potential to promote Raw264.7 macrophage transition to the M2 phenotype. These results suggest that the P-TB-3 coating prepared by EPD is considered as a promising implant replacement material.
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