Mechanical, thermal physical properties and thermal shock resistance of in situ (TiB₂+SiC)/Ti₃SiC₂ composite

Dense (TiB₂+SiC)/Ti₃SiC₂ composite with 20 vol% TiB₂ and 10 vol% SiC was synthesized by in situ reaction hot pressing. The room and high temperature mechanical and thermal physical properties, as well as thermal shock resistance of the composite were investigated and compared with SiC/Ti₃SiC₂ composite as prepared by the same process. The synergistic action of TiB₂ and SiC produced a significant strengthening and toughening effect and (TiB₂+SiC)/Ti₃SiC₂ composites exhibit superior room- and high-temperature mechanical properties compared with SiC/Ti₃SiC₂ composite. Especially, (TiB₂+SiC)/Ti₃SiC₂ composite shows higher Young's modulus from 25 °C to high temperature and can retain a high modulus of 313 GPa (about 81% of room temperature value) up to 1200 °C. From 25 °C to 800 °C, (TiB₂+SiC)/Ti₃SiC₂ composite has higher thermal conductivity and slightly lower coefficient of thermal expansion. Both water quenching test results and calculation of thermal shock resistance parameters, R, R_st and R^IV indicate an improved thermal shock resistance of (TiB₂+SiC)/Ti₃SiC₂ composite, with an increase of the critical thermal shock temperature difference ΔT_c from 325 °C for SiC/Ti₃SiC₂ to 440 °C for (TiB₂+SiC)/Ti₃SiC₂. Superior properties render (TiB₂+SiC)/Ti₃SiC₂ composite a promising prospect as high temperature structural materials.