Investigating the effect of nano SiC particles on fracture toughness and oxidation behavior of ZrB2-ZrC-SiC composite produced by PS method

The structures used in the military and aerospace industries require properties such as melting points, thermal shock resistance, and high erosion/oxidation resistance, and ZrB2-ZrC-SiC composites are the best choice due to their physical, mechanical, and oxidation properties. They are a suitable option for the protection of re-entry and supersonic structures.The strength of this research is the use of SiC in nano dimensions, the amount of its addition on the physical, mechanical properties and resistance to oxidation of ZrB2-ZrC-SiC nanocomposite has been investigated. For this purpose, SiC nanoparticles were added as reinforcement with amounts of 0, 5, 10, 15 and 20 wt% to the ZrB2 ‒10 wt % ZrC matrix and were sintered by PLS method. Also, B4C was used as a sintering aid in the amount of 3% by weight. The sintering process was carried out at a temperature of 2100°C for 1 hour with an approximate heating rate of 10°C/min. The results indicate that by adding 5% by weight of SiC in nano dimensions, the relative density reaches its highest value (98.5%). Also, by adding the same amount of nano SiC, the hardness of the samples reaches 13.8 Gpa. By examining the oxidation rate of the samples, it was proved that the sample containing 5% by weight of Nano SiC has the highest resistance to oxidation. The mass erosion rate in the sample containing 5% by weight of nano SiC is equal to 0.18 mg/s. However, increasing the amount of SiC nano has decreased the toughness so that the highest toughness is related to the sample without SiC.