| 초록 |
The effects of adding HfC particles on the mechanical properties and ablation resistance of HfC–W composites were investigated. The HfC–W composites were fabricated by ball milling and spark plasma sintering process. The increase in mechanical properties of the HfC–W composite at room temperature as well as high temperature was attributed to the reinforcement effect of the HfC particles. One of the strengthening mechanisms of the composite can be attributed to the formation of mixed carbide (Hf,W)C by interdifussion at the interface, which assured the effective load transfer from the W matrix to the hard HfC particles. An oxy-acetylene torch was used to ablate the samples at high temperature. Ablation resistance improved with an increasing volume fraction of HfC particles, with a value of 15.7×10-3g/cm2 s at 30 vol%, which is much lower than those of monolithic tungsten. The improvement in ablation resistance was attributed to thermochemical oxidation of the W and HfC particles, forming an HfO2 layer on the surface. The outstanding elevated temperature ablation resistance of HfC–W was attributed to the low thermal conductivity, high oxidation resistance, and high melting point of the HfC reinforcement. Therefore, HfC–W composites may be particularly suitable for high temperature applications such as the rudders and nozzles of rocket motors, turbines, and fusion reactors. |
