Evaluation Of Properties Of Zirconium Diboride-Based Ultra-High Temperature Ceramics

Ultra-high-temperature ceramics (UHTCs) in the article are a group of materials consisting of zirconium diboride (ZrB₂) plus silicon carbide (SiC), and in some instances,ZrC.They offer a combination of properties that make them candidates for airframe leading edges on sharp-bodied reentry vehicles.These composites used the mechanical ball grinding, hot pressing technology to prepare ZrB₂ base composites.In the preparation process, used the analysis test method SEM, XRD and so on ,and it was forming each stage to the composites.the microscopic organization to evolve has carried on the analysis and the research.to the ZrB₂ based composites mechanics performance which prepared has made the preliminary analysis and the discussion.The ZrB₂/ZrC/SiC ultrahigh temperature ceramics were studied. It has studied their density, strength, fracture toughness, ablation and thermal shock resistance, and the microstructure of before or after ablation and thermal shock. The three ZrB₂-SiC ultrahigh temperature ceramics with particle or whisker softening were prepared by means of mixing and hot-pressing, and it was studied their density, properties and microstructure. The results showed that the densities of the ZrB₂ composites were high and their relative densities all were over 98.5% of the theory density. The ablation properties of the ZrB₂-SiCw ceramics were finer than those of the ZrB₂-SiCp ceramics, and the ZrB₂-SiCw1 composites were not ruptured after they had been burn on the plasma-arc heater for different seconds. Despite the original microstructure of SiC whisker in the ZrB₂-SiCw1 ceramics was different from that in ZrB₂-SiCw2 ceramics, their thermal shock properties and thermal shock microstructure are similar.64%ZrB₂+ZrCp20%+ SiCp16%, 80%ZrB₂+SiCp10%+SiCw10% composites were prepared by hot-pressing. It has studied their density, flexural strength, fracture toughness, ablation resistance, and the microstructure of before or after thermal shock.The whisker and particle hybrid softening ZrB₂ composites were prepared by means of mixing and hot-pressing in order to improve their toughness, it has been studied their property and microstructure. Those at high temperature decreased sharply. After the ZrB₂ composites with the microstructure of equal...