Densification Behavior And Properties Of ZrB₂-Based Ceramic

Ultra high temperature ceramics material is a new type of material that can maintain physical and chemical stability and work for a long time in high temperature environment and reaction atmosphere.It is mostly applied to the field of aerospace.ZrB2-based ultra-high temperature ceramic material has become the most promising high-temperature structural material among ultra-high temperature ceramic materials because of its excellent oxidation resistance and mechanical properties.Due to the physical properties of ZrB2 itself,its crystal structure determines that ZrB2-based ceramics need to be sintered at a higher temperature to achieve densification.The density of ZrB2-based ceramics is affected by many factors.The density,mechanical properties and oxidation resistance of ZrB2-based ceramics prepared by different processes would change.The effect of powder size on the densification behavior and mechanical properties of ZrB2 and ZrB2-SiC ceramics was studied.Studies have shown that by reducing the particle size of the powder and increasing the sintering temperature,the dense sintering of ZrB2 ceramics can be promoted.ZrB2 ceramics obtained by 200nm particle size powder plasma sintering at 1900? have higher density and bending strength.The introduction of SiC in ZrB2 can significantly promote the densification and sintering of the material and improve the mechanical properties.ZrB2-SiC ceramics with spark plasma sintering at 1900? obtained the highest density and bending strength(98%?498.2MPa).At the same time,the introduction of SiC also significantly improved the oxidation resistance of ZrB2 ceramics.After static oxidation at 1500?,the surface of ZrB2-SiC ceramics was covered with a dense layer of SiO2,which hindered the ingress of oxygen and played an effective anti-oxidation effect.The effects of powder particle size and carbon fiber content on the densification behavior,microstructure evolution and mechanical properties of ZrB2-SiC-Cf composites were studied.Using nano-ZrB2 powder can promote the densification and sintering of ZrB2-SiC-Cf composite materials at low temperature.The density of ZrB2-SiC-Cf composite materials prepared by spark plasma sintering at 1900? can reach 93%,bending strength and fracture toughness Respectively reached 3 04.1MPa and 4.9MPa·m1/2.At the same time,after the composite material undergoes static oxidation at 1500?,a dense SiO2 layer is formed on the surface,which protects the carbon fiber inside the material from being oxidized and exhibits excellent anti-oxidation performance.