放电等离子烧结制备高纯Ta₂AlC陶瓷及其高温氧化行为

High purity and bulk Ta₂AlC ceramics had been synthesized by self-propagating high-temperature synthesis, pressure-less sintering and spark plasma sintering, using Ta, Al and carbon black powders as raw materials. Microstructures and properties of the as-fabricated Ta₂AlC ceramics were investigated. The Vickers hardness, flexural strength and fracture toughness of the as-fabricated bulk Ta₂AlC ceramics are 5.6 GPa, 510 MPa and 6.16 MPa•m^1/2, respectively. The fast heating rate, short sintering time and fine grain formation in the spark plasma sintering resulted in a fine-grain strengthening effect which led to the high hardness and strength. The Ta₂AlC ceramics oxidized at the temperature range of 700-900 ℃ showed a linear oxidation kinetics trend. When the Ta₂AlC ceramic was oxidized at 700 ℃ for 15 h, the oxidation layer of the Ta₂AlC was mainly composed of Ta₂O₅. And the oxidation products would become Ta₂O₅ and AlTaO₄ while the oxidation temperature was risen up to 800-900℃.