多孔碳化硅陶瓷的原位氧化反应制备及其性能

以SiC为陶瓷骨料,Al2O3作为添加剂,通过原位氧化反应制备了Sic多孔陶瓷,并对其氧化反应特性及性能进行了研究.结果表明:在1 300～1 500℃,随烧结温度的升高,SiC的氧化程度增加,SiC多孔陶瓷的强度逐渐增加,但开口孔隙率有所降低.莫来石相在1 500℃开始生成·当烧结温度升高到1 550℃时,莫来石大量生成,得到了孔结构相互贯通且颈部发育良好的莫来石结合SiC多孔陶瓷;由于在SiC颗粒表面上覆盖了致密的莫来石层,SiC的氧化受到抑制,开口孔隙率因而升高,SiC多孔陶瓷的强度因莫来石的大量生成而增加.由平均粒径为5.0um的SiC,并添加20%(质量分数)Al2O3,经1 550℃烧结2h制备的SiC多孔陶瓷具有良好的性能,其抗弯强度为158.7MPa、开口孔隙率为27.7%.

FABRICATION AND PROPERTIES OF POROUS SILICON CARBIDE CERAMICS BY AN IN-SITU OXIDIZING REACTION

Porous silicon carbide (SIC) ceramics were prepared in air from SiC by an in-situ oxidizing reaction technique using Al2O3as additive. The oxidizing reaction characteristics and properties of the porous silicon carbide ceramics were studied. With the in-crease in sintering temperature from 1 300℃ to 1 500℃, the oxidation degree of SiC increases and the strength of the porous SiCceramics increases gradually, while the open porosity decreases. MuUite phase appears at 1 500℃. A large amount of mullite isformed and mullite-bonded open porous SiC ceramics with well-developed necks are obtained at 1 550℃. The oxidation of SiC issuppressed at 1 550℃ because the surface of SiC particles is covered by a dense mullite layer, and the open porosity of the ceramicsincreases, while the strength increases sharply. Porous SiC ceramics with good properties can be prepared by using 80% (mass frac-tion, the same below) SiC powder with an average particle size of 5.0um and 20% Al2O3 as raw materials. These porous SiC ceramicsexhibit a flexural strength of 158.7 MPa and an open porosity of 27.7% when sintered at 1 550℃ for 2 h.