SiCf对重结晶碳化硅陶瓷的烧结颈结构作用机制

Mechanism of SiCf on Sintering Necks of Recrystallized Silicon Carbide Ceramics

以SiC粉体及SiC纤维(SiCf)为原料,在氩气气氛下经1600℃~2200℃保温1 h热处理制备得到多孔碳化硅陶瓷,研究了外加SiCf对重结晶碳化硅物相组成、显微结构、力学性能和孔径分布的影响规律及作用机理。结果表明,碳化硅纤维在高温下发生分解,使材料中蒸发—凝聚的物质传输速率增大,并有效促进了碳化硅烧结颈的生长,提升了重结晶碳化硅陶瓷的力学性能。当SiCf外加量为20wt.%时,材料的显气孔率、体积密度及常温抗折强度分别为(36.4±0.1)%、(2.02±0.01)g·cm^(-3)及(76.40±8.16)MPa。

Porous silicon carbide ceramics were prepared by using SiC powders and SiCf as raw materials treated at 1600-2200℃for 1 h in Ar atmosphere.The effects of SiC fiber on phase composition,microstructure,mechanical properties and pore size distribution of recrystallized silicon carbide were studied.It is demonstrated that the mass transfer rate of evaporation-condensation was increased at high temperatures owing to the decomposition of the silicon carbide fibers.Moreover,the growth of silicon carbide sintered necks and the mechanical properties of recrystallized silicon carbide ceramics were effectively promoted.When the content of SiC fiber was 20 wt.%,the apparent porosity,bulk density and flexural strength at room temperature were(36.4±0.1)%,(2.02±0.01)g·cm^(-3)and(76.40±8.16)MPa,respectively.