In-Situ Characterization of SiC-AlN multiphase ceramics

摘要

AlN and SiC can react and form a solid solution attemperatures above 1800℃, a results that may be beneficial forsintering silicon carbide ceramics. The pressureless sintered AlN-SiC multiphase ceramics have reached high density at atemperature of 2100℃ for 1 hr in Ar. Analytical scanningtransmission electron microscopy was then used to determined thegrain boundary, fracture surface, and the local compositions.Because AlN has a higher solid vaporization pressure than SiC, thevaporization rate of the AlN solid would far exceed that of SiC ata sintering temperature. The vaporizing AlN was deposited on thesurface of SiC powder; SiC grains then elongated in a randomarrangement. The form of elongated rod crystals of 4H SiC is 5 to8?m in length and 1 ?m in width. It resulted in the sample fracturesection producing-pulling out and a strong tearing-open effect. Thebending strength and the fracture toughness of the materialobtained are 420 Mpa and 4.40 Mpa×m1/2, respectively.