Improved sintering ability of SiC ceramics from SiC@Al2O3 core-shell nanoparticles prepared by a slow precipitation method

Abstract

SiC@Al2O3 composite nanoparticles with core-shell structure were prepared by a slow precipitation method, aimed at improving the sintering ability of SiC. SiC nanoparticles with average particle size of 100 nm were prepared by a fluidized bed-chemical vapor deposition (FB-CVD) method. The Al(OH)3 coating was formed by slow precipitation of aluminum nitrate in urea solution. The coating layer was then transformed to Al2O3 after further heat treatment. By controlling the rate of urea hydrolysis and the aluminum nitrate concentration in the solution, the thickness of the coating layer could be adjusted. The results of X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM) and Energy Dispersive Spectrometer (EDS) indicated that Al2O3 was uniformly coated on the surface of SiC particles and the two phases were closely contacted. The improved sintering ability of SiC@Al2O3 composite nanoparticles were validated, and better mechanical properties were obtained compared with the sintering results using the conventional ball milling method.