Abstract
The aim of the present research is to prepare well dense sintered nano-SiC. Two samples of Nano-silicon carbide prepared by pyrolysis of rice-husk ashes as starting materials. The first was fine (hand-ground) rice-husk ash, and the second was prepared by ball milled technology. The firing temperature to obtain well crystalline nano SiC was 1550oC. The effect of pyrolysis under vacuum atmosphere had been tested. Herein the liquid phase sintering is used as a good sintering technique. The oxides sintering additives (3 wt% Y2O3 and 7wt% Al2O3) play very crucial role in decreasing the apparent porosity and increasing the relative density of the sintered body if compared with that prepared without any oxide additives. Different sintering temperature firing range was applied here, and the optimum firing temperature that used to obtain well dense sintered SiC was 1950oC. With decreasing additive content, the consolidation of the materials became increasingly dependent on solid-state sintering. The microstructure underwent a transition from a microcrystalline matrix with nano-crystalline second phase (micro–nano) to a nano-crystalline matrix with nano-crystalline second phase (nano–nano) when the yttria and alumina content was lowered to 3 wt%.