Oxidation prevention of silicon carbide powders

Abstract

Oxidation creates an important problem with the increasing temperature and additionally if one of the components contains an amount of carbon, then there will be a COx emission risk which has a detrimental effect for the atmosphere. One of the methods to prevent the oxidation of silicon carbide (SiC) is to coat it with Al2O3 which has high thermal stability. In this study, the properties of Al2O3 coated SiC composite powders were examined to prevent the oxidation of SiC particles by developing a thermal barrier coating and it is aimed to contribute for reducing the gases which make a greenhouse effect and cause global warming. Firstly, boehmite sol was prepared via the solgel route and then 5 wt% beta-SiC (< 100 nm) nanosized particles were added to the boehmite sol and gelation was completed. Alumina coated SiC powders were heat treated at 100, 550, 1,000, 1,300 and 1,600 degrees C under dry air and argon atmospheres. Characterisation analyses showed that alumina coated SiC particles underwent to slightly internal oxidation with the partial oxidation depending on the oxygen ion mobility during the transformation from boehmite to alumina in the interior atmosphere while alumina coated SiC particles gained oxidation resistance against the outer atmosphere.