Surface characterisation and modification of submicron and nanosized silicon carbide powders

The surface characteristics of two grades of silicon carbide powders were analyzed and modified with the aim to control and tailor their behaviour in colloidal suspensions. The as-received submicron and nanosized SiC particles were both found to be covered with a thin oxygen-containing layer, composed mostly of SiO2 and SiCxOy; however, their electrokinetic behaviours in aqueous suspensions were observed to be different. We coated the powders with a thin layer of aluminium oxy-hydroxide, which was found to modify their electrokinetic behaviours in aqueous suspensions. The composition and structure of the aluminium-containing layer were characterized by X-ray photoelectron spectroscopy (XPS) and TEM analyses. This coating may subsequently serve as a homogeneously distributed source of a low amount of sintering additive in manufacturing the SiC-based material for fusion application.