Nonoxide Ceramics with Nanocrystalline Layers Made By Chemical Liquid Deposition

Chemical liquid deposition (CLD) has been used to modify the surface of non-oxide ceramic powders (silicon nitride, silicon carbide) by means of controlled precipitation of inorganic additives and subsequent heat treatment. The processes which occur during the decomposition of the deposited layers (2-10 nm thickness) are discussed from the results of thermal analysis. The extent of nanolayer formation is considered to depend on the details of processing methods, the ceramic powder particle size distribution, the relative densities of the ceramic and of the deposited material, and the mass concentration of the latter relative to the base powder. The preliminary results indicate that CLD can provide unconventional ways of surface modification of ceramic powders and hence of their processing properties.