The Surface-treatment of Ceramic Powders and its Application

Surface-treatment and Surface Properties of Silicon Nitride Exposed to the Atmospheric Surroundings

Abstract

The surface properties and the surface-treatment of the sillicon nitride exposed to the atmosphere with alcohols (n-octanol, n-cetanol) and octadecyl trichlorosilane were investigated through Xray photoelectron spectroscopy, Xray diffraction method, scanning electron microscopy, dispersive properties, infrared absorption spectra and pyrolysis, respectively. The followings were ascertained from these results : (1) The surface properties of silicon nitride were converted from hydrophilic to hydrophobic through the surface-treatment, but the composition and the structure of the substrate were invariable. (2) The characteristic absorption of surface group of surface-treated silicon nitrides was not detected by means of the infrared absorption spectra because of the small number of surface group per unit weight due to small surface area of the nitrides. (3) The pyrolysis curves and pyrolysis products of the surface-treated silicon nitrides showed the same as those of the surface-treated silica gel with the same reagents used for the surface-treatment. (4) Since the O_1s peak was observed in the Xray phtoelectron spectrum of silicon nitride, the surface of silicon nitride was perceived to be covered by the silicon dioxide. (5) Thus, the surface of silicon nitride exposed to the atmosphere was composed of the silicon dioxide layers formed by the reaction with the atmospheric oxygen or water and its surface was covered by the surface hydroxide (surface silanol), therefore, the methods for the surface-treatment of silica gels were acertained to be effective also for that of silicon nitride.