Desorption of gases from the surface of silicon nitride powders

The influence of fabrication and treatment techniques and of carbon coating onto silicon nitride powders on the process of gaseous component desorptio n has been studied. The N-2, H2O, CO2, and CO molecules, as well ns OH and NH radicals, were revealed to be absorbed on the particle surface. Differen t hydrocarbons are the products of reaction in the gas phase and on the sur face. Carbon coating on the powder particle surface alloys one to protect t he surface from absorbed gases and from chemosorbed compounds, in particula r hydroxylic groups. The results obtained permit one to determine the condi tions of intended modification of surface and thermal treatment of powders in order to activate their sintering.