Abstract: A structural article for high temperature applications comprises a body formed of at least partially consolidated, particulate silicon nitride, a conformal outer coating of silicon nitride or silicon carbide on the body, and a conformal intermediate layer of a silicon, oxygen and nitrogen-containing compound, i.e. silicon oxynitride, chemically bonded to both the body and the outer coating. The method for making such an article comprises providing a body formed of at least partially consolidated, particulate silicon nitride, oxidizing the surface of the body, removing silicon dioxide from the oxidized surface of the body; and chemically vapor depositing a conformal outer coating of silicon nitride or silicon carbide. The conformal outer coating provides a protective envelope around and assists in high temperature isostatic pressing of the body and hence permits one to use the structural article in isostatic pressing processes.