Preceramic compositions which have particular utility in providing protective ceramic coatings on normally oxidizable materials, such as carbon/carbon and other carbon-containing composites and other materials, are obtained by dispersing solid particles comprising aluminum nitride particles in an organic solvent solution of a polysilazane. Ceramic coatings derived from the dispersions may serve as intermediate strata in multilayer ceramic coatings over substrates, such as carbon/ carbon composites, to provide even greater protection to the substrates, even when exposed to humidity.