Preparation of ceramic coatings from pre-ceramic precursors: Part I SiC and ?Si 3N4/Si2N2O? coatings on alumina substrates

Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) has indicated that adherent crack-free coatings of amorphous SiC and «Si 3 N 4 /Si 2 N 2 O» can be built up on planar alumina substrates by pyrolysis of layers of polycarbosilane (PCS) and poly(diphenyl)silazane (PDPS) precursors applied by spin- or dip-coating methods. In general, multilayers of black SiC can be prepared by pyrolysis of PCS layers at 1100 o C in a nitrogen atmosphere while transparent coatings consisting of multiple layers of Si 3 N 4 are prepared by pyrolysis of either PCS or PDPS layers in a flowing atmosphere of ammonia at 1100°C (...)