Silicon nitride films by chemical vapor deposition in fluidized bed reactors at atmospheric pressure (AP/FBR-CVD)

Silicon nitride thin films with thicknesses around 1 μm were deposited on AISI316 steel by Chemical Vapor Deposition in a Fluidized Bed Reactor at Atmospheric Pressure (AP/FBR-CVD). The films were obtained by reaction of SiCl4 and NH3 in a reducing atmosphere at temperatures in the range 725-775 °C. They were amorphous and substoichiometric. Activation of the bed particles through alternating reaction steps resulted in a higher deposition rate. The formation of chromium nitride was detected for several microns beneath the film. The deposition temperature was found to have a great influence in their morphology and mechanical properties. The coatings presented hardness values up to 26 GPa.