Multilayer coatings by chemical vapor deposition in a fluidized bed reactor at atmospheric pressure (AP/FBR-CVD): TiN/TaN and TiN/W

TiN/W and TiN/TaN multilayer coatings were deposited on stainless steel by Chemical Vapor Deposition in a Fluidized Bed Reactor at Atmospheric Pressure (AP/FBR-CVD). First, the conditions for the deposition of TiN single layers were investigated, both from the experiment and thermochemical estimations. TiN was deposited from TiCl₄ and NH₃ at temperatures in the range of 750-950 °C. In the synthesis of multilayers, the W- and Ta-based layers were obtained by reduction of tungsten chloride or tantalum chloride with H₂. During the deposition of the TiN layers on top of the Ta layers, Ta reacted with NH₃ to form a mixture of tantalum nitrides. Multilayer coatings were characterized by means of GD-OES, AES and XRD. Preliminary results of nanoindentation hardness and oxidation resistance are also presented. Our results show for the first time that AP/FBR-CVD can be tuned for the deposition of multilayered coatings with periodicities in the submicron range.