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

Abstract

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.