Microstructure, Adhesion, and Properties of Multilayer Structure WC/W/MCrAlY Coating on gamma-TiAl Alloy Prepared by Plasma Surface Metallizing Technique and Microwave Plasma Chemical Vapor Deposition

The WC coatings with a multilayer structure are synthesized on a gamma-TiAl alloy by the combined treatments of plasma surface metallizing technique and microwave plasma chemical vapor deposition. The morphology, microstructure, and phases of the coatings are examined by a white light profilometer, scanning electron microscope, and X-ray diffraction analysis techniques. The formation of tungsten carbide coating leads to high hardness and good wear resistance. Because of a W transition layer and MCrAlY bonding layer, the good adhesion is achieved between coatings and substrate. This result provides a new approach for designing refractory metals and/or their carbide coatings on metals/alloys substrates, for example, WC and/or W coating on TiAl alloy and titanium alloys.