Synthesis, characterization and application by HVOF of a WCCoCr/NiCr nanocomposite as protective coating against erosive wear

Abstract

The scope of this work is to synthetize and characterize a WCCoCr/NiCr nanocomposite evaluating its application as protective coating against erosive wear when applied by High Velocity Oxygen Fuel (HVOF). The composite was formed by carbide of tungsten-cobalt-chrome (WCCoCr) processed by high energy milling and a metallic matrix of nickel-chrome (NiCr). The milled material was added to the NiCr in the fraction of 5%wt. The powders were investigated by X-ray diffraction and and scanning electron microscopy, analysing particle size distribution and surface area. The protective layers were deposited by HVOF and evaluated for their microhardness, microstructure, porosity, and erosive wear. Their microstructure showed lamellar character, with a low level of oxides and porosity between 0.5 % and 1 %. The coating formed by NiCr and WCCoCr milled for 3 hours presented microhardness of 635 HV and erosion rates 50 % smaller than the commercial coating.