Comparison of WC-CrC-Ni coating properties subject to powder characteristics and coating method

Thermal sprayed coatings of tungsten carbide (WC) in a cobalt or nickel base matrix are often used in applications which require wear and corrosion protection. Feedstock powders produced by agglomeration and sintering exhibit a spherical shape with a certain inherent intra-particle porosity. Chromium carbide (CrC) is sometimes added to WC-Ni powders to increase service temperature capability as well as enhance corrosion and wear resistance.

High velocity oxy-fuel (HVOF) spray guns have evolved through several generations since the early 1980s with both gas fuel (GF) and liquid fuel (LF) variants as industrialized processes. The development of high velocity air fuel (HVAF) spray guns, which use air instead of oxygen for combustion, was begun in the 1990s based on a patent from Browning. HVAF gun designs were improved and optimized in subsequent years, where by circa 2010, guns suitable for industrial production processes were available on the market.

The aim of the presented work is to systematically evaluate the influence of characteristics of several commercially available WC-CrC-Ni powders along with several high velocity spraying methods (HVOF-GF, HVOF-LF and HVAF) on the microstructure as well as the mechanical, tribological and corrosion properties of the applied coatings.