Effect of Spray Condition and Heat Treatment on the Structure and Adhesive Wear Properties of WC Cermet Coatings

An improved HVOF spray process called ‘‘Gas-shrouded HVOF’’ (GS-HVOF) has been developed over the past several years. By using an extension nozzle at the exit of a commercial HVOF spray gun, GS-HVOF is capable of controlling the oxidation of sprayed materials during flight as well as achieving higher velocity of sprayed particles. These features result in extremely dense and clean microstructure of the sprayed coatings. The process has been successfully applied to corrosion resistant alloys such as SUS316L, HastelloyC, and alloy 625 as well as cermets such as WC-Cr3C2-Ni. Wear properties of WC cermet coatings were measured by using a pin-on-disk wear tester. The specific wear rates of the coatings prepared by the GS-HVOF with a reducing (fuel rich) flame were close to that of chrome plating. The wear amount of the heat-treated GS-HVOF coatings could not be detected after testing. It is believed that transition to mild wear appeared early because of the increased surface oxidation due to the heat treatment.

[1]  S. Kuroda,et al.  Development of corrosion resistant coatings by thermal spray technique , 2004 .

[2]  Lidong Zhao,et al.  Influence of spray parameters on the particle in-flight properties and the properties of HVOF coating of WC-CoCr , 2004 .

[3]  Baode Sun,et al.  Effects of structure and processing technique on the properties of thermal spray WC–Co and NiCrAl/WC–Co coatings , 2004 .

[4]  Paul M. Natishan,et al.  Validation of HVOF WC/Co Thermal Spray Coatings as a Replacement for Hard Chrome Plating on Aircraft Landing Gear , 2004 .

[5]  A. Igartua,et al.  Mechanical and tribological properties of high velocity oxy-fuel thermal sprayed nanocrystalline CrCNiCr coatings , 2003 .

[6]  H. Kato.  Severe–mild wear transition by supply of oxide particles on sliding surface , 2003 .

[7]  S. Kuroda,et al.  Development of dense corrosion resistant coatings by an improved HVOF spraying process , 2003, Thermal Spray 2003: Proceedings from the International Thermal Spray Conference.

[8]  Justin C. Sanchez,et al.  Role of heat treatments in the improvement of the sliding wear properties of Cr3C2–NiCr coatings , 2002 .

[9]  D. Toma,et al.  Wear and corrosion behaviour of thermally sprayed cermet coatings , 2001 .

[10]  H. Kreye,et al.  Oxidation of stainless steel in the high velocity oxy-fuel process , 2000 .

[11]  P. H. Shipway,et al.  Abrasive wear behaviour of conventional and nanocomposite HVOF-sprayed WC–Co coatings , 1999 .

[12]  M. Hyland,et al.  Study of the influence of microstructural properties on the sliding-wear behavior of HVOF and HVAF sprayed WC-cermet coatings , 1999 .

[13]  J. K. Lancaster,et al.  Surface Film Formation and Metallic Wear , 1956 .

[14]  Chang-jiu Li,et al.  Effect of sprayed powder particle size on the oxidation behavior of MCrAlY materials during high velocity oxygen-fuel deposition , 2003 .