Inner-Diameter HVOF deposition of Chrome Carbides using an evolved ID-Nova design

Chrome carbide Cr₃C₂ 25(80Ni 20Cr) is an important wear and corrosion resistance coating material and is often an alternative to tungsten carbide (WC-Co-Cr) protective coating for high temperature environments up to approximately 900 °C. Applying chrome carbide coatings in small inner diameters by HVOF can pose some challenges, since its lower density over tungsten carbide allows more rapid acceleration of the sprayed particles by the high velocity gas jet and thereby, in combination with a short standoff distance, limit the particle heating required to form high quality coatings. Further, the small and light particles are readily decelerated and diverted before impact, limiting build-up rates and compressive stresses. While the ID-HVOF deposition process for tungsten carbide is increasingly maturing, chrome carbide coatings can still pose some constrains.

Spraywerx has developed a high power ID-HVOF torch than can spray high quality chromium carbide coatings with stand-off distances below 40 mm. The presentation will discuss the development of these coatings and key features of ID-Nova MK7 HVOF gun.