The slurry erosion behaviour of high velocity oxy-fuel (HVOF) sprayed aluminium bronze coatings

This paper investigates the erosion aspects of a novel high velocity oxy-fuel (HVOF) sprayed aluminium bronze coating under sand particle impingement conditions, using a free-jet impingement erosion rig. Erodents at various kinetic energies (0.1–0.8 μJ) and impingement angles (30, 60 and 90°) were used to simulate actual service conditions. Gravimetric measurements, surface profilometry and microscopy techniques were utilised to determine both the erosion rate and the mechanisms of coating failure. The erosion rate of the coating was found to be comparable to bulk 90/10 cupro-nickel (C70600) and about twice that of Marinel and AISI 316L stainless steel. These results suggest that HVOF aluminium bronze coatings are suitable candidates for marine applications. Analysis of the erosion scars suggest that coating erosion occurred by a combination of cutting wear, plastic deformation, and crack propagation at splat boundaries (brittle oxides) leading to the detachment of coating splats, cutting wear was found to be the most dominant. The cutting process was dominated by smaller particle impacts. The number of these particles which cause damage appears to be a function of kinetic energy.