Slurry erosion behaviour of HVOF sprayed WC–10Co–4Cr and Al2O3+13TiO2 coatings on a turbine steel

Abstract

Hydroturbine components generally suffer from severe wear due to slurry erosion caused by solid particles entrained in the flowing water. High-velocity oxy-fuel (HVOF) spray process is known for depositing protective coatings on the materials. In this work, WC–10Co–4Cr and Al2O3+13TiO2 coatings were deposited on CF8M turbine steel by HVOF spray process and studied with regard to their performance under slurry erosion conditions. High speed erosion test rig was used for slurry erosion tests and effect of three parameters namely average particle size, speed (rpm) and slurry concentration on slurry erosion of these materials was investigated. The bare steel and Al2O3+13TiO2 coating followed ductile and brittle mechanisms respectively under slurry erosion, whereas the WC–10Co–4Cr coating exhibited mixed behaviour (mainly ductile). WC–10Co–4Cr coating was found to be useful to increase the slurry erosion resistance of steel remarkably.