Correlation of Microstructure with Abrasion and Oscillating Wear Resistance of Thermal Spray Coatings

Abstract

Detailed studies concerning influence of microstructural features on the resistance of different thermal spray coatings against dry abrasive wear (Taber Abraser test) and oscillating wear (ball on disk configuration) are carried out. Besides WC and Cr3C2 based cermet coatings produced by a triple cathode APS system with axial powder feed and by HVOF systems using kerosene fuel also APS Cr2O3 and Al2O3 coatings are tested. At the example of WC/CoCr coatings the influence of carbide size and content, powder size fraction, powder manufacturing process and spraying process parameters is studied. For APS Al2O3 investigations concerning the influence of powder feed rate and nozzle geometry of single cathode APS torch are imparted. Oscillating wear tests are performed using alumina and hardened steel balls as counter bodies. Coatings are characterized concerning phase composition and residual stress state by means of XRD. Additionally microstructure is evaluated by SEM investigations and micro hardness is measured. Guidelines for manufacturing of thermal spray coatings fitting the specific demands of the two applied wear conditions are deduced.

Microstructural Characterization and Oscillating Sliding Wear Investigations of the Aqueous Suspension Sprayed HVOF WC-12Co Coatings

“…The coatings made of ultra-fine powders show thus higher performances under oscillating wear/sliding wear loading. In contrast, coatings produced from powders with coarser carbides show high loading resistance under dry abrasive wear (Ref 4,5,(12)(13)(14). Tillmann et al (Ref 15) processed HVOF WC-10Co4Cr (-10 ?…”