Effect of feedstock characteristics and operating parameters on the properties of Cr2O3 coatings prepared by suspension-HVOF spray

Chromium (III)-oxide (Cr2O3) is a widely used coating material for applications in the printing, paper and textile industry, pumps and mechanical sealing systems. Cr2O3 coatings offer high hardness, excellent sliding wear performance and corrosion resistance. Suspension-HVOF process (S-HVOF) allows the production of dense, finely structured coatings with smooth surfaces and improved mechanical properties. The current work presents a study on the development of ready-to-spray aqueous Cr2O3 suspensions starting from different commercial available powders and the effect of suspension characteristics (particle size distribution, viscosity, stability) and operating parameters (gas composition, spray distance) on the microstructure, microhardness and deposition efficiency of the S-HVOF Cr2O3 coatings. By appropriate choice of the suspension and spraying parameters, thick (> 100 mm) and mechanical stable (microhardness higher than 1500 HV0.3) suspension sprayed Cr2O3 coatings were produced.