Deposition efficiency is an important metric for thermal spraying, but it can be difficult to measure in some cases. In this study, a volume-based deposition factor is developed that can be used to estimate deposition efficiency simply by evaluating process parameters, coating thickness, and porosity. Coating thickness or thickness per pass is measured from the sample and parameters like feed rate, step size, and surface speed are taken into account. The correlation to deposition efficiency is demonstrated for various plasma and HVOF processes using powder and suspension feedstock materials. An example is also given showing how the method can be used to evaluate older data sets collected without regard to deposition efficiency.

Chromium (III)-oxide (Cr 2 O 3 ) is a widely used coating material for applications in the printing, paper and textile industry, pumps and mechanical sealing systems. Cr 2 O 3 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 Cr 2 O 3 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 Cr 2 O 3 coatings. By appropriate choice of the suspension and spraying parameters, thick (> 100 μm) and mechanical stable (microhardness higher than 1500 HV0.3) suspension sprayed Cr 2 O 3 coatings were produced.