Wear and corrosion behaviour of thermally sprayed FeCrMnBC coatings for pump parts

Especially for industrial applications like in pump, mining or off shore industries, where high demands on the abrasive properties of the materials are required, thermal spray coatings like Fe-based coatings are becoming more important. In order to produce adequate coatings with a three-cathode plasma torch, different powder fractions (-45+20 µm, -25+10 µm) and varying chemical composition of FeCrMnBC coatings have been examined and compared with respect to corrosion, abrasion and erosion properties. In case of wear reduction, selected coatings were additionally plasma nitrated to study the effect of this treatment on coating morphology and microstructure. The corrosion and tribological behavior were examined by means of current/density potential curve measurements and ball-on-disc experiments. Erosion-corrosion behavior has been investigated in a pump test rig with 10 wt.-% solid content of corundum in artificial sea water. In general, samples with small powder fractions exhibit accelerated corrosion and decreased erosion behavior, based on their microstructural characteristics. Plasma nitrated coatings exhibit a decrease in corrosion and erosion resistance, which is hypothesized on partial formation of chromium carbide in the coatings. Based on the results, the advantages and disadvantages of FeCrMnBC coatings for the application as wear and corrosion are discussed with respect to varied parameters.