Abstract
Especially for industrial applications like pumps, mining or off shore industries, where high demands on the abrasive properties of the materials are required, thermal sprayed Fe-based coatings become increasingly important. Novel FeCrMnBC alloys, which have economic and ecological advantages compared to Ni-based or Co-based coatings, are in the focus of this work. 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 investigated and compared with respect to corrosion, abrasion, and erosion properties. In case of wear reduction, selected coatings were additionally subsequent plasma nitrided to study the effect of this treatment on coating morphology and microstructure. The corrosion and tribological behavior were investigated by means of current/density potential curve measurements and ball-on-disc experiments in view of wear morphologies. 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 nitrided coatings show a decrease in corrosion and erosion resistance, which is presumably due to 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 protection of complex pump parts are discussed with respect to varied parameters.
