Improvement of Wear Resistance by Thermal Spraying of Surface Layers prepared by Plasma Transferred Arc Welding on Gray Cast Iron Components

Duplex stainless steel and bronze layers are surfaced with plasma transferred arc surfacing on gray cast iron components. The corrosion properties are greatly enhanced, however for the duplex stainless steel surface layers it is found that these strongly depend on the dilution with the base material, while for bronze surface layers there is no such correlation. Under the applied test conditions, the wear resistance is found to mainly depend on the hardness of the surface layers. To improve the wear resistance, various oxide compounds with different thicknesses are thermally sprayed on top of the welded surface layers. The corrosion properties of these multilayer-systems are investigated with electrochemical and immersion tests. The wear resistance is tested with an oscillation tribometer. Multilayer-systems that show good resistance against corrosion and wear are subjected to complex loadings, e.g. erosion and cavitation testing. Microstructural characterizations of the single layers and the interfaces assist in defining the damage mechanisms. An assessment of the feasibility of the functional separation of the highly corrosion resistant surface welded layers and the highly wear resistant thermally sprayed layers concludes the research.