Synthesis, Microstructural Evolution, and Wet Wear Performance of an Fe55-Based Coating Reinforced with CeO2 and TiN Particles Fabricated via Plasma Beam Spraying

Valve leakage mainly comes from worn sealing surfaces caused by abrasive particles. This study uses plasma beam spraying to create Fe55 alloy coatings with CeO2 and TiN added to improve microstructure and wear resistance. Five coatings were prepared: Fe55 with 0.02% CeO2 (FC2), 0.04% CeO2 (FC4), 1% TiN (FT1), 2% TiN (FT2), and 2% TiN/0.02% CeO2 (FC2T2). These coatings were tested for wear and erosion using wet sand and slurry experiments. Results showed that FC2T2 had the most uniform microstructure with fully equiaxed grains (20.32 μm size) and no columnar grains. This was due to CeO2 and TiN co-working effect: CeO2 was adsorbed onto TiN surfaces, reducing TiN decomposition and acting as nucleation sites. The FC2T2 coating also showed the highest hardness uniformity (no large changes with depth) and the lowest surface roughness after wear (41% lower than pure Fe55). In wear tests, FC2T2’s Cr7C3 hard phases blocked abrasive cutting, while the γ-Fe matrix prevented Cr7C3 from breaking off. Erosion tests confirmed FC2T2’s superior performance, as its uniform structure limited deep grooves. Adding both CeO2 and TiN improved wear resistance by providing a balanced microstructure, reducing leakage risks in valve sealing surfaces.