Effects of CeO2 addition on microstructure and properties of ceramics reinforced Fe-based coatings by laser cladding

To reduce deposition defects (cracks and porosity) of the ceramics reinforced Fe-based coatings, and improve their microstructure uniformity, microhardness, and wear resistance, different content of CeO2 (0, 1.0, 2.0, 2.5, and 3.0 wt.%) was added to the Fe-based powders. The effects of CeO2 addition on the microstructure, phase composition, and mechanical properties were investigated by an optical microscope, X-ray diffraction (XRD), scanning electron microscopy (SEM), Vickers hardness tester, and friction wear tester. The results show that appropriate CeO2 addition not only can reduce the cracks and porosities but also improve the bonding performance between the composite coating and the substrate. The study also finds that the addition of CeO2 promotes the melting of large-size ceramic particles, increases the nucleation sites, and further refines the microstructure. The mechanical properties of each coating show that the microhardness and wear resistance firstly increases and then decreases with the increase of CeO2 addition. The ceramics reinforced Fe-based coatings with 2.5 wt.% CeO2 addition exhibites the highest and most uniform microhardness, and the smoothest worn surface despite the higher friction coefficient. Thus, CeO2 addition is an effective method to refine the microstructure, reduce cracks and porosities in the TiN and Ti (C, N) reinforced Fe-based coating, and further improve microhardness and wear performance.