Characteristics of plasma cladding Fe-based alloy coatings with rare earth metal elements

The characteristics of plasma cladding Fe-based alloy coatings with rare earth (RE) oxide CeO2 and La2O3 have been investigated. Fe-based alloy powders with different contents of CeO2 and La2O3 were cladded onto a steel substrate. The clad coatings were examined and tested for microstructural features, chemical compositions, phase structures and hardness of the clad coatings. A scanning electron microscope (SEM) equipped with energy dispersive analysis X-rays energy dispersive spectrum (EDS) was employed to observe the microstructure and analyze the chemical compositions of the clad coatings. The crystallographic phases formed during plasma cladding were characterized by an X-ray diffractometer. And the microhardness was tested by HVS-1000 digital microhardness tester. The results showed that when the addition content of CeO2 and La2O3 was 0.5 wt.%, the microstructure of the coatings could be refined and purified. And the dilution of clad material from the substrate was reduced. Moreover, some new compounds such as LaNi4Si and Ce2Ni22C3 and hard crystallographic phase, Cr3Si, formed in the coatings and the microhardness values were higher than those of other coatings. The mechanism of the effects of RE oxide on the coating was discussed in the paper.