Air jet erosion behaviour of high-velocity air–fuel-sprayed WC-10Co-4Cr coatings reinforced with 2 wt-% La 2 O 3 on SS410 steel

The present investigation aimed to evaluate the influence of 2 wt-% La 2 O 3 addition on the microstructural characteristics, mechanical properties, and air jet erosion behaviour of high-velocity air–fuel-sprayed WC-10Co-4Cr coatings deposited on SS410 stainless steel. Cross-sectional examination revealed continuous and defect-free coating layers with average thicknesses of 346 ± 10 μm and 298 ± 22 μm for WC-10Co-4Cr and La 2 O 3 reinforced coatings, respectively. XRD analysis confirmed WC as the predominant phase, while elemental mapping demonstrated uniform distribution of W, Co, Cr, C, and La throughout the coating matrix. The incorporation of La 2 O 3 reduced the porosity from 1.84 ± 0.12% to 1.26 ± 0.09% and increased the hardness from 1138 ± 32 HV to 1312 ± 28 HV, accompanied by an increase in elastic modulus from 286.4 ± 4.8 GPa to 311.8 ± 5.3 GPa. Air jet erosion tests conducted under varying particle velocities, erodent sizes, and impact angles revealed significantly lower mass loss for the La 2 O 3 -reinforced coating compared with the plain WC-10Co-4Cr coating and SS410 substrate. Post-erosion analysis indicated that La 2 O 3 addition effectively suppressed severe surface degradation and enhanced the erosion resistance of the coating.