Effect of feedstock particle sizes on wear resistance of plasma sprayed Fe-based amorphous coatings

Fe-based amorphous coatings were fabricated by plasma spray technology using Fe43Cr16Mo16C10B5P10 powders with different particle sizes (median size of 33 μm, 66 μm and 84 μm, respectively). XRD results indicated that all of the coatings exhibited a large fraction of amorphous phase. The effect of the feedstock particle sizes on the morphology and microstructure of as-sprayed coatings was investigated by SEM and TEM observations. It was found that the smaller the particle size, the denser the structure with the lower porosity and lesser cracks the coating exhibited. The feedstock particle sizes had a significant effect on the wear resistance of coatings. With a decrease in the particle sizes, the porosity decreased and the cohesion at the intersplat regions and the hardness of the coating improved. Hence, the wear resistance of coating was enhanced. Moreover, the sliding velocity also had different influences on the wear resistance of coatings. Raising the sliding velocity could aggravate the oxidation of the coating and lead to a decrease in the wear resistance. The analysis of the worn surfaces of coatings indicated that the dominating wear mechanism of Fe-based amorphous coatings was fatigue wear accompanied with oxidative wear.