Fabrication, microstructure and wear properties of novel Fe-Mo-Cr-C-B metallic glass coating layers manufactured by various thermal spray processes

The metallic glass powder of newly designed Fe46.8-Mo30.6-Cr16.6-C4.3-B1.7 composition was employed to fabricate Fe-based metallic glass coating layers using representative thermal spray processes, viz. atmospheric plasma (plasma), HVOF and vacuum plasma spray (VPS). The microstructure and wear properties of the thermal sprayed Fe based metallic glass coating layers were investigated. XRD analysis results showed that all the three coating layers had broad halo peaks. Alloying element depletion was observed in the coating layer in the vicinity of the oxides. However, the VPS coating layer showed no depletion area. Wear test results showed that the VPS coating layers had the best wear resistance among all the three coating layers, whereas the plasma material had the poorest wear resistance property. Worn surface and cross-section observation revealed that the plasma material had particle boundary delamination because of its lower bonding force between the particles. Directly below the worn-out surface of the HVOF coating layers, microcracks were generated along the particle boundaries. By contrast, no defects were found at all directly under the worn-out surface of the VPS materials. The wear behavior of Fe based metallic glass coating layers fabricated in diverse thermal spray processes was discussed with respect to the microstructure.