Comparison of a cold‐sprayed and plasma‐sprayed Fe25Cr20Mo1Si amorphous alloy coatings on 40Cr substrates

Abstract

AbstractThe purpose of this paper is to examine whether cold spraying is capable of manufacturing high‐quality ferrous‐based amorphous alloy coatings by comparing the performance of a cold‐sprayed with a plasma‐sprayed Fe25Cr20Mo1Si amorphous coating on a 40Cr substrate. The hardness, microstructure, wear resistance, and corrosion resistance of the two coatings were determined with potentiodynamic polarization curves, neutral salt spray tests, scanning electron microscopy, energy dispersive spectroscopy, and X‐ray diffraction and their performance differences were examined. The results show that the cold‐sprayed Fe25Cr20Mo1Si coating has an amorphous content of 97.63%, which is slightly higher than that for the raw powder (97.24%) and plasma‐sprayed coating (96.55%). The coating hardness ranges from 720 HV to 1,030 HV, which is higher than plasma‐sprayed coating (590–610 HV) and decreases the wear rate to about 2/3. The average porosity is 2.97 ± 0.59%, which is lower than that of the plasma‐sprayed coating (4.95 ± 0.13%). The cold‐sprayed Fe25Cr20Mo1Si coating can pass the 3,000 hr neutral salt spraying test, while the plasma‐sprayed coating fails within 120 hr. The corrosion current in 3.5% NaCl solution reached to its stable value about 1.66 A/cm2, which is about 1/4 of the plasma‐sprayed coating (5.81 A/cm2). Upon analyzing the properties and the anticorrosion performance, it was found that there are no through‐thickness pores in the cold‐sprayed coating that impact its long‐term anticorrosion performance. Cold spraying can be used to fabricate ferrous‐based amorphous coatings instead of traditional thermal spraying technologies to obtain high‐quality ferrous‐based amorphous coatings.