Microstructure and tribological properties of iron-based metallic glass coatings prepared by atmospheric plasma spraying

Iron-based metallic glass coatings (denoted as FeWCrNiMoBSiC) were prepared on 1Cr18Ni9Ti stainless steel cylinders by atmospheric plasma spraying at different parameters. The morphology, microstructure, and crystalline structure of as-prepared Fe-based metallic glass coatings were analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. A Pycnometer and a Vickers hardness tester were adopted to measure the porosity and microhardness of iron-based metallic glass coatings. Moreover, differential scanning calorimetry analysis was conducted to investigate the crystallization behavior of various iron-based metallic glass coatings, and a ball-on-disk tribometer was performed to evaluate the tribological properties of the coatings coupled with silicon nitride ceramic balls under unlubricated conditions. It has been found that the microhardness of iron-based metallic glass coatings increases with increasing plasma arc power, which is related to the degree of melting of feedstock powders and the compactness of as-prepared coatings. Besides, the phase compositions of as-sprayed coatings consist of amorphous structure and limited crystalline structure, and the contents of the amorphous structure and crystalline structure vary with plasma arc power. Moreover, iron-based metallic glass coatings deposited at different plasma arc powers show similar steady-state friction coefficients (0.8-0.9), but their wear rate varies with varying plasma arc power. Particularly, iron-based metallic glass coating with next to the highest hardness exhibits the best anti-wear ability, which is the outcome of the compromise between the hardness and brittle fracture as well as abrasive wear of the coatings during sliding process. (C) 2014 Elsevier Ltd. All rights reserved.