Effect of microwave heating on microstructure and elevated temperature adhesive wear behavior of HVOF deposited CoMoCrSi-Cr3C2 coating

This research reports the improvement of high-temperature sliding wear resistance of a grade 15 titanium alloy protected by an HVOF sprayed CoMoCrSi-Cr3C2 coating. The coatings have been tested in as-sprayed condition and after a post-deposition microwave heating step. The powder feedstock has been manufactured by high energy ball milling. X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) equipped with the Energy Dispersive Spectroscopy (EDS) methods were used for coatings characterization. Surface roughness, microhardness, adhesion strength, and porosity of coatings were also measured. The wear test was conducted at an applied load of l0 N and 20 N with varying temperatures of 200 °C, 400 °C, and 600 °C under dry sliding conditions. Co3Mo2Si, Co7Mo6, Mo3Si, Co3Mo, and Co2Mo3 were the intermetallic laves phases generated in the CoMoCrSi feedstock during HEBM process. The microwave-fused coating exhibited metallurgical bonding, homogeneous structure, less porosity, and greater hardness as compared to as-sprayed coating. Microwave-treated coating revealed better wear property than an as-sprayed coating. This was mainly due to the intermetallic formation and metallurgical bonding in coatings. The fused coatings exhibit tribo-oxide layers during sliding action which was the main phenomenon of improving the wear resistance of the fused composite coatings. [Display omitted] •Higher fraction of hard intermetallic laves phases is generated in CoMoCrSi feedstock by processing through high energy ball milling process.•Reinforcement of Cr3C2 is added into processed feedstock and sprayed on pure titanium substrate using HVOF technique.•Refinement of as-sprayed coating is done by fusing it with the help of microwave hybrid heating process.•Metallurgical bonding, homogeneous structure, and higher hardness are achieved in microwave fused composite coatings.•Both as-sprayed and fused composite coatings exhibits lesser co-efficient of friction at higher temperatures, whereas microwave fused composite coatings showed better wear resistance than as-sprayed composite coatings.