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This work aimed to explore the effect of cBN (cubic boron nitride) content on the microstructures and wear-corrosion resistance of the CoCrFeNiTi0.8-xcBN (x = 0, 2, 4, 6 wt.%) particle-reinforced high-entropy alloy coatings. Laser cladding technology was used to prepare the coatings on TC18 substrate. The microstructures, volume wear rates and polarization curves were characterized. The results showed that the CoCrFeNiTi0.8-xcBN coatings had an optimal forming quality under the process parameters: laser power of 1500 W, scanning rate of 12 mm/s and overlapping rate of 60%. As the cBN content increased, plenty of TiN and TiB2 hard particles formed in situ in the coatings, significantly improved the wear resistance. As a result, the volume wear rate of CoCrFeNiTi0.8-6cBN was only 4.0% and 16.5% of that of TC18 substrate and CoCrFeNiTi0.8 coating, respectively; the wear mechanism changed from adhesive wear + oxidative wear to abrasive wear + oxidative wear gradually. Moreover, CoCrFeNiTi0.8-xcBN coatings can effectively inhibit the infiltration of corrosive media by dense organizational characteristics and the physical barrier effect of oxidation-protective films. After 480 h of neutral salt spray (NSS) test, the CoCrFeNiTi0.8-xcBN coatings exhibited excellent corrosion resistance, both of the appearance and protection rating reached level 10. Therefore, it can be used as the wear-corrosion-resistant coating for the TC18 substrate in a NSS environment. [ABSTRACT FROM AUTHOR]

In this study, malleable and heavy Ta particles were introduced into soft Al powders to prepare Al-Ta composite coatings through a low-pressure cold-spray process; for comparison, Al-A2O3 composite coatings were also deposited. The surface and cross-sectional morphologies, deposition efficiency, microstructure, hardness and composition of the coatings were investigated. The results demonstrated that the Al-Ta coatings had roughness values that were almost twice as large as those of the Al-Al2O3 coatings for the same volumetric fraction of reinforcement particles used in the feedstock. Ta particles were more effective in improving the deposition efficiency and densification than were Al2O3 particles. The formation mechanism of the Al-Ta coatings was mainly attributed to the malleable and heavy nature of Ta particles, which allowed them to bond with the formed coating and impact the coating strongly through the peening effect. [ABSTRACT FROM AUTHOR]