Abstract
The remelting method is introduced to improve the properties of the as-sprayed NiCrBSi coatings. In this work, tungsten carbide (WC) was selected as reinforcement and the as-sprayed and remelted NiCrBSi/WC composite coatings were investigated by X-ray diffraction, scanning electron microscopy, hardness test and tribology test. After spraying, WC particles are evenly distributed in the coating. The remelting process induced the decarburizing reaction of WC, resulting in the formation of dispersed W2C. The dispersed W2C particles play an important role in the dispersion strengthening. Meanwhile, the pores and lamellar structures are eliminated in the remelted NiCrBSi/WC composite coating. Due to these two advantages, the hardness and the high-temperature wear resistance of the remelted NiCrBSi/WC composite coating are significantly improved compared with those with an as-sprayed NiCrBSi coating; the as-sprayed NiCrBSi coating, as-sprayed NiCrBSi/WC composite coating and remelted NiCrBSi/WC composite coating have average hardness of 673.82, 785.14, 1061.23 HV, and their friction coefficients are 0.3418, 0.3261, 0.2431, respectively. The wear volume of the remelted NiCrBSi/WC composite coating is only one-third of that of the as-sprayed NiCrBSi coating.
Highlights
Some moving parts in industrial machinery, such as aero engines, gas turbines, turbochargers and so on, are employed in a high-temperature environment
The results showed that in-situ laser remelting induces the growth of a dendritic structure, which increases the adhesion of coatings on the substrate
The results indicated that the induction remelting improves the microstructure and hardness of the NiCrBSi coating, and changes the coating/substrate interface bonding from mechanical bonding to metallurgical bonding
Summary
Some moving parts in industrial machinery, such as aero engines, gas turbines, turbochargers and so on, are employed in a high-temperature environment. Surface modification methods for improving wear resistance include thermal spraying [2,3,4], laser processing [5,6,7,8], friction stir processing [9,10], micro-arc oxidation [11], shot peening [12,13] and so on. Among these methods, thermal spraying is an efficient technology to produce reliable coatings on the workpieces [14]. Plasma spraying is one of the thermal spraying technologies and prepares coatings to improve the wear resistance and hardness of metallic parts
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