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Ni60 alloy is one of the important brands of nickel-based self-fusing alloys. It is widely used in industries such as metallurgy, mining, and other fields for the repair and protection of fragile parts. However, there is little literature on the effect of C content on its properties. In this study, two Ni60 alloy coatings with different C contents prepared by flame spraying and remelting were investigated by means of XRD, SEM, EBSD, friction wear testing, thermodynamic calculation, etc. The results showed that the calculated freezing range (FR) of Ni60 decreased from 983-1165.90 °C to 980-1154.28 °C and the melting range (MR) of Ni60 decreased from 966.27-1089.28 °C to 958.91-1045.41 °C when the C content increased from 0.72 wt.% (S1) to 1.01 wt.% (S2). Besides, the Cr7C3 phase size of the Ni60 layer increased with the increase of C addition. The coating shrinks during the remelting and solidification process, and the inner pores do not have sufficient time to escape, caused by the decreased FR, leading to the generation of holes and the degradation of surface quality in S2. However, the hardness of the S2 was 66 HV higher than that of S1, and the wear resistance of the S2 coating was superior as well because of more precipitated carbides therein. This work would give a hint at balancing the processability and mechanical properties for the development of high-performance coatings. [ABSTRACT FROM AUTHOR]

The industry widely uses WC coatings to protect vital machine parts, including industrial gas turbines, ball valves, and aircraft landing gear shafts. To enhance the comprehensive performance of WC-10Co cemented carbide coatings, this study added VC and Cr 3 C 2 grain inhibitors to refine the WC particles. Two novel powder compositions, S1 (WC-10Co-2Cr 3 C 2 -2VC) and S2 (WC-10Co-2VC-2Cr) were developed using the spray granulation method, alongside a commercial WC-10Co-4Cr powder as a control. These coatings were applied to 316 stainless steel substrates using the HVOF technique and subjected to XRD, SEM, hardness, friction, and electrochemical analysis. The microstructures, phase compositions, and various properties of WC-10Co-2Cr 3 C 2 -2VC and WC-10Co-2VC-2Cr coatings were systematically investigated. The results indicate a significant reduction in decarburization and porosity in S1 and S2 coatings compared to the commercial WC-10Co-4Cr coatings. VC and Cr 3 C 2 suppressed the Ostwald ripening phenomenon, leading to smaller WC particle sizes in S1 and S2 coatings. In terms of performance, WC-10Co-2Cr 3 C 2 -2VC exhibited the highest hardness and superior wear resistance, while the WC-10Co-2VC-2Cr coating displayed the lowest corrosion rate in a 5 wt% H 2 SO 4 solution at 25 °C, all while maintaining excellent mechanical properties. This study opens potential directions for the creation of high-performance WC-based coatings. • VC and Cr 3 C 2 suppressed the Ostwald ripening phenomenon, leading to smaller WC particle sizes. • WC-10Co-2Cr 3 C 2 -2VC exhibited the highest hardness and superior wear resistance. • WC-10Co-2VC-2Cr coating displayed the lowest corrosion rate in a 5 wt% H 2 SO 4 solution at 25 °C. [ABSTRACT FROM AUTHOR]

The 1.0C-1.5Cr steel was subjected to conventional quenching and laser surface quenching treatment. A process combing double quenching and laser surface quenching was proposed for enhancing surface hardness and obtaining finer microstructure. The cementite dissolution and grain growth behavior in the austenitizing process of single quenching, double quenching, and laser surface quenching were studied. The results indicated that compared with single quenching, mean diameter of undissolved cementite particles (UCP) was much finer in double quenching, and the final prior austenite grain size (PAGS) could be decreased by nearly 40% to about 4.5 μm. Both grain and cementite particles near the surface will coarsen after laser surface treatment. Compared with single quenching, the PAGS within hardened layer can be decreased by at least 11% through double quenching, and the mean diameter of UCP at the bottom of hardened layer can be decreased by about 20%. Compared with conventional quenching, surface hardness was enhanced by about 20% through laser surface quenching, contributing to the wear resistance. However, the hard and brittle surface layer tends to be crack source during the impact process, leading to the deterioration of final impact toughness. Under the identical laser parameters, the impact absorbed energy is similar in both single and double quenching, which is about 25% of that before laser surface quenching. The impact absorbed energy can be increased from 22J to 28J by preheating at 160 °C during the laser surface quenching. [ABSTRACT FROM AUTHOR]