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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]

High-efficiency gas turbines require high-temperature sealing by use of abradable porous ceramic coatings to increase engine efficiency. In this study, porous AlO coatings were deposited by flame spraying; the coatings were applied in a semi-molten state by controlled melting of the sprayed powder particles. The effects of the degree of melting of the sprayed particles, which depends on spraying conditions, on coating microstructure and porosity were investigated. The degree of melting of the sprayed particles was characterized by use of 3D confocal laser microscopy. The porosity of the coating was estimated by image analysis. The results showed that the degree of melting of alumina particles can be changed from 70 to 30%, and thus coating porosity can be increased from 30% up to over 70%. The standard hardness test yielded no useful data for porous coatings deposited by use of sprayed particles with a degree of melting <60%, and a hardness of 32-75 HR15Y for AlO coatings deposited by use of sprayed particles with a degree of melting >60%. Pin-on-disk abrasion tests, performed at room temperature by use of an Inconel 738 (IN738) nickel-based superalloy pin with a spherical tip 5 mm in diameter, were conducted on the porous alumina coating to evaluate its abrasion behavior. It was found that for coatings of hardness <32 HR15Y and porosity >40% the wear weight loss of the IN738 pin was negligible despite the high rate of wear of the coating. It is evident that flame-sprayed porous alumina coatings of high porosity prepared by this approach have potential for use as abradable coatings for gas turbines operating at high temperatures. [ABSTRACT FROM AUTHOR]