Microstructure and Wear Resistance of Laser-Clad Ni–Cu–Mo–W–Si Coatings on a Cu–Cr–Zr Alloy

Abstract

To improve the wear resistance of high-strength and high-conductivity Cu–Cr–Zr alloys in high-speed and heavy load friction environments, coatings including Ni–Cu, Ni–Cu-10(W,Si), Ni–Cu–10(Mo,W,Si), and Ni–Cu–15(Mo,W,Si) (with an atomic ratio of Mo,W to Si of 1:2) were prepared using coaxial powder-feeding laser cladding technology. The microstructure and wear performance of coatings were chiefly investigated. The results revealed that (Mo,W)Si2 and MoNiSi phases are found in the Ni–Cu–10(Mo,W,Si) and Ni–Cu–15(Mo,W,Si) coating. WSi2 phases are found in the Ni–Cu–10(W,Si) coating. The degree of grain refinement in Ni–Cu–10(Mo,W,Si) was greater than that of the Ni–Cu–10(W,Si) coating after the effect of Mo. The excellent wear resistance and micro-hardness of the Ni–Cu–15(Mo,W,Si) coating were attributed to the increase in its dispersion phase, which were approximately 34.72 mg/km and 428 HV, 27.1% and 590% higher than the Cu–Cr–Zr substrate, respectively. The existence of silicide plays an important role in grain refinement due to the promotion of nucleation and the inhibition of grain growth. In addition, the wear mechanism transformed from adhesive wear in the Ni–Cu coating with no silicides to abrasive wear in the Ni–Cu–15(Mo,W,Si) coating with high levels of silicides.

Microstructure and Properties of Nickel-Based Gradient Coatings Prepared Using Cold Spraying Combined with Laser Cladding Methods

“…It is worth noting that the value of the average microhardness of the fourth layer of CLGC is 478.8 HV 0.5 , being almost eight times that of the Cu substrate. This increasing microhardness is due to the formation of hard intermetallic compounds such as Ni 11 Si 12 and Mo 5 Si 3 and the strengthening effect of the Ni-Cu solid solution [ 33 ]. More importantly, in addition to reflecting the gradient change of its coating composition, the gradient distribution of the CLGC microhardness also improves the overall anti-wear properties and bond strength between the two neighboring layers of the coating [ 12 ].…”

“…Subsequently, the obtained samples based on the optimal cold spraying process were preheated in an oven at 200 °C for 0.5 h and then underwent the laser cladding process using ZKZM-10000 W high speed laser cladding equipment (Xi’an Zhongke Zhongmei Laser Technology Co., Xi’an, China). The optimum laser cladding process parameters, determined from earlier research, were as follows: laser power of 4500–5000 W, laser diameter of 5 mm, scanning speed of 1.8–3.6 m/s, and powder feed rate of 18 g/min [ 33 ]. The parameters for cold spraying and laser cladding are shown in Table 2 and Table 3 , respectively.…”

Microstructure and Wear Resistance of Ti6Al4V Titanium Alloy Laser-Clad Ni60/WC Composite Coating

“…The hardness of the cladding layer is significantly higher than that of the substrate due to the TiC, TiB2, W5Si3, and WSi2 hard phases generated in the composite coating, which is conducive to the improvement of the microhardness of the coating. The high cooling rate and the presence of silicides in the laser cladding inhibit grain growth [36], thus leading to grain refinement and strengthening. A tiny grain size means that there are more grain boundaries in the composite coating, which prevents the movement of dislo- The hardness of the cladding layer is significantly higher than that of the substrate due to the TiC, TiB 2 , W 5 Si 3 , and WSi 2 hard phases generated in the composite coating, which is conducive to the improvement of the microhardness of the coating.…”