Abstract
Nickel-based alloy coatings were widely used for the remanufacturing of dies and moulds by laser cladding, but the crack sensitivity would be increase due to the higher strength and hardness, which reduced the wear resistance of Ni-based alloys. In this paper, Ni-based coatings with the addition of a plastic phase (an austenitic stainless net) were prepared using laser cladding technology, and the CeO2 was added in cladding layers. The cracking mechanism, microhardness, microstructure, phase composition, and wear properties were investigated. The relationship between thermal stress and the elastic and plastic fracture had been developed from the standpoint of fracture mechanics and thermal elastic fracture mechanics. The fracture criterion of the nickel-based coating was obtained, and the study has shown that the crack sensitivity could be reduced by decreasing the thermal expansion coefficient Δα. Thus, a new method was proposed, which the stainless steel nets were prefabricated on the substrate. It was found that the number of cracks reduced significantly with the addition of stainless steel net. When the stainless steel net with 14 mesh was added in Ni-based coatings, the average microhardness of nickel composite coating was 565 HV0.2, which was 2.6 times higher than that of the 45 steel substrate. Although the rare earth oxide 4 wt.% CeO2 and stainless steel net were added in the Ni-based coating reducing the microhardness (the average microhardness is 425 HV0.2), the wear resistance of it improved substantially. The wear volume of Ni-based composite coating was 0.56×10−5 mm3·N−1·m−1, which was 85.1% lower than that of 45 steel. The experiment results have shown that the Nickel-based composite coating is equipped with low crack sensitivity and high abrasive resistance with austenitic stainless net and the rare earth oxide 4 wt.% CeO2. This research offers an efficient solution to produce components with low crack susceptibility and high wear-resistance coatings fabricated by laser cladding.
Highlights
It is well-known that abrasive wear is a severe problem to industrial components and equipment, resulting in energy consumption [1,2,3]
Ni-based alloy coatings fabricated with rare earth, which plays a key role in producing grain refinement effect, might have superior anti-friction properties, coating’s cracking susceptibility could not be reduced, which attributed to the existence of the eutectics network providing a route for crack growth [25]
This study focused on the mechanistic studies of cracking in the Ni-based coatings and presenting a fracture criterion for coatings from the viewpoint of fracture mechanics
Summary
It is well-known that abrasive wear is a severe problem to industrial components and equipment, resulting in energy consumption [1,2,3]. Tang et al [22] reported that Ni60 cladding layers added nano-WC particles displaying high hardness and abrasive wear resistance than the Nickel-based alloy coatings without nano-WC particles. Ni-based alloy coatings fabricated with rare earth, which plays a key role in producing grain refinement effect, might have superior anti-friction properties, coating’s cracking susceptibility could not be reduced, which attributed to the existence of the eutectics network providing a route for crack growth [25]. As a common method that, pre-heating had been applied to decrease crack susceptibility [33,34,35] These studies had been conducted mostly from rare earth additions, optimizing process parameters, and preheating the substrate to reduce the crack. The present results will offer an efficient solution to produce components with low crack susceptibility and high wear-resistance coatings fabricated by laser cladding
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