Abstract
To improve the anti-wear and friction-reducing properties of self-lubricating coatings, Ni60/Nickel-coated graphite/TiB2 composite coatings with different contents were prepared by laser cladding. The coating properties were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), energy spectrometer (EDS), electrochemical workstation, micro-Vickers hardness tester, and friction and wear tester. The results showed that with the increase in TiB2 content, the graphite morphology changed from spherical at 0 wt.% TiB2 content to a little black graphite alone at 14 wt.% TiB2 to irregular agglomerates at 22 wt.% TiB2. Furthermore, the hardness of the coatings increased with increasing TiB2 content, and the 63% Ni60 + 15% nickel-coated graphite + 22% TiB2 coating had the highest hardness. TiC and Cr7C3 were generated in the coatings with the addition of nickel-coated graphite, creating a dispersion reinforcement effect, so that the hardness of these coatings was higher than that of the 86% Ni60 + 0% nickel-coated graphite + 14% TiB2 coating without the addition of nickel-coated graphite. In addition, the 71% Ni60 + 15% Ni-coated graphite + 14% TiB2 coating had the lowest friction coefficient, wear loss, and wear volume, thus exhibiting excellent friction reduction and anti-wear properties. The 71% Ni60 + 15% nickel-coated graphite + 14% TiB2 coating had excellent corrosion resistance.
Highlights
Cracking may be caused by thermal mismatch between the reinforced, toughened, and lubricated phases, which may have increased the thermal stress in the TiB2 phase and the surrounding coating, leading to the formation of cracks [30]
In the W3 coating, the addition of a moderate amount of TiB2 helps to make the reinforcing phase and the toughening phase in the structure combined with lubrication denser, reducing the oxidation rate
Compared with coating W5 without nickel-coated graphite, the carbide Cr7 C3 and TiC were formed in the W3 coating with nickel-coated graphite, which improved the corrosion resistance of the W3 coating
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Liu et al [16] studied the friction and wear properties of the laser cladding Ti-containing Ni60/graphite self-lubricating composite coatings. Some studies have been conducted on self-lubricating wear-resistant composite coatings with the addition or in situ generation of lubricant phases and hard reinforced phases. Xia et al [21] investigated a laser cladding TiB2 /graphite coating on the surface of 9Cr18 stainless steel, and found that the presence of carbides greatly increased the hardness of the coating, and the wear resistance of the coating was higher than that of the substrate stainless steel. To break through the technical bottleneck of existing research, this paper used TiB2 as the reinforcement phase, Ni60 as the toughening phase, and nickel-clad graphite as the lubrication phase to prepare the self-lubricating composite coating by laser. Exploring the influence of the change in TiB2 content on the performance of the coating, which provides support for the process optimization of the self-lubricating coating in engineering
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