Abstract
In this study, advanced surfaces and coatings have been developed using plasma thermochemical treatment, PVD coating, electroless Ni-BN plating and duplex surface engineering to produce low-friction and wear-resistant surfaces for cast iron stamping tools. Their microstructural and nano-mechanical properties were systematically analysed and the tribological behaviour of these new surfaces and coatings were evaluated. The experimental results have shown that under dry sliding condition, the tribological behaviour of aluminium differed great from that of steel regardless of the counterpart material. Highly reactive aluminium had a strong tendency to solder with tool surfaces during dry sliding. However, the lubricity of gray cast irons can be significantly improved by Ni-BN and DLC coatings. The coefficient of friction reduced from about 0.5 for untreated cast irons to about 0.2 sliding against aluminium. Duplex treatment combining plasma nitrocarburising with low- friction coatings showed superior durability than both DLC and Ni-BN coatings.
Highlights
Metal stamping process is widely used for production of thin-wall products such as vehicle body panels because of its high productivity
Based on the experimental work conducted on the microstructural characterisation and tribological studies of the surface engineered G3500 gray cast iron, the following conclusions can be drawn:
A range of surface engineering techniques including plasma nitrocraburising (PNC), electroless Ni-BN plating, PVD diamond-like carbon (DLC) coating and duplex treatment combining plasma nitrocarburising (PNC) with Ni-BN coating have been successfully applied to G3500 gray cast iron
Summary
Metal stamping process is widely used for production of thin-wall products such as vehicle body panels because of its high productivity. In a typical car body, there are 40–50 major panels produced by 150–250 die sets [1]. Current hot stamping tools for forming aluminium alloys are normally made of hot work tool steels, such as H13. Hot stamping tools are costly because of the high materials price (expensive hot work tool steels) and manufacturing costs (poor formability and machinability). The tool cost could be reduced by the use of low-cost cast irons with good castability and machinability. Cast irons lack of adequate hardness (
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