Gradient DLC-Based Nanocomposite Coatings as a Solution to Improve Tribological Performance of Aluminum Alloy
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The low hardness and poor tribological performance of aluminum alloy as moving component greatly restricts their wide applications in automotive fields. In this letter, an attempt to deposit gradient Ti/TiN/Si/(TiC/a-C:H) multi-layer on aluminum alloy is thus effectively performed by a combined arc ion plating and magnetron sputtering process based on the concept of involving coatings with a functionally graded interface. Multi-layered structure within DLC-based coatings has shown to significantly improve the load-bearing capacity, anti-wear and self-lubricating ability of Al alloys. The friction coefficient of gradient DLC-based coatings decreased to 0.18 under dry sliding condition while kept at 0.05 under the oil-lubricated conditions. The wear rate of gradient DLC multilayers was lower by two and even three orders of magnitude when compared with Al alloys both under dry wear and oil-lubricated conditions. Such gradient DLC-based coatings with good adhesion strength, high hardness, and excellent tribological performance are considered as potential protective surfaces of Al alloys for engine parts.
KeywordsAluminum alloy Diamond-like carbon coatings Graded and multilayer Friction Adhesion wear
The authors are grateful to the National Natural Science Foundation of China (Grant No. 50772115 & 50905178) and the 863 program of Chinese Ministry of Science and Technology (No. 2009AA03Z105) for financial support.
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