Duplex treatment for surface improvement of 2024 Al

Duplex treatment, a newly developed surface modification method, was used t o improve the tribological properties of an aluminum alloy. In this paper, the 2024 Al was anodically oxidized first and then coated with REMF-MoS2-Au nanocomposite film and Ti/Ag dual layer him by rf-sputtering and multi-are ion-plating, respectively. It is shown that duplex treatment, especially s puttered REMF-MoS2-Au nanocomposite film, can decrease the friction coeffic ient and improve the endurance life of 2024 Al in vacuum. The lubrication f ailure mechanism of the duplex treated 2024 Al is attributed to the generat ion of the cracks in the anodic oxide coating induced by normal load combin ed with friction force (shearing force) and the crack propagation mainly ca used by friction force. It is proposed that pores of several tens of nanome ters in diameter in the anodic oxide coating can postpone the propagation o f the cracks. (C) 2001 Elsevier Science Ltd. All rights reserved.