Surface and tribology characterization of diamond-like carbon flakes reinforced oxide film by pulse anodizing

Abstract

Hard anodizing by using direct current (DC) is one of the conventional approaches to fabricate composite oxide film. However, the formation of high porosity and microcracks lead to significant surface defects that limit its usage in load-bearing application. The present study aims to fabricate composite oxide film by applying pulse current (PC) with incorporating Diamond-like carbon (DLC) flakes to improve surface quality. For the first phase, the growth mechanism was studied by different anodizing time at constant (1 g/L DLC) in the electrolyte. Meanwhile, the mechanical and tribological performance of DLC content in the electrolyte were determined at second phase. Oxide film has been successfully fabricated on the surface of Aluminum alloy AA2017-T4 by anodizing in diluted sulphuric acid (20 wt%) containing DLC flakes. Then, surface morphological and tribological properties were evaluated. Results showed the thickness and growth rate of (1 g/L) DLC flakes reinforced oxide film fabricated by pulse current and direct current, approximately measured at 34.41 μm (growth rate: 0.58 μm/min) and 118.08 μm (growth rate: 1.97 μm/min), respectively. By increasing the DLC content (0–20 g/L) in electrolyte, it enhanced the microhardness and durability of the composite oxide film. However, oxide film fabricated with 5 g/L DLC in electrolyte formed enough transfer layer to reduce friction during the sliding wear process.