Obtention of hard coating using electrochemical process in aluminum-silicon alloys for automotive vehicles

Abstract

Automotive industry is searching for new ways to improve vehicles’ energy efficiency through mass reduction, using aluminum alloys. This change requires a surface protection to extend the life cycle of the components and aluminum anodization is the most used solution. This research is focused on the intake and exhaust ducts’ surfaces of aluminum internal combustion engines cylinder head, which are subject to chemical agents and temperature variation. To extend the working life of this component it is necessary to obtain a covering protective layer. The process targeted the anodization of an internal surface of a much larger part of a cast aluminum-silicon alloy cylinder head. The anodization was obtained using a H2SO4 solution (184 g.L-1) and a DC voltage starting at 20 V. The Al2O3 layer obtained, inside the cylinder head´s ducts, has an average thickness of 120 μm in accordance with the proposal of providing a suitable surface protection.