The effect of sulphuric anodisation of aluminium alloys on contact problems

Damage of aluminium alloys is a major problem in industrial applications. Especially under contact loadings, aluminium alloys show surface degradation independently of contact configurations and operating conditions such as fretting in bearing holder for gear box and abrasion in buckets of trucks. To improve wear resistance, some surface treatments have been performed, particularly sulphuric anodisation (SA) which is often used.The present work deals with the effect of such treatment in two different contact problems. The first concerns abrasion of the 5xxx alloy, whereas the second treats fretting of the A357 alloy. It was found that SA treatment effect depends on the contact configurations. It has been shown that SA treatment decreases wear resistance and provides a transition wear mechanism from ploughing to cutting under scratch. However, in fretting mode, SA treatment eliminates wear kinetics transition and maintains a low wear regime.