Avaliação do revestimento de óxido de alumínio sobre liga de alumínio fundida

Abstract

Often the design functions require the mechanical elements to work under severe conditions of friction and temperature. In order to maximize wear resistance and extend its service life a protective metal layer called coating can be applied to the scoring surfaces. There are several processes that can be used to coat surfaces in order to minimize wear. Chroming, for example, is a process that stands out for the production of highly resistant chrome coatings. However, from the perspective of environmental impacts and damage to human health this process is not fully evaluated due to the release of highly harmful chromium ions. Thus, there is a need to search for alternative coatings with near or similar wear resistance to the less damaging chrome surface. In this sense, the present work aims to conduct a preliminary study of the coating of aluminum oxide on molten aluminum alloy (Al-Si) 403.2 and to compare it to the chromium coating. Anodized samples in two different submersion times, 5 and 10 minutes, were compared to chromium samples according to industrial parameters for roughness, coefficient of friction and adhesion. The roughness parameters of the samples coated with aluminum oxide were generally smaller than those of the chromium-coated samples and in the wear tests with 2N load and frequency of 5Hz the chromium coating ruptured. With the results obtained it was possible to conclude that the aluminum oxide coating, under the tested conditions, has a low coefficient of friction, a higher resistance to wear.