Estudo comparativo da aplicação do revestimento intermediário de cobre alcalino em ligas de alumínio no processo de cromagem

Abstract

This Conclusion Paper aims to make a comparison between the application of alkaline copper, as an intermediate coating, on the surface of 6063 aluminum alloys. The studied material is directed to the automotive industry, that has a growing interest in the use of aluminum and deposition of protective layers, to assist in combating corrosion and improve aesthetic aspects of parts. The study was conducted by comparing two kinds of coating, one with the addition of alkaline copper and one without. The coating deposition process starts with layers of zincate and chemical nickel, followed by the application of alkaline copper and, finally, the multilayer of nickel and chromium. Samples that had alkaline copper deposition and samples without this intermediate coating were evaluated by analysis over time, exposed to the environment; intermediate layer adhesion test, by Scanning Electron Microscopy (SEM); corrosive performance in salt spray; acetic mist; and alkaline immersion. The intermediate layer adhesion results showed satisfactory results, as well as the alkaline immersion tests carried out with all surface layers. The test related to the analysis over time demonstrates fragility in the copper layer, highlighting the need to deposit the subsequent layers as soon as possible. The specimens that contained the alkaline copper layer also performed worse in relation to corrosion resistance, both in the neutral salt spray test and in the acetic mist test. [resumo fornecido pelo autor]