Influence of ageing on the corrosion behaviour of 2024 aluminium alloy coated with a trivalent chromium conversion layer

摘要

Time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy were used to study the influence of ageing of 2024 aluminium alloy at 190 degrees C on subsequent degreasing and deoxidation behaviour. After degreasing and deoxidation of the aged alloy, an increase in the surface Cu coverage and a surface roughening were observed as compared to a non-aged alloy. The Cu surface enrichment affected the growth mechanisms of the trivalent chromium process (TCP) coating. The TCP coating formed on an aged sample was thicker, but more defective leading to the decrease of its anticorrosion properties, as compared to a non-aged sample.