Pre-cleaning and multi-functional pretreatment of magnesium alloys for aerospace and other applications

摘要

Fabrication of the most magnesium semi-finished products requires application of lubricants and oils. After rolling or extrusion operations the magnesium surface should be properly cleaned from the lubricants as it is required by the majority of customers. Some evidences of corrosion and small corrosion pits that can be formed as a result of interaction between magnesium surface and dissimilar metals should be removed without negative influence on surface quality. Even minor surface defects such as micro-cracks must be removed. Usually, pre-cleaning process employs pickling in acidic solution. The pickling operation also removes natural magnesium oxide/hydroxide layer that decreases bare corrosion resistance of magnesium. However, it is not always possible to apply finishing process after pre-cleaning operation. In order to solve this problem, magnesium surface should be protected by a temporal coating immediately after pre-cleaning.