Surface Treatment for Aluminum Bonding.
Final technical rept. 28 Jul 78-15 Jul 79,
ROCKWELL INTERNATIONAL THOUSAND OAKS CA SCIENCE CENTER
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At present the most widely used method for treating aluminum prior to bonding is the sulfochrom etch process FPL, etch. Due to the carcinogenic nature of chromates, various companies and government agencies have been attempting to find new durable nonchromate-containing systems which can be used to treat aluminum prior to bonding. The objective of this project was to discover a nonacid nonchromate surface treatment for Al 2024-T3 that would be both strong and durable. Initial studies indicated that a simple degrease and water soak process STAB1 would provide strong durable joints. However, further testing revealed this process to be hard to reproduce on a consistent basis. A second process STAB2 was discovered that was equally as simple but was also difficult to reproduce. A third process, even more simple STAB3 was discovered which did prove reproducible. This process eliminates the degrease step and involves no energy input room temperature dip in super-concentrated sodium hydroxide. There are only three steps involved, a sodium hydroxide solution dip, a rinse and dry. This report gives the details of these three processes, the bond strength and endurance results and why each process did or did not work satisfactorily. Author
- Adhesives, Seals and Binders
- Properties of Metals and Alloys
- Fabrication Metallurgy