Strategies for the replacement of chromic acid anodising for the structural bonding of aluminium alloys

• Published in: International journal of adhesion and adhesives Vol. 26; no. 6; pp. 419 - 453
• Main Authors: Critchlow, G.W., Yendall, K.A., Bahrani, D., Quinn, A., Andrews, F.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.09.2006; Elsevier
• Subjects: Adhesive bonding; Aluminium; Application fields; Applied sciences; Durability; Exact sciences and technology; Joining, thermal cutting: metallurgical aspects; Metals. Metallurgy; Microscopy; Polymer industry, paints, wood; Surface treatment by chemical solutions; Technology of polymers; Surface treatment by chemical solutions; Durability; Aluminium; Microscopy; Adhesive bonding; Aluminium alloy; Experimental study; Property processing relationship; Surface treatment; Mechanical treatment; Anodizing; Chemical treatment; Pretreatment
• ISSN: 0143-7496; 1879-0127
• DOI: 10.1016/j.ijadhadh.2005.07.001

The 40/50 V Bengough–Stuart chromic acid anodise process is widely used in demanding applications as a prebond treatment. This process has a number of disadvantages and its replacement is the subject of much interest in the aerospace, automotive and defence sectors, amongst others. This paper details a number of modifications to the standard boric–sulphuric acid anodising (BSAA) process specifically to achieve satisfactory structural bond performance. These included: variations in the deoxidiser and anodising parameters; and the use of a post-anodising dip. It has been demonstrated in these studies that there are three possible methods of providing excellent durability using a variation of the standard BSAA process: the use of an electrolytic phosphoric acid deoxidiser; a high temperature anodise at 35 °C; and the use of a post-anodise phosphoric acid dip.