Titanium and Titanium Alloys

The chapter discusses various methods used to treat titanium and titanium alloys for adhesive bonding. It is reported that both alkaline cleaning and phosphate-fluoride prebond treatments produce surfaces of good wettability, equal thickness and similar composition. Stabilized phosphate-fluoride process retards the conversion of anatase to rutile. It is also reported that the anodic process produces a porous oxide structure and is superior to the surface formed by the phosphate-fluoride process. Specific treatments for aluminum and aluminum alloys are presented in a process specification format including anodize process, Turco 5578, liquid hone/Pasa-Jell 107 process, dry hone/Pasa-Jell 107 process, alkaline peroxide process and stabilized phosphate-fluoride process. A study of the morphology and decomposition of the various surfaces revealed that different surface morphologies are obtained with the different treatments. The treatments were classified into three different groups. The Group I processes were characterized as producing surfaces which have thin oxide layers with little macro-roughness while Group II processes resulted in surfaces which had a high degree of macro-roughness. The Group III processes produced surfaces which were characterized by a primarily micro-rough porous oxide.