Accession Number : ADA140057

Title :   Anodic Oxide Formation on Ti-6A1-4V in Chromic Acid for Adhesive Bonding.

Descriptive Note : Interim rept. 30 Sep 82-30 Dec 83,


Personal Author(s) : Cheng,A M T ; Dwight,D W

PDF Url : ADA140057

Report Date : Mar 1984

Pagination or Media Count : 114

Abstract : Chromic acid anodization (CAA) of Ti-6Al-4V alloy has been shown to produce desirable oxide for adhesive bonding. The highly porous oxide layer provides mechanical interlocking with the adhesive or the primer forming a much stronger interface. This leads to stronger and more durable bond than most other surface pretreatments. Since anodization is a electrochemical process, electrochemical methods are used to elucidate the mechanism and kinetics of the oxide formation. From galvanostatic anodization, the preimmersion oxide thickness is calculated to be in the order of 10 Angstrom. Oxygen evolution is dominant at above 10 V. Oxide breakdown or cracking was observed at potentials above 10 V and at current density above 11 mA/sq cm. Hydrofluoric acid was found to be essential in the initiation and formation of pores desirable for adhesive bonding. Without HF addition, the oxide formed was compact and uniform regardless of anodizing conditions (before breakdown). In the presence of HF, porous oxide was obtained with pore size distribution increased with temperature and HF concentration. (Author)

Descriptors :   *Titanium alloys, *Adhesive bonding, *Welding, *Electrochemistry, Anodic coatings, Oxidation, Chromic acid, Hydrofluoric acid, Oxides, Cracks, Formates, Porosity, Optical properties, Corrosion, Surface properties, Structural analysis, Thermodynamics, Chemical composition, Test methods

Subject Categories : Physical Chemistry
      Properties of Metals and Alloys
      Fabrication Metallurgy

Distribution Statement : APPROVED FOR PUBLIC RELEASE