Surface Preparation and Priming of Aluminum Alloy Parts for High Durability Structural Adhesive Bonding, Hand Applied Phosphoric Acid Anodizing
This document describes a hand-applied, nontank, phosphoric acid anodizing process for surface preparation of aluminum alloys required to achieve optimum bondline durability for structural adhesive bonding. This surface preparation system is designed to be used where a metal bond repair is required on a component or assembly that cannot be immersed in a tank. This surface preparation system has been validated for use with 180 degrees F (82 degrees C) and 250 degrees F (121 degrees C) service, elastomer-modified, epoxy adhesive and corrosion-inhibiting primer. The process described herein is the result of extensive evaluation of structural and durability performance and detailed analysis of the individual bonding surfaces. While the process described herein was originally developed for use in the adhesive-bonding of parts, components, or assemblies for aircraft, it is applicable to nonaircraft bonding operations as well. The procedure is normally used in repair operations.