ARMY ARMAMENT RESEARCH AND DEVELOPMENT CENTER DOVER NJ LARGE CALIBER WEAPON SYSTEMS LAB
In a continuing effort to minimize the use of toxic and hazardous materials for the adhesive bonding of aluminum, a suitable alternative for the standard chromate-containing FPL etchant is being sought. This has resulted in the development of a chromate-free etchant of minimal toxicity etchant P2 which consists of an aqueous solution of sulfuric acid and ferric sulfate. Surfaces produced with the new etchant composition when adhesively bonded result in joint strengths comparable to those obtained with the standard chromated etchant. Adhesively bonded 6061-T4 alloy specimens prepared with the new etchant exhibited stress durabilities superior to those prepared with the standard FPL etchant. No difficulties are expected to result from the use of the new etchant under production conditions.