Preparation of Steel Surfaces for Adhesive Bonding.
DEPARTMENT OF THE ARMY WASHINGTON DC
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A principal object of the present invention is to provide a novel process and composition for etching steel, which avoids the use of ethanol solvent with phosphoric acid yet produces a steel surface which, when adhesively bonded, yields joints of comparable strength and stress durability to those obtained by use of the phosphoric acid-ethanol etchant. According to the present invention the foregoing and other objects can be achieved by contacting the steel parts with an etchant composition consisting essentially of phosphoric acid and a liquid polyhydric alcohol, particularly a didhydric andor trihydric alcohol. Exemplary polyhydric alcohols suitable for use in the process and compositions of the present invention include ethylene-glycol, dietryleneglycol, triethylene glycol, polyethylene glycol 400, 1,2- and 1,3- propylene glycol, 1,4- butanediol and glycerine.
- Metallurgy and Metallography
- Fabrication Metallurgy