Protective Finishing Systems for Magnesium Aircraft Components.

摘要

Evaluations of magnesium finishing systems were made to select surface treatments and topcoats for rework and repair of naval aircraft parts. Corrosion resistance of finishes for the power section was determined on QE 22A-T6magnesium alloy cyclically exposed to 5% NaC1salt spray and 400F. Magnesium airframe part finishes were evaluated after immersion testing in a NaC1solution. MIL-M-45202B,Type II Dow 17 anodize exhibited high corrosion resistance with several topcoat systems. A lesser degree of protection was provided by the hot RAE alkaline treatment,the best chemical surface treatment of those evaluated. All the finishing systems which included the MIL-L-46079A(MR) baking type epoxy surface seal were most resistant to corrosion. Topcoats of modified silicone epoxy,MIL-P-23377epoxy primer or epoxy primer-polyurethane topcoat over the preferred surface treatments resulted in effective corrosion resistant systems for magnesium aircraft parts. Repair of corroded areas by filling with MIL-C-24176A(SHIPS) Type II aluminum epoxy cement proved very successful. (Author)