マグネシウム合金とアルミニウム合金の接着特性に及ぼす化成皮膜の影響

抄録

Magnesium is a light metal with high specific strength and electromagnetic shielding properties. In recent years, it is required to adhere magnesium alloys with different metals. Bonding method is one of easy joint process between magnesium alloys and other materials. Contact corrosion of magnesium and different metals can be suppressed by using of adhesive. On the other hand, chromate conversion coating on magnesium was known as carcinogen and one of the methods to limit use of conversion coating. This paper describes the effects of conversion coatings on bond properties of magnesium and aluminum alloys. AZ31B magnesium alloy and A2017, A6022 aluminum alloys were used as specimens. Bond properties were evaluated by pull-off test, bond torque test and tensile lap-shear strength test. In addition, galvanic corrosion was evaluated by salt spray test. As a result of investigation on the bond strength of conversion coatings, the highest bond strength was obtained from the specimen of Mg(OH)₂ coating on magnesium alloy and boehmite on aluminum alloy using epoxy resin for cure temperature of 373 K. The Mg(OH)₂ coatingis expected as one of the alternatives of the chromate conversion coating.