Preparation and Properties of Cerium Conversion Coatings on the Surface of Aluminum Alloy LY12

Abstract

In order to improve the repairing quality of aircraft envelope of the aluminum alloy LY12， the cerium conversion coating technology was studied by using the surface modification technique. Principle experiment was on the basis of aviation repair technological requirement, refers to the related technique, through examination of corrosion resistance and wear resistance performance of cerium conversion coating, the principal composition of the formula for making cerium conversion coating:Ce(NO3)3 + KMnO4+ Ce-1 (chemical additive), In order to determine each composition of the formula and the technology parameters scientifically, L9(34) orthogonal testing method was adopted, and the formula of surface modification solution was optimized, the technological conditions for making cerium conversion coating on the surface of aircraft envelope were determined. Results of corrosion resistance and wear resistance of the cerium conversion coating on the surface of the aluminum alloy LY12 aircraft envelope obtained by the new technology showed: 1. On the given test conditions, the best content of each chemical composition in the formula of modification solution for making cerium conversion coating on the surface were: l.Ce(NO3)3：14g/L,KMnO4：1g/L,addictive Ce-1:0.3g/L；Main technology parameters were ：pH=1.5～2.7;temperature：20°C；time:15~25 min.；2. Under the same test condition, the corrosion resistance of surface of the cerium conversion coating obtained in test modification solution was better than Alodine 1001 obtained from Bombardier Corporation of Canada, and can meet the repairing demands of Aircraft Envelope.