AN IMPROVED METHOD FOR THE DEPOSITION OF CORROSION-RESISTANT ALUMINUMCOATINGS FOR AEROSPACE APPLICATIONS

The gradual reduction in the use of electroplated cadmium as a corrosi on barrier for aircraft parts has led to the development of ion-vapour -deposited (IVD) aluminium as an alternative. The most common IVD tech nique is the McDonnell Douglas ''Ivadize'' process, but the morphology of such aluminium coatings is usually open and columnar. Consequently , a post-deposition shot peen is used to density the structure. This h as led to very poor control over the thickness and uniformity of the c oating, and precision parts cannot be coated by such techniques. The u se of multimagnetron ion plating can guarantee close control over the coating dimensions by the precise deposition of fully dense aluminium films which do not require peening. To further improve the properties of the films, a series of aluminium alloys have been deposited to prov ide enhancement of the corrosion and tribological properties of the fi lms.