STUDY OF INFLUENCE OF ZINC-NICKEL AND CADMIUM ELECTROPLATED COATINGS ON FATIGUE STRENGTH OF AERONAUTICAL STEELS

摘要

Cadmium electroplating have been widely applied to promote corrosion protective coatings in aeronautical components. However, ecological considerations have led searchers to work on news coatings. The aim of this work was to study the effects of rotative bending fatigue behavior of electroplated zinc-nickel alloys coatings on AISI 4340 and 35-NCD-16 high strength steels, both used in aeronautical applications and to compare with results showed by cadmium electroplated coatings. S-N curves were used to evaluate the performance of these coatings with respect to rotative bending fatigue behavior. Results obtained with chromium were used to confront the performance of these coatings with respect to fatigue. Scanning electron microscopy technique (SEM) and optical microscopy were used to observe crack origin sites, thickness, adhesion and uniformity in all coatings on both steels studied.