Investigation of Internal Stresses in Thin Layer Oxide Coatings on Aluminum Alloys

Among physical and mechanic properties of coatings the internal stresses are of special interest. Internal stresses include stresses which exist and are counterbalanced within a rigid body in cases when there is no external action which caused them. In coatings obtained on the basis of nickel, chrome they can decrease the adhesive strength, cause cracking, peeling, anticorrosion properties deterioration. But the definite level of internal stresses leads to increase of hardness and coatings wear resistance and also facilitates porous coatings obtaining. The results of theoretical and experimental investigations of the internal stresses that appear in oxide ceramic coatings formed by plasma-electrolytic oxidation (PEO) on aluminum surfaces are presented.