Microstructural Analysis Of Aluminum Coatings Deposited By Hvof Process On Complex Surfaces

Aluminum coatings applied by thermal spraying are widely used for protection against marine corrosion. The HVOF process produces aluminum coatings with high particle velocity, at a higher temperature for longer, permitting a high adhesion among the deposited particles. The objective of this work was analyze how the microstructure of the aluminum coating sprayed by HVOF was formed on different complex surfaces, and if there was transformation on the type of aluminum oxide. The influence of different deposition process parameters on the coating, varying the angle of incidence of deposition, substrate preheating and nitrogen flow was studied. Curved surfaces presented greater uniformity in the formed microstructures. The angle of incidence was the most influential parameter on the coatings, producing lower porosity and higher microhardness, with 90° of incidence, not changing the type of aluminum oxide contained in the powders before deposition. Oxidation tests in salt spray are in progress in order to evaluate the corrosion resistance of coatings.