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 to analyze how the microstructure of the aluminum coating sprayed by HVOF was formed on different complex surfaces. The influence of different deposition process parameters on the coating, varying the angle of incidence during deposition, substrate preheating and nitrogen flow was studied. Outer corner and convex surfaces presented greater uniformity in the formed microstructures. The angle of incidence was the most influential parameter on the coatings, filling complex profiles better, with 60° of incidence, although the 90° of incidence increased the adhesion. The potentiodynamic polarization test was performed to evaluate the corrosion resistance of coatings. The higher preheating and lower angle of incidence increased the corrosion resistance of coatings. Corrosion tests in salt spray are in progress in order to compare with continuous results.

Ceramic coatings are applied in mechanical components subject to high temperature conditions, normally are deposited by plasma thermal spraying process. In this work, the porosity of YSZ ceramic coatings, deposited with different parameters conditions were analyzed by optical microscopy, scanning electron microscopy using back-scatter electron (SEM-BSE) detector and ultrasonic technique. It was verified that porosity measurement by optical and scanning electron microscopy is very sensitive with respect to metallographic preparation, mainly cutting process, and gray level adjustment. SEM-BSE technique showed less scatter results with easier porosity visualization, compared with optical microscopy. The porosity of the coatings was also measured by ultrasonic technique. It was observed that the ultrasonic velocity increase with porosity reduction. Ultrasound technique showed a good correlation with OM and SEM porosity measurement.