Formability and electrochemical characteristics of aluminium dry powder coatings

The formability and electrochemical characteristics of aluminium powder coated steel sheets have been determined as functions of the coating sintering time and temperature. The coatings were fabricated on the laboratory scale using a dry powder coating process, followed by rolling to achieve a 10% extension. The sintering temperatures studied were in the range 573–873 K (300–600°C). Coatings were also fabricated using Al–0·16Ti prealloyed powder and their characteristics were studied. Heat treatment temperature in the range 723–748 K (450–475°C) has been found to have a deleterious effect on the coating formability and electrochemical characteristics of both the aluminium and the Al–Ti coatings. This deterioration in properties has been attributed to the change in aluminium powder sintering characteristics in this temperature range. The electrochemical characteristics have also been compared with those of the more commonly used galvanised steel sheets. It has been shown that using this dry powder coating process, aluminium coatings of high formability and corrosion resistance can be fabricated using low economical sintering temperatures of about 623–673 K (350–400°C). MST/552