PLASMA SPRAY DEPOSITION AND ENGINEERING APPLICATIONS OF MAGNESIUM HYDROXIDE-POLYAMIDE COMPOSITE COATINGS

Magnesium hydroxide is shown to dehydrate endothermically to magnesium oxide over a similar temperature range to that of the thermal degrada tion of polyamide. The extent of dehydration in plasma spraying is sho wn to be a function of particle size. However the research indicates t hat the use of magnesium hydroxide as a filler in plasma sprayed polya mide composite coatings does not significantly increase the quality of the matrix by suppressing its degradation. A high content of unreacte d magnesium hydroxide can be obtained in plasma sprayed polyamide comp osites by control of the feedstock particle size. The practical implic ations of the results for potential engineering applications of the co mposite are discussed in terms of wear resistance and fire retardance.