Growth of AlN coating on Al-6061 alloy surface

Abstract

The objective of the study was to grow uniform nitride coatings over Al-6061 alloys to resist fluorine diffusion. This paper discusses a process of carrying out surface nitridation of an Al-6061 alloy substrate. Through this method, a dense aluminum nitride coating can be grown on Al-6061 alloy with complete area coverage of the samples having complex geometries. The method uses nitrogen gas alone as the nitrogen carrier, and not ammonia derivatives used in conventional processes. Magnesium powder was also used in the process to reduce the protective alumina layer on the alloy and to facilitate the aluminum nitride growth. The process led to uniform coating coverage over the flat sample surfaces as well as over the surfaces of drilled holes in the sample. The coatings were stable when subjected to several 400 °C thermal cycles.