Effect of nitrogen content on the phase transformation of alumina scale on a nanocrystalline NiCrAlYSiHfN/AlN multilayer coating

摘要

The nanocrystalline NiCrAlYSiHfN/AlN multilayer coatings with three different nitrogen contents were prepared by mid-frequency dual-magnetron reactive-sputtering. Oxidation tests were carried out in air at 1100 degrees C for 20 h. It is showed that the theta- to alpha-Al2O3 transformation was remarkably accelerated with the increase of the N-content in the coating. More N-content in the coating generated more amount of N-doping in the alumina scale. The formation of more Al-N bonds might induce more oxygen vacancies that accelerated the transformation process.