Microstructure of thick chromium–nitride coating synthesized using plasma assisted MOCVD technique

Thick and hard chromium nitride (CrN) films have been developed by plasma assisted metal organic chemical vapor deposition (PAMOCVD) technique. The coating has been characterized using X-ray diffraction, scanning electron microscopy and analytical and conventional transmission electron microscopy. The coating exhibits two phenomena on different length scales: (i) formation of nanocrystals, and (ii) the formation of the globular structure on a micron scale. These globules are thought to be clusters of nanocrystalline CrN. Cross-sectional transmission electron microscopy of the film has revealed an extremely complex microstructure. However, the film has been found to have uniform Cr incorporation. The coating cross-section has shown bands of varying contrast. It has been shown that adhesion of the coating can be improved by corrugating the substrate surface.