Abstract
This paper is a review of the thermal stability of nanostructured nitride coatings synthesised by reactive magnetron sputtering technique. In the last three decade, nitride based coatings have been widely applied as hard wear-protective coatings in mechanical components. More recently, a larger interest has been addressed to evaluate the thermal stability of such coatings, as their mechanical and tribological properties are deteriorated at high working temperatures. This study describes the microstructural, mechanical and compositional stability of nano-crystalline Cr-N and nano-composited Ti-N based coatings (Ti-Al-Si-B-N and Ti-Cr-B-N) after air and vacuum annealing. For Cr-N coatings annealing in vacuum induces phase transformation from CrN to Cr2N, while after annealing in air only Cr2O3 phase is present. For Ti-N based coatings, a well-definite multilayered structure was shown after air annealing. Degradation of mechanical properties was observed for all the nitride coatings after thermal annealing in air.
Highlights
Corrosion resistance is usually one of the major requirements in the selection of a particular grade of stainless steel for a given application
Crystal structure, surface morphology and hardness of thin chromium nitrides (Cr-N) coatings, deposited by reactive sputtering on AISI 304 stainless steel sheets, were investigated after deposition and after thermal annealing in air and vacuum. - Transmission electron microscopy inspections showed that the as-deposited coatings have a very fine grain structure. - CrN phase was found on all the samples, with a predominant (111) texture
- Annealing in vacuum induced formation of Cr2N phase with (111) texture from CrN phase. - Anneal in air induced formation of Cr2O3 phase, with higher oxidation speed for Cr2N phase. - Surface roughness increased for all the samples after annealing in air and large features appeared on the surface, as a consequence of Cr2O3 phase formation
Summary
Corrosion resistance is usually one of the major requirements in the selection of a particular grade of stainless steel for a given application. Among all the stainless steels [1], AISI 304 grade is one of the most commonly used It has good corrosion resistance in most environments and in saturated oxidizing acid solutions. The application of one of these three coating processes can be used for depositing virtually any solid film to the surface of any metallic material. This versatility makes PVD especially useful for depositing hard coatings for corrosion and wear-applications [5]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
