Corrosion resistance of PVD coatings ?

[Techcitizen]

Can somebody tell how corrosion resistance is a PVD coating ? Can it withstand a salt spray resistance test (ASTM B117) of 2000 hours ? Which PVD coating (TiN, CrN, AlTiN, etc.) is best suited for a good corrosion resistance and what should be the coating thickness ?

 

[gdodd]

CrN has the best corrosion resistance and oxidation resistance but the worst wear resistance. For the best wear resistance use a TiCN coating.
Not sure of salt spray test data as it is not a regular test used for coating assessment.

 

[Chinnia]

My obervations on PVD coatings:
- PVD coatings generally used for wear resistance (e.g. TiC, TiCN, Alumina, CrN, etc). We have seen wonderful wear resistance of 3to5 micron thick CrN in metal stamping operations. CrN on die steel outperformed TiN in that particular situation.
- re. corrosion: most ceramic are very resistant to corrosive environments. Obviously the selection of a psecific materials requires other considerations. A major problem I have seen was the microstructure of the PVD coating - porpous/columnar defects, etc. If you ca get dense (pore/coulmnar free) coating, it should resist salt spray test.
- thickness? most PVD coatings are produced under 10 microns. Maybe multiulayer thick coatings should do the job.
- why PVD an why not other coating techniques?

Good luck

Chinnia

 

If you require a combination of wear resistance and corrosion resistance I would suggest a multilayer PVD CrN/NbN coating.