Re: coating homoginization

Posted by Hong Wei Wang ( on 17:23:02 13/12/05

In Reply to: Re: coating homoginization posted by Gordon England

MCrAlY is highly enriched with Cr and Al compared with typical Ni- or Co-base superalloys. A drawback is the metallurgical instability of these coatings in service condition such that there would be service high temperature driven inwards diffusion of these elements and outwards diffusion of base-alloy elements to create a brittle interdiffuison zone (due to sigma, mu phases formation). Post coating HT (1050 oC) for stabilisation is a general requirement for LPPS MCrAlY. other reasons of PCHT is to reduce the brittleness and close loose porosity (sintering) of the as-sprayed coating by plasma spray.
As for the absence of need to HT HVOF MCrAlY, are you sure this is true (certainly for the hi-temperature applications)?
Dr. Hong Wei Wang
ERA Technology Ltd

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