question about powder reaction during plasma spray process

[greentree]

Hi,dear friends! I am greentree. I'm a new member of the surface engineering forum.I am a student majored in thermal spray technology.
Recently, I want to fabricate a solid lubricant coating using plasma spray. The powder I want to use is BaF2,CaF2,Ni,Cr,Cr3C2. Some literature said fluoride will react with active metal, but they didn't show the specific reaction process, equation and details.
I really want to know the reaction among them during plasma spary.
If you konw something about it, please tell me. Including the test methods, the reaction equation, some papers on it, etc. I will very appreciated with you. Thank you very much.
My email is csuhcb2000@163.com.

[Gordon]

Hi Greentree

to the Surface Engineering Forum.

If your powder is a simple blend of BaF2,CaF2 and chromium carbide/nickel chromium I would suspect there to be little interaction due to limited time at high temperature and limited physical contact between constituents during spraying. BaF2 and CaF2 are used as flux agent in welding rods/powders so I doubt reactions would be harmful.

This may be of interest, see page 119 fused fluoride coatings and plasma sprayed coatings ASM Handbook

[greentree]

Thank you very much for your response,Gordon!

I couldn't open the link you gived above ,would you please send a copy to my email:csuhcb2000@gmail.com or csuhcb2000@163.com ?

Also I wondered is that will BaF2 or CaF2 be changed to BaO or CaO in the high temperature?if so, what compound will the elment F be changed to ?
Thanks a lot!

[Gordon]

Hi Greentree

Sorry if the link does not work for you, it works fine for me Anybody else have problems with ASM Handbook p119. Sorry, I can not email a copy as it is not easily copied and more importantly because of copyright.

BaF2 or CaF2 i think (not sure) will be resistant to changing to BaO or CaO in normal plasma spraying (not vapourising constituents ). When used in fluxes, I think there action is to lower melting temperatures of more refractory oxides and acts to absorb and dilute oxides rather than take part as a chemically active constituent.