Hydrofluorosilicic Acid/Fluorosilic acid and HF(aqueous)

[MrMetals]

Does anyone have any experience with HFS(FSA)? I am trying to figure whether or not, corrosion data will be close to that of aqeous HF against Ni-Cr-Mo alloys like C276. I know Monel 400, is highly resistant to HF, and I have found some data to show that C276 and monel are good, but also Ni-Cr-Fe alloys can also be resistant. Any thoughts?

 

[EdStainless]

Isn't FSA the product of the wet phosphate process that is then further processed to yield HF?

You might try the MTI publication MS-4 on Hydrogen Fluoride and Hydrofluoric Acid.
(Materials Technology Institute of the Chemical Process Industries,Inc., St Louis MO)

This is real touchy, what concentrations, impurities, and temperature and all critical.
As I recall 400 has limited use because of the risk of SCC.

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[MrMetals]

Yea that's what I found out that HF is derived from, but I actually found some data in Corrosion Data Survey from NACE that showed as 400 having good resistance and c276 having a little less good, but like you said all the other factors need to be known. I did not find that much information on FSA in particular in the MTI material selector books so I started digging else where. Thanks for the reply!

 

[EdStainless]

I believe that alloy G30 is used in this application. You might look for papers on this grade and see what connections you can make.

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