SiC in nitric acid Re:"thread330-

[KevinAustinTX]

In reference to thread "thread330-264284",

Does anyone have experience with CVD-SiC coated, SiC bulk material and nitric acid? The previous thread was closed.

I am in semiconductor and we use SiC cintered wafer boats which have a final step of CVD coating of SiC. The assumption has been that the bulk material is susceptable to nitric acid and thus it was coated with the denser layer. I dip these in acids for cleaning of deposition which they see in the plants. If there is a breach of the outer CVD layer, it is assumed that the nitric then attacks the bulk material, turning it green.

Does anyone know of this?

Thanks,
Kevin

 

[EdStainless]

What grade of SiC are the boats?
In many grades there is excess free Si (reaction bonded). These grades are susceptible to lots of things.
Has anyone ever done chemical analysis on the green?
It may not be the SiC reacting.

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P.E. Metallurgy, Plymouth Tube