how to remove SiO2 layer from Si3N4 powders

[Cleopatra]

Hi,

I want to remove SiO2 layer which occurs naturally on the Si3N4 powders. But I do not want to use HF because it is not safe. Is it possible to remove SiO2 by using any other acids/bases?
Any information is appreciated. Thanks for all.

 

[unclesyd]

Sometime back we needed to remove a SiO2 layer form a metal. This was accomplished by an outfit in (Michigan) that used anhydrous HF a a relatively high temperature.

Work was then done using an electrolytic process and as I recall it used a Ca Salt. They were able to remove the SiO2 with very little damage to the substrate. I don't know how your substrate will stand up. I wasn't directly involved as this project was at the PHD level

Can you use something like a SS White abrasive blast system to clean your SiN4?

 

[unclesyd]

These are the people (Ti Coating) who accomplished the HF ion cleaning for us. It may not work as the process removes some nitride coatings. I think it's worth a phone call for information if nothing better than to eliminate this route.

http://www.ticoating.com/a.html