Acid Stripping - with Ultrasonic Assist

[lewdtenant]

Hello PF,

I am trying to chemically strip a metal oxide film from fused silica. The film was deposited at a fairly high temperature, which makes it more difficult to strip than at lower temperatures. During deposition, the film makes its way into the pores of the substrate and slow cooling induces a strong mechanical attraction of the film onto/inside the surface of the substrate.

It appears that this mechanical attraction is stronger than any chemical attraction with heated phosphoric acid, my acid of choice for this particular metal oxide film. I will probably experiment some with other acids, but my main question is with using an ultrasonic bath.

Does anyone have any knowledge of or experience using an ultrasonic bath to assist in chemical stripping? I am thinking about putting my pieces into a heated bath of phosphoric acid and then placing this container inside an ultrasonic cleaning tank. I am thinking that the cavitations from the ultrasonic action will allow the acid to penetrate further into the substrate and help remove the film.

Any insight is welcome/appreciated. Thanks

 

[chemisttree]

Every time I used ultrasound to assist in a surface cleaning, stripping or etching it went bad. My experience showed that patterns of standing waves developed on the surface which resulted in a patterned etch.