Plating the inside of a glass vial
I have been conducting research in the absorbance of acetic acid by glass headspace vials. One of the treatments that we used to halt the absorbance of acetic acid was to sputter coat the inside of the vial with gold. This procedure leaves the neck of the vial thoroughly coated with gold with a gradient of lessoning deposition as you move toward the bottom of the vial. We have found that this treatment shows promising results but I would like to find a technique which will uniformly distribute gold throughout the inside of the vial. The vial size is 22.5 x 75 mm. and it is made of borosilicate glass.
Any ideas how to plate the inside of the vial?Christopher M. Strauch
ACS Labs - Cleveland, Ohio, USA
You could try the following:
- Etch (Roughen) the surface of the glass using HF dilute
- Apply a Palladium Activator
- Electroless nickel plate
- Immersion Gold
Most electroplating suppliers can supply their version of the above chemicals.Kenneth Kelleher
This may sound far-fetched, but you might be able to use an ion beam to even out the sputter deposited coating. Basically, you fire a low energy ion beam down the tube. Because the beam is not going to be perfectly aligned (you may want to rotate the tube while you do it) some of the beam will hit the side walls, sputtering gold off of the walls. The sputtered gold will travel down the tube and resettle in another region. Thus, you remove gold from the upper part of the tube and redeposit it on the lower part. An argon beam will work, though a gold beam would be best. Almost any beam energy over ~1 keV will work.
PVD Consultant - San Diego, California
If you don't want any nickel present, you can find electroless (autocatalytic) gold baths. They are not as stable or easy to use as the electroless nickel, but you get a fairly pure gold deposit. All you need to do is clean and activate the inside of the tube, then immerse.Joel Weine
- Columbia, Maryland
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