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Registered Member #2123
Joined: Sat May 16 2009, 03:10AM
Location: Bend, Oregon
Posts: 312
Pirhana clean is used to remove organics. Addition of hydrogen peroxide to sulfuric acid is very exothermic, and causes the hydrogen peroxide to eventually decompose. Pirhana clean has a limited lifetime, but would be a good trace-organic clean for any glass, ceramic, or silicon components, but NO organic components with the exception of PFA or PTFE. A longer-lived version, not as effective, would be sulfuric acid and peroxysulfuric acid heated to 50C.
A de-ionized water rinse would of course be required to remove the acid.
For semiconductor cleaning, the RCA clean is very effective. It is a 3-stage clean, ammonium hydroxide/hydrogen peroxide (removes organics), DI water rinse, 20:1 hydrofluoric acid/water (removes native silicon dioxide), DI water rinse, and finally hydrochloric acid/hydrogen peroxide (removes trace metals), DI water rinse. Stay away from hydrofluoric acid, very dangerous, destroys bone and tissue, and you don't need it for what you are doing anyway. The other two cleaning soluctions are very effective for cleaning glass and ceramic, and may be useful for what you are doing.
Keeping your x-ray apparatus dry once components are cleaned and assembled may require ovenization as well as dessicants etc, particularly if you live in a humid climate.
Registered Member #193
Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022
Once the surface is fairly clean it's probably more important to keep it dry than to put too much effort into cleaning it. I haven't tried but I think Silica gell would work- provided that you can dry it in an oven then let it cool in something airtight enough to stop it picking up water again.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Bored Chemist wrote ...
Once the surface is fairly clean it's probably more important to keep it dry than to put too much effort into cleaning it. I haven't tried but I think Silica gell would work- provided that you can dry it in an oven then let it cool in something airtight enough to stop it picking up water again.
Registered Member #193
Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022
You can regenerates the stuff in an ordinary oven- it only takes about 150-200C. A vac oven might be quicker but the vac pump might not like to deal with the water vapour.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Bored Chemist wrote ...
You can regenerates the stuff in an ordinary oven- it only takes about 150-200C. A vac oven might be quicker but the vac pump might not like to deal with the water vapour.
Registered Member #2123
Joined: Sat May 16 2009, 03:10AM
Location: Bend, Oregon
Posts: 312
In my military surplus dealings, I've seen many desscant packs with cobalt chloride moisture indicators (blue=dry, pink =wet). This might be a helpful indicator for the status of your dessicant packs.
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
MinorityCarrier wrote ...
In my military surplus dealings, I've seen many desscant packs with cobalt chloride moisture indicators (blue=dry, pink =wet). This might be a helpful indicator for the status of your dessicant packs.
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Chromic-Nitric Acid versus Triton X-100 scintillator grade.
