Difference between revisions of "Minutes-8-9-2012"
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== Cathode corrosion == | == Cathode corrosion == | ||
| − | - Lubomir: a test with cathode foils, Viton | + | - Lubomir: a test with cathode foils, Viton/EPDM O-rings and water was done (at Blue Crab dirty area). First, the O-ring samples were pressed against the foils with a lead brick, also using G10 and aluminum plates to equalize the pressure. After a couple of days, water (from the tab) was put on the samples. Corrosion appeared immediately on the next day: very well pronounced on the EPDM sample and resembling the same dark traces that we had on the cathodes of the first and second packages (see first picture above), also some corrosion but with lighter color on the Viton sample. Olga did SEM analyses on the two sample foils at the places of the O-rings: second link above. Generally the experiment was not done in a clean environment and tab water was used, so you see a lot of dirty stuff like chlorine. At the same time sulfur is visible in almost all the areas of the EPDM sample, while for the Viton sample it's present in much smaller areas visible with high magnification. We started the same experiment inside the clean room using distilled water; expect results next week. |
- Vlad (also with the help of his dad who's chemist) studied the literature about the copper corrosion. Normally as a first step copper reacts with watter (moisture) CO2 and O2 forming hydrides of Cu2O (copper oxide) that has redish color (Cu2O is good conductor). On the next step due to again water and sulfur (or chlorine) copper salts are formed like CuSO4, CuS and CuO (copper monoxides, mono-sulfides) having black/gray color what we are actually seeing, which are moderate conductors. Especially hydrogen sulfide is dangerous, we can identify it with lead acetate paper that we have ordered. Important is also that carbon serves as catalyst. We see that the EPDM O-ring leaves carbon traces very easily just by pressing it against the copper foil. | - Vlad (also with the help of his dad who's chemist) studied the literature about the copper corrosion. Normally as a first step copper reacts with watter (moisture) CO2 and O2 forming hydrides of Cu2O (copper oxide) that has redish color (Cu2O is good conductor). On the next step due to again water and sulfur (or chlorine) copper salts are formed like CuSO4, CuS and CuO (copper monoxides, mono-sulfides) having black/gray color what we are actually seeing, which are moderate conductors. Especially hydrogen sulfide is dangerous, we can identify it with lead acetate paper that we have ordered. Important is also that carbon serves as catalyst. We see that the EPDM O-ring leaves carbon traces very easily just by pressing it against the copper foil. | ||
Revision as of 17:37, 9 August 2012
August 9, 2012 FDC meeting
Agenda
- Cathode corrosion
- Status tests with water, SEM results
- Testing chambers photos
- Production Construction Tracking (Dave)
- Cathode production
- Fixing cathodes
- Second package refurbishment
- Engineering (Bill)
- Electronics (Chris, Nick)
- TDR, page 132-145 (Lubomir)
- Other
Minutes
Participants: Bill, Dave, Chris, Nick, Vlad, Eugene, and Lubomir
