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| PK:
--- Quote from: Will_D on August 28, 2017, 11:09:05 AM ---Nitric acid is getting very gard to obtain these days --- End quote --- Ha! I went into the same battery shop I've been going to for years to buy some more battery acid for this test. It's not that they wouldn't sell me any, it's their business, they can do as they wish. It's the look of fear and concern in their eyes as they called the boss....... I lectured them for about 5 minutes..... man I was pissed off... PK |
| PekkaNF:
--- Quote from: PK on August 28, 2017, 06:07:44 AM ---.... I decided to look into electro-polishing and a quick search turned up a candidate solution of Citric and Sulfuric acids, neither at nasty concentrations... This looked promising as I'd assumed we would have to use hot phosphoric/sulfuric acid. Out came an old mop bucket, in went some lead flashing for a cathode, and 7 minutes at 10A later out came the part. All it needed was a quick wipe under running water and presto! .... --- End quote --- Interesting. This process is a complete stranger to me. What sort of concentrations we are talking here? Few %? Another quesion is about lead cathode....Does it has to be lead? So, yo need a "tank" that works same priciple than ultrasonic cleaner - drop parts in basket, clse the lid, press "start" and it chime when process is over? Wih pre/post rinse buckets? Not the fullyautomatic conveyor system like in metal plating lines. Pekka |
| PK:
--- Quote from: PekkaNF on August 28, 2017, 10:35:51 PM --- Interesting. This process is a complete stranger to me. What sort of concentrations we are talking here? Few %? --- End quote --- I just made up 4L of a saturated solution from dry acetic acid (150ish g/l) and added about 1L of battery acid. It sounds a lot worse than it is. I'll be telling the guys to wear gloves, but I didn't. It's certainly no nastier than an anodising tank. --- Quote ---Another question is about lead cathode....Does it has to be lead? --- End quote --- Nope, anything that lasts will do. You could even try stainless steel. Graphite would work and titanium would be perfect. Just make sure it has a large area WRT the job. --- Quote ---So, yo need a "tank" that works same priciple than ultrasonic cleaner - drop parts in basket, clse the lid, press "start" and it chime when process is over? Wih pre/post rinse buckets? Not the fullyautomatic conveyor system like in metal plating lines. --- End quote --- would be nice, but it'll probably be a small rack with Ti fingers that clip into the part. Push the button and the rack lowers into the tank, a few minutes later the power is turned off and the rack rises out of the tank and the unit starts making some irritating noise. Add in some fume extraction and call it done. We only do batches of 100 of these parts so there's no need to go too stupid with it... PK |
| PekkaNF:
Thank you. Very nice to know....I'm trying not to gravitate towards stainless steel bending and welding, but it has it's benefits. Normal grocery store grade vinegar here has about 10% acetic acid and pretty cheap on 5 litre gallons, wonder if that would make the base for that. Mental note: Go and buy battery acid bottle (or two) while it's still freely available. Pekka |
| simon.baldwin69:
Well depends on where you are, in the uk you can buy 3% nitric acid without a license and that should do the job, hydrochloric acid is easy to come by but sulfuric acid is difficult to buy at 98% but you can get drain cleaners that are 98%, I refine precious metals! Sent from my EVA-L09 using Tapatalk |
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