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I have some pzt rings but the electrodes have worn off. It was originally a silver screen print. Is there a way of repairing these? Without the screen print solder simply roles off the pzt. I tried a nickel pen that contains liquid but it didn't work. Any ideas? Szzuk.
If you have silver nitrate, you can use the Tollens' reaction to silver plate a surface. Then use high temp solder. Tollens reagent can be made using ordinary kitchen chemicals, except the silver nitrate. Google or Wikipedia will tell you how.
There is a nice variation of that reaction published recently by Walker and Lewis that uses silver acetate and ammonium carbonate (JACS, 2012,134(3), p. 1419-1421). You may be able to access it at: **broken link removed**. You don't need the whole article. Fortunately, the abstract contains everything you will need along with a little common chemical sense to repeat the work.
Tollens is super simple. What you need is a soluble silver salt (like silver nitrate or silver acetate) and a reducing agent (glucose can be used). With the price of silver today, say $30/oz or $1/gram, the silver salt will be expensive.
One of the early uses of the reagent was to silver mirrors, including telescopes. You need an actual metal to solder to. Silver paint and nickle paint probably won't work, as you have found out. There may be some conversion coatings for other metals that may work, but have no experience with them. As a last resort, I might try a mercury/silver amalgam, but if you are going to do that, why not go the Tollens route?.
I'm going to try. The price isn't a critical factor, it's more the difficulty of finding the right materials, mixing and it working. Any idea where to order in the U.K.? Farnell isn't showing anything, and neither RS. Thanks. Szzuk.
I just searched on "buy silver nitrate UK" and got too many hits to mention. Remember, it can be used as a medicinal, so a pharmacy may have it. I suspect the price at a pharmacy will be a premium.
Be careful with the silver nitrate. It will stain your skin black, just like a photograph negative. Also, although silver is not particularly toxic, you need to read and follow the other precautions.
I'll wear gloves, thanks for the info. I can buy the glucose at the supermarket, so what would you recommend i do to mix? The glucose comes in 140g tubes, so is it 10g glucose and 10g silver nitrate? And after mixing am I to brush it on? Regards, Szzuk.
Here is the Wikipedia reference (https://en.wikipedia.org/wiki/Tollens_reagent). Scroll down to silver mirroring. It has been about 45 years since I did those demonstrations. I don't remember the exact compositions of the reagents. I suggest looking up how to do it. There may even be a YouTube or Instructable on it. Do you know how to calculate moles and molarity? I don't think the ratios need to be or should be stoichiometric (i.e., one mole of glucose per two moles of silver ion).* Remember too, there is also ammonia involved. Household ammonia will work. It is a pretty forgiving reaction. The piezo must be CLEAN.
BTW, Are you an adult? Have you had high school chemistry?
John
*Oxidation of the aldehyde function in glucose gives two electrons. Reduction of a silver cation to silver requires only one electron.
I found the youtube video below, its simply demonstrated but not in English. It doesn't give mixing ratios but I can find that without much difficulty. The practicality of getting the mirror onto the piezo still has me scratching my head a little. What would you suggest?
Although I don't speak that language, the chemistry part is clear. Note, it is just a little of this and a little of that type of recipe.
Here is a little more formal description in English: **broken link removed**
The silver simply precipitates onto the glass surface. I am assuming the piezo devices, if in the bottom of the beaker or whatever you use, will get coated. I have done the test many times as mentioned, but it was simply to demonstrate reducing and non-reducing sugars. I have not tried using it to coat piezo devices. You can mask off areas that you don't want coated with tape or a paint. I have never tried soldering to the silvered surface. It is quite thin. It is electrically conductive, so if need be, you could plate more metal onto it.
Caution: There is some wrong information out there too. This "how to" is one example: https://www.wikihow.com/Make-Mirrors-by-Silvering-Glass. The comments bash it, but don't give details. I tired to comment, but was unable to do so -- maybe it was too old. In particular, note that ordinary sucrose (aka sugar) is non-reducing and should not give a positive result in this reaction.
You can buy conductive silver paint, it is used in appliance repair to fix thin tracks as used in remotes and membrane keypads. It's not cheap but it works.
The web link to regensburg uni is a good one and I don't think i'll need to look any further, thanks for that. I will get the ammonia and glucose from the supermarket and the silver nitrate will arrive in a day or two. It will be interesting to try! And should work after a few attempts. I will mask the pzt as you mentioned, that is a useful thought.
I have tried silver conductive paint, silver epoxy resin and the membrane repair kits. None of the 3 worked, so I have a long standing problem with fixing pzt electrodes. I'm not saying categorically they will never work, perhaps they do for other people, but I'd given up on those. At a guess I'd say those compounds work with piezos but not the bare pzt that I have.
I've not been able to solder to them. But I can never work out if its me not doing something correctly, or there is something else that other people use. It is hard to tell.
If the Tollens doesn't work, the silver ink method (my first post) may give a better surface for soldering. It also uses common chemicals, except of course the silver nitrate.
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