#Witchcraft-and-Alchemy #video about #bootstrapping thinner aluminum #foil material for a ribbon microphone, noting that the usual stuff is about 10μm, testing with a micrometer, while ribbon-microphone #sensors are ideally 1.5–3μm. He reduces the thickness of household foil by etching the foil with NaOH #materials, 4g dissolved in 200mℓ of water (½ molar, he says), which evidently thins the foil fairly evenly. He glued foil to some plastic roundrects to hold it in place during the process. There’s a point where the foil becomes a very fine mesh, some time before being ripped apart by the hydrogen bubbles after about half an hour. He did a 4-liter test to try to hold temperature more constant. I suspect you could get smoother dissolution with the proper regime of #electrolysis, reducing asperities, but he didn’t try that. For thickness measurement, he did the same repeated-folding-in-half thing that I did, but with a micrometer instead of calipers or a ruler to measure the result. He says some of the foil had “the structural integrity of a wet paper towel,” making the process more difficult. The thinnest acts like gold leaf, sticking to his tweezers. The data shows a linear decline in thickness from 10μm at 5 minutes to 0 at 40 minutes, with a 35-minute sample being 2.2μm thick.
So he made some more samples; he tried to etch them for 32 minutes (before a citric-acid stop bath and water rinse) but they fell apart at 25 minutes.
In order to compensate for unknown temperature and agitation variations, he decided to measure the foil’s resistance during the etch process with a constant current. For #metrology, he amplifies the voltage drop across the foil with a differential-to-single-ended converter based on a LM833 dual op-amp #electronics, with an LM317 set up as a 100mA constant-current source, and a couple of relays set up to reverse the current direction through the foil to eliminate any offset errors, including from any unintended galvanic cells. Also he used an angle grinder to cut some blank PCB into a four-wire Kelvin probe so he’s only measuring the resistance of the foil itself, not the resistance of the copper leading down to the foil. The copper is painted black, presumably to protect it from the NaOH. And he’s using something like a Black Pill to record the data.
The 10μm foil is about 70mΩ (=7mV) at first, decreasing roughly linearly with less than 10nm of noise, enabling thinning the foil down to under a micron before it broke.
If you were doing this electrolytically, you could presumably stop the etch directly from the microcontroller with a transistor or even directly from a GPIO.
Then he repeats the etching with a large sample in the same bath with the thin foil strip whose resistance he’s measuring. And then he corrugates his foil ribbon microphone ribbons before etching them to thin them, which answers a burning question I had, and then he recorded the video with the resulting microphone!
An amusing editing trick is that he recorded himself erasing a whiteboard drawing line by line with his finger, then played the video backwards with a voiceover to make it look like he’s drawing with his finger.
on 02026-08-11#Nighthawk #video about #electrolysis for, e.g., electrowinning metal #materials. First big science error is at 8'08": “Actually everything that dissolves in water splits into ions when it does so.” Nope. He claims to be making #DIY ion-selective membranes using Robert Rowow’s recipe, using off-the-shelf PVC cement and ion-exchange resin beads from water softeners, reinforced with fiberglass cloth, but I’m not clear how he validates them. He recommends using a hot glue gun to hold the membranes in place in his water buckets with EVA. He also turns carbon welding blankets into conductive carbon felt electrodes. He reports 250mA at 1.2 volts from his semipermeable-membrane plastic-bucket Fe⁺⁺/Fe⁺⁺⁺ flow battery with roughly A5-paper-sized carbon-fiber electrodes. Also he makes hydrogen sealed into the cathode compartment of a cell with one of these semipermeable membranes.
on 02026-06-03#Kolbe #electrolysis can make ethane, sebacic acid, etc. #materials
on 02026-04-28#Scrap-Science video of the #Kolbe #electrolysis of slightly acidified sodium acetate #materials to ethane (diluted with carbon dioxide) via free methyl radicals in a U-tube, requiring a platinum anode to hinder oxygen generation
on 02026-04-27#video about #electrolysis technique "SEM TECH" for refining metals for #mining with salt water. Touts closed-loop no-waste processing and mostly precious metals. #toread
on 02026-04-14apparently aluminum rectifiers using borax #electrolysis make a faint glow. #electronics #materials
on 02024-12-13discussion of how apparently aluminum rectifiers using borax #electrolysis make a faint glow. #electronics #materials
on 02024-12-13“Progress toward Commercial Application of Electrochemical Carbon Dioxide Reduction” #PDF #paper on #electrolysis of #CO2 for #carbon-capture #toread
on 02024-12-05“Catalysis of the electrochemical reduction of carbon dioxide” #PDF #paper on #electrolysis of #CO2 for #carbon-capture #toread
on 02024-12-05#PDF of the nickel plating handbook #electroplating #electrolysis #manufacturing
on 02024-11-20#video on #DLyte brand #electrolysis #finishing with dry electropolishing
on 02024-09-16#electroplating pennies and nickels in lime juice with spent batteries. #electrolysis #materials
on 02024-07-05#electroplating bath #materials recipe: 5% vinegar, 3% hydrogen peroxide, mixed half and half, heated in the microwave until it steams, used to oxidize a copper scouring pad to copper acetate, but don’t let the solution get too concentrated, and apply a minimum of ½V. #electrolysis #bootstrapping
on 02024-07-01#video on unsuccessfully attempting to oxidize SO₂ #materials with #electrolysis instead of catalysts or H₂O₂, using a platinum anode and a copper cathode. His electrolyte is dilute H₂SO₄. The hydrogen and oxygen being generated in a closed flask seems like a baad idea to me. His electrolyte turns orange, maybe because of reducing back to sulfur on the cathode. Oops, he got backflow from suckback and lost all his product. In a second run he got copper sulfide on his cathode and sulfur in the solution, which fortunately defecated. In two hours he did get the H₂SO₄ concentration up from 4% to 4.2% in his 100mℓ batch. Then he did a control test without the electrolysis and it went up to 6%.
on 02024-06-26#video about #manufacturing #aluminum-air #batteries with either KOH or NaCl electrolytes. #energy #electrolysis Unfortunately “members only”.
on 02024-06-25#video about #manufacturing #aluminum-air #batteries with dual electrolytes: potassium hydroxide and 50% H₂SO₄, separated by a membrane, to get a higher voltage, over 2 volts. Uses “activated carbon felt” (??) for the air electrode. With a single electrolyte he gets 1.56V. He suggests bleach as an alternative alkaline electrolyte and vinegar as an alternative acid. He uses paper towels to hold the electrolytes in place. For “some short testing” he uses baking paper as the membrane, but of course it won’t last long in that environment! He suggests Nafion as the only viable membrane option. His postage-stamp-sized test cell gets 2.2 volts and can light an LED. He adds MnO₂ to his graphite electrode as, I think, a depolarizer, boosting the cell to 2.5V. (Maybe it’s an actual electrolyte material, though?). For whatever reason he never measures its short-circuit current, except for showing that the LED lights and doesn’t immediately burn out, so the battery presumably has on the order of 100Ω of equivalent resistance. Finally he builds a version of the battery with a salt bridge instead of a membrane, but using zinc rather than aluminum. Surprisingly the salt-bridge version is also able to light the LED, despite presumably having much higher ESR. #energy #electrolysis
on 02024-06-25#ScrapScience #video on #bootstrapping HNO₃ #materials from KNO₃ using a terracotta flowerpot as an #electrolysis membrane with the drainage hole plugged with silicone, incorrectly described as a “semipermeable membrane”, in an HDPE container made from cutting the bottom off a plastic milk bottle. Copper cathode made from thick wire, graphite anode made from some round graphite bars. 100g KNO₃, unknown quantity of water (maybe 500mℓ), some distilled water added to the anode chamber. Initially he gets 90mA at 7.5V (=80Ω), but pretty soon that rises to 630mA (≈12Ω), and he limited the current to 1.02A. No hydrogen is generated at the cathode, surprising him, but he says it’s because the nitrate ions are reduced to ammonium. After about a day the graphite anode has been completely eaten, which makes me think it wasn’t really graphite, but like carbon arc gouging electrodes or something. The cathode compartment ended up being very basic and smelling very strongly of ammonia, so he made ammonia too. He says his crude titration (not shown) tests the acid at 0.7 molar, which apparently isn’t enough to attack copper, so he boils it with some copper in it, eventually dissolving the copper after boiling it down 4×. While this method does seem to work, it seems a little bit like a method of making an engine starting with only a car — the cheapest way to get KNO₃ is by neutralizing HNO₃ with KOH. He also thinks it “isn’t good enough to be practical” because of how dilute the product is.
on 02024-06-25#ElAngelito #video on #electrolysis sharpening of steel wires in a stainless steel sugar bowl with a saturated table salt solution. He’s using an inverter arc welder as his power supply set at the lowest amperage. He got thick fencing wire to sharpen to a point in three or four minutes of holding it in the salt water. #materials #manufacturing #bootstrapping
on 02024-06-10#video on #electroplating: 200g blue vitriol (Zep root killer), a drop of HCl(aq) (Klean Strip concrete etchant), 50mℓ H₂SO₄ (Zep drain opener), 950mℓ distilled water, and an unspecified brightener not shown. He plates at 0.4 volts, getting about 150-400 milliamps on a Star Trek TNG communicator badge. #electrolysis #materials
on 02024-06-10#video about “putting salt on your electronics soldering iron” is actually using a tin/lead solder electrode for #electrolysis with tuz (NaCl) to tin(?)-plate an oxidized copper wire and then his carbon-coated kind of ruined soldering-iron tip
on 02024-04-28#Fraser #video on #electrolysis and Faraday changed how I thought about electrolysis and electrochemistry.
on 02024-04-10#3D-printing and #electroplating #tutorial with graphite. He’s using an LCD SLA printer to get nice smooth prints and graphite spray paint, but shows that some graphite paints are not compatible with some automotive body work putties, because the paint cracks. He’s measuring 12.5kΩ between points a few centimeters apart, which is similar to what I get with a pencil on paper, but after he burnishes it with a towel, he gets only 5kΩ. To burnish his Benchy he tumbles it in walnut shells for four hours. He uses an unspecified commercial bright acid copper electrolyte for the initial plating, using coffee filters for the anode bags on his copper anodes. He recommends using a constant-current power supply with 1A/dm² while rotating the workpiece, but he suggests also using the voltage (0.6–1.0V) to tell if your current setting is right! He gets a lovely mirror finish with his trade-secret electrolyte composition, but then sands and buffs it. Before plating gold, nickel, or silver over the copper, he suggests galvanic degreasing, using a stainless steel anode and 6V; he applies gold with a galvanic brush (electrolyte not disclosed) and 6 volts. #manufacturing #bootstrapping #video #electrolysis
on 02024-04-03#manufacturing ethane (R170) #materials for refrigerant (for the second stage of a cascade). His R600a tabletop icemaker compressor was able to condense CO₂ and N₂O despite only reaching 10 bar, but only barely handled ethylene, which he had made by running ethanol through Al₂O₃ at 450°. So he’s making ethane by Kolbe #electrolysis of sodium acetate on a platinum anode, liberating CO₂, which he has to remove with a Ca(OH)₂ scrubber. To avoid producing lye and thus oxygen, he includes an excess of acetate, in the form of vinegar; he got a weird oil making the sodium acetate. He uses ABS putty dissolved in acetone to seal his electrolysis electrode junctions inside an ABS sleeve he 3-D printed. He switched to using a float switch because his conductivity probe made of two stainless-steel screws was failing, maybe because of the oil. Includes Faraday calculations from first principles. Demonstrates burning soap bubbles of C₂H₆/CO₂ squeezed out of a syringe. He didn’t use enough vinegar, so his pH rose to 9.6, meaning that this process is an effective way to make alkali (probably Na₂CO₃, as evidenced by CO₂ bubbles when he adds more vinegar), since the anion turns into gas. With the pH at 5.6 he got 1.08ℓ/hour of gas from 700mA, close to the theoretical 0.94. His scrubber and gas drier are two packed-bed jam jars with pipes and hoses glued onto their lids and bases, sitting on 3-D-printed supports. By spraying liquid ethane all over the place after precooling it to -12° with his first refrigeration stage, he gets to -90°. He thinks a PbO₂ anode would work too. #video #Hyperspace-Pirate
on 02024-04-03#lead chloride #electrolysis in #molten-salt at 320° with 34 mol% LiCl, 39 mol% KCl, 27 mol% PbCl₂, Bureau of Mines Report of Investigations 8166: “Recovery of Lead From Lead Chloride by Fused-Salt Electrolysis”
on 02023-07-02a reformatting of most of the Haver, Bixby, and Wong report about #lead chloride #materials #electrolysis and #hydrometallurgy
on 02023-06-17Haver, Bixby, and Wong published Bureau of Mines Report of Investigations 8276, “Aqueous #Electrolysis of #Lead Chloride”, in 01978, as part of the US Department of the Interior. They leached galena with aqueous FeCl₃ and NaCl at 100° to get #materials solid #sulfur and lead chloride (which is reasonably water-soluble at this temperature). They were able to reduce the PbCl₂ to metallic lead through electrolysis, either in molten salts (which requires less energy) or in aqueous solution. “Optimum results [for the #hydrometallurgy process] (96-pct current efficiency, 0.23 kwhr[sic]/lb Pb) were obtained with 20 pct HCl at 25° C, using a current density of 15 amp/ft² and an electrode spacing of one inch.” They also got reasonable efficiency at up to 20× higher current densities. Apparently the NaCl functions as a catalyst. They purified the “pregnant solution” by passing it over lead shot before cooling to remove silver, copper, and antimony. If they did the electrolysis in the “spent” leach solution, the FeCl₂ in it would reabsorb the chlorine thus produced and become FeCl₃. They used a graphite anode and a lead cathode at the bottom of the electrolysis cell. For the molten-salt process they centrifuged out the PbCl₂ and reabsorbed gaseous Cl₂ into the stripped spent leach solution in an absorption tower for recycling back into the leach tank.
on 02023-06-17US5641391A: Three dimensional microfabrication by localized electrodeposition and etching, by Ian W. Hunter, Serge R. Lafontaine, and John D. Madden, applied in 01995. 10 μm/s localized electrodeposition of nickel in a sulfamate with a platinum electrode “at high voltages,” saying a voltage between 2.5 V and 5.0 V is appropriate. They used “microstepping motors”. To deposit polyaniline on stainless they cycled the voltage between -100mV and +750mV in a 1.0M sulfuric acid 0.1M aniline solution. Expired in 02015. #electrolysis
on 02021-11-06