exotic tungsten electrodes - Page 1
Forum section: electronics / general

author: coppercone2
author_rank: Super Contributor
timestamp: August 17, 2024, 05:19:25 pm
content: since its very esoteric I thought I would make a threadCommon tig electrodes are Yttrium, Cerium, lanthanum, Thorium ZirconiumThere is alot of other elements. The main push was to get away from Thorium, so they must have done research sometime in the 80's to figure out which available rare earth oxides are possible substitutes and there must have been some research database.Now they started mixing the ones they had. I assume they have data on those 5 elements because they were studied in force and the idea that if individually adopted for standards, a mixture might also pass the standard.However, humans get more access to elements since the 1980's (i.e. proliferation of rare earth magnets and semiconductor and optics manufacturing) lead to more mining and availability of metals that probobly were not considered economical back during this thorium replacement period. Obviously if something was too expenisve it might have gotten excluded from research.I am wondering if anyone has read or seen anything about other oxides being used. I searched a bunch 1 by 1 and I could not really come up with anything.https://en.wikipedia.org/wiki/Rare-earth_elementSome might be toxic and unusable, but I bet there is something else out there.Also, does anyone know anything about non thorium cryo treated electrodes? They have thorium tungsten thats liquid nitrogen cooled for longer life. I don't like thorium but I do have tungsten and the welding store happens to have liquid nitrogen. It would be trivial to try it with something like a $20 entry fee

author: coppercone2
author_rank: Super Contributor
timestamp: August 17, 2024, 11:38:35 pm
content: I am also interested in a good documentary about how they refine rare earth metal. I have watched plenty on copper, steel, etc.Does anyone know of a nice long boring production video where they go through how they smash the ore, extract the minerals and so forth? Not like some news reel clippings going on about politics, market segments, geopolitics, labor etc . Like a industrial chemistry video lecture that shows some machines and stuff like that

author: Smokey
author_rank: Super Contributor
timestamp: August 17, 2024, 11:41:31 pm
content: I've been using the blue Lanthanated for everything. Works fine for me. (Not an expert)

author: coppercone2
author_rank: Super Contributor
timestamp: August 18, 2024, 12:56:01 am
content: I know people don't use it, its probobly for robot welders if it exists. I thought it would be a good read if anyone knows anything.I kind of wonder how big the research effort was into replacing thorium. Was it a big effort like hard drives, or was it like a few people in a labIt seems that usually the very engineered electrodes basically bottom out for humans, the idea is if you have a robot welder that needs to continuously consistently weld for 45 minutes, you start needing exotic tungstens... or maybe the other way around, if your machine is doing 5000 arc starts an hour on a assembly line. Everyone starts to say they don't see any difference other then it lasts longer (at least, people that compared the various mixtures, which I think are the newest TIG technology.Usually demanding scenarios for electrodes might be something like high current reverse polarity, or AC with very high cleaning... I think. Those processes give alot more heat to the electrode, so if for some reason you can't up the size of the electrode, you might need a better material for those settings. At least that is the easiest conclusion to come to based on reading for me. They do have their variables.Regardless of what for, the work function of a material is a interesting thing to studyAnother thing I was wondering about, is there molybdenum arc welding? Same process, different rod.And of course, uranium rods. Thorium sounds like something they let the civilians have. Maybe los alamos has some secret U235 rods

author: Phil1977
author_rank: Frequent Contributor
timestamp: September 05, 2024, 07:10:59 am
content: Quote from: coppercone2 on August 18, 2024, 12:56:01 amSome reactors even use Plutonium-(oxide)-rodsSome H-bombs seem even to use metallic Pu-rods, but I can't find detailed information about this on Hackaday or Kickstarter - I´m wondering why?But AFAIK has the radioactivity of the Thorium-electrodes very little to do with their welding qualities. You don't have enough Thorium atoms on the outermost surface of the electrode so that alpha-particles would help starting any arc. It´s seems to be just the chemistry of vaporized Thorium that was or is helpful for welding.But because it´s only chemistry it´s only reasonable that it can be replaced by something non-radioactive. My gut feeling is that many welders feel a kind of placebo effect, that if they use something special like something a little radioactive it must be better than something harmless. Like many people think a real sportscar needs to be loud and thirsty

author: coppercone2
author_rank: Super Contributor
timestamp: September 05, 2024, 07:16:12 am
content: it has to do with work function, you can look it up for various rods. Th has the highest magnitude difference, but those metal mix rods really do last longer on some tests I sawwell for arc starting , the rest is complicated

author: Phil1977
author_rank: Frequent Contributor
timestamp: September 05, 2024, 07:26:11 am
content: Quote from: coppercone2 on September 05, 2024, 07:16:12 amIt´s all complicatedThe work function of pure Thorium is not that special, the relatively non-toxic barium is much better in that single aspect:https://en.wikipedia.org/wiki/Work_functionBut the work function of the alloy, the mechanical properties of the heated alloy, the redox-potential of the vapour, and many things I don't know will affect welding. And without any doubt - Thorium was/is a good dopant for this purpose, the only discussion is if it still is better than its alternatives

author: coppercone2
author_rank: Super Contributor
timestamp: September 05, 2024, 07:35:03 am
content: when it was chosen it was primarily because TIG is hard to arc start because of poor control on early machines. I think that gives it a good chance of not being the ultimate alloy, since the primary problem that it was meant to solve is been solved pretty well with electronicsthe biggest selling point was that it makes easy arc starteverything else is useless toward manufacturing unless you can get it started. Whatever lowest defect rate the most will win out in most cases, aka bad start = defect. They are happy to throw expensive consumables in companies, so long you don't mess up the turbine or whatever, its peanuts in comparison. For the 'best' tig uses back then, how many man hours of manual machining could you fuck up with a bad start on a high reliability thing like a turbine?I doubt there was much concern for durability, you would probobly get a fresh tungsten on every single time you started a weld, sharpened by your assistant, doing whatever expensive things TIG did in those days..so I think that market focus was 100% on "be the rod that never screws up someones work" because it was just not something that was cheap in any regard at that time. Golden age of nuclear reactors, old-style military budgets, hypersonic manned vehicles, apollo program, etc.. all preposterously expensive with the welder being the tip of the spear of manufacturing... if he messed up its 3 mile island, apollo 13, a cold war national embarrassment, etc. 1 bad arc start meant some insanely complicated mission critical mechanical dodad could fail..so i have hope in other periodic elements being more useful...

author: Doctorandus_P
author_rank: Super Contributor
timestamp: September 05, 2024, 10:19:36 am
content: Cryogenic treatment is very strange.It is a "heat" treatment, and it is a continuation of heat treatments in the other direction, such as heating steel and then dunking it in water (or oil) to cool it very quickly. As far as I know there is a time limit for cryogenic heat treatment, and it has to be done within weeks (maybe months) of manufacturing. If you fist put it on a shelf for a year, then it does not work anymore, unless you first heat it again to a temperature hot enough to change the crystal structure (Which is pretty hot for tungsten).So at the very least, if you want to attempt this, don't just dunk your electrodes into liquid nitrogen, but do your own research first.

author: coppercone2
author_rank: Super Contributor
timestamp: September 05, 2024, 08:59:42 pm
content: you can get it melting hot with the tig welder on the tip where it matters for a test between treated, treated and aged or just untreatedyou won't get a re-grind out of it, but it should be dataa A1 tube furnace might also do the trick (easy to make one) for 1 rod