I have some bars that I think are elconite (75% tungsten/25% copper).
Here's what I know about them: they came from a defunct die shop from their EDM department. Each weighs about 1,448 grams, is about 207mm long and 25.5 mm thick. This works out to approximate density of 13.62 grams per cubic centimeter. This is way more than density of pure copper (8.8 g/cm^3). On the outside, it is silvery in appearance but when ground (I ground off yellowish paint from one end) it is coppery/silvery.
My question is, is there some easy way to make sure that they are Elconite? (like, say, flame turning green with this bar's powder, or some such).
I'm not familiar with that material, but if your question is does it contain copper, or not, a quick test with nitric acid will answer that question. Apply a drop of nitric to a clean portion, avoiding getting any of the acid on your skin. You should get an instant reaction of blue/green color from the acid, and, possibly, some brown fumes. A drop of ammonium hydroxide on the drop of acid, once it's done its work, should produce a vivid, deep blue color, much deeper than it was with acid alone. If that's the reaction you get, it's copper. If it goes more greenish with the application of the ammonium hydroxide, it is likely nickel. A test with dimethylglyoxime solution would turn the blue spot pink if it was nickel, but that test should be performed without having added any ammonium hydroxide. Tungsten, for the most part, is inert, so you won't see much of a reaction from it. It is likely to turn a gray color once cleaned of the matrix that bonds it.
I wonder-----did they use this material for electrodes? I'm not familiar with EDM operations------which were just coming of age when I closed the doors on my commercial shop.
"Tungsten salts colour the microcosmic salt bead blue in the reducing flame. Tungsten minerals, fused with sodium carbonate, and then dissolved in hydrochloric acid, give, on the addition of a small piece of tin or zinc, a blue solution when heated."
Harold, thanks. There is no doubt that this thing has copper due to unmistakable color. The question is what makes it 54% heavier than copper. These bars are indeed gray colored on the outside.
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I read about it, it is not a true alloy (like if molten copper was mixed with molten tungsten). It was obtained by mixing and then pressing copper and tungsten powder together (it is called sintering).
I think, at this point, I am satisfied that it is Elkonite or some other copper tungsten alloy.
If you can machine it..it would make some really interesting bullets....I think Id sleeve on some driving bands....
Or a really marvelous shotgun slug.....
Gunner
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects. Lazarus Long
As am I. I've machined tungsten for guidance systems components (balance weights for gyroscopes), so I'm somewhat familiar with its appearance and machining characteristics. I've also turned a large number of tensile specimens. As far as I know, all tungsten alloys are made with sintering technology due in part to the melting point of tungsten being totally unreasonable in the scheme of things.
I think you'd be hard pressed to find another element that would display the characteristics you've described-----more or less leaving you no choice but to consider tungsten.
I have a stinking hunch it's not cheap stuff! I wouldn't be surprised at $15.00/lb.
Just how old are you! :) EDM has been around since the 60's, maybe even before! :)
I've used carbide for electrodes, it has nice wear characteristics. I've also used copper, cause it's easy to machine. I've never used them mixed, I wonder if they were after a blend of the two properties.
You may be able to take advantage of the fact that tungsten is immune to attack by hot hydrochloric acid, copper is not. The manufacture of lamp filaments involves dissolving out a steel mandrel in hot HCl.
At a bright red heat in air tungsten forms a light greenish oxide on its surface, though you may need a furnace to see this, torch heating may or may not work.
Seems to go for about $25/lb on ebay, though data is hard to come by as this stuff is rare and is not sold often. See item 250100404736.
Regarding a suggestion by another poster to make bullet cores from it, I am not sure how this allow would behave on impact due to how it was made (copper and sintering). For myself, I would rather try to use my
3/16" tungsten TIG welding electrodes. That said, I do have small bits and pieces of this Elkonite material, so if anyone is interested, let me know.
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A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects. Lazarus Long
Interesting you should mention the greenish oxide. I have on hand a couple of the 1/8" diameter tensile specimens I spoke of. I made them back in the late 60's, and have had them in my toolbox since. I noticed, recently, they have a strange green cast to them, very unlike the appearance when they were turned and polished.
Are you asking how old I am, or how old I feel? :-)
My first exposure to EDM was in the late 50's, but it was nothing more than a tap burning machine, an Elox. At that point in time, there was nothing on the market that could accomplish the work you see done today. Electrodes for tap burning were nothing more than various thin walled stainless tubing bits.
I started working for myself in '67-------with minimal equipment. I sold my skill, not machine capabilities. While CNC and other technology was developing rapidly, I steadfast stayed the course, applying what I knew to make a living and totally ignoring new developments. Didn't matter-----I was too busy making a living, and being isolated because I worked alone. I'm constantly amazed at how the world went on without me. In '83, I permanently closed the doors on my shop (but I kept the machines). I have never tried to stay abreast of current technology-----I'm truly a dinosaur. I still live in a manual world, right down to running all my machines without so much as a DRO. I am, dear sir, one of the last of the old school, where it was the man running the machine that did the work, not the machine.
If you've machined tungsten, you know that it's damned hard on tools----and we all know that copper is one of the best conductors. I imagine that for critical profiles, the material in question would be the best choice due to its ability to resist erosion from arcing, for conductivity, and somewhat easier machining than other grades of tungsten. By its nature, I'd imagine that stringy chips are not a problem as they would be with pure copper. I would expect that electrodes made by this material would be somewhat difficult to machine, but have great longevity.
It would be nice to hear from some EDM geeks for a better understanding. Anyone?
It looks like I started in the trade about the time you stopped. I was lucky enough to work in a shop that didn't have CNC's. I got to learn how to do things on rotary tables, die mills, and manual grinders. I even ran a shaper once. :)
At that time (early 80's), the EDM's that we had didn't have any computer ability, but they had decent accuracy. They certainly were better than just a tap burner.
tools----and
No, not really machined. We only cut them to length.
I kinda am an EDM geek. Although I'm not up on the latest and greatest, I've run them for years. I know in Europe they use a lot of copper for electrodes, but here in the states, most shops would rather use graphite. You can get a better finish with copper, but it's harder to machine, and more prone to thermal expansion.
"Where multiple electrodes are constantly required, a 70/30 mixture of tungsten and copper powder is pressure molded and sintered in a furnace. This process can produce close tolerance electrodes."
Tungsten/copper is used for EDM, providing the benefits of copper electrodes while increasing resistance to wear by adding tungsten in the typical ratio of 70/30 tungsten/copper. Copper electrodes alone have high wear rates compared to graphite in sinker EDM useage, due to the lower melting point of copper. The addition of tungsten is an attempt to reduce the wear rate, which forces the EDM'er to have to replace the electrode.
Maybe you can use them as hi-tech fishing weights?
I have about 30 lbs of lead that I use for sinkers (melted down bullet residue/floor sweepings from an indoor gun range), it has about same density as this alloy and a lot easier to work with. I will keep a couple of pieces to maybe make experimental bullet cores one day, and will get rid of the rest.
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