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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#81
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I want to buy a solid piece of pure tungsten, 3 to 15 lbs.
"Doug White" wrote in message ... You can also try contacting these guys: http://members.aol.com/blkholela/home/ I bought some tungsten rod from them a number of years ago. If you talk to Ed (the owner), tell him I sent you. I grew up in Los Alamos & he and I go WAY back. Doug White Thanks! |
#82
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I want to buy a solid piece of pure tungsten, 3 to 15 lbs.
wrote in message ups.com... On Oct 25, 8:43 pm, "Harold and Susan Vordos" wrote: wrote in message ps.com... On Oct 19, 11:53 pm, "Harold and Susan Vordos" wrote: "Todd Rich" wrote in message ... Adam Corolla wrote: snip----- If it wasn't my only one, I've got a sintered 5# block from work. An unneeded engineering sample. I'll ask and see if they have any others, but I don't think they'll have one for a couple of weeks/months. It is weird how dense it is. If you thinktungsten'sweird to handle, try gold, or even platinum. Both are heavier, platinum by a considerable amount. It's about 10% heavier than gold, which is about 12% heavier thantungsten. Both are very strange to hold, and easily slip from your grip. Harold Harold, If I'm not mistaken, gold has a density of 19.32 grams/cc andtungsten has a density of 19.3, making them almost identical. You are correct about the platinum, though, as it has a density of 21.45. Thanks. Earlier, someone pointed out that I was mistaken, thattungsten and gold are almost identical in specific gravity. I quickly verified that they were correct, although there's considerable debate on the true specific gravity oftungsten. There seems to be a consensus on the reason. Tungstenis not melted when processed, but is worked via powder metallurgical procedures. It, apparently, doesn't always end up at the same level of density, or concentration. Can you add anything to that concept? Harold- Hide quoted text - - Show quoted text - Yes, I can elaborate a bit. Tungsten has the highest melting point of any metal, making it difficult to consolidate by smelting, melting, and casting. Typically, tungsten is liberated from the ore by chemical extraction as opposed to smelting. Crushed ore is sent through a series of chemical reactions until one is left, finally with tungsten oxide powder. This powder is then roasted in a hydrogen furnace to yeild water and very pure tungsten powder. This powder then must be consolidated. In the powder metallurgy process, the powder is blended with a small amount of binder and pressed under high pressure to form a fragile bar. This bar is placed in a molybdenum tray and put into a hydrogen furnace to presinter. The solidifies the bar a bit and drives out the binder. This bar is then placed in a "sintering bottle" which is a quartz tube with two spring-loaded, water-cooled contacts. A large electric current is then passed through the bar, which heats it to very high temperatures. The bar then sinters, or consolidates, shrinking as this happens, thus the need for the spring loaded holders. The sintered bar is not fully dense. Depending on the particle size and the sintering temperature it is about 88% to 96% dense. However, this bar is usually densified further by millwork, typically rolling or drawing, so that the final product will come quite close to theoretical density. This is by far the most common way of consolidating tungsten, but there are others such as arc casting, electron beam melting, and plasma spraying. Some of these methods will produce a result that is very near or at theoretical density. Inkydog That's fascinating. You might want to consider adding that info to Wikipedia. Would tungsten be melted if there was a way to make an effective crucible that wouldn't melt or react with the tungsten? |
#83
Posted to rec.crafts.metalworking
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I want to buy a solid piece of pure tungsten, 3 to 15 lbs.
On Oct 26, 11:07 am, "Adam Corolla"
wrote: wrote in message ups.com... On Oct 25, 8:43 pm, "Harold and Susan Vordos" wrote: wrote in message oups.com... On Oct 19, 11:53 pm, "Harold and Susan Vordos" wrote: "Todd Rich" wrote in message ... Adam Corolla wrote: snip----- If it wasn't my only one, I've got a sintered 5# block from work. An unneeded engineering sample. I'll ask and see if they have any others, but I don't think they'll have one for a couple of weeks/months. It is weird how dense it is. If you thinktungsten'sweird to handle, try gold, or even platinum. Both are heavier, platinum by a considerable amount. It's about 10% heavier than gold, which is about 12% heavier thantungsten. Both are very strange to hold, and easily slip from your grip. Harold Harold, If I'm not mistaken, gold has a density of 19.32 grams/cc andtungsten has a density of 19.3, making them almost identical. You are correct about the platinum, though, as it has a density of 21.45. Thanks. Earlier, someone pointed out that I was mistaken, thattungsten and gold are almost identical in specific gravity. I quickly verified that they were correct, although there's considerable debate on the true specific gravity oftungsten. There seems to be a consensus on the reason. Tungstenis not melted when processed, but is worked via powder metallurgical procedures. It, apparently, doesn't always end up at the same level of density, or concentration. Can you add anything to that concept? Harold- Hide quoted text - - Show quoted text - Yes, I can elaborate a bit. Tungstenhas the highest melting point of any metal, making it difficult to consolidate by smelting, melting, and casting. Typically,tungstenis liberated from the ore by chemical extraction as opposed to smelting. Crushed ore is sent through a series of chemical reactions until one is left, finally with tungstenoxide powder. This powder is then roasted in a hydrogen furnace to yeild water and very puretungstenpowder. This powder then must be consolidated. In the powder metallurgy process, the powder is blended with a small amount of binder and pressed under high pressure to form a fragile bar. This bar is placed in a molybdenum tray and put into a hydrogen furnace to presinter. The solidifies the bar a bit and drives out the binder. This bar is then placed in a "sintering bottle" which is a quartz tube with two spring-loaded, water-cooled contacts. A large electric current is then passed through the bar, which heats it to very high temperatures. The bar then sinters, or consolidates, shrinking as this happens, thus the need for the spring loaded holders. The sintered bar is not fully dense. Depending on the particle size and the sintering temperature it is about 88% to 96% dense. However, this bar is usually densified further by millwork, typically rolling or drawing, so that the final product will come quite close to theoretical density. This is by far the most common way of consolidatingtungsten, but there are others such as arc casting, electron beam melting, and plasma spraying. Some of these methods will produce a result that is very near or at theoretical density. Inkydog That's fascinating. You might want to consider adding that info to Wikipedia. Wouldtungstenbe melted if there was a way to make an effective crucible that wouldn't melt or react with thetungsten?- Hide quoted text - - Show quoted text - Tungsten does melt. You have correctly discerned that the issue becomes containing it. Molds of carbon which may be water-cooled and/ or plasma sprayed with a tungsten coating are used in the arc casting process. There are other methods as well which utilize water cooled tubes where powder forms thin layer which is continually melted by an arc or an electron beam. Powder is continually added and the solidified cylinder which is created moves downward out of the tube as each new layer is melted. Thus only a small amount of material is melted at any one time. You will generally not ever see large quantities of molten tungsten in a big crucible, such as those found in a steel refinery. |
#84
Posted to rec.crafts.metalworking
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I want to buy a solid piece of pure tungsten, 3 to 15 lbs.
"Harold and Susan Vordos" wrote:
I've noticed when holding something *expensive* that my grip is a lot tighter and more tiring. I want to put it down as soon as I can. You mean like when holding Aunt Martha's Tifffany compote? :-) I was thinking more of a gentlemans fine rifle or shotgun. |
#85
Posted to rec.crafts.metalworking
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I want to buy a solid piece of pure tungsten, 3 to 15 lbs.
"Wes" wrote in message ... "Harold and Susan Vordos" wrote: I've noticed when holding something *expensive* that my grip is a lot tighter and more tiring. I want to put it down as soon as I can. You mean like when holding Aunt Martha's Tifffany compote? :-) I was thinking more of a gentlemans fine rifle or shotgun. Oh, yeah! I must remember, not all folks here are art glass collectors! (We are) :-) Harold |
#86
Posted to rec.crafts.metalworking
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I want to buy a solid piece of pure tungsten, 3 to 15 lbs.
wrote in message ups.com... On Oct 26, 11:07 am, "Adam Corolla" wrote: wrote in message Would tungsten be melted if there was a way to make an effective crucible that wouldn't melt or react with the tungsten?- Hide quoted text - - Show quoted text - Tungsten does melt. You have correctly discerned that the issue becomes containing it. Molds of carbon which may be water-cooled and/ or plasma sprayed with a tungsten coating are used in the arc casting process. There are other methods as well which utilize water cooled tubes where powder forms thin layer which is continually melted by an arc or an electron beam. Powder is continually added and the solidified cylinder which is created moves downward out of the tube as each new layer is melted. Thus only a small amount of material is melted at any one time. You will generally not ever see large quantities of molten tungsten in a big crucible, such as those found in a steel refinery. Why don't they just use a tantalum hafnium carbide crucible? Is that stuff too expensive? If not, it should work--it's melting point is over 1400 degrees F. higher than Tungsten's. Or for that matter, they could use a carbon crucible. Carbon remains solid at temperatures considerably higher than tungsten. Maybe they can't be used as crucibles for tungsten because those materials would react with the molten tungsten? |
#87
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Ned S.: I want to buy a solid piece of pure tungsten, 3 to 15 lbs.
"Ned Simmons" wrote in message ... On Wed, 24 Oct 2007 19:07:48 -0500, "Adam Corolla" wrote: "Ned Simmons" wrote in message . .. I did ask about prices and learned that the current price for ingots is around $60 to $70 per kilo. I didn't get to the guy who sells the scrap, but I'd guess it goes for around half that, which would make it about 1-1/2 times the price of carbide scrap. -- Ned Simmons Sounds great! 1/2" square by 2' long would be fine. I am guessing they would weigh almost 1.9 kilo or a little under 4.2 pounds each? Unless my math is rusty...? One of those would be perfect! So, I'm guessing it would cost around $65-70 before shipping? Very reasonable. Let me see if I can pin down the price. It may be a couple weeks before I'm up there again. -- Ned Simmons Hi, Ned! I was just wondering if you had a chance to check on that. Thanks! |
#88
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Ned S.: I want to buy a solid piece of pure tungsten, 3 to 15 lbs.
On Mon, 26 Nov 2007 16:38:38 -0600, "Adam Corolla"
wrote: "Ned Simmons" wrote in message Let me see if I can pin down the price. It may be a couple weeks before I'm up there again. -- Ned Simmons Hi, Ned! I was just wondering if you had a chance to check on that. Thanks! No, I haven't been at my customer's place since our last exchange, but I'll do my best to remember when I do get there. -- Ned Simmons |
#89
Posted to rec.crafts.metalworking
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Ned S.: I want to buy a solid piece of pure tungsten, 3 to 15 lbs.
"Ned Simmons" wrote in message news On Mon, 26 Nov 2007 16:38:38 -0600, "Adam Corolla" wrote: "Ned Simmons" wrote in message Let me see if I can pin down the price. It may be a couple weeks before I'm up there again. -- Ned Simmons Hi, Ned! I was just wondering if you had a chance to check on that. Thanks! No, I haven't been at my customer's place since our last exchange, but I'll do my best to remember when I do get there. -- Ned Simmons Thanks! :-) |
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