Copyright 2002 Knoxville News-Sentinel Co.
Knoxville News-Sentinel (Knoxville, TN)
October 25, 2002 Friday Final Edition
SECTION: ORNL RENAISSANCE; Pg. R4
LENGTH: 924 words
HEADLINE: Better bullets built;
Cleaner than lead, they can be created not to richochet
BYLINE: [By Frank Munger, News-Sentinel staff]
BODY:
The government said get the lead out, and researchers responded with tungsten and tin.
When pressed together in powder form, tungsten and tin produce a bullet just like those made of lead - only better.
"What we do is really easy," said Rick Lowden, a materials scientist at Oak Ridge National Laboratory.
It's so simple it's fascinating. Instead of melting and casting or extruding metals, Lowden uses a hydraulic press to compact the powder mix at 50,000 pounds per square inch. Within a few seconds a small pile of ugly gray powder becomes a shiny silver slug. A quick swaging and you've got a bullet. To add a copper jacket takes no time at all.
Whereas the traditional alloying process often creates unwanted microstructures and other problems, the powdered-metal technology brings together the best of the different metals.
"Tungsten is dense, and tin is soft and ductile," Lowden said. "Without heat or sintering, they combine to form a composite material that acts just like lead."
The initial motivation for the ORNL project was environmental. Tungsten doesn't foul the environment like lead or require costly cleanups, and "green" bullets are easily recycled. Because tungsten has a very high melting point, bullets can be heated until the tin melts away, separating the two metals.
The Army now stocks the lead-free ammo for selective uses, making it available to National Guard units around the country and other military agencies. Aerojet, a company in Jonesborough, Tenn., produces the slugs, which are further processed into bullets by an Army contractor in Missouri.
Environmental friendliness is a plus, but what really stirred the interest of the homeland-security program is another quality.
Tungsten-tin bullets can be made so they don't ricochet. The bullets disintegrate when they hit a hard surface, such a wall.
"If you're in a crowded airport or urban environment, you really don't want ricochets," said Mike Kuliasha, who directs ORNL's work on homeland security.
Likewise, the U.S. Department of Energy was interested in having guards armed with bullets that might kill a terrorist but wouldn't blow a hole in nuclear-processing equipment or endanger other sensitive operations.
Lowden said: "You can make a bullet just the right shape and size to optimize its properties or change the weight distribution to enhance the ballistics. The technology is really interesting in that it gives you so much variety and variability."
Researchers can fabricate bullets that reportedly will penetrate a "bulletproof" vest yet not exit the body. By increasing the density of the slug, changing the weight distribution and inserting a ceramic penetrator, they can make bullets that, at least on paper, would double the shooting range of an M-16 rifle and increase accuracy by 40 percent.
By adding traces of phosphorescent powder, they can incorporate a "marker" that can be used for evidence if the ammunition is used in criminal activities.
According to Lowden, potential applications for compacted tin and tungsten powder are many, ranging from cores for perfectly weighted golf balls to shielding for nuclear reactors.
Some special military uses that Lowden won't discuss may be in the works.
When the powders are compressed, most of the changes occur with the tin because tungsten is hard and doesn't deform. The tin particles meld and bend and stretch around the bigger tungsten particles through a mechanical interlocking process.
At the same time, however, a second process is taking place, Lowden said.
"Every particle of metal has a little rust on it, an oxide coating, but as you put it under pressure and it starts deforming and ripping and tearing, you get these really clean, shiny metal surfaces," he said. "As you put two clean surfaces together like that under pressure in the presence of air, they weld together in a process called cold welding."
By adjusting the particle size of the tin, researchers can dictate how much of each process, mechanical interlocking or cold welding, takes place. That, in turn, affects the properties of the bullets.
"We can make a bullet that's not really welded together and it's really fragile. Or we can make it weld together more and bonded with the tin so it's more ductile and it splatters like a lead bullet. So we can make a bullet that disintegrates or one that's more like a lead bullet. It's kind of nice."
When evaluating the possibilities several years ago, Lowden and colleagues at ORNL did a check of scientific literature and a patent review and found nothing at all. Nobody had ever suggested cold-compacting the two metals to simulate lead.
Indeed, reference books on metals basically conclude that pressing two powders together will not result in anything worthwhile, Lowden said.
"Guess what? They're wrong," he said smugly.
Early on, it appeared the downside of the powdered-metal bullets would be the cost. But, when factoring in cleanup costs, the tungsten bullets are actually cheaper than lead ones, Lowden said.
It's the simplicity of the process that he finds most attractive.
Lowden makes his own bullets at home, and he said serious shooters could probably do the same by changing the dies in a commercial reloading press.
Instead of pushing a bullet into the cartridge case, the reloader compacts the powder and forms a slug that can be made into a bullet. With the computer software that's now available, people could even design their own bullets.
"It's the ultimate science project for a shooter," Lowden said.
LOAD-DATE: November 13, 2002
Knoxville News-Sentinel (Knoxville, TN)
October 25, 2002 Friday Final Edition
SECTION: ORNL RENAISSANCE; Pg. R4
LENGTH: 924 words
HEADLINE: Better bullets built;
Cleaner than lead, they can be created not to richochet
BYLINE: [By Frank Munger, News-Sentinel staff]
BODY:
The government said get the lead out, and researchers responded with tungsten and tin.
When pressed together in powder form, tungsten and tin produce a bullet just like those made of lead - only better.
"What we do is really easy," said Rick Lowden, a materials scientist at Oak Ridge National Laboratory.
It's so simple it's fascinating. Instead of melting and casting or extruding metals, Lowden uses a hydraulic press to compact the powder mix at 50,000 pounds per square inch. Within a few seconds a small pile of ugly gray powder becomes a shiny silver slug. A quick swaging and you've got a bullet. To add a copper jacket takes no time at all.
Whereas the traditional alloying process often creates unwanted microstructures and other problems, the powdered-metal technology brings together the best of the different metals.
"Tungsten is dense, and tin is soft and ductile," Lowden said. "Without heat or sintering, they combine to form a composite material that acts just like lead."
The initial motivation for the ORNL project was environmental. Tungsten doesn't foul the environment like lead or require costly cleanups, and "green" bullets are easily recycled. Because tungsten has a very high melting point, bullets can be heated until the tin melts away, separating the two metals.
The Army now stocks the lead-free ammo for selective uses, making it available to National Guard units around the country and other military agencies. Aerojet, a company in Jonesborough, Tenn., produces the slugs, which are further processed into bullets by an Army contractor in Missouri.
Environmental friendliness is a plus, but what really stirred the interest of the homeland-security program is another quality.
Tungsten-tin bullets can be made so they don't ricochet. The bullets disintegrate when they hit a hard surface, such a wall.
"If you're in a crowded airport or urban environment, you really don't want ricochets," said Mike Kuliasha, who directs ORNL's work on homeland security.
Likewise, the U.S. Department of Energy was interested in having guards armed with bullets that might kill a terrorist but wouldn't blow a hole in nuclear-processing equipment or endanger other sensitive operations.
Lowden said: "You can make a bullet just the right shape and size to optimize its properties or change the weight distribution to enhance the ballistics. The technology is really interesting in that it gives you so much variety and variability."
Researchers can fabricate bullets that reportedly will penetrate a "bulletproof" vest yet not exit the body. By increasing the density of the slug, changing the weight distribution and inserting a ceramic penetrator, they can make bullets that, at least on paper, would double the shooting range of an M-16 rifle and increase accuracy by 40 percent.
By adding traces of phosphorescent powder, they can incorporate a "marker" that can be used for evidence if the ammunition is used in criminal activities.
According to Lowden, potential applications for compacted tin and tungsten powder are many, ranging from cores for perfectly weighted golf balls to shielding for nuclear reactors.
Some special military uses that Lowden won't discuss may be in the works.
When the powders are compressed, most of the changes occur with the tin because tungsten is hard and doesn't deform. The tin particles meld and bend and stretch around the bigger tungsten particles through a mechanical interlocking process.
At the same time, however, a second process is taking place, Lowden said.
"Every particle of metal has a little rust on it, an oxide coating, but as you put it under pressure and it starts deforming and ripping and tearing, you get these really clean, shiny metal surfaces," he said. "As you put two clean surfaces together like that under pressure in the presence of air, they weld together in a process called cold welding."
By adjusting the particle size of the tin, researchers can dictate how much of each process, mechanical interlocking or cold welding, takes place. That, in turn, affects the properties of the bullets.
"We can make a bullet that's not really welded together and it's really fragile. Or we can make it weld together more and bonded with the tin so it's more ductile and it splatters like a lead bullet. So we can make a bullet that disintegrates or one that's more like a lead bullet. It's kind of nice."
When evaluating the possibilities several years ago, Lowden and colleagues at ORNL did a check of scientific literature and a patent review and found nothing at all. Nobody had ever suggested cold-compacting the two metals to simulate lead.
Indeed, reference books on metals basically conclude that pressing two powders together will not result in anything worthwhile, Lowden said.
"Guess what? They're wrong," he said smugly.
Early on, it appeared the downside of the powdered-metal bullets would be the cost. But, when factoring in cleanup costs, the tungsten bullets are actually cheaper than lead ones, Lowden said.
It's the simplicity of the process that he finds most attractive.
Lowden makes his own bullets at home, and he said serious shooters could probably do the same by changing the dies in a commercial reloading press.
Instead of pushing a bullet into the cartridge case, the reloader compacts the powder and forms a slug that can be made into a bullet. With the computer software that's now available, people could even design their own bullets.
"It's the ultimate science project for a shooter," Lowden said.
LOAD-DATE: November 13, 2002
