Environmentally Safe Bullets Developed

Lead shot and bullets may present a double threat to ducks and geese. They can be killed by ammunition from hunters' guns during waterfowl season. Or, if they eat near recreational shooting ranges tainted with lead from bullets, they may die from lead poisoning. Lead bullets are not environmentally safe.

ORNL has found a solution that may prevent this environmental problem from getting worse. The Laboratory has developed lead-free, environmentally safe bullets that may keep new shooting ranges from becoming hazardous waste sites.

The new bullets, which are being developed to replace lead bullets used for training and security at DOE's production and research sites, are made of mixtures of tungsten and other metals or alloys. The composite-metal bullets are called environmentally safe projectiles, or ESPTM.

DOE is committed to reducing environmental pollution from lead ammunition. Each year DOE expends approximately 17 million rounds of small arms ammunition, depositing more than 300,000 pounds of lead and copper on DOE ranges. DOE estimates that for each dollar spent on ammunition, $100 is spent for cleanup and reclamation of shooting ranges contaminated with lead.

Powell River Laboratories, Inc., of Oak Ridge has been granted the right to manufacture ESPTM bullets in a licensing agreement with Lockheed Martin Energy Systems, Inc., which manages ORNL for DOE. ORNL is working with Delta Defense, Inc., in Alexandria, Virginia, in a cooperative research and development agreement to test the bullets to ensure that they meet all appropriate standards.

Tens of billions of lead bullets are fired each year in the United States. It is estimated that 400 to 600 tons of lead per day are used to produce bullets.

"The grounds of some of the nation's 8000 public and private recreational shooting ranges are contaminated with hundreds of tons of lead from bullets," says Rick Lowden, chief developer of the ESPTM bullet and a metallurgist in ORNL's Metals and Ceramics Division. "The most contaminated ranges pose a threat to humans and wildlife. Duck and geese have been found poisoned in lakes polluted by lead shot. Shooting ranges could be declared hazardous waste sites by the Environmental Protection Agency when they are shut down, and it will cost millions of dollars to clean them up.

"DOE recognizes the contamination problem that exists at its own shooting ranges, which are used by security personnel. So it plans to switch from lead bullets to ESPTM bullets for training and security."

At this time, each ESPTM bullet costs about five times more than a lead bullet--a quarter instead of a nickel per bullet. However, Lowden says, the ORNL bullet offers several advantages over lead bullets. It has been proven to be nontoxic. The ESPTM material is completely recyclable. In addition, the bullets can be made to be both lethal and "frangible"--that is, they will break apart upon impact, minimizing property damage and the risk of accidents at facilities containing hazardous materials.

The ORNL metallurgist and his colleagues started on this project in early 1993 when ORNL was asked by DOE to evaluate a plastic-metal bullet developed by Delta Defense for training purposes. A group led by Tom McCoig in ORNL's Safeguards and Security Division found the bullets wanting. "The plastic-metal bullets were half as dense as lead bullets," Lowden says, "so they did not function as well as lead bullets from the security guards' guns."

McCoig and Joe Dooley of the Special Projects Office of Energy Systems met with Lowden and asked him if he could make ceramic bullets to replace lead bullets. Lowden replied that ceramic bullets would be too light in weight and too hard to adequately replace lead bullets. He proposed using powder metallurgy techniques to make a metal-composite bullet that has the same weight, density, and mechanical properties as a lead bullet.

"We set out to make a metal-composite bullet with the same density as a lead bullet. We mixed hard, heavy, high-density metals like tungsten with soft, low-density metals or alloys and found compositions that worked.

"We used a powder metallurgy technique in which we press powders of the metals into a solid cylindrical core at room temperature in a cylindrical die. Then we squash them into the shape of a bullet using a technique called swaging. Major manufacturers would have to make only minor changes in their equipment to add the powder metallurgy step to mass produce the metal-composite bullets."

ORNL's Industrial Hygiene Department checked the hazard ratings for the individual metals and alloys in the ESPTM material. It determined that the metal composites for the bullets are environmentally safe. "By changing the composition, shape, and size of the bullet and the amount of heat treatment," Lowden says, "we can control its penetration and optimize its performance for any specific use. We can meet DOE's request to make bullets that don't ricochet off indoor range targets."

"For the future," Lowden says, "We hope to learn how to make fine shot for skeet shooting using metal composites." In 1986 lead was phased out as a material for shot; steel shot is now being used, and bismuth-tin may be approved as a replacement for steel. "We also hope to learn how to manufacture our bullets using casting instead of swaging to give industry another production option."

Lowden has been assisted in the laboratory by Norman Vaughn, a co-op student at Tennessee Technological University in Cookeville. The development and testing of the bullets at ORNL is supported by DOE's Office of Safeguards and Security.

Ducks may not feel any safer, but they could be now that Americans are no longer ducking the issue of the environmental harm posed by bullets.

Self-Lubricating Coating for Engine Parts Developed

A self-lubricating composite coating that could make engine and other moving parts last longer has been developed at ORNL.

"Oil-based lubricants break down at high temperatures," says Ted Besmann, a scientist in ORNL's Metals and Ceramics Division and one of the developers of the new coating. "As a result, components of engines that are run at high temperatures to improve their fuel-use efficiency tend to wear rapidly and require replacement. Our composite coating should help engine parts last longer because it incorporates a solid lubricant that makes them slide more easily."

The self-lubricating coating may be used for high-speed bearings, piston rings, cylinder linings, valve guides, and other parts in jet and internal combustion engines. Coated samples from ORNL are now being tested at the General Electric Company's Aircraft Engines Division in Cincinnati, Ohio.

Metals and Ceramics Division staff members Woo Lee and Peter Blau, postdoctoral scientist Y. Bae, and Besmann developed a composite coating made of titanium nitride, a hard, wear-resistant material at high temperatures, and of molybdenum sulfide, a solid lubricant. Electron micrographs of the composite coating show that separate grains of the solid lubricant are dispersed near the surface of the titanium nitride coating.

To make the coating, the researchers at ORNL used chemical vapor deposition (CVD). In this process, vapors or gases are allowed to flow over a heated solid surface (called a substrate), react, and form a solid coating.

The researchers simultaneously deposited the desired materials on substrates such as silicon and graphite. Then they deposited the composite coating on a titanium alloy used for parts in engines.

"To make the coating for a titanium alloy substrate," Besmann says, "we flowed several gases at a temperature of 800NC and low pressure into a reactor containing the heated substrate. To get the best coating composition, we varied the composition of the gases, which included molybdenum hexafluoride, hydrogen sulfide, ammonia, and argon, that carried the titanium organometallic vapor into the reactor."

Researchers elsewhere have used CVD, sputtering, or plasma spraying to deposit films of titanium nitride and of molybdenum sulfide. But the ORNL group is the first to co-deposit the two materials to form a composite coating.

"Solid lubricating films of molybdenum sulfide have been deposited on moving parts, but the lubricant tends to be worn away quickly," Besmann says. "Our composite coating increases the sliding life of the molybdenum sulfide lubricant by incorporating it in a hard material."

Besmann proposed that CVD could be used to develop a low-wear, low-friction composite coating. The development of the coating was carried out primarily by Bae and Lee.

Other division members who contributed to the work are Blau and Charles Yust, who measured the coating's friction and wear characteristics; Karren More, who took electron micrographs of the experimental coatings to reveal their structure; and David Braski, who analyzed the coating structure using Auger electron spectroscopy.

"Through the analytical work," Besmann says, "we are determining which coating structures and compositions are lowest in wear and friction. We have found that the friction of our best coatings containing titanium nitride and molybdenum sulfide is three times lower than a titanium nitride coating alone."

The coating development was supported by the Division of Advanced Energy Systems Projects in the Department of Energy's Office of Basic Energy Sciences.

ORNL Software for Salt Solutions Saves Time and Money

Highway maintenance crews battle icy roads by salting them. But how much salt should be sprinkled on the ice to melt it as quickly as possible? Moonis Ally of ORNL can provide the answer in a few minutes using a personal computer program he helped to write.

"If you add just the right amount of salt," Ally says, "the freezing point of the ice will be lowered as much as possible, and the ice will melt faster. But if you add too much salt, compounds called hydrates will form, raising the freezing point. The salt then becomes a burden instead of a benefit. In fact, too much salt not only wastes taxpayers' money but also can be toxic to roadside vegetation."

To develop the software, Ally, a researcher in ORNL's Chemical Technology Division, and retired consultant Jerry Braunstein developed the theory and algorithm, a step-by-step method for arriving at answers using available information; Andrea Sjoreen, a programmer in ORNL's Computational Physics and Engineering Division, converted the algorithm into a computer program. The result is a labor-saving software package that rapidly and inexpensively predicts the properties of various water-based salt solutions. Called Aqueous Electrolytes (AE), the software eliminates the need for researchers to measure such properties in the laboratory--a time-consuming, laborious, and expensive process.

"In only one day," Ally says, "AE can predict the thermodynamic properties of mixtures of different salts in water that would take chemists several months or even a year to obtain in the laboratory. These properties include boiling and freezing points, density, and vapor pressure as a function of solution temperature, salt concentration, and salt composition.

"In addition, our software can predict the properties of aqueous electrolytes that have higher salt concentrations than those treated by competitive programs. Also, it can be used on difficult problems such as predicting when a salt solution will form solid crystals."

For example, results obtained by the new software have confirmed that ORNL has selected the correct design for an evaporator. This device must supply enough heat to remove water from low-level liquid radioactive wastes in ORNL's eight Melton Valley storage tanks. The evaporator, which was ordered in October 1994 and will be installed in May 1995, will further concentrate these wastes to make space for recently generated waste.

"The wastes are salt solutions, and their boiling points depend on the salt concentration," Ally says. "If a solution is 30% salt, its boiling point is higher than that of a solution that is 10% salt. Salt concentration also affects freezing points."

"Using the software, Ally also helped us determine whether the liquid wastes might freeze in the aboveground transfer lines if the evaporator is run in the winter," says Vic Fowler, a contractor with ORNL's Chemical Technology Division. "He found that the wastes will not freeze in winter, so costly heating equipment is not needed."

In another example at ORNL, a proposal was made to use a wiped film evaporator to evaporate water from some hazardous wastes containing zinc bromide that are stored in several ORNL buildings. But before a final decision was made on treating the wastes, a decision was made to determine the thermodynamic properties of the waste solution.

"It would have taken too much time to get the answers in the laboratory," Ally says, "so we were asked to determine the properties of the waste solution using AE. We did it in 15 minutes. We found that boiling the wastes would require a higher temperature than the proposed evaporator could achieve. So that method was abandoned, and an alternative method was later used."

Ally also has used AE to help ORNL's Energy Division screen salt solutions in the search for the best refrigerants for absorption heaters and chillers--refrigerators under development that do not require energy-hungry compressors. Such refrigerants remove heat from the refrigerator cabinet at lower temperatures and reject it to the outside at higher temperatures. To make such machines more energy efficient, developers are trying to identify aqueous salt mixtures that have even better heat-transfer properties than the more fully understood mixtures of lithium bromide and water and of ammonia and water. Several potential salt combinations have been identified by AE for advanced absorption machines.

ORNL Researchers Test Trash-Based Fuel Cubes

The paper you throw away at ORNL may someday be used to heat your office, reducing the need for coal and landfill space. ORNL researchers have begun work on a pilot project to demonstrate the feasibility of burning fuel cubes made of shredded wastes collected from DOE facilities in Oak Ridge.

The pilot project will allow testing of air emissions and ash from various fuels and fuel mixtures to determine if refuse-derived fuel (RDF) is suitable for use in steam plant boilers. The project will proceed with a full-scale ORNL steam plant demonstration if the pilot demonstration identifies no air emission or ash problems as a result of burning the RDF fuels and fuel mixtures.

Tens of millions of pounds of sanitary waste are produced on the Oak Ridge Reservation annually. A successful RDF program would reduce both the amount of waste placed in landfills and the amount of coal burned at the ORNL steam plant, with possible savings of more than $300,000 per year.

The Oak Ridge project may be a model for other DOE facilities. Municipalities across the country already are implementing similar programs to comply with new Environmental Protection Agency and state mandates to reduce the volume of waste placed in landfills.

World Record Set for System Size in Molecular Dynamics

A team of researchers from ORNL, Brookhaven National Laboratory (BNL), and the State University of New York (SUNY) at Stony Brook have set a new world record for system size in molecular dynamics, using the 1024-node Intel Paragon XP/S 150 supercomputer at ORNL.

Molecular dynamics, a field of study that models the interactions among atoms in a chemical, biological, or solid-state system, is a cornerstone of applications ranging from the study of DNA-protein interactions to the design of new materials.

In two record-breaking runs, members of the Partnership in Computational Sciences (PICS) consortium performed molecular dynamics simulations for systems of 200 million and 400 million particles, with each simulation step taking 80 and 160 seconds, respectively. These results far exceed recently reported simulations of 10 million particles on the 512-node Intel Touchstone Delta system at the California Institute of Technology at Pasadena and 180 million particles on a 1024-node Thinking Machine CM-5.

"This breakthrough is yet another example of the High Performance Computing and Communications program bearing fruit for U.S. science and industry," said Ken Kliewer, director of the Center for Computational Sciences (CCS) at Oak Ridge. "It demonstrates the ability of key molecular dynamics algorithms to scale up to the large sizes needed for biologically interesting problems. This achievement should lead to major breakthroughs in molecular biology by permitting the simulation of realistic systems over significant time scales."

The computer code used to achieve this feat was developed by Osman Yasar of ORNL's CCS, Robert B. Marr and Ronald F. Peierls of BNL, and Yuefan Deng and R. Alan McCoy of SUNY. All three institutions are members of the PICS consortium, which uses the large Intel Paragon system at ORNL.--Jennifer Ball

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