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[Sandia Lab News]

Vol. 55, No. 20           October 3, 2003
[Sandia National Laboratories]

Albuquerque, New Mexico 87185-0165    ||   Livermore, California 94550-0969
Tonopah, Nevada; Nevada Test Site; Amarillo, Texas

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Sandia researchers develop ultra-high-temperature ceramics to withstand 2,000 degrees Celsius New Water attracts crowd to Hobbs meeting as demand, available technologies converge Galileo's 14-year odyssey of discovery ends



Sandia researchers develop ultra-high-temperature ceramics to withstand 2,000 degrees Celsius

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By Michael Padilla

The ultra-high-temperature ceramics (UHTCs) created in Sandia's Advanced Materials Laboratory can withstand up to 2,000 degrees C (about 3,800 degrees F).

Ron Loehman, a senior scientist in Sandia's Ceramic Materials Dept. 1843, says the results from the first seven months of the project have exceeded his expectations.

"We plan to have demonstrated successful performance at the lab scale in another year with scaleup the next year," says Ron, adding that results suggest these materials meet the thermal insulation requirements of Sandia's Prompt Global Response project. The program also provides NASA Ames Research Center with analysis of UHTCs.

Composite materials

Ron says thermal insulation materials for sharp leading edges on hypersonic vehicles must be stable at very high temperatures (near

2,000 C). The materials must resist evaporation, erosion, and oxidation, and should exhibit low thermal diffusivity to limit heat transfer to support structures. Materials with those properties are required for development of hypersonics for prompt and precise delivery to difficult targets.

UHTCs are composed of zirconium diboride (ZrB2) and hafnium diboride (HfB2), and composites of those ceramics with silicon carbide (SiC). These ceramics are extremely hard and have high melting temperatures (3,245C for ZrB2 and 3,380C for HfB2). When combined, the material forms protective, oxidation-resistant coatings, and has low vapor pressures at potential use temperatures.

"However, in their present state of development UHTCs have exhibited poor strength and thermal shock behavior, a deficiency that has been attributed to inability to make them as fully dense ceramics with good microstructures," says Ron.

Ron says the initial evaluation of UHTC specimens provided by the NASA Thermal Protection Branch about a year ago suggests that the poor properties were due to agglomerates, inhomogeneities, and grain boundary impurities.

"All of which we believed could be traced to errors in ceramic processing," Ron says.

During the first seven months the researchers have made UHTCs in both the ZrB2 and HfB2 systems that are 100 percent dense or nearly so, and that have favorable microstructures, as indicated by preliminary electron microscopic examination. In addition, the researchers have hot pressed UHTCs with a much wider range of SiC contents than anyone previously has been able to make. Availability of a range of compositions and microstructures will give system engineers added flexibility in optimizing their designs.

Collaborations

The project is part of the Sandia Thermal Protection Materials Program and represents work from various Sandia researchers. The

primary research team includes Jill Glass, Brian Gauntt, and Dale Zschiesche (all 1843), Paul Kotula (1822), David Kuntz (9115), and University of New Mexico PhD student Hans-Peter Dumm.

David Kuntz, project investigator, says his primary responsibility is to compute aeroheating, design thermal protection systems (heat shields), compute material thermal response on high-speed flight vehicles, and develop tools to improve these capabilities.

"If a vehicle flies fast enough to get hot, we analyze it," David says. "Our tools consist of a set of computer codes that compute the flowfield around a high-speed flight vehicle, the resultant heating on the surface of the vehicle, and the subsequent temperatures and ablation of the materials which form the surface of the vehicle."

Jill works with high-temperature mechanical properties and fracture analysis.

Paul's role in the project involves microstructural and microchemical analysis of this important class of ceramic materials. Paul applies the Automated eXpert Spectral Image Analysis (AXSIA) software (developed by Paul and Michael Keenan (1812), recently patented and winner of a 2002 R&D 100 award) to the characterization of hafnium and zirconium diboride/silicon carbide UHTCs. Paul looks at these materials at the micron to subnanometer length scale for grain size and phase distribution as well as impurities or contaminants that can adversely affect their mechanical properties.

Creative analysis

Boron and carbon are difficult to analyze because they give off low-energy, or soft,

X-rays when excited with an electron beam as in a scanning or transmission electron microscope typically used for such analyses. Instead of using X-ray analysis techniques the research team has developed other analytical capabilities based upon electron energy-loss spectrometry to determine amounts and nanometer-scale lateral distributions of the light elements in the UHTCs.

In particular, oxygen is an important impurity since in combination with the silicon present in the UHTCs and other impurities it can form glasses or other phases.

These other phases typically can't take the required high operation temperatures and would melt or crack in service causing the material to fail.

"If enough of the wrong contaminants find their way into the process, the material will have no high-temperature strength or stability," says Paul. - - Michael Padilla

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'New Water' attracts crowd to Hobbs meeting as demand, available technologies converge

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By Will Keener

To Sandia's Allan Sattler (6113) and Mike Hightower (6251), a forum in Hobbs, N.M., was successful because of a convergence of events. A five-year drought and the development of more efficient technologies for removing salt from water have combined to create an opportunity for New Mexico to develop "new water." While most of the attendees were concerned about the potential benefits and uses of this "new water" in New Mexico and West Texas, water shortage problems are national in scope and potential benefits reach far beyond state boundaries.

This new water isn't really new, but it has long been ignored in New Mexico and elsewhere, the two researchers note. Water generated in association with the production of oil and gas has been more a nuisance than a potential benefit in the past. Water found in many water wells, high in salt, or brackish, has very often been passed by, with little information as to its character and extent recorded by drillers concerned mainly with developing freshwater supplies.

But times have changed. "We're at the point where it is becoming economically feasible to use these brackish resources," says Mike, of the Labs' Energy Infrastructure and Distributed Energy Resources Dept. 6251. "People need the water and it's becoming cost-effective to treat."

Reading about communities and farmers in New Mexico with water problems has become too commonplace, says Allan, of

Sandia's Underground Storage Dept. 6113. "New Mexico has severe water problems, statewide in scope." Among cities expressing concern about future water supplies are

Alamogordo, Albuquerque, Jal, Eunice, Chama, Las Cruces, Santa Fe, and Gallup.

These and other municipalities, running short of local freshwater supplies, face the possibility of piping water from other locations at much higher costs to meet demands. As desalination technology becomes competitive economically, however, it could be possible to use brackish or produced water to fill in some of the demand.

In Lea County, for example, developed oil fields produce an estimated 42 million gallons a day of water that is too salty for consumption and has some slight hydrocarbon content. "If you could treat that water for agriculture or industry, even if you could only use part of it, you're still ahead," says Allan.

Knowing this, 150 interested participants showed up at a forum on produced and brackish water, held in Hobbs in late July. Sandia, along with a number of New Mexico organizations, sponsored the two-day event. "We were pleasantly surprised at the turnout," says Mike. "It was twice what we expected." The meeting featured 20 papers on various aspects of technology evaluations of the use of brackish or produced water in New Mexico and in West Texas.

Emphasis on coordination

"Everyone wanted to be there," says Mike. "We had participants from universities, oil and gas companies, municipalities, agriculture, mining, electric power, and other areas. They know the problems and they know the issues. There was a lot of emphasis and interest in coordinating the use of these nontraditional water resources." That led to the formation of a steering committee, with Mike and Allan along supporting the group.

Forum participants identified seven key issues and suggested organizing a steering group, with appropriate expertise, to address those problems. Three executive members, representing the petroleum industry, water resource researchers, and agriculture, were selected to help form the steering committee. The committee will include representatives from soil and water conservation districts, oil and gas organizations, the Municipal League and Association of Counties, business interests, research organizations, and regulatory agencies in the state.

Sandia's role will be to provide technology evaluation support and to help integrate activities. Sandia will provide a statewide framework to integrate further work and funding opportunities, while keeping the national perspective in mind. The big picture, centered about addressing water shortage issues, reaches well beyond New Mexico and West Texas, Allan and Mike point out.

An example of one of the issues the group will have to address is eliminating jurisdictional conflicts, an effort needed to accelerate use on nontraditional water resources, says Mike. Right now a variety of state and federal agencies are involved in oversight of produced and brackish water. "We need to get the regulators to recognize the value of this water. In the past, it's always been an environmental liability. Now it's a potential asset, and they haven't figured out how to best deal with that yet," says Allan.

Another primary focus of the group will be education of state and federal legislators as well as the public. "Science can do a lot in this area, but without an institutional base of support, it's not going to go anywhere," says Allan.

Experience-based support

Sandia is an ideal advisor for the group for a number of reasons, Mike says. The Labs are by no means new to the issues, the technologies, or the current efforts to move desalination forward. Sandia has experience in the field of brackish water

engineering from its work in geothermal drilling, salt geochemistry, and geoscience capabilities. These capabilities were developed for projects at the Waste Isolation Pilot Project, near Carlsbad; the Strategic Petroleum Reserve, on the US Gulf Coast; and at a variety of environmental projects involving groundwater characterization and treatment. "We have a lot to add," says Allan.

In addition, Tom Hinkebein of Geochemistry Dept. 6118 helped coordinate the development and completion of a national desalination technology roadmap last year with the Bureau of Reclamation. The roadmap has been reviewed by the National Research Council and will form the basis for a national desalination research program for the next 20 years.

Also, Congress approved funding for the design and construction of a national desalination research facility near Alamogordo, in New Mexico's Tularosa Basin. Groundbreaking for the facility, which is strongly supported by Sandia, is scheduled for December, says Mike. "Sandia has had a major role in cooperation with the Bureau of Reclamation to develop a vision and goals for this facility. Sandia is expected to have a continuing major role in the oversight of the operations and research at the facility," Mike says.

New Mexico is a good place to be for desalination research, Allan and Mike agree. "We have good technical resources in our universities and national labs as well as extensive brackish water resources and pressing water supply needs. Why shouldn't we be a leader in desalination?" Mike asks. From New Mexico's experience, the word can be expected to spread quickly. The potential use of desalination technologies in the US is widespread. All but about four or five of the states have brackish surface or groundwater resources that could be put to beneficial use.

Internationally, the potential is even higher. "Increasing demand for limited water resources is a major international issue in the Middle East, India, Pakistan, Southeast Asia, and China," says Mike. "All these areas are seeing conflicts over scarce freshwater resources. If we can solve issues in New Mexico and the Southwest in utilizing nontraditional water resources, such as brackish and impaired waters, we may be able to help these countries improve utilization of nontraditional or impaired water supplies and help reduce future conflicts over water. It may be an important step in helping us foster peace in the world." -- Will Keener

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Galileo's 14-year odyssey of discovery ends

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By Ken Frazier

The Galileo spacecraft's 14-year solar system odyssey -- eight of those years in orbit around Jupiter -- came to a fiery end, Sunday, Sept. 21, as the gallant craft was intentionally guided into the Jovian atmosphere, where it disintegrated. Galileo worked to the very end, its last signal reaching the Deep Space Network tracking station in Goldstone, Calif., at 12:43 p.m. PDT. Hundreds of former Galileo project members and their families gathered at the Jet Propulsion Laboratory in Pasadena to bid it goodbye.

Galileo, the first spacecraft to orbit one of the outer planets, will go down as one of the most successful planetary exploration missions in history.

"We learned mind-boggling things," said Galileo project manager Claudia Alexander. "This mission was worth its weight in gold."

JPL announced last week that "the hardy spacecraft had endured more than four times the cumulative dose of harmful radiation it was designed to withstand," a final tribute to the radiation-hardened computer chips Sandia designed and built and JPL installed in Galileo. Sandia delivered the chips in 1985. Galileo was eventually launched Oct. 18, 1989. (See "Galileo's epic odyssey around Jupiter. . . and the Sandia connection," Lab News, Feb. 9, 2001; also at http://www.sandia.gov/LabNews/LN02-09-01/galileo/galileo.pdf.)

The prime mission ended six years ago, but Galileo worked so well that NASA extended the mission three times.

JPL also noted last week, "The mission was possible because it [Galileo] drew its power from two long-lasting radioisotope thermoelectric generators provided by the Department of Energy."

Galileo flew by Venus once and Earth twice on its convoluted, gravity-assisted path to Jupiter. From launch to impact, it traveled 2.878 billion miles (orbiting Jupiter 35 times in eight years) and returned 30 gigabytes of data and 14,000 pictures.

Galileo's list of discoveries is astounding. Even on its way to Jupiter, in 1993, it discovered and photographed the first moon around an asteroid (Ida and its moon Dactyl). Once in the Jovian system it proceeded to investigate the geologic diversity of Jupiter's four largest moons. It documented the extraordinary volcanism on Io. It found evidence that Europa may have a salty ocean beneath its fractured, ice-encrusted surface. It showed that Ganymede and Callisto might have a liquid-saltwater layer. It found that Ganymede has a magnetic field, the only moon known to have one. It recorded gigantic thunderstorms and lightning strikes on Jupiter a thousand times more powerful than on Earth and took observations and measurements of Jupiter's atmosphere and magnetic fields that changed our understanding of the solar system's largest planet.

Ironically it was that discovery of a probable sub-ice ocean on Europa that led to NASA's difficult decision, as Galileo's steering propellant ran low, to cause it to plunge into Jupiter and be destroyed there rather than risk a later accidental crash into Europa where it might bring earthly contamination to a moon that now seems at least to have the possibility of harboring some form of life.

"It was truly exciting to be part of the Sandia team that enabled the Galileo mission to be such a major success," Paul Dressendorfer (1141) told the Lab News last week. Paul and Ron Jones (1741) directed the technology development effort for the rad-hard chips and were responsible for circuit fabrication and manufacture. "At the time Sandia was the only organization capable of designing, fabricating, and qualifying the critical parts needed for the spacecraft, and to see it greatly exceed expectations and generate such a wonderful set of data over the years has been very rewarding." -- Ken Frazier

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Last modified: October 7, 2003

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