Commercial Materials Processing Experiments

1. Equipment for Controlled Liquid Phase Sintering Experiments

The Consortium for Materials Development in Space (CMDS), based at the University of Alabama in Huntsville (UAH), has developed the Equipment for Controlled Liquid Phase Sintering Experiments (ECLIPSE), making its first long-duration space flight on STS-57 in the SPACEHAB Space Research Laboratory. The UAH CMDS is a NASA Center for the Commercial Development of Space (CCDS).

The ECLIPSE experiment investigates the Liquid Phase Sintering (LPS) of metallic systems. Sintering is a well-characterized process by which metallic powders are consolidated into a metal at temperatures only 50-75% of that required to melt all of the constituent phases.

In LPS, a liquid coexists with the solid, which can produce sedimentation, thus producing a material that lacks homogeneity and dimensional stability. To control sedimentation effects, manufacturers limit the volume of the liquid. The ECLIPSE experiment examines metallic composites at or above the liquid volume limit to more fully understand the processes taking place and to produce materials that are dimensionally stable and homogeneous in the absence of gravity.

The ECLIPSE project focused on composites of hard metals in a tough metal matrix. This composite will have the excellent wearing properties of the hard material and the strength of the tough material. Applications of such a composite include stronger, lighter, more durable metals for bearings, cutting tools, electrical brushes, contact points and irregularly-shaped mechanical parts for high stress environments.

Kennametal, Inc. is an industry partner of the UAH CMDS participating in the ECLIPSE experiment, and has immediate applications for materials improvements in the ceramic composites tested. Kennametal is developing stronger, more durable tool bits. Wyle Laboratories is also an industrial partner with the UAH CMDS on the ECLIPSE experiment.

Principal Investigator for ECLIPSE is Dr. James E. Smith, Jr., Associate Professor and Head, Department of Chemical and Materials Engineering, University of Alabama in Huntsville.

2. Gas Permeable Polymeric Materials

The Gas Permeable Polymeric Materials (GPPM) payload was sponsored by the Instrument Research Division, NASA Langley Research Center (LaRC), through a joint NASA/industry program initiated in 1987 with the NASA Office of Advanced Concepts and Technology. This polymer study program will determine if certain types of polymers made in microgravity are very different from the same polymers made simultaneously on the ground.

Plastic materials, which are made of very large molecules called "polymers," are used in everyday life in many ways. Some polymers prevent gases, such as oxygen, from passing through. These polymers are used in keeping foods fresh for long periods of time in a refrigerator or freezer. Other polymers allow one or more gases to pass through. These polymers, called gas permeable polymeric materials, also have many uses.

Gas permeable polymeric materials are being developed for many uses. These include special contact lenses for long-term wear and for use by pilots and astronauts; medical applications such as dialysis and blood gas monitoring; control of fermentation and other industrial processes; and, commercial production of pure gases.

Another promising use is the development of sensors that will measure any gas in the air in very small amounts. In this device, a very thin layer of the polymer is coated on a sensor. The polymer allows only the gas which is to be measured to pass through it. The sensor then measures the amount of gas that is present. These devices will be used in monitoring indoor air quality and in detecting dangerous gases, such as carbon monoxide.

Gravity may affect many properties of the polymer while it is being made. As early as 1984, it was suggested that these effects may be eliminated or at least reduced if the polymer was made in the low gravity of space. A better understanding of how these polymers are formed can also be learned under these conditions. These experiments must be carried out on the Space Shuttle with the assistance of the astronaut crew because the rates at which the polymers are formed are very slow. If these polymers are very different as expected, many new and improved products will result from them.

3. Investigations into Polymer Membrane Processing

The Investigations into Polymer Membrane Processing (IPMP) payload made its eighth Space Shuttle flight for the Ohio-based Battelle Advanced Materials Center, a NASA Center for the Commercial Development of Space.

The objective of IPMP is to investigate the physical and chemical processes that occur during the formation of polymer membranes in microgravity, such that the improved knowledge base can be applied to commercial membrane processing techniques.

Polymer membranes are porous films which have numerous industrial applications in separation and filtration devices for pollution control, food, chemical and drug purification, and kidney dialysis. The largest potential market may be the environmental sector. Space-based polymer membrane experiments and resulting product improvements could play an important role in pollution control and may serve to significantly reduce the growing problem of dangerous gas emissions in our environment. Amoco Chemical Co., Du Pont, and Bend Industries, Inc., have contributed to this project due to the impact it may have on gas separation technology.

The results and knowledge gained from all of the IPMP commercially-applied research flights are being analyzed for potential process-enhancing applications in existing industrial processing plants. Through the dissemination of this information, it is expected there will be increased interest on the part of U.S. materials, chemical and environmental companies to grow polymers and other materials in space on a commercial basis.

IPMP Principal Investigator is Dr. Vince McGinniss, Battelle Advanced Materials Center, Columbus, Ohio. IPMP Program Manager is Lisa McCauley, also of Battelle.

4. Liquid Encapsulated Melt Zone

The Liquid Encapsulated Melt Zone (LEMZ) experiment on STS-57 was sponsored by the Consortium for Commercial Crystal Growth based at Clarkson University, Potsdam, NY, a NASA Center for the Commercial Development of Space (CCDS). The LEMZ payload is developed by the University of Florida, Gainesville, an academic affiliate of the Consortium.

LEMZ was the first experiment in a series of activities to determine the feasibility of commercial, space-based production of materials for applications in the computer industry, optics industry, and sensor/detector industry. These materials are needed for the next generation of high speed optoelectronic digital circuits, optoelectronic devices and transportation systems.

One of the major thrust areas in materials science is the growth of single crystals with improved homogeneity (uniform parts), purity and structural perfection. However, single crystals grown on earth have many flaws and impurities because they are in contact with a container. The naturally-occurring low gravity conditions of space allow large crystals to be grown without touching a container -- a process called floating zone crystal growth. Floating zone crystal growth in space is expected to result in large single crystals with purity, compositional homogeneity and structural perfection unattainable on the ground.

The Consortium for Commercial Crystal Growth is teaming with Rockwell International, the University of Florida, McDonnell Douglas and the State of Florida Technology Research and Development Authority (TRDA) on the LEMZ payload. The LEMZ program is part of the Consortium's goal to produce high quality single crystals of semiconductors, complex oxides, non-linear optical materials and sensor/detector crystals.