Glass Processing in a Microgravity Environment
- PDF / 686,356 Bytes
- 10 Pages / 414.72 x 648 pts Page_size
- 51 Downloads / 198 Views
269
GLASS PROCESSING IN A MICROGRAVITY ENVIRONMENT
DONALD R. UHLMANN Department of Materials Science and Engineering, Technology, Cambridge, Mass. 02139.
Massachusetts Institute of
ABSTRACT The scientific and technological aspects of processing glasses in a microgravity environment offer considerable challenge and potential. Activities directed to obtaining information relevant to processing materials on earth and eventually processing materials in space for use in space will be considered. The features on the space environment-reduced gravitational forces, vacuum of large capacity, unique radiation conditions, and unlimited dimensions of space--will be discussed, with emphasis directed to the first. The implications of reduced gravitational forces for containerless processing, freedom from deformation, the study and control of weak forces, and the absence of convection and density segregation will be explored. On-going programs concerned with glass processing in space will be reviewed, and additional areas which merit investigation will be considered.
INTRODUCTION As should be clear from other papers at this Symposium, the Materials Processing in Space (MPS) program originated in the late 1960's from a consideration of potentially novel behavior of materials in a microgravity environment. The original thrust of the program was directed principally toward the development of unique products by manufacturing in space. While most attention was directed toward unique metal alloys and metallic composites and novel geometric configurations of materials, early consideration was also given to the development of unique new glasses [1, e.g.]. For many years, however, activities directed toward glasses represented only a very small part of the MPS program. With the passage of time, it became apparent that very few materials could economically be processed in space for use on earth. This point of view was forcefully expressed by the STAMPS Committee in 1978: "The Committee has not discovered any examples of economically justifiable processes for producing materials in space ... " [2]. The same Committee recognized, however, the potential use of space to obtain materials--such as "exemplary glasses"-for research. Freedom from contamination of containers and an attendant reduction or elimination of nucleating heterogeneities were noted as bases for such "exemplary" glasses. If manufacturing in space does not seem an attractive use of scarce resources, what ought to be the basis for a reasonable MPS program? The answer seems clear: the use of near-space to develop improved understanding of the properties of materials and the processes important in their formation. Viewed from this perspective, it becomes essential to develop a rigorous ground-based presently on sabbatical leave at Departement des Matdriaux, F~ddrale de Lausanne.
Ecole Polytechnique
270 program to accompany a program organized around experiments conducted in space, and to provide a detailed characterization of the space environment (e.g., magnitude and dir
Data Loading...
