It is not good to have zeal without knowledge * . . . Book of Proverbs This volume constitutes the proceedings of the Third International Workshop on Materials Processing at High Gravity. It offers the latest results in a new field with immense potential for commercialization, making this book a vital resource for research and development professionals in industry, academia and government. We have titled the proceedings Centrifugal Materials Processing to emphasize that centrifugation causes more than an increase in acceleration. It also introduces the Coriolis force and a gradient of acceleration, both of which have been discovered to play important roles in materials processing. The workshop was held June 2-8, 1996 on the campus of Clarkson University in Potsdam, New York, under the sponsorship of Corning Corporation and the International Center for Gravity Materials Science and Applications. The meeting was very productive and exciting, with energetic discussions of the latest discoveries in centrifugal materials processing, continuing the atmosphere of the first workshop held in 1991 at Dubna (Russia) and the second workshop held in 1993 in Potsdam, New York. Results and research plans were presented for a wide variety of centrifugal materials processing, including directional solidification of semiconductors, crystallization of high Tc superconductors, growth of diamond thin films, welding, alloy casting, solution behavior and growth, protein crystal growth, polymerization, and flow behavior. Also described were several centrifuge facilities that have been constructed for research, with costs beginning at below $1000.

There are two motives for studying materials processing in centrifuges. First, such research improves our understanding of the influence of acceleration and convection on materials processing. Second, there are commercial opportunities for production of unique and improved materials that cannot be prepared under normal earth conditions or in space. Through a combination of experiments and theory, we are gaining an understanding of centrifugation on phenomena of importance to materials processing. We find that it is necessary to consider not only acceleration, but also the Corio lis effect and the variation of acceleration with position. As one consequence, the vigor of buoyancy-driven convection is sometimes increased by centrifugation and sometimes decreased. Similarly, the tendency of the convection to become unstable or oscillatory may either be increased or decreased by centrifugation. On the other hand, the observed effects of centrifugation on product quality have largely gone unexplained. This volume constitutes the proceedings of The Second International Workshop on Materials Processing at High Gravity, hosted by Clarkson University in June of 1993. The concept for a workshop on materials processing in centrifuges was born at a series of informal meetings held in Paris in 1990. The First International Workshop on Materials Processing at High Gravity was held in May of 1991 in Dubna, USSR, on the banks of the Volga River. The proceedings of this workshop was published in 1992 as a special issue of the Journal of Crystal Growth.

This volume constitutes the proceedings of the Fourth International Workshop on Materials Processing at High Gravity, held at Clarkson University, May 29 to June 2, 2000. There were 73 attendees from 16 countries. Since the topics extended well beyond materials processing, it was felt appropriate to name this proceedings "Centrifugal Processing." Processing by Centrifugation includes the traditional bench-scale centrifuges, as well as all rotating systems utilizing the centrifugal and Coriolis forces to provide unique performance. Centrifugation led to the formation of sticky porous Teflon membranes, as well as improved polymeric solar cells. Centrifugation on large equipment improved the chemical vapor deposition of diamond films, influenced the growth and dissolution of semiconductor crystals, and elucidated the influence of gravity on coagulation of colloidal Teflon. A million g centrifuge was constructed and used to study sedimentation in solids and to prepare compositionally graded materials and new phases. Rotation of a pipe about its axis allowed the casting of large-diameter metal alloy pipes as well as coating the interior of pipes with a cermet utilizing self-propagating high-temperature synthesis. Such coatings are highly corrosion and erosion resistant. Flow on a rotating disk was shown to be useful for process intensification, such as large-scale manufacturing of nano-particles, polymerization reactions, and heat & mass transfer. Several theoretical studies dealt with the influence of rotation on fluid convection on surfaces and in pipes, tubes, and porous media. These have applications to integrated-circuit chip manufacturing, alloy casting, oil production, crystal growth, and the operation of rotating machinery.

There has been considerable interest recently in microgravity physics and the effects of gravitation on crystal growth, alloy solidification, and other processes in space manufacturing. Regel' [1] has provided an extensive but not exhaustive bibliography on micro gravity physics and materials science in space, in which the major aspects are discussed along with the state of the art and future research prospects. The literature survey in [1] covered a period of about 10 years, including some publications appearing in 1983 that reflected not only theoretical and experi mental studies completed by 1983 but also a list of experiments to be carried out in the next few years. In particular, the closing part of the survey [1] enumerated ex periments planned under the Intercosmos program and by the European Space Agency (ESA) for the flight of Spacelab-l and D-l in 1985 and under the Eureka programs. Some of the space experiments planned in 1983 have now been com pleted, and the results have been published. It is therefore desirable to survey again research on materials science in space for the last few years and extend the literature survey begun in [1]. The literature listing on materials science in space begun in [1] is supplemented (there were 1061 citations in [1]) by recent publications (beginning with 1982).

This volume constitutes the proceedings of the Fourth International Workshop on Materials Processing at High Gravity, held at Clarkson University, May 29 to June 2, 2000. There were 73 attendees from 16 countries. Since the topics extended well beyond materials processing, it was felt appropriate to name this proceedings "Centrifugal Processing." Processing by Centrifugation includes the traditional bench-scale centrifuges, as well as all rotating systems utilizing the centrifugal and Coriolis forces to provide unique performance. Centrifugation led to the formation of sticky porous Teflon membranes, as well as improved polymeric solar cells. Centrifugation on large equipment improved the chemical vapor deposition of diamond films, influenced the growth and dissolution of semiconductor crystals, and elucidated the influence of gravity on coagulation of colloidal Teflon. A million g centrifuge was constructed and used to study sedimentation in solids and to prepare compositionally graded materials and new phases. Rotation of a pipe about its axis allowed the casting of large-diameter metal alloy pipes as well as coating the interior of pipes with a cermet utilizing self-propagating high-temperature synthesis. Such coatings are highly corrosion and erosion resistant. Flow on a rotating disk was shown to be useful for process intensification, such as large-scale manufacturing of nano-particles, polymerization reactions, and heat & mass transfer. Several theoretical studies dealt with the influence of rotation on fluid convection on surfaces and in pipes, tubes, and porous media. These have applications to integrated-circuit chip manufacturing, alloy casting, oil production, crystal growth, and the operation of rotating machinery.

Centrifugal Materials Processing; L.L. Regel, W.R. Wilcox. Convection in Crystal Growth under High Gravity on a Centrifuge; J. Friedrich, G. Muller. Segregation in Crystal Growth under High Gravity on a Centrifuge: A Comparison between Experimental and Theoretical Results; J. Friedrich, G. Muller. Analysis of Thermal Convection in Molten Tin Under Centrifugal Conditions; L. Bergelin, A. Chevy. Thermal Stability During Centrifugation: Flow Visualization Experiment; Numerical Results; W.A. Arnold, L.L. Regel. Flow Visualization Study of Convection in a Centrifuge; P.V. Skudarnov, et al. Determination of Solid/Melt Interface Shape and Growth Rate During Gradient Freeze Solidification on a Centrifuge Using Current Interface Demarcation; I. Moskowitz, et al. In Situ Observation of Directional Solidification in High Gravity; Y. Inatomi, et al. Impurity Distribution and Superconducting Properties of PbTe: T1 Crystals Grown in a Centrifuge; R. Parfeniev, et al. A Low Cost Centrifuge for Materials Processing in High Gravity; Y.A. Chen, et al. 20 Additional Articles. Index.