The use of NMR imaging to measure porosity and binder distributions in green-state and partially sintered ceramics: 38841 Ackerman, J.L.; Garrido, L.; Ellingson, W.A.; Weyand, J.D. Massachusetts General Hospital, Boston (United States), CONF-870856-3, DE88-003099, 34 pp. (Sep. 1987)

Abstract

Nonuniformities in porosity or binder distribution in green-state ceramic compacts can lead to failure in the final densified material. NMR imaging is a nondestructive characterization technique, most commonly used in medical diagnosis, which we have adapted for the production of tomographic images of porosity and of binder distributions. We measure open porosity by the imaging of a suitable filler fluid introduced into the part by vacuum impregnation. Our results on partially sintered bodies show rough correlations with predicted porosity distributions. Binders with a high content of plasticizer may be imaged directly. Binder distributions with a plasticizer weight percent typical of those used in cold-pressing and injection molding cannot be imaged with conventional clinical or animal research instrumentation and methods. We have been successful in imaging such binders directly. We present results illustrating our techniques in a series of green-state and partially sintered aluminas. 26 refs., 12 figs., 1 tab.