NMR CHARACTERIZATION OF INJECTION-MOLDED ALUMINA GREEN COMPACTS .2. T-2-WEIGHTED PROTON IMAGING

Injection-moulded alumina green compacts containing polypropylene, wax , and stearic acid were studied for binder distribution by proton nucl ear magnetic resonance (H-1 NMR) imaging. The solid imaging technique of nuclear spin-spin relaxation time, T-2, weighted imaging at 400 MHz was used. This imaging technique utilizes a multiple pulse sequence o f 0-(pi/2)(+/-)-tau-D-10-D-7-(pi)(x)-D-7-D-10-AQ-D-0 for echo detectio n and phase encoding. Two-and three-dimensional images were constructe d from the intensities of these nuclear echo signals. Spatially resolv ed two-dimensional images obtained by the application of this techniqu e indicated that the green compacts fabricated from the same nominal b inder composition did not contain the same amounts of binder. This obs ervation agrees well with our previous conclusion drawn from nuclear s pin echo studies by Hahn's pulse sequence. A 64 x 64 x 64 three-dimens ional imaging revealed that the inhomogeneity of binder distribution a nd internal imperfection do exist at certain locations of the samples. A binder-rich folding line was also detected in one of these green co mpacts.