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 nuclear 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 of D-0-(pi/2)(+/-)-tau-D-10-D-7-(pi)(x)-D-7-D-10-AQ-D-0 for echo detection and phase encoding. Two-and three-dimensional images were constructed from the intensities of these nuclear echo signals. Spatially resolved two-dimensional images obtained by the application of this technique indicated that the green compacts fabricated from the same nominal binder composition did not contain the same amounts of binder. This observation agrees well with our previous conclusion drawn from nuclear spin echo studies by Hahn's pulse sequence. A 64 x 64 x 64 three-dimensional imaging revealed that the inhomogeneity of binder distribution and internal imperfection do exist at certain locations of the samples. A binder-rich folding line was also detected in one of these green compacts.