Application of Aqueous Proton T2-Weighted NMR Imaging in Material Characterization
P S. Wang
Proton spin-spin relaxation times (T2) of water molecules in various physical states were measured by nuclear spin-echo sequence. Different pulse sequences for proton nuclear magnetic resonance (1H NMR) imaging were demonstrated for mapping of free and bound water molecules. Water distribution in aqueous injection moulded ceramic green compacts were studied by T2 -weighted imaging technique. The technique utilizes the characteristic nuclear spin-spin relaxation time (T2) weighting in the multiple pulse sequence of DO-O/2) x- -D10-D7 () x-D7-D10-AQ-DO for echo detection and phase encoding. Three-dimensional images were constructed from the intensities of these nuclear echo signals. Radio frequency soft pulses show clearly the location of mobile water in the agarose gels and hard pulses map the distribution of surface adsorbed bound water in the green compacts. Three dimensional 64x64x64 T2-weighted mapping of LiAlSiO4/SiO2/agarose gel green compacts indicated an overall homogeneous distribution of water throughout the samples. Only occasional deviation spots were detected. A comparison with the results from samples of conventional orgainc solid binder was presented.