One-Dimensional NMR Imaging of High-Temperature First-Drying in Monolithics

• Published in: Applied magnetic resonance Vol. 49; no. 7; pp. 739 - 753
• Main Authors: Barakat, A. J., Pel, L., Adan, O. C. G.
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.07.2018; Springer Nature B.V
• Subjects: Atoms and Molecules in Strong Fields; Castability; Coils; Drying; High temperature; Laser Matter Interaction; Magnetic fields; Moisture content; NMR; Nuclear magnetic resonance; Organic Chemistry; Original Paper; Physical Chemistry; Physics; Physics and Astronomy; Porous media; Solid State Physics; Spatial resolution; Spectroscopy/Spectrometry; Steel production; Temperature; Temperature profiles
• ISSN: 0937-9347; 1613-7507
• DOI: 10.1007/s00723-018-1018-x

In this study a specialized high-temperature nuclear magnetic resonance (NMR) setup is presented for measuring free moisture in monolithic refractory castables during one-sided heating (100–300 °C). This setup makes use of a high thermal-stability Birdcage-coil for measuring the quantitative moisture content at high-temperatures, while also utilizing a mini-coil for calibrating transverse relaxation changes, as a function of temperature and hydration state, taking place in the sample throughout a drying experiment. We employ a high-temperature correction scheme that calibrates the effects of rising temperatures on the NMR signal. With this configuration, we can non-destructively measure moisture and temperature profiles continuously and achieve a spatial resolution of 2–3 mm for samples as long as 74 mm. After applying the NMR correction, we can extract information about the physical and chemical components of water as they are released from the porous matrix during first heat up. As a model material, we demonstrate the capability of our setup with a conventional castable after it has been cast and cured for 48 h.