Assessment of Moisture Measurement Techniques for Ceramic Processing
P S. Wang
This report presents an assessment of moisture measurement tests by techniques currently available for ceramic processing applications. The techniques tested include near infrared, microwave, proton nuclear magnetic resonance, magnetic resonance imaging and the gravimetric method. The principles of the techniques are briefly described, and the strengths and limitations of the techniques are compared. The forms of tested samples include powders, pugs, slurries, and greenbodies before and after drying. Near infrared can be installed on-line; it is a low cost and simple method; but it has a limited penetration depth and the results are influenced by the sample color. While microwave techniques allow for deeper penetration depths with advantages of simple operation, low cost, as well as on-line, the high dielectric constant of some materials can complicate the measurement procedure. The emerging NMR and NMR imaging techniques can provide additional information on physical state of water and its spatial distribution in a ceramic sample. These techniques are not widely used due to the high cost, operational complexity and limitation imposed by the size of RF-coil. It is concluded that the gravimetric method should be considered as the primary technique for calibration of all other techniques.
Assessment of Moisture Measurement Techniques for Ceramic Processing, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD
(Accessed March 3, 2024)