(19c) Investigating the Effects of Particle and Bulk Powder Properties On Microwave Sensor Measurements

In solids manufacturing, it is desirable to know the properties of the processed materials in real-time for effective process and quality control.  Though many laboratory techniques have been well developed to measure particulate properties, most are not suited for rapid, on-line, non-destructive measurements.  Many successful techniques to measure properties on-linerely on the use of low-power electromagnetic radiation.  Most notable among these is the use of near infrared (NIR) radiation.  Although NIR has been employed successfully in many situations, it does suffer from some significant drawbacks.  For instance, NIR spectra are often very complicated and require chemometric software to extract useful information.  Additionally, NIR frequently suffers from poor sampling efficiency due to the shallow penetration depth of NIR waves and the small size of most fiber-optic probes.

Microwave dielectric sensing is an alternative to other, more common process monitoring techniques.  Microwave sensors do not require chemometric software to decode their outputs and possess significantly improved sample penetration.  However, as has been reported recently, microwave sensors, like NIR sensors, may be sensitive to particle size and other particle properties.  This study was designed to examine these claims as well as investigate the effects of other particulate properties not already correlated to microwave sensor measurements.  In total, over 15 particulate and bulk powder properties were investigated and their effects on microwave sensor measurements were elucidated.