NONTHERMAL MICROWAVE EFFECTS

Although there is evidence of enhancements of processes due to the effects of microwaves alone (e.g., enhanced ceramic sintering, grain growth, and diffusion rates, and faster apparent kinetics in polymers and synthetic chemistry), the evidence is equivocal due to questionable temperature measurement techniques, uncertain process characterization methods, and conflicting evidence.

Recommendations:

  • Establish standards for measurement of temperature to ensure reproducibility. In addition, the techniques and procedures used to measure temperature should be reported in detail, so an evaluation of accuracy can be made. The level of uncertainty in temperature measurements should also be reported. Perform experiments using several temperature-measurement techniques to determine the relative accuracy and reproducibility of the various techniques against a known standard (melting point, phase-transition temperature, etc., of well-characterized materials).

  • Conduct detailed and controlled experiments to determine if microwave enhancement effects reported for materials are valid. Care should be taken to use a microwave source with predictable and reproducible fields and to have an internal temperature calibration to avoid temperature measurement uncertainties.



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