Application of Millimeter-Wave Heating to Materials Processing

Shoji MIYAKE  Yukio MAKINO  

IEICE TRANSACTIONS on Electronics   Vol.E86-C   No.12   pp.2365-2370
Publication Date: 2003/12/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: INVITED PAPER (Special Issue on Recent Trends on Microwave and Millimeter Wave Application Technology)
millimeter-wave heating,  non-thermal effect,  gyrotron,  rapid sintering,  low tempreature crystallization,  

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Recently, millimeter-wave energy has attracted much attention as a new and novel energy source for materials processing. In the present paper, several unique features of millimeter-wave heating in materials processing are reviewed briefly and development of materials processing machines by mm-wave radiation is also described. In the application of mm-wave heating, sintering of high quality alumina ceramics having a high bending strength of about 800 MPa are first demonstrated and followed by preparation of aluminum nitride with a high thermal conductivity over 200 W/(mK) at a sintering temperature lower by 473-573 K than the conventional method, by which this processing can be expected to be one of the environment-conscious energy saving processes. A newly developed post-annealing process with mm-wave radiation is described, in which crystallization of amorphous perovskite oxide films prepared by plasma sputtering was attained at temperatures lower than that by the conventional heating and the dielectric constant of post-annealed SrTiO3 (STO) films by mm-wave radiation were drastically improved.