Millimeter-wave dielectric measurement of SiC powders as a basis of millimeter-wave sintering of ceramics

This chapter reveals that the dielectric measurements at the millimeter-wave frequency are done by the free-space method and the wave-guide method. Millimeter-wave transmittance of a silicon carbide (SiC) powder is increased with the decrease of particle size, namely the millimeter-wave absorbability of α-SiC powder is increased with the increase of particle size. $21 value of α-SiC powder decrease with the increase of frequency at the millimeter-wave frequency. Loss tangent (tan δ) value is almost constant at a frequency range from 46 to 110 GHz. Tan δ measured by the free-space method showed little value than that measured by using the wave-guide fixture. SiC is used as a sintering aid by adding to the heating objects or a heating assistance by surrounding the heating object in studies of microwave and/or millimeter-wave sintering of ceramics. Therefore, it is important to know electric behaviors, dielectric constant, and loss tangent (tan δ) of SiC at the microwave and/or millimeter-wave frequencies. Millimeter-wave dielectric measurement of a-SiC powder performed by using measuring fixtures, wave-guide and free-space fixtures, with a millimeter-wave network analyzer system in the chapter.