Akihiro Matsubara

Precise measurements of optical constants of SiC in 40 to 120 µm wavelength region

Optical constants of 6H-SiC have been measured by using far infrared (FIR) lasers of 48, 57, 71, and 119 µm in wavelength. The refractive index and absorption coefficient at the wavelength have been determined from the transmittance of a rotating SiC etalon. For the application of the SiC to optical elements in the FIR region, it was compared with other materials (crystal quartz, high resistive silicon, and CVD-diamond).

EVOLUTION OF THE NEAR-UV EMISSION SPECTRUM ASSOCIATED WITH THE REDUCTION PROCESS IN MICROWAVE IRON MAKING

The structure of the emission spectrum in the near-UV range (240 nm-310 nm) changes drastically from the continuous spectrum to a discrete line spectrum with increasing sample temperature during the carbothermic reduction of magnetite in a 2.45 GHz microwave multimode furnace. The continuous spectrum can be assigned as a cathodoluminescence of magnetite. The dynamic evolution of the spectrum from continuous to discrete represents the progress of the reduction from magnetite to iron.

In-situ IR diagnostics for the mmWave/microwave material heating

Two topics of IR-diagnostics performed in the fundamental experiment of microwave iron making will be presented. One is tunable diode laser absorption spectroscopy for both CO and CO2 gas generated during microwave irradiation. The other is spectroscopic thermography for iron oxide powder of which surface would be metalized by microwave carbothermic reduction.

Investigation of the process of microwave iron-production with the integrated microscopic imaging spectrometer

This paper reports on spectroscopic observations of the process in microwave carbothermic reduction of magnetite with the integrated microscopic imaging spectrometer (IMIS) that has been introduced in order to demonstrate microscopic- thermal activation of material due to microwave selective and/or localized heatings. The IMIS allow capturing spectroscopic image including the specimen body, the specimen-plasma interface, and plasma above the specimen. It is expected that the continuous spectrum, which has been found in microwave iron productions and believed to be due to cathodoluminescence of magnetite, will be observed mainly at the specimen surface. The localization of the continuous spectrum can be a strong evidence of the cathode-luminescence of magnetite, leading the importance of plasma-surface interaction for the reaction process of the microwave iron making.

Investigation of malting iron by millinieter-wave heating

An experimental investigations on the production of pig iron from magnetite by using high frequency microwaves is described. X-ray diffraction is used to characterize the magnetite powder samples. Results show that samples without porosity show only peaks related to alpha Fe, while samples with large porosity exhibit some peaks from oxide which, however, come from the surface of the sample. The interior of all the samples are soft and consisted of pig iron.

Reduction of magnetite in air by use of microwave heating

Microwave technology is not a mere substitute for conventional heating, but it resides in the new domain of materials science, namely, microscopic and strong thermal non-equilibrium systems. The key factor for application of microwaves in the iron industry, is its high potential for an essential reduction of carbon dioxide emission. Iron ore refinement by means of blast furnaces was realized with the same basic furnace structure based on the same principle for two centuries. We have conducted a series of experiments to prove effectiveness of rapid and high purity refinement under low temperature and oxygen-containing environment by means of microwave application, and achieved highly positive results.