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Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Nagakawa, Genta*; Tamaru, Ayaka*; Fukasawa, Tomonori*; Ishigami, Toru*; Fukui, Kunihiro*
no journal, ,
Microwave heating in combination with an external heating source has been used to improve powder properties by compensating for heat transfer losses. However, the external heating source in the microwave irradiation field may degrade the heating elements. A hybrid heating method has been developed to use composite ceramic jacket prepared by adding carbon nanotube (CNT) to alumina. To evaluate the effect of CNT-containing alumina composite ceramic jacket (CNT jacket), experiments were implemented. In both copper nitrate solution and nickel nitrate solution, the time to reach the maximum temperature was earlier when the CNT jacket was used than when the alumina jacket was used. The temperature of the nickel nitrate solution was kept at the maximum temperature when the CNT jacket was used, while the temperature tended to decrease after reaching to 280
C when the alumina jacket was used. The hybrid heating method using the CNT jacket can obtain metal oxides.
Tamaru, Ayaka*; Nagakawa, Genta*; Segawa, Tomoomi; Fukasawa, Tomonori*; Ishigami, Toru*; Fukui, Kunihiro*
no journal, ,
This study aims to investigate the effect of hybrid heating on the denitration reaction of a nickel nitrate aqueous solution to evaluate the feasibility of hybrid heating method with an alumina jacket containing carbon nanotube (CNT) as a microwave heating medium. When an alumina jacket without CNT was used, the temperature decreased and the denitration reaction stopped due to the formation of an intermediate product Ni
(NO
)
(OH)
with low dielectric loss. Whereas, when an alumina jacket containing 0.2 mass% CNT was used, the denitration reaction was completed and nickel oxide particles were obtained. It is presumed that the denitration reaction proceeds by heat conduction from the CNT-containing alumina jacket because the jacket is selectively heated by microwaves more than the Ni(NO)(OH). It is clarified that hybrid heating can be realized by a CNT-containing alumina jacket.
Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori; Yamada, Masaaki*; Tamaru, Ayaka*; Nagakawa, Genta*; Fukasawa, Tomonori*; Ishigami, Toru*; Fukui, Kunihiro*; Murakami, Hiroyuki*
no journal, ,
To compensate for heat dissipation through the vessel and reduced microwave absorption due to intermediate in the fabrication process of the metallic oxide powder by the microwave heating denitration method, alumina composite ceramic material containing CNT which has a high relative dielectric loss as the external heating source with self-heating by microwave heating. The CNT was observed by SEM of the CNT-containing alumina composite ceramic material to observe the CNT presence in the base material of alumina. The surface resistivities decreased significantly when the CNT content increased from 0.2 to 0.5 mass%, and there was not much of a significant difference when the CNT content increased from 0.5 to 1.0 mass%. These results are consistent with the results of the previous studies of the apparent dielectric loss that showed a trend toward an increase in the apparent dielectric loss as the CNT content increased from 0.2 to 0.5 mass% in the CNT-containing alumina composites.