Method and device for microwave sintering large ceramic articles

Electric heating – Metal heating – Of cylinders

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219 1055F, 219 1055R, 264 26, 4251748E, H05B 680

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active

049637096

ABSTRACT:
A microwave sintering system and method are provided for extremely uniform sintering of large and/or irregular shaped ceramic articles at microwave frequencies of at least 28 GHz in the hundreds of kilowatts power range in an untuned cavity. A 28 GHz, 200 kw gyrotron with variable power output is used as the microwave source connected to an untuned microwave cavity formed of an electrically conductive housing through an overmoded waveguide arrangement which acts in conjunction with a mode promoter within the cavity to achieve unexpected field uniformity. The part to be sintered is placed in the cavity and supported on a removable high temperature table in a central location within the cavity. The part is surrounded by a microwave transparent bulk insulating material to reduce thermal heat loss at the part surfaces and maintain more uniform temperature. The cavity may be operated at a high vacuum to aid in preventing arcing. The system allows controlled increased heating rates of greater than 200.degree. C./min to provide rapid heating of a ceramic part to a selected sintering temperature where it is maintained by regulating the microwave power applied to the part. As a result of rapid heating, the extent of non-isothermal processes such as segregation of impurities to the grain boundaries are minimized and exaggerated grain growth is reduced, thereby strengthening the mechanical properties of the ceramic part being sintered.

REFERENCES:
patent: 3585258 (1971-06-01), Levinson
patent: 3732048 (1973-05-01), Guerga et al.
patent: 3845270 (1974-10-01), Widugris, Jr.
patent: 3858329 (1975-01-01), Koide et al.
patent: 4140887 (1979-02-01), Sutton et al.
patent: 4147911 (1979-04-01), Nishitani
patent: 4179595 (1979-12-01), Chiron
patent: 4307277 (1981-12-01), Maeda et al.
patent: 4323745 (1982-04-01), Berggren
patent: 4810846 (1989-03-01), Holcombe et al.
H. D. Kimrey et al., "Initial Results of a High Power Microwave Sintering periment at ORNL," Handout from The Proceedings of 21st Microwave Power Symposium, Memphis, Tenn., Jul. 28-30, 1986.
H. D. Kimrey et al., "Techniques for Ceramic Sintering Using Microwave Energy," IEEE Conference Digest--12th International Conference on Infrared and Millimeter Waves, Orlando, Fla., Dec. 14-18, 1987, pp. 136-137.
M. A. Janney et al., "Microwave Sintering of Alumina at 28 GHz," Ceramic Transactions--Proceedings of the First International Conference on Ceramic Powder Processing Science, Orlando, Fla., Nov. 1-4, 1987, pp. 919-924.
H. D. Kimrey et al., "Microwave Processing of Silicon Nitride," ORNL Ceramic Technology Newsletter, No. 20, Jul.-Sep. 1988, pp. 3-6.
Berta S. Swain, Editor, "Microwave Sintered Ceramics", ORNL Materials Research Newsletter, vol. 5, No. 2, Summer 1988.

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