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Title: A device for microwave sintering large ceramic articles

Abstract

A microwave sintering system is provided for uniform sintering of large and/or irregular shapes 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. 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 on 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 ceramicmore » part being sintered. 1 fig.« less

Inventors:
Issue Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
OSTI Identifier:
6742633
Patent Number(s):
6077580
Assignee:
TIC; ERA-14-001257; EDB-88-185530
Patent Classifications (CPCs):
B - PERFORMING OPERATIONS B29 - WORKING OF PLASTICS B29L - INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
Y - NEW / CROSS SECTIONAL TECHNOLOGIES Y10 - TECHNICAL SUBJECTS COVERED BY FORMER USPC Y10T - TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
DOE Contract Number:  
AC05-84OR21400
Resource Type:
Patent
Resource Relation:
Other Information: Portions of this document are illegible in microfiche products
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 36 MATERIALS SCIENCE; MICROWAVE EQUIPMENT; DESIGN; SINTERING; CERAMICS; INVENTIONS; MICROWAVE HEATING; SINTERED MATERIALS; ELECTRONIC EQUIPMENT; EQUIPMENT; FABRICATION; HEATING; MATERIALS; 420200* - Engineering- Facilities, Equipment, & Techniques; 360601 - Other Materials- Preparation & Manufacture

Citation Formats

Kimrey, Jr, H D. A device for microwave sintering large ceramic articles. United States: N. p., 1987. Web.
Kimrey, Jr, H D. A device for microwave sintering large ceramic articles. United States.
Kimrey, Jr, H D. Fri . "A device for microwave sintering large ceramic articles". United States.
@article{osti_6742633,
title = {A device for microwave sintering large ceramic articles},
author = {Kimrey, Jr, H D},
abstractNote = {A microwave sintering system is provided for uniform sintering of large and/or irregular shapes 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. 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 on 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. 1 fig.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1987},
month = {7}
}