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Thermal Cleaning of Glass-Ceramic Powders and Achieving a White Sample After Sintering in an Inert Atmosphere

IP.com Disclosure Number: IPCOM000044016D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Anderson, HR: AUTHOR [+3]

Abstract

This article describes a thermal cleaning process for glass powders that does not affect their physical properties but prevents the formation of an undesired dark grey color in fired glass-ceramic. Glass powders being used in MLC (multilayer ceramic) and thin film substrates are prepared by ball-milling glass-ceramic cullets in a methanol grinding medium. When such powders are later sintered under an inert atmosphere at elevated temperatures, dark grey colored samples have been observed to result, due probably to unwanted carbonaceous residues associated with the methanol used in the ball-milling process. The thermal cleaning process here disclosed is imposed immediately following normal ball-milling and drying operations.

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Thermal Cleaning of Glass-Ceramic Powders and Achieving a White Sample After Sintering in an Inert Atmosphere

This article describes a thermal cleaning process for glass powders that does not affect their physical properties but prevents the formation of an undesired dark grey color in fired glass-ceramic. Glass powders being used in MLC (multilayer ceramic) and thin film substrates are prepared by ball-milling glass- ceramic cullets in a methanol grinding medium. When such powders are later sintered under an inert atmosphere at elevated temperatures, dark grey colored samples have been observed to result, due probably to unwanted carbonaceous residues associated with the methanol used in the ball-milling process. The thermal cleaning process here disclosed is imposed immediately following normal ball-milling and drying operations. The glass powders are placed in aluminum crucibles and are heated in a furnace at 700OEC for 24 hours, using moist-oxygen as the carrier gas. Normal cooling to room temperature follows. A typical gas flow rate is about 6 liters/ minute. The thermal cleaning process eliminates the discoloration problem referred to previously and has been shown capable of removing such residual organic grinding vehicles as have previously been held by the glass particles. By the use of this process, sintering operations can also proceed under an N2 atmosphere rather than one of O2 or H2+ steam, thereby vastly simplifying that operation. The same process...