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Controlling the Sintering Rate and Shrinkage of Ceramic Materials

IP.com Disclosure Number: IPCOM000080767D
Original Publication Date: 1974-Feb-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 26K

Publishing Venue

IBM

Related People

Swiss, WR: AUTHOR [+2]

Abstract

It is well known in the ceramic industry that the ultimate density of a ceramic body will often depend on the atmosphere in which it is sintered. In order to achieve the ultimate, or theoretical density of the ceramic, it is often necessary to sinter the ceramic in a vacuum or in a gas with a very high mobility, such as hydrogen. This is due to the fact that gases can be entrapped inside the ceramic during the sintering process. The sintering rate decreases considerably, due to the slow-diffusion processes by which the entrapped gases are removed. The sintering rate in hydrogen is, therefore, considerably higher than in a gas such as oxygen, due to the higher mobility of the lighter gas. Sintering in vacuum further alleviates the problem of entrapped gases.

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Controlling the Sintering Rate and Shrinkage of Ceramic Materials

It is well known in the ceramic industry that the ultimate density of a ceramic body will often depend on the atmosphere in which it is sintered. In order to achieve the ultimate, or theoretical density of the ceramic, it is often necessary to sinter the ceramic in a vacuum or in a gas with a very high mobility, such as hydrogen. This is due to the fact that gases can be entrapped inside the ceramic during the sintering process. The sintering rate decreases considerably, due to the slow-diffusion processes by which the entrapped gases are removed. The sintering rate in hydrogen is, therefore, considerably higher than in a gas such as oxygen, due to the higher mobility of the lighter gas. Sintering in vacuum further alleviates the problem of entrapped gases.

This phenomenon can be used to advantage in the control of the sintering rates and ultimate shrinkages of ceramic materials, especially multilayer ceramics. Experiments have shown that by adjusting the proportions of hydrogen and nitrogen in a sintering atmosphere, the shrinkage of the ceramic can be controlled. The graph illustrates an example of the control process.

The shrinkage of multilayer ceramic modules using high alumina, glass frit ceramic has been varied between 16.8% and 17.4% simply by changing the proportions of hydrogen in the sintering ambient. No detrimental effects on either the ceramic or internal refractory metallization in t...