Water-thinnable poly(urethanecarbamide) dispersions in die pressing of alumina

Paweł Wiśniewski 1Janusz Kozakiewicz 2Anita Koncka-Foland 2Mikołaj Szafran 1Gabriel Rokicki 1

1. Warsaw University of Technology, Faculty of Chemistry, Noakowskiego 3, Warszawa 00-664, Poland
2. Industrial Chemistry Research Institute (ICRI), Rydygiera 8, Warszawa 01-793, Poland

Abstract

In ceramics technology, different polymeric binders with various chemical structure are applied for different molding methods. A narrow range of water-soluble organic binders, such as poly(vinyl alcohol) and poly(oxyethylene glycol) are most often used in die pressing method. The samples obtained with these binders mentioned are characterized by a relative small density and small mechanical strength before and after sintering.An organic binder is very important additive in the dry pressing process of ceramic powders. It must attend many demands such as miscibility with ceramic powder, low toxicity, low burnout residue, sufficient suitable glass transition temperature, must assure high green density, suitable green strength etc.In the die pressing the most important problem is to determine the binder system providing high mechanical green strength and high green density. The green density depends on granules packing and it determines the final density after sintering.Such polymeric dispersions should, at their minimal amount, cause a decrease the friction forces between the ceramic powder particles and between the ceramics powder particles and matrix, providing a high mechanical strength of green samples. The content of organic binders should not exceed 0.5-3% wt.% with respect to alumina powder.Due to small numbers of accessible water-thinnable polymeric binders studies have been undertaken on the application in the ceramics technology of specially synthesized poly(urethanecarbamide) binders characterized by different chemical structure, contained oligooxosilanediol in their composition.The purpose of this work was to study the effect of new water-thinnable dispersions on the thickening ability of ceramic granulates obtained by them; density, Weibull modulus, mechanical strength of green and sintered samples obtained by die pressing method.

The work was supported by the Polish Ministry of Science and Higher Education No 3 T09B 022 29

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Presentation: Poster at E-MRS Fall Meeting 2008, Symposium I, by Paweł Wiśniewski
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-12 12:35
Revised:   2009-06-07 00:48
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