Ceramics-Silikáty 43 (1) 1-11 (1999)

RHEOLOGY OF CERAMIC INJECTION-MOLDING FEEDSTOCKS

W. Pabst, J. Havrda, E. Gregorová

The flow behavior of ceramic alumina pastes with high solid loading designed for injection molding was studied in the relevant temperature range. In order to enable an adequate and experimentally sound rheological characterization the measurements were carried out with a laboratory capillary viscometer which had been specially adapted for measurements under conditions that could to a sufficient degree of accuracy be considered as isothermal. Detailed results including experimentally measured flow curves are shown for an alumina paste containing 66 vol.% (88.9 wt.%) of a commercial a-Al₂O₃ powder and 34 vol.% (11.1 wt.%) of a newly developed prototype binder mixture. The material parameters yield stress, consistency coefficient and flow index as well as apparent viscosities are compared for different temperatures (from 65 to 80 °C) and solid loadings (61, 63.4 and 66 vol.%). Motivated by the experimental results, the role of rheology for ceramic injection molding is discussed in general.

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