Abstract
Phosphatic porcelain (PP), commonly known as bone china, constitutes approximately 50 wt% bone ash, 25 wt% kaolin, and 25 wt% feldspar, and its primary characteristics are high translucency and a high impact resistance. However, the low plasticity of these ceramic raw materials makes its moulding difficult owing to the plastic deformation due to the throwing wheel. Plasticizers or plasticity-promoting additives, such as sodium bentonite and methyl hydroxyethyl cellulose, modify the rheological behavior to pseudoplastic with a yield stress. Ceramic raw materials with plasticizers were prepared and characterized using helium pycnometry density, X-ray fluorescence, X-ray diffraction, and particle size distribution. In addition, characterization analysis was performed in commercial porcelain P905 for comparison purposes. The squeeze flow technique (compression of a cylindrical sample between two parallel plates) was employed to assess and compare the rheological behavior of the PP compositions with and without additives with the behavior of the commercial material. Results show that the addition of 4 wt% bentonite in the PP introduced a plasticity similar to that of the commercial porcelain, easing the shaping process using a throwing wheel. Plasticity index (PI) from the Atterberg test is useful; however, it is not sufficiently detailed to predict conformation performance of the ceramic raw materials in the throwing wheel as per the rheological information provided by the squeeze flow test.
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