Correlation of Rheology with Pressure Casting Performance
Date
2017-08
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Publisher
New York State College of Ceramics at Alfred University. Inamori School of Engineering.
Abstract
Pressure casting is increasingly a more valuable alternative for whiteware slip casting because it is less labor intensive, more efficient and requires less floor space in factories compared to bench casting in gypsum molds. The correlation of slip properties with pressure casting performance has been unclear. Additionally, until now there were no efficient methods of characterizing slips for pressure casting.
The initial work evaluates the role of the dispersants, solids content and the temperature on the rheology of clay-based suspensions. To obtain repeatable data, testing protocols were developed. A suitable viscosity window was defined for both slips for pumping. The results consistent with previous work show high effectiveness in Na-PAA and Na-silicate as dispersants of porcelain bodies whereas Na-Ash does not work as a dispersant. It is demonstrated that temperature does not contribute to rheological performance of the analyzed slips. The final work evaluates the pressure casting performance using a specially designed, in-house pressure casting device and applying a statistical experimental design to evaluate solids concentration, temperature and pressure with responses of casting rate, cast hardness and pore volume in the cast cakes. The results showed that temperature does not contribute to casting performance over the temperature window tested. Although casting rate is commonly assumed to be a critical performance indicator but it is of secondary importance compared to cast hardness. Cast hardness and water retention level are the most important responses despite it is common to assume casting rate as an important response. It also was demonstrated that increases in solids content and pressure increases the cast hardness and casting rate. The effects that solids content and pressure have on both cast hardness and casting rate are proposed to be due to the rate of fluid flow through the cast layer.
Description
Thesis completed in partial fulfillment of the requirements for the degree of Master of Science in Ceramic Engineering at the Inamori School of Engineering, New York State College of Ceramics at Alfred University
Type
Thesis
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Keywords
Slip casting, Rheology, Slips (Ceramics)