This experimental investigation examines the influence of surface treatment on the strength of low-fired tempered ceramic bodies. Specimens prepared with commercial raw materials are employed, either finger-smoothed, burnished, textured, slipped/burnished, or resin coated; two building techniques, coiling and paddle-and-anvil, are also included since these forming processes affect the vessel surface. The modulus of rupture or flexural strength is determined by means of a four-point bending test, which is sensitive to critical surface flaws. By means of a univariate analysis of variance, small differences in strength are found between ceramic briquettes with different surface treatments. Although the differences in means for the moduli of rupture values are statistically significant, the differences are of such a low magnitude that they cannot be considered behaviorally relevant. These results are only valid for the materials, mode of preparation, and test procedures employed.

Abstract not available

The excellent particulate removal efficiency of ceramic candle filters has prompted efforts to develop a more durable and economical alternative to existing ceramic candle filters. Porous ceramic candle filter elements were successfully fabricated from calcium aluminate cement, calcined fireclay aggregate, and organic pore formers using refractory concrete casting techniques. Methods used to characterize the porous ceramic filter elements included determination of pore size and distribution, permeability, resistance to alkali attack, and mechanical strength. Various pore formers and casting, curing, and sintering conditions were examined to produce highly permeable and structurally sound filter elements. The optimized fabrication procedure produced porous ceramic candle filter elements with pore diameters between 20.3 to 43.1 tlm, porosities of 38 to 60%, and pressure drops of 3 to 24 mbars at a face velocity of 100 mjh. These characteristics are comparable to existing ceramic filters which are noted for their > 99% collection efficiencies of submicrometer-sized particles, but short-term durability in advanced coal combustion clean-up systems. Test specimens of the alumino silicate refractory concrete proved more durable by showing no severe attack following exposures to alkali-containing atmospheres at 700-1000°C. The strength of the cast samples ranged from 200 to 1139 psi depending on the relative densities and pore formers. Porous fliter elements with different porous structures, permeabilities, and shapes can be easily produced with this technique. / Master of Science