Resistance of Fortified Kaolin to Attack by Molten Frit

Introduction: Low cost refractory mixes of adequate resistance to molten glass attack is required for frit furnace lining, but when the corrosion behaviour of alumino-silicate type refractories are studied, kaolin is often neglected. Meanwhile clay is cheap in the study area and studies had shown that clays that are comprised largely of kaolinite are refractory, and are applicable for various refractory purposes. In this study, the effect of addition of zirconia and alumina to selected kaolin on its physicomechanical properties and corrosion resistance were examined.

Aims: The study is aimed at developing a corrosion resistant refractory for lining frit furnaces used in studio practice by fortifying a locally available kaolin in Nigeria know refractory materials.

Study Design: The experimental design in which the effect of percentage addition of alumina and zircon on the sintering properties and corrosion resistance of base kaolin were measured against the desired properties of the resultant bodies.

Methodology: The clay mineralogical analysis was conducted using XRD. The refractoriness was measured by the pyrometric cone equivalence (PCE) method. The effects of varying percentage additive refractory material on the sintering properties of bodies formulated and sintered at 1300 oC were assessed using the ASTMC20 00 Standard test method. The corrosion resistance of the bodies was assessed using the crucible (slag cup) method.

Results: Results indicated that the clay was predominantly kaolinite. The addition of alumina increases the porosity of the mix. The stabilized zircon increased the specific gravity the most. It increased the bulk density at both 5% and 10 % addition but decreased at 15% addition. The sample mix which contained 10% stabilized zircon and 5% alumina shows appreciable resistance to corrosion by the molten frit.

Conclusion: This study confirms that clay that is predominantly composed of kaolinite is a potential base material for composing refractory lining for a fritting furnace.