LOW-TEMPERATURE POTTERY MADE FROM LIGNITE FLY ASH AND THALEKAEW CLAY IN PHITSANULOK PROVINCE

Abstract

This research aimed at studying the properties of the raw material and physical properties of clay mixed with lignite fly ash and Thalekaew clay in the production. Lignite fly ash is the remain of coal used in electricity production. Thalekaew clay has a good quality and can be used in the production of low temperature pottery. This research applied the mixing ratio all ingredients by base line diagram to get ten ingredients. Then test pieces were formed by press archetype. The physical characteristics of the clay were examined before burning. After that the sample was burned at a temperature of 1100 ⁰C in both atmosphere (oxidation and reduction). Then, the characteristics of archetype were examined. The results showed that the most average finesse range of both raw materials (lignite fly ash and Thalekaew clay) was 251μ-2 mm. The chemical composition analysis of the lignite fly ash and Thalekaew clay indicated that the percentage of silica oxide was 35.50% and 62%, alumina oxide 18.80% and 18.20%. It was found that the percentage of calcium oxide was 17.30% and zinc oxide 12.90% in lignite fly ash. The results also showed that the first ingredient (mixture with 5 % of lignite fly ash) was the best ingredient of all the atmosphere. In the oxidation atmosphere, it was found that the highest strength was 244.79 kg/cm²; the highest density was 2.04 g/cm^3; and water absorption was 12.60 %. In the reduction atmosphere the results showed that the highest strength was 244.03 kg/cm²; the highest density was 1.95 g/cm^3; and water absorption was 5.47 % with light red color of 6/8 2.5YR all of atmosphere. Therefore, the two atmospheres were chosen to manufacture the products because the properties of the ingredients were equivalent to the properties of earthenware.