Abstract
A Korean kaolin, a Kawamata feldspar, a Shijonawata quartz, and a porcelain body were heated at temperatures varying from 600°C to 1300°C, every 100°C, for 2 hours. The products were examined for the solubility in 20% hydrochloric acid at 100°C. On the other hand, pyrometric cone equivalents were determined for the ternary system kaolin-feldspar-quartz up to cone 19. The melted-down and glassified cones made from 15 mixtures among 24 were tested similarly for the acid-resistibility.
The results of the investigation seem to justify the following conclusions:
1. The acid-resistibility of the heated kaolin changes distinctly at those heating temperatures where marked changes occur in its thermal reaction, microstrueture, and thermal expansion. Neither the feldspar nor the quartz undergo any noticeable change in their acid-resistibility by a previous heating. On heating at temperatures between 600°C and 1000°C, the porcelain body shows about mean solubility of the three raw materials, and the relations between the solubility and the heating effects is not so distinct as in the kaolin. After heating the kaolin, feldspar, quartz, and porcelain body at 1100°C or 1200°C, there are only slight differences among their solubilities.
2. When the quartz is dissolved in the feldspar, an increase in the quartz causes almost no change in the acid-resistibility of the glasses, while their refractoriness is raised evidently.
3. When the kaolin is dissolved in the feldspar, both of the acid-rebistisility and refractoriness are raised with the increating kaolin.
4. When the quartz and kaolin are dissolved in the feldspar at the asme time, the acid-resistibility of the products is raised markedly with an increase in the kaolin, and is probably favored a littele by an increase in the quartz.
