Dissolution of Quartz Grains in Feldspathic Fusions

Abstract

The purpose of this paper is to study the behaviour of melting of coarse quartz gains in feldspathic fusions, one of the most important reactions occurring in porcelain bodies during firing. Small tablets consisting of 97% fine ground potash-or soda-feldspar and 3% definitely sized quartz graines (mean intersection diameter, 150.4 μ) were prepared. Some of them were fired at 1150°-1450°C with different rates of 60°, 120°, and 180°C per hr., and the others were maintained for 0.5 hr. -4hr. at 1300°, 1330°, 1350°, or 1400°C in anelectric furnace, and thence abruptly cooled in air. Intersection diameters of 100-300survived quartz grains scattered within glassy phases were measured through thin sections by polarization microscope, and, then, the mean values were calculated. Fromthe values obtained, melting behaviour of quartz grains in feldspathic fusions was inferred as follows:(1) The dissolution of quartz grains into feldspathic fusions was markedly slower than had been usually considered. In general, coarse quartz grains were more easily dissolved in potash-feldspathic fusions than in soda-feldspathic ones.(2) Jander's equation was applied approximately to the dissolution of quartz grains in feldspathic fusions, as treated in this paper.(3) It seems that Arrhenius' equation did not strictly hold for the dissolution of quartz grains into the feldspathic fusions.(4) The following relationship was obtained between firing temperatures and dissolution of quartz grains in the fusions:1-(1-x)1/3=Be-C/Twhere x: reaction ratio in volume, T: firing temperature, (°K), B and C: constants.(5) In the system soda-feldspar-quartz, it was found that the dissolution behaviour of quartz grains might show a marked change at some temperatures within 1250°-1300°CIt was also certified that the microscopical method was very advantageous and precise for the quantitative study on the dissolution of solid crystalline grains into fusion.