| 摘要 |
<p>The ceramic compsn. contg. a plasticity-diminishing natural stone component is improved by using as the latter a natural quartz porphyry contg. (in%) SiO2 60-80 (70-80) Al2O3 5-25 (10-15), Na2O 0-10 (0-1), and K2O 0-14 (7-9). The material phase compsn. comprises (in %): orthoclase 25-50 (33-38), quartz 25-55 (30-48), and muscovite 5-30 (10-20). Whisker-reinforcement of the product is promoted by the acicular mullite crystallisation effected by controlled cooling of the orthoclase-rich melt. In particular, the cooling rate from 1200-750 degrees C is decreased to 0.2 degrees C/min.; then, down to 280 degrees C, the cooling is 0.8 degrees C/min.; the final cooling to 20 degrees C is again very slow (0.2 degrees C/min.). The strength of the products is greatly increased. This is partly due to high compressive stresses arising in the material after the firing. The strength loss by a long-time exposure to moisture is decreased, because the moisture access to the ceramic material is hampered by the pressure-stressed glaze.</p> |
