在熔模精密铸造生产中,常采用石英砂和石英粉作耐火材料。但是由于石英在加热和冷却过程中发生可逆的多晶形转变及体积膨胀和收缩:(?)575℃时,石英体积急骤增加(见附图曲线1),线膨胀达1.4%,1470℃时,急剧线膨胀达6%,只有870℃的体积变化进行得较为缓慢。 In investment casting production, quartz sand and quartz powder are often used as refractory materials. However, due to reversible polymorphic transformation and volumetric expansion and contraction of quartz during heating and cooling (?), The volume of quartz increases sharply at 575 ° C (see curve 1 in the accompanying figure), the linear expansion reaches 1.4%, and at 1470 ° C, Dramatic linear expansion of up to 6%, only the volume change of 870 ℃ carried out more slowly.