论文部分内容阅读
Plato热分析法(冷却曲线法)是测定晶化热的一种简便方法,曾有许多人应用。我们在合成云母的研究工作中,曾用此法测定晶化热,发现熔体在不同过冷度下结晶时,其晶化热有显著差别。图1是对氟金云母的同一个试样在不同过冷度下结晶时测得的Plato曲线和晶化热,测定方法见文献。由图可见,这种方法应用于过冷熔体显然是不适宜的。下面讨论用Plato法测定过冷熔体晶化热引起误差的原因,以及为验证它而进行的实验结果。 Plato是根据图2中以虚线表示的热分析曲线推导出了如下的晶化热计算公式:
Plato thermal analysis (cooling curve method) is a simple method for determining the heat of crystallization, which has been used by many people. We in the study of synthetic mica, this method has been used to determine the crystallization heat, found that the crystallization of the melt at different undercooling, the crystallization heat were significantly different. Figure 1 shows the Plato curve and heat of crystallization measured on the same sample of fluorophlogopite mica at different subcooling degrees. The determination method is given in the literature. It can be seen from the figure that this method is apparently not suitable for applying to subcooled melt. The reason for the error caused by the heat of crystallization of the subcooled melt as measured by the Plato method and the experimental result for verifying it are discussed below. Plato is derived from the thermal analysis curve shown in dashed lines in Figure 2 as follows: