模拟高放玻璃固化体的析晶行为

摘要

In the production process of high-level waste(HLW)glass,there was crystalline phase in the centre area of the HLW glass tanks,due to high temperature.Crystallization increases phase interface of HLW glass,having an effect on the physical and chemical prop-erties of HLW glass.In order to avoid the occurrence of crystallization,it’s necessary to study the crystallization behavior of HLW glass.Crystallization behaviors of the simulated HLW glass were researched by the isothermal heat treatment in this paper.The simulated HLW glass powders were respectively heated at 500,600,700,800,900 ℃ in the range from 0.5 h to 9 6 h.After heat treatment,the crystallinity and crystallinity phase of samples were detected by X-ray diffraction (XRD).The results of XRD show that the maximum degree of crystallinity of the simulated HLW glass appears at about 700℃.After isothermal heat treatment,there are three different crystals:omphacie,cerianite and albite.Omphacite is the major crystalline phase,which has always existed in the range from 600 ℃ to 900 ℃. Cerianite always precipitates in the range from 700 ℃ to 900 ℃.Albite only precipitates at 700 ℃.%在高放废物玻璃熔制过程中,高放废物罐中心区域玻璃长时间处于高温状态,发生析晶现象。析晶增加了高放玻璃固化体的相界面,改变了其物理性质和化学性质。为了避免析晶的发生,必须研究高放玻璃固化体的析晶行为。本工作采用恒温热处理方式,研究模拟高放玻璃固化体的析晶行为。将模拟高放玻璃粉末分别在500、600、700、800、900℃下进行了0.5~96 h的热处理。采用 X射线衍射法(XRD)检测热处理后样品的结晶度和晶相。XRD测试结果表明：模拟高放玻璃固化体的最大结晶度析晶温度在700℃左右；热处理后产生了三类晶相辉石、斜长石和方铈矿,辉石出现在600~900℃,为主要晶相,方铈矿出现在700~900℃,斜长石只出现在700℃。