氩提取系统中的石墨熔样炉

随着地质年代学研究的深入和发展,对同位素年龄测试方法和技术的要求愈来愈高。目前国内氩稀释法实验室的超高真空提取系统的结构基本相似,主要由熔样、纯化和转移等部分组成。熔样方法主要有三种:1)电子轰击炉加热;2)高频感应加热;3)不同材料电阻炉加热。前两者虽具有加热温度高的特点,但设备价格较高、辅助设备体积较大,电子轰击炉结构又较复杂。因此,在没有相应设备条件的实验室仍然采用传统的电阻炉加热熔样。电阻炉的加热材料一般采用钼丝或钨丝,以及石英衬管。这种电阻炉结构简单,但寿命较短,更换频繁。

A NEW APPROACH TO SAMPLE FUSION IN ARGON EXTRACTION SYSTEM

Based on the distinctive features of graphite, such as high melting-point, low re-sistenee and the excellent thermal-conductivity and mechanical properties, the authors propose and design a new technique for sample fusion, the graphite furnace, instead of the conventional metal filament (Mo or W) resistence heater. The preliminary results of the test indicate that the graphite furnace can provide higher temperature of fusion with low Ar blank and low cost as well as with ease and simplicity of operation.It is demonstrated that this technique applied to the Ar extraction system is quite effective and feasible, so it is the relative ideal material for sample heating. A series of measurements on the standard reference samples (biotite ZBH-25 and Hornblende ZBJ, both from Zhoukoudian area) and some geological samples have been, performed using this new technique, the reliable results have been obtained.