饱水文物传统脱水方法与超临界流体干燥技术的应用

饱水文物的脱水加固是文物保护中的一个重要组成部分,为了克服干燥应力引起的文物结构的收缩和塌陷,传统脱水方法中常采用加填充剂浸渍等方法,从而使文物处理周期延长。超临界流体干燥技术利用气体在临界温度以上无论加多大压力都不能液化的特性,控制饱水文物内部的液体在临界点之上,使气/液界面消失,在无液相表面张力情况下进行的干燥过程。本工作在回顾传统饱水文物脱水加固的常用方法和存在问题的基础上,利用液体表面张力与温度的关系,从理论上解释超临界流体干燥技术用于干燥饱水文物具有能消除干燥应力的特点,介绍了国外学者利用该技术实际处理饱水文物时采用的实验装置、操作条件和干燥效果。与传统脱水方法对照,超临界流体干燥技术还具有能缩短文物处理周期、干燥过程中能同时杀菌等优点。

The application of supercitical drying in dehydrating waterlogged archaeological artifacts

Consolidating and drying of waterlogged archaeological artifacts is the main branch of conservation. In order to prevent shrinkage and collapse of structure caused by drying stresses, the method of impregnation with consolidants is adopted traditionally. There are longtime for the structure of treated sample to be filled by agents, also the structure will be probable to be damaged during drying because of the existence of surface tension. This paper reviewed the traditional methods and its shortages, on the basis of this, the paper introduced the supericritical fluid and its properties and applications in recent years, mainly described the theory of the technique of supercritical drying applied in dehydration of waterlogged archaeological artifacts . The technique of supericritical drying use the property of that gas can' t be liquefied when the temperature is controlled above critical point, it avoids the problems associated with the phase changes encountered in the other methods. Compared to traditional method, the supericritical technique has many advantages including that prolonged pretreatment are avoided and that no drying stressed are encountered. Besides the paper also introduced the actual application of this technique in consolidating archaeological artifacts abroad. Some experiment equipment, operating condition and result are mentioned.