X射线荧光光谱高压制样方法和技术研究

Study on High Pressure Sample Preparation Method for Pressed Powder Pellet and Its Application in X-Ray Fluorescence Spectrum Analysis

使用自行设计研制的高压制样模具和高压制样技术(专利号:201310125772.5),对岩石、土壤,水系沉积物等地质样品进行高压制样研究,这是国内首次的高压制样尝试,并取得了显著的成果。不加粘结剂,用1600 kN高压能使各种类型地质粉末样品压制成型。而且,经高压制备的试样片表面致密、平整、光滑、光亮,不龟裂,不分层,不掉粉末,消除了对X射线荧光光谱仪分析室的污染,为X射线荧光光谱分析粉末制样开辟了一条新途径。通过对元素分析线、背景强度、校准曲线斜率、方法的精密度和制样的重现性的对比研究表明:高压(1 600 kN)制备的试样片较常规压力(400 kN)元素的峰背比值、灵敏度显著地提高,检出限明显降低、分析结果更接近标准值、精密度和样品制备的重现性均有较大提高。还利用电子显微镜和X射线衍射对这些高压试样片(1600 kN)和常规压力的试样片(400 kN)作了表面形态和结构的对照研究,研究表明:高压试样片(1 600 K)较常规压力的试样片(400 kN)二氧化硅谱峰的半高宽均变宽。表明峰形发生了变异,变化的原因可能是在高压下SiO_2晶格被破坏,粒度减小,因而使高压制备的试样片表面更加坚实、致密、平滑、不掉粉末,减少了颗粒度和矿物效应,提高了分析结果的精密度和准确度。

Using the independently designed high pressure sample preparation mold and high pressure sample preparation tech- nology （patent number： 201310125772.5）, studies on the high pressure pressed various geological samples such as rocks, soils and stream sediments were first described in the present paper. It is the first experiment conducted in this field with significant achievements obtained. Without any binder, various types of geological powder samples can be pelleted well using 1600KN high pressure method. Such pellet has the characteristics of dense, flat, smooth and shiny surface, no cracks, no delamination, and no powder dropping. The study provides a new and contamination-free approach to sample preparation of X-ray fluorescence spectrum analysis. The comparison study conducted between the same samples pelleted under the low pressure （400 kN） and high pressure （1 600 kN） showed that using the high pressure the element peak to background ratios, and sensitivities are signif- icantly improved, the detection limits are lowed, and the accuracies, the precisions and sample preparation repeatability are greatly improved. The Si FWHM became wider for the high pressure （1 600 kN） pellet than the same sample pelleted under the lower pressure （400 kN）. The further SEM observation revealed that variation of Si spectrum shape may be caused by that the silica crystal lattices are destroyed and the particle size becomes smaller by using the high pressure pelleting techniques. So the particle size and mineral effects are also effectively reduced and the precisions and accuracies of the analytical method are im- proved.