提高氢氟酸法分析精度的探讨

用传统的氢氟酸溶渣称重法分析 Al_2O_3—SiO_2陶瓷材料中玻璃相含量时,由于试样中的莫来石在氢氟酸中有部分溶解而呈现出较大的分析误差。本文提出一种对传统的氢氟酸法进行修正的方法,可以消除由于莫来石溶解所导致的分析误差,显著提高分析精度。用玻璃相数量为已知的标准样品,对 X 射线衍射分析法、传统氢氟酸法和修正氢氟酸法的分析精度进行了比较,结果表明,修正氢氟酸法的分析精度明显高于 X 射线衍射分析法和传统氢氟酸法。文中以分析 Al_2O_3—SiO_2系陶瓷型壳中玻璃相的数量和成分为例,介绍了修正氢氟酸法的应用。

On Improving the Accuracy of the HF Leaching Technique

The HF leaching technique is widely used to determine the amount of glassyphase in Al_2O_3-SiO_2 ceramics.So far,however,to the authors' best knowledge,no research work on the error of this technique has been reported in the openliterature,though many researchers believe that the error must be considerable.The authors find,through experiments,that there does exist significant errorin this technique,which mainly comes from the dissolution of mullite in hydro-fluoric acid.In this paper,a method to modify the HF leaching technique isput forward.According to this modified method,the dissolution rate of mullite in hydro-fluoric acid is measured for the sample to be analyzed,and the amount of mullitein the residue is calculated from the results of chemical analysis.With these,theamount of mullite dissolved in hydrofluoric acid can be calculated and subtractedfrom the weight loss of the sample,resulting in satisfactory accuracy of thequantitative analysis of the amount of glassy phase.A comparison of the accuracy of the modified HF leaching technique withthose of the unmodified HF leaching technique and the X-ray diffraction techniqueis made by applying these techniques to a group of standard samples in which theamount of glassy phase is already known.It is shown that the accuracy of themodified HF leaching technique is much higher than those of the other techniqueswhen these techniques are used to determine the amount of glassy phase in Al_2O_3-SiO_2 ceramics.An example is given to show how to use the modified HF leachingtechnique.