材料期刊网

根据阴极溅射和低压气体放电的一般理论,提出了用辉光放电光源作发射光谱分析时,能对电流强度进行校正的工作曲线的数学形式。并证明:在选择合适的放电条件下,经过校正,光源中的“基体效应”可以略去不计。在此基础上,以纯金属作标样,建立了用辉光放电光源对金属表面进行逐层定量分析的新技术。用它进行了钼钛合金上渗硼-硅钛-硅硼三元涂层的逐层定量分析,得到的数据与电子探针、X光衍射和金相结构观察的结果一致。该技术可测定平板状导体样品中深度为几到几十微米范围内的金属元素,层间分辨力约2—3微米。

An attempt has been made to use glow discharge as a light source for emis-sion spectroscopy to in-depth analysis of metal surface on a quantitative basis.According to the general theory of the cathode sputtering and low-pressure dischar-ge, a formula of working curve for spectrographic analysis corrected with currentstrength is given as: (I_j)_a=k(ε_j)_aAq_a(C_j)_awhere the subscripts "j" and "a" refer to a particular element "j" in a sample "a";"I" is the line intensity of element "j"; "ε", the excitation efficiency is a functionof the effective cross section of an atom colloided by electrons, the electron con-centration and the velocity distribution of an electron; "c", the weight percentageof elements; "A", the current strength; "q", the sputtering rate and "k" a constant. Experimental results show that under constant electrical potential and gas pres-sure, the working curves of pure Fe, Cr, Ni, Cu, Zn and the Fe, Cr, Ni, Cu, Znin Fe-Cr, Ni-Cr, Cu-Zn alloys respectively are in complete coincidence after tak-ing into account of the correction of current strength. Thus, the excitation effi-ciency appears to be solely characteristic for a particular element and is independentof the chemical composition of the sample. Moreover, the matrix effect has beenfound to be negligible in the glow discharge source after current correction. Basedon the above results, a new technique for spectrographic quantitative in-depth analy-sis of metal surface with a pure metal as a standard has been adopted for the de-termination of the composition of a B-SiTi-SiB coating on a molybdenum alloysheet. The results are in good agreement with those obtained by electron probe,X-ray diffraction and metallographic observations. The total thickness analyzed bythis technique is capable of being from a few micrometers up to ten or more mi-crometers and the depth resolution as estimated may be 2-3 micrometers.