SU1250925A1 - Method of x-ray spectral fluorescent analysis of alloys - Google Patents

Abstract

This invention relates to methods for analyzing the composition of homogeneous substances by the X-ray fluorescence method. The purpose of the invention is to improve the accuracy of background accounting by taking into account both the permanent components of the background. and depending on the chemical composition of the sample. The radiation intensities are preliminarily measured in the spectral regions corresponding to the analytical lines of the elements to be determined and the basic elements of the matrix for a number of samples of known composition that are close in composition to the measured alloy. For the same samples, theoretically, the intensities of the analytical lines of the determined elements, free from the background, are calculated. From these data, the coefficients are determined in the regression equation, which relates the intensity of the analytical line of the element being determined, which is free from the background, and the intensity of spectral regions corresponding to the analytical lines of the elements being determined and the main elements of the matrix of the alloy being measured. Further, these intensities are measured and, using the established equation, the intensity of the analytical line of the element being determined in the alloy under study is calculated, which is free from background. 1 tab. (O (L tsD SP O so y ate

Description

The invention relates to methods for studying the chemical composition of substances and can be used in determining the composition of homogeneous materials, in particular alloys in metallurgy, geology, medicine, in studies related to environmental protection, and other areas of national economy.

The purpose of the invention is to increase the accuracy of accounting for the background.

For homogeneous samples, the discrepancy between theoretical I and experimental 1. intensity values of the analytical line of the element being detected, often present in a sample in small quantities, is mainly due to the contribution of background radiation to the measured value 1. The use of regression equations allows to take into account the contribution to the intensity I, both constant components of the background and dependent on the chemical composition of the sample. At the same time, the fluorescence intensity I, the main elements of the matrix, are used as the characteristics of the latter.

Example. For ten standard steel samples of sets 129, 118, 2-FM, similar in composition to stainless steel, excite and record the spectrum of characteristic radiation, select the spectral regions corresponding to the analytical lines of the main and impurity elements (Mo, Cr, Ni, Ti, Fe, C, Mn, V) and theoretically calculate the fluorescence intensity of the detected elements

The range of contents of these elements in the sample under consideration is given in the table.

 Using the established Ij values and the least-squares method, the coefficients in the multiple linear regression equations

-

3 LI, a „, + a, 1, + a, I.

(one)

t

de I., I. - theoretical and experimental intensity of the analytical line of the determined i-ro element;

1 - experimental intensities of analytical lines of the main elements of the matrix;

K is the number of major components that make up the matrix of the material being analyzed;

aa .a - constant coefficients

° / h

Coefficients of equation U; the contribution of the background radiation to the value of the measured intensity of the analytical line of the element being determined is taken into account. As applied to the products in question, the following equations were obtained:

, 692 + 2,1761-; -0.6551 -2, -C, 0161 -0.0231 -4.3311;

 I 1 Mo

lj 0.958 + 3.87b4 -1.4641, -0, -1,

ij -2.642 + 1, 460Iv +0.1761;,; - 0 ,,, 0111, + 1.597G

(-2)

When analyzing steel samples, intensities of analytical lines of the determined elements and the main elements of the matrix are excited and recorded

Using equations (2), the experimental fluorescence intensities 1 of impurity elements are reduced to theoretical 1, the values of fluorescence intensities of the elements being determined in this way are free of background radiation superposition and are used in calculating the desired concentrations for any kind of bond equation.

The proposed method allows to improve the accuracy of X-ray fluorescence analysis by significantly improving the accuracy of the background accounting, which is of great importance in determining low concentrations.

element radios in samples with large variations in chemical composition, if a spectrometer with fixed measuring channels is used for the analysis. In particular, the use of this background metering method in comparison with the prototype method reduces the error in establishing small contents of elements in a group of stainless steel samples by means of my external standard: MP from 5.3 to 3.4%; C from 34.5 to 4.2%; V from 16.4 to 6.1%; Lukas-Tusa method: MP from 2.0 to 1.2%; C from 6.2 to 1.4%; V from 4.1 to 3.1%; by the method of theoretical corrections: MP from 6.1 to 2.0%; C from 30.8 to 2.5%; V from 15.3 to 4.2%. The detection limit of these elements has decreased to 11; 12.5; 7.5 times, respectively.

Claims (1)

Invention Formula The method of X-ray fluorescence analysis of alloys, excitation and recording of the characteristic X-ray spectrum of the alloy being analyzed, measuring the intensities of spectral regions corresponding to the analytical lines of the elements being determined, and correcting the measured intensities, in order to improve the background accounting accuracy, selected measurement conditions are excited and recorded The range of contents of the element,% 0.03–13.65, 0– 0.01– 0.36– 0.02– 0.03–4, 0 –24.4 19.3 -0.9 Editor S. Lisin Compiled by M.Viktorov Tehred I.Gaydog Order 4402/38 Circulation 778 Subscription VNNPI State Committee of the USSR for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 the intensity of radiation in the spectral regions corresponding to the analytical lines of the determined I- and main I elements of the matrix of a group of alloy samples of known composition, close to the composition of the alloy being analyzed, is theoretically calculated Intensities I. Analytical Li1 The scientific research institutes of the determined elements in these samples, free from superimposing calculate the coefficients of the equations M “Oh, + but. I In addition, the intensities of the analytical lines of the main elements of the matrix of the alloy being analyzed are measured, and the intensities of the analytical lines of the elements being determined free from background overlay are calculated from the equations found. -2.2 -0.40 -0.31 Proofreader S. Shekmar