阅读说明：本技术 基于激光诱导击穿光谱的叶片元素无损测量方法 (Blade element nondestructive measurement method based on laser-induced breakdown spectroscopy ) 是由 方丽 赵南京 马明俊 孟德硕 殷高方 刘建国 刘文清 于 2020-06-05 设计创作，主要内容包括：本发明提出的一种基于激光诱导击穿光谱的叶片元素无损测量方法,利用叶片中元素含量的自然分布不均匀性建立定标关系,包括：获取烘干至恒重的待定标的叶片,制成干叶标本；通过激光诱导击穿光谱技术获取干叶标本上待测元素的光谱强度值分布,并根据光谱强度值大小将干叶标本划分为N个标定区域,每一个标定区域对应一个光谱强度值；测量干叶标本上每一个标定区域的待测元素浓度,根据测量结果绘制横坐标为待测元素浓度,纵坐标为光谱强度值的定标曲线；获取烘干至恒重的待测叶片,通过激光诱导击穿光谱技术获取待测叶片的光谱强度值,并对照定标曲线获得待测叶片的待测元素浓度。本发明适用于激光诱导击穿光谱同时无损测定叶片样品中多种元素。(The invention provides a laser-induced breakdown spectroscopy-based blade element nondestructive measurement method, which establishes a calibration relation by utilizing natural distribution nonuniformity of element content in a blade, and comprises the following steps: obtaining leaves to be calibrated which are dried to constant weight, and preparing dry leaf samples; obtaining the spectral intensity value distribution of elements to be measured on the dry leaf specimen by a laser-induced breakdown spectroscopy technology, dividing the dry leaf specimen into N calibration areas according to the spectral intensity value, wherein each calibration area corresponds to one spectral intensity value; measuring the concentration of elements to be measured in each calibration area on the dry leaf specimen, and drawing a calibration curve with the abscissa as the concentration of the elements to be measured and the ordinate as the spectral intensity value according to the measurement result; obtaining the blade to be measured which is dried to constant weight, obtaining the spectral intensity value of the blade to be measured through a laser-induced breakdown spectroscopy technology, and obtaining the concentration of the element to be measured of the blade to be measured by contrasting a calibration curve. The method is suitable for simultaneously and nondestructively measuring various elements in the blade sample by laser-induced breakdown spectroscopy.)

1. A blade element nondestructive measurement method based on laser-induced breakdown spectroscopy is characterized by comprising the following steps:

s1, obtaining the leaves to be calibrated which are dried to constant weight, and preparing dry leaf samples;

s2, obtaining the spectral intensity value distribution of the elements to be measured on the dry leaf specimen through a laser-induced breakdown spectroscopy technology, and dividing the dry leaf specimen into N calibration areas according to the spectral intensity value, wherein each calibration area corresponds to one spectral intensity value;

s3, measuring the concentration of the element to be measured in each calibration area on the dry leaf specimen, and drawing a calibration curve with the abscissa as the concentration of the element to be measured and the ordinate as the spectral intensity value according to the measurement result;

s4, obtaining the blade to be measured dried to constant weight, obtaining the spectral intensity value of the blade to be measured through the laser-induced breakdown spectroscopy technology, and obtaining the concentration of the element to be measured of the blade to be measured by contrasting with the calibration curve.

2. The method for nondestructive measurement of blade element based on laser-induced breakdown spectroscopy as claimed in claim 1, wherein in step S3: and carrying out normalization processing on the spectral intensity value of each calibration area on the dry leaf specimen, and drawing a calibration curve according to the spectral intensity value after the normalization processing.

3. The method for nondestructive measurement of blade element based on laser-induced breakdown spectroscopy of claim 2 wherein in step S3, the model for normalization of the spectral intensity values is:

4. The laser-induced breakdown spectroscopy-based blade element nondestructive measurement method of claim 2, wherein the step S4 specifically comprises the steps of:

s41, selecting a calibration curve corresponding to the blade to be measured;

s42, selecting an alloy sample as a reference standard, and obtaining a spectral intensity value of the alloy sample in a dry leaf specimen measurement environment by a laser-induced breakdown spectroscopy technology;

s43, measuring the spectral intensity value of the blade to be measured and the spectral intensity value of the alloy sample in the same measuring environment through a laser-induced breakdown spectroscopy technology;

s44, carrying out normalization processing on the actually measured spectral intensity value of the blade to be measured, and correcting the spectral intensity value of the blade to be measured by combining the measurement results of the alloy sample in different environments to obtain a spectral intensity value correction value of the blade to be measured;

and S45, obtaining the content of the element to be measured of the blade to be measured according to the comparison result of the spectral intensity value correction value and the calibration curve.

5. The method for nondestructive measurement of blade element based on laser-induced breakdown spectroscopy of claim 4 wherein in step S44, the calculation model of the correction values of spectral intensity values is:

wherein, I 'is the correction value of the spectral intensity value, I' is the normalized spectral intensity value, I_{Standard of merit}Spectral intensity values, I, of alloy samples measured in a measuring environment for dry leaf specimens_{Reference to}For the spectral intensity value I of the alloy sample measured in the measuring environment of the blade to be measured_{Reference to}。

6. The method for nondestructive measurement of blade element based on laser-induced breakdown spectroscopy of claim 4 wherein in step S41, a calibration curve obtained by measuring a dry blade specimen of the same type as the blade to be measured is selected.

7. The method for nondestructive measurement of blade element based on laser-induced breakdown spectroscopy as claimed in claim 4, wherein in step S41, the method for selecting the calibration curve corresponding to the blade to be measured is as follows:

listing characteristic parameters influencing the slope of the breakdown spectrum line, and obtaining a neural network model taking the characteristic parameters as input and the slope of the breakdown spectrum line as output through sample training; and obtaining the spectral line slope of the blade to be measured through a neural network model, and selecting a calibration curve according to the spectral line slope.

8. The laser-induced breakdown spectroscopy-based blade element nondestructive measurement method of claim 7, wherein the neural network model is specifically trained using a genetic-error back propagation neural network.

9. The method of claim 7, wherein the characteristic parameter comprises a base element content of the blade, and the base element content comprises: C. one or more of H, O, N, P, S, Si, K, Mn.

Technical Field

The invention relates to the technical field of laser-induced breakdown spectroscopy analysis, in particular to a blade element nondestructive measurement method based on laser-induced breakdown spectroscopy.

Background

Laser-Induced Breakdown Spectroscopy (LIBS) is a technique for rapidly analyzing elements of a substance, a beam of short-pulse Laser light is focused by a lens and then ablates the surface of the substance to be detected to generate a micro plasma, and spectral signals radiated from the micro plasma and the intensity of the spectral signals are analyzed to determine the elements and the concentration of the elements. This analytical technique has a number of distinct advantages: the method has the advantages of no need of sample preparation, no damage, real-time and rapid detection, in-situ detection in site, simultaneous detection of multiple elements, various detection object forms and the like, and has wide application prospect. However, when the heavy metal of the leaf blade is actually measured, the technology is influenced by a sample matrix, a standard sample with similar matrix is usually difficult to find, and the calibration is difficult. And the heavy metal distribution of blade is inhomogeneous, in order to eliminate the influence, need to grind the back analysis with the sample, carry out the calibration based on the sample after grinding, consequently also need grind the sample in order to guarantee unanimously during the measurement, greatly reduced measuring speed. In order to eliminate or reduce the matrix effect, the currently adopted calibration methods mainly comprise an internal calibration method, a standard addition method and a free calibration method. The application of the methods promotes the development of the LIBS analysis technology, but the methods are only limited in the laboratory analysis and research stage, and some methods are complex in process and not beneficial to on-site on-line monitoring.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides a blade element nondestructive measurement method based on laser-induced breakdown spectroscopy.

The invention provides a laser-induced breakdown spectroscopy-based blade element nondestructive measurement method, which comprises the following steps of:

s1, obtaining the leaves to be calibrated which are dried to constant weight, and preparing dry leaf samples;

s2, obtaining the spectral intensity value distribution of the elements to be measured on the dry leaf specimen through a laser-induced breakdown spectroscopy technology, and dividing the dry leaf specimen into N calibration areas according to the spectral intensity value, wherein each calibration area corresponds to one spectral intensity value;

s3, measuring the concentration of the element to be measured in each calibration area on the dry leaf specimen, and drawing a calibration curve with the abscissa as the concentration of the element to be measured and the ordinate as the spectral intensity value according to the measurement result;

s4, obtaining the blade to be measured dried to constant weight, obtaining the spectral intensity value of the blade to be measured through the laser-induced breakdown spectroscopy technology, and obtaining the concentration of the element to be measured of the blade to be measured by contrasting with the calibration curve.

Preferably, in step S3: and carrying out normalization processing on the spectral intensity value of each calibration area on the dry leaf specimen, and drawing a calibration curve according to the spectral intensity value after the normalization processing.

Preferably, in step S3, the model for normalizing the spectral intensity values is:

i is a spectral intensity value, I' is a normalized spectral intensity value, and f (E · T) is a mapping function with the laser energy E and the plasma temperature T as arguments.

Preferably, step S4 specifically includes the following steps:

s41, selecting a calibration curve corresponding to the blade to be measured;

s42, selecting an alloy sample as a reference standard, and obtaining a spectral intensity value of the alloy sample in a dry leaf specimen measurement environment by a laser-induced breakdown spectroscopy technology;

s43, measuring the spectral intensity value of the blade to be measured and the spectral intensity value of the alloy sample in the same measuring environment through a laser-induced breakdown spectroscopy technology;

s44, carrying out normalization processing on the actually measured spectral intensity value of the blade to be measured, and correcting the spectral intensity value of the blade to be measured by combining the measurement results of the alloy sample in different environments to obtain a spectral intensity value correction value of the blade to be measured;

and S45, obtaining the content of the element to be measured of the blade to be measured according to the comparison result of the spectral intensity value correction value and the calibration curve.

Preferably, in step S44, the calculation model of the correction value of the spectral intensity value is:

wherein, I 'is the correction value of the spectral intensity value, I' is the normalized spectral intensity value, I_{Standard of merit}Spectral intensity values, I, of alloy samples measured in a measuring environment for dry leaf specimens_{Reference to}For the spectral intensity value I of the alloy sample measured in the measuring environment of the blade to be measured_{Reference to}。

Preferably, in step S41, the calibration curve obtained from the dry leaf specimen of the same type as the leaf to be measured is selected.

Preferably, in step S41, the method for selecting the calibration curve corresponding to the blade to be measured includes:

listing characteristic parameters influencing the slope of the breakdown spectrum line, and obtaining a neural network model taking the characteristic parameters as input and the slope of the breakdown spectrum line as output through sample training; and obtaining the spectral line slope of the blade to be measured through a neural network model, and selecting a calibration curve according to the spectral line slope.

Preferably, the neural network model is trained using a genetic-error back propagation neural network.

Preferably, the characteristic parameter comprises a base element content of the blade, the base element content comprising: C. one or more of H, O, N, P, S, Si, K, Mn.

According to the nondestructive measurement method for the blade elements based on the laser-induced breakdown spectroscopy, provided by the invention, the concentration of the elements to be measured is conveniently calibrated subsequently and directly according to the measured spectral intensity value of the blade to be measured by presetting the calibration curve, the blade to be measured does not need to be subjected to grinding, tabletting and other treatment, the field application of LIBS (laser induced breakdown spectroscopy) nondestructive measurement of the blade elements is realized, the nondestructive measurement method is suitable for simultaneously and nondestructively measuring various elements in a blade sample by using the laser-induced breakdown spectroscopy, overcomes the influence of different matrixes on quantitative analysis, and is suitable for field rapid.

Drawings

FIG. 1 is a flowchart of a nondestructive measurement method for blade elements based on laser-induced breakdown spectroscopy, which is provided in embodiment 1;

FIG. 2 is a flow chart of another nondestructive measurement method for blade elements based on laser-induced breakdown spectroscopy, which is provided in example 2.

Detailed Description