RU2583858C1 - Method for laser-spark emission determination of beryllium in metal alloys and powders - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to analytical chemistry element analysis and can be used for laser-spark emission determination of beryllium in metal alloys and powders. Method is based on exposing surface of analysed sample to focused laser radiation with pulse duration of 240-250 mqs and pulse energy of 1.3-1.4 J. Laser spark luminescence analysis enables to pick out spectral lines of vapours of beryllium and identification of its spectral lines.

EFFECT: for determination of beryllium experimentally most sensitive laser emission lines of element in spectral range 310-321 nm are used.

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Description

The invention relates to the field of analytical chemistry of elemental analysis and can be used for laser-spark emission determination of beryllium in metal alloys and powders.

The relevance of the invention is due to the need to develop a modern method for determining beryllium in metal alloys and powders, largely devoid of the disadvantages inherent in the applied determination methods.

The invention can find application in aerospace, nuclear, metallurgical, chemical, instrument-making and other industries.

A known photometric method for determining beryllium in aluminum cast and wrought alloys. The method is based on dissolving the sample in a mixture of nitric, sulfuric, and hydrochloric acids in a sodium hydroxide solution, masking the interfering elements with Trilon B, forming a complex compound of beryllium with beryllon 4 in the presence of hexamethylenetetramine and measuring the optical density of the solution at a wavelength of 536 nm [GOST 11739.3-99 Alloys aluminum foundry and deformable. Methods for the determination of beryllium]. The disadvantages of the method is the long and difficult preparation of the studied samples. Application at the stage of sample preparation and the stage of analysis of a significant amount of chemicals, acids, as well as the use of chemically clean laboratory glassware. The duration of the analysis of the studied samples.

Known luminescent method for determining beryllium. The method is based on dissolving the sample in hydrochloric acid, establishing a pH in the solution (13 ± 0.2), forming a complex compound with morin, initiating fluorescence at a wavelength of 430 nm and measuring the fluorescence of the complex at a wavelength of 520 nm [GOST 11739.3-99 Aluminum alloys foundry and deformable. Methods for the determination of beryllium]. The disadvantages of the method is the long and difficult preparation of the studied samples. Application at the stage of sample preparation and the stage of analysis of a significant amount of chemicals and acids, as well as the use of chemically clean laboratory glassware.

Known atomic absorption method for the determination of beryllium. The method is based on dissolving the sample in a solution of hydrochloric acid in the presence of hydrogen peroxide and measuring the atomic absorption of beryllium at a wavelength of 234.9 nm in a flame of acetylene-nitrous oxide. The disadvantages of the method include a long and difficult preparation of the studied samples. The use at the stages of sample preparation and analysis of a significant amount of chemicals, acids, as well as the use of chemically clean laboratory glassware. The use of spectrally pure combustible gases in the research process.

The closest analogue adopted for the prototype is an atomic emission method for determining beryllium with induction plasma. The method is based on dissolving a sample in a solution of hydrochloric acid in the presence of hydrogen peroxide, spraying the solution into an induction plasma torch, measuring the radiation intensity of beryllium at a wavelength of 234.8 nm [GOST 11739.3-99 Cast and wrought aluminum alloys. Methods for the determination of beryllium]. The main disadvantages of the method is the long and difficult preparation of the test samples. The use of a significant amount of chemicals and acids at the sample preparation stage and the research stage. The use of spectrally pure combustible gases in research

The objective of the invention is to develop a modern method for the determination of beryllium in metal alloys and powders, which allows, without a long and complicated preparation of samples, without the use of spectrally pure combustible gases, chemicals and acids, chemically clean laboratory glassware, to automatically determine the beryllium content in the test sample.

The solution of this problem is achieved by experimental determination of the optimal parameters of the laser-spark action on the studied samples; determination of spectral ranges with the most intense lines of laser emission of beryllium in the absence of interference of lines of background elements and the maximum signal to noise ratio; development of methods for laser-spark emission determination of beryllium in metal alloys and powders.

Method for determination of beryllium in metal alloys and powders

1. Equipment and materials

Laser-spark emission spectrum analyzer with specially designed software, Gosstandart certificate of the Russian Federation No. 7450, number in the State Register 19155-00.

Scales analytical AB 60-01 GOST 24104-2001.

Porcelain mortar and pestle GOST 9147-80.

Press hydraulic desktop manual PGPR-4 GOST 22690-88.

Mold for forming tablets.

Powder graphite of high purity GOST 23463-79.

2. Sampling

The selection and preparation of the test sample for analysis is carried out in accordance with the developed methodology.

3. Preparation for the test

3.1. Preparation of a laser-spark emission spectrum analyzer for operation and selection of measurement conditions.

Preparation of the spectrum analyzer for operation, its inclusion and putting it into operation is carried out in accordance with the instruction manual.

3.2. Preparation of samples for research

A sample of a certain mass is taken from samples of materials, placed in a porcelain mortar, where it is ground to a state of dust, mixed. Next, the sample is placed in a special mold under a bench-top laboratory hydraulic press, where a disk-shaped tablet is pressed under a certain pressure.

4. Measurement

4.1. In the menu of the laser-spark emission spectrum analyzer software, the experimentally established parameters of laser exposure are set, namely, the laser pulse duration is 240-250 μs, the laser radiation energy is 1.3-1.4 J. The most sensitive element laser emission lines are experimentally determined to determine beryllium in the spectral range of 310-321 nm.

4.2. The sample prepared according to Section 3.2 is placed on the substrate of a program-controlled stage of a laser-spark emission spectrum analyzer, which allows step-by-step examination of the entire surface of the sample. Pulses of focused laser radiation are produced on the surface under study. The resulting plasma contains vapors of the substance of this sample. An analysis of the glow of a laser spark using a polychromator, a multi-element photodetector, and a matching unit with a PC makes it possible to isolate the spectral lines of beryllium vapor in the sample. The identification of the beryllium spectral lines is carried out automatically using software containing a library of emission spectra. Each sample is measured at least 2 times.

5 Processing Results

5.1. Special software for the laser-spark emission spectrum analyzer automatically calculates the concentration of beryllium by the value of laser emission.

5.2 The results of the qualitative and quantitative analysis of the beryllium content in the sample are displayed on the PC monitor screen.

Under the influence of focused laser radiation with a pulse duration of 240–250 μs and a radiation energy of 1.3–1.4 J on the surface of the sample in the form of a disk, a laser spark of optical breakdown occurs. At instant temperature heating due to the effect of layer-by-layer sublimation, a sample of the substance is taken from the surface of the sample. In this case, a plasma is formed containing the pairs of the test sample. Excitation and ionization of free beryllium atoms takes place in plasma. The subsequent transition of atoms back from the excited state to the usual one and ion recombination is accompanied by the emission of light of certain wavelengths in the spectral range 310-321 nm, which is detected by a multi-element photodetector and transmitted via a matching device to a PC, where the obtained spectral lines are compared with the lines from the spectral data library -analytical program. Based on this, a qualitative and quantitative determination of beryllium in the test sample is performed.

Claims (1)

The method of laser-spark emission determination of beryllium in metal alloys and powders, including the action of focused laser radiation on the surface of the test sample, for this a disk-shaped sample is placed on the substrate of a program-controlled stage of the laser-spark emission spectrum analyzer, laser pulses are produced on the surface of the test sample, in this case, a laser spark of optical breakdown occurs, the resulting plasma contains pairs of the substance under study, analysis of the luminosity of the laser Using a polychromator, a multi-element photodetector and a PC interface, it is possible to isolate the spectral lines of beryllium vapor, the identification of spectral lines and analysis is carried out automatically using software that contains a library of emission spectra, characterized in that with this method of determining beryllium to excite spectra of this element, a laser-spark action is applied to the test sample with a laser pulse duration of 240-250 μs and a radiation energy of 1.3-1.4 J, and To identify the most sensitive element uses laser emission lines in the spectral range 310-321 nm.