Analysis of metals and alloys
Analysis of metals and alloys serves to determine the composition of elements in the metal and alloys.
Analysis of the chemical composition of the metal is necessary for testing the grade or type, as well as quantitative analysis of alloys. Chemical analysis of metals in modern industry is carried out by two methods: X-ray fluorescence and emission.
The emission method is used mainly in the mining, processing and processing industries with the output control of products and input control of raw materials, processing of nuclear waste.
Analysis of non-ferrous metals is also carried out, as a rule, by emission spectrometers. Another feature of this method is the quantitative determination of elements in iron-based alloys (in particular, analysis of carbon, sulfur, phosphorus in steel).
The random error in measuring impurity concentrations during emission analysis can be caused by the instability of the parameters of the excitation sources of the spectrum. In order to ensure that the random error is as small as possible, low-voltage spark discharge (C, R, L-discharge) is used in optical emission spectrometers. This method stabilizes the voltage and energy in the discharge circuit, on which the processes of optical excitation and emission depend. It is the stabilization of these parameters that reduces the random error.
Analysis of color alloys is performed by spectrometers based either on a spark method, or on an air-arc method, or on a combination of these two methods. To date, every modern metal analysis laboratory has an optic-emission device among the analyzers.
Along with the emission method, spectral analysis of metals is performed using X-ray fluorescence analysis. This method is based on obtaining and analyzing the spectrum obtained by the action of X-ray radiation on the material under study. When irradiated with x-ray, each atom of the substance passes into an excited state, then returns to a calm state. But the entire process is accompanied by the formation of an excess of energy, which is emitted in the form of a photon. Depending on the metal, a photon is emitted with an energy of a certain value (fluorescence phenomenon).
Analysis of metals in this method is based on the recognition of matter in terms of energy and the number of quanta emitted during irradiation of the metal. An X-ray fluorescence spectrometer for analyzing metals as a radiation source may contain an X-ray tube or isotopes of certain elements. Recently, the analysis of the metal composition is carried out by irradiation with the help of an X-ray tube with a rhodium, copper, molybdenum or silver anode. Also, in order to improve the determination of light elements (sodium, magnesium, aluminum, phosphorus, sulfur), vacuum evacuation of air, or purging the chamber with helium, is used, which reduces the effect of the atmosphere on the results.
And the scope of application of these analyzers continues to expand due to the ease of use, the opportunity to conduct an express analysis of metals without special sample preparation. Analysis of alloys by the X-ray fluorescent method is widely used in industry and scientific laboratories. In particular, the analysis of precious metals and analysis of heavy metals.