NdFeB chemical composition analysis (ICP atomic emission spectroscopic analysis)
The chemical composition analysis of NdFeB materials generally includes:
1-Chemical composition analysis of raw materials, including the chemical composition of rare earth metal raw materials, as well as industrial pure Fe, B-Fe alloys and other metals, such as Ga, Al, Nb, Zr, etc.;
2- The chemical composition of the magnet, if the unknown magnet or the magnet has a problem, it needs to be analyzed. If the product quality is normal, it does not need to be analyzed. The chemical composition of the magnet includes rare earth metal elements, such as Nd, Pr, Ce, Dy, Ho, Gd, Tb, etc., and other metal elements, such as Cu, Al, Nb, Zr, Ga, Co, Ti, etc.;
3- Content analysis of other non-metallic elements, such as hydrogen, oxygen, carbon and other element content analysis.
In this article, we mainly introduce the composition analysis of raw materials and magnets. The analysis of hydrogen, oxygen, and carbon in magnets will be discussed in the next issue.
The composition analysis of NdFeB is the same as that of iron and steel materials and non-ferrous metal materials, including traditional analysis methods and modern physical analysis methods.
The traditional analysis method is to use the color, mass and volume changes of the reactants produced by the chemical reaction between a certain element in the material and a certain substance for chemical analysis. This method is time-consuming and laborious, and personal experience has a significant impact on the analysis results, so it is rarely used in the quality monitoring of NdFeB materials.
Modern physical analysis mainly uses the wavelength and intensity of the spectral lines emitted by electrons in certain element atoms when they jump in different shells to analyze the elements and content contained in the material. Modern physical analysis methods mainly use instruments for analysis, which can analyze multiple elements at the same time. The analysis speed is fast, but the cost is also high. There are three main types of modern physical analysis methods: plasma spectroscopy, atomic absorption spectroscopy, and atomic fluorescence spectroscopy. Plasma spectroscopic analysis is more commonly used in the component analysis of iron and steel materials, rare earth metals and compound materials, and rare earth permanent magnet materials.
ICP Atomic Emission Spectroscopy Analysis
ICP emission spectroscopy is an analytical method combining inductively coupled plasma (ICP) and atomic emission spectroscopy (AES), abbreviated as ICP-AES spectral analysis, which is simplified to ICP emission spectral analysis.
1. Basic principles
The emission spectrometer is based on the atoms or ions of the measured elements, which are excited in the light source to generate characteristic radiation. By judging the existence and intensity of these characteristic radiation, qualitative and quantitative analysis of each element is carried out.
The ICP emission spectroscopy analysis process is mainly divided into three steps, namely emission, spectroscopy and detection.
Use the plasma emission light source (ICP) to vaporize, dissociate or decompose the pattern into an atomic state, and the atoms may be further ionized into an ion state, and the atoms and ions are excited to emit light in the light source;
Using a spectrometer to decompose the light emitted by the light source into a spectrum arranged by wavelength;
The photoelectric device is used to detect the spectrum, and the pattern is qualitatively analyzed according to the measured wavelength, and quantitatively analyzed according to the emission intensity.
2. Analyzable elements and scope of application
Among the 109 elements in the periodic table of elements, 74 elements can be measured by ICP emission spectrometer, including 3d, 4d, 5d transition metals and La series rare earth metals. The undetectable elements are fluorine, helium, inert gas elements, carbon elements, Oxygen, nitrogen, hydrogen and all radioactive elements.
Can be used for constant analysis (0.x%~20%), trace analysis (0.00x%~0.0x %), and trace analysis (0.0000x%~0.000x %) of the measurable elements, but separation and enrichment are required), However, elements with a content above 30% cannot be analyzed.
3. Types of ICP emission spectrometers
ICP emission spectrometers are divided into three categories according to different excitation types and detection systems:
Inductively coupled plasma emission spectrometer (ICP for short), including sequential scanning type, multi-channel simultaneous type, full-spectrum direct-reading type, etc.
Spark/arc direct-reading spectrometer, referred to as direct-reading spectrometer, including large-scale and portable Spectrograph