Direct reading spectrum sample requirements - Database & Sql Blog Articles

Sample requirements for direct reading spectra

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Photoelectric direct reading spectrometer

What are the requirements for the sample being tested during the analysis? How should I prepare samples?

In order to obtain accurate analysis results, samples are required:

(1) There must be no defects such as trachoma, small holes, segregation;

(2) The surface of the sample must be flat and can completely cover the excitation pores;

(3) The surface of the sample must be clean, not contaminated, and must not contain other substances, nor can it be touched by hand;

Sample preparation requirements: Under normal circumstances, samples of non-ferrous metal substrates such as aluminum and copper need to be driven or milled, and samples of ferrous metal substrates such as iron and nickel can be ground (cast samples need to be cut first). It is required that the surface of the sample after grinding is smooth and clean, the lines are clear, and the temperature is suitable. In addition, samples of different substrates should not be sampled on the same sandpaper.

The cast iron must be whitened for analysis, and the following points should be noted when whitening:

1) Generally, the sample is cast by a sample. The sample is taken as far as possible to take a diameter of 35-40mm and a thickness of 6-8mm. The sample is cooled quickly and the white mouth is good. It is taken out about 30 seconds after the molten iron is poured, and then boiled and then cold water cooled.

2) Do not cast too fast to avoid segregation;

3) Try to select sand molds to reduce shrinkage holes and inclusions.

2. Selection of the excitation site: Where is the most suitable after the sample is prepared?

Generally selected in the circumferential part of two-thirds of the center of the sample. (See the Analytical Chemistry Laboratory Manual)

If the steel sample is solidified in the mold, three crystal regions, that is, a fine grain region, a columnar crystal region, and an equiaxed crystal region are formed. The outermost layer of the sample is a fine grain region, which has a disordered grain and a small area (generally only two or three millimeters); the central region of the sample is an equiaxed crystal region, which is more suitable for spectral analysis in terms of the crystal itself, but the region Many shrinkage holes, sand holes, inclusions and other defects; so two-thirds of the circumference from the center of the sample is the most ideal analysis area, which is mostly columnar crystal, and the macrosegregation is also small, which is most suitable for spectral analysis. (About macrosegregation and microsegregation are also related to the content of easily segregated elements. See metallurgical related books.)

In addition, the shorter the solidification time of the as-cast sample, the better the analysis is to avoid the occurrence of segregation.

3. Can wire and bar be analyzed by direct reading spectrometer?

Yes, but special small sample holders must be used. In order to meet the requirements of the analysis results, different samples need to be equipped with different types of fixtures. At present, many manufacturers' instruments can measure small samples.