GB/T 14849.5-2014Methods for chemical analysis of silicon metal—Part 5: Determination of impurity contents—X-ray fluorescence method (English PDF)

1 Scope

This Part of GB/T 14849 stipulates the determination method of iron, aluminum, calcium, manganese, nickel, titanium, copper, phosphorus, magnesium, chromium, vanadium, cobalt content in industrial silicon.

This Part is applicable to the determination of iron, aluminum, calcium, manganese, nickel, titanium, copper, phosphorus, magnesium, chromium, vanadium, cobalt in industrial silicon. The determination range is as shown in Table 1.

2 Normative references

The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) is applicable to this standard.

GB/T 8170 Rules of rounding off for numerical values & expression and judgement of limiting values

3 Method summary

X-ray fluorescence spectrometry is a qualitative and quantitative analysis, by measuring the wavelength and intensity of the X-ray spectral lines, which are emitted by the secondary excitation of chemical elements. The primary X-ray beam, which is generated by the light pipe, is irradiated on the specimen. Each chemical element in the specimen is excited, to emit its own secondary characteristic radiation. This secondary ray reaches the spectroscopic crystal, through the collimator. Only the radiation of a specific wavelength, that satisfies the diffraction conditions, is strengthened when it exits the crystal, the radiation of other wavelengths is weakened. This method is based on Bragg's theorem, namely formula (1):

Where: n - Diffraction order;

lambda - The wavelength of the incident beam (characteristic radiation), in nanometers (nm); d - Spacing between crystal planes, in centimeters (cm);

theta - The angle between the incident light and the crystal plane, in degrees (°).

In quantitative analysis, first measure the analytical line intensity of a series of standard samples; draw a standard curve of intensity versus concentration; perform the necessary mathematical correction for matrix effects; then calculate the element content, according to the intensity of the element spectral lines in the analytical specimen.

4 Instruments and materials

4.1 Wavelength dispersive X-ray fluorescence spectrometer, Rh target light tube (refer to Appendix A, for instrument parameter settings).

4.2 Vibration mill (including tungsten carbide grinding disc).

4.3 Tablet press (including press ring), which can provide 40 t pressure.

4.4 Balance: Sensitivity is 0.1 g.

4.5 Binder: Boric acid or starch (analytical pure).

4.6 Lining agent: Boric acid (industrial pure).

4.7 Triethanolamine (Analytical pure).

5 Specimens

The specimen shall be able to pass through a 0.149 mm standard sieve.

6 Steps