GB/T 16597-2019Analytical methods of metallurgical products—General rule for X-ray fluorescence spectrometric methods (English PDF)

3.1 X-ray intensity

The count of intensity in X-ray fluorescence spectroscopic analysis per unit time, usually represented by I.

3.2 Energy resolution

The ratio -- of the half height width of the pulse height distribution TO the average pulse height, expressed as a percentage.

3.3 Background

The continuum superimposed on the analytical line, which is mainly due to the scattering of incident radiation by the sample.

3.4 Analytical line

The characteristic spectral line, whose intensity needs to be measured to determine the content of the analyzed element accordingly.

Note: In X-ray fluorescence spectroscopic analysis, the characteristic spectral lines with high intensity, less interference, low background are generally selected as the analytical lines.

3.5 Interference line

Spectral line, that overlaps or partially overlaps with the analytical line, thereby affecting the accurate measurement of the analytical line intensity.

4.1 Basic principles of wavelength dispersive X-ray fluorescence spectroscopy

The atoms of elements are excited by high-energy radiation, to cause the transition of electrons in the inner shell, at the same time emit X-rays with a certain characteristic wavelength.

4.2 Basic principles of energy dispersive X-ray fluorescence spectroscopy

The analysis sample is excited by the excitation source, to emit characteristic X-rays.

An X-ray detector, which has a certain energy resolution, is used to detect various energy characteristic X-rays, which are emitted by the sample.

5.1 Composition of instrument

5.1.1 Wavelength dispersive X-ray fluorescence spectrometer

The schematic diagram of the wavelength dispersive X-ray fluorescence spectrometer is as shown in Figure 2.

5.1.2 Energy dispersive X-ray fluorescence spectrometer

5.1.2.1 Instrument composition

The composition of the energy dispersive X-ray fluorescence spectrometer is as shown in Figure 3; the whole set consists of four parts.

5.1.3 X-ray generator

The X-ray generator is composed of X-ray tube, high-voltage power supply, and controller.

5.1.5 X-ray analysis target

5.1.5.1 Commonly used targets for wavelength dispersive X-ray fluorescence analyzers

5.1.7 Counting-recording systems

Select the desired pulses from the output pulses of the detector to count; display and record it. It is composed of a pre-positioned amplifier, a single-channel wave height analyzer, a scaler, a timer, and a counting rate meter. The functions of each part are as follows: […]

5.1.8 Data processing system

The computer and its software are used to correct the X-ray intensity AND convert it into the content of the analyzed elements.

5.1.9 Ventilation mechanism

In order to reduce the absorption of long-wave X-rays by the atmosphere, there shall be a vacuum system or a helium replacement system, as well as a device to maintain its pressure stably.

5.2 Selection of instrument parameters

5.2.1 Optical path medium

It is divided into three different optical path media: air, vacuum, helium. Light elements shall be measured in vacuum media. Liquid and wet powder samples shall be measured in a helium system, because of the evaporation of water; however, only elements after fluorine can be measured.

5.2.3 Commonly used analyzing crystals and their scope of application

Commonly used analyzing crystals and their scope of application are listed in Table 3.

5.2.4 Recommended instrument parameters

The recommended instrument parameters for wavelength dispersive X-ray fluorescence analysis are as shown in Figure 6.

5.3 Placement of instrument

In order to keep the X-ray fluorescence spectrometer in normal working condition, the following points shall be paid attention to, when placing the instrument.

5.4 Calibration of instrument

In addition to doing daily maintenance and correcting the drift of the instrument with standardized samples, the technical indicators of the instrument shall be verified regularly every year, including precision, stability, X-ray counting rate, detector resolution, counting linearity of the instrument.

7.1 Solid sample preparation method

For bulk samples such as metal, alloy, cast iron, ore, glass, etc., if a suitable standard sample can be found, the bulk sample can be put into the instrument for measurement, as long as it is cut and surface polished.

7.2 Powder briquette method

Weigh an appropriate amount of powdery sample, which has a particle size of less than 75 µm.

7.3 Vitreous fusion method

In the gold platinum crucible, quantitatively weigh the analysis sample, the main flux, the flux aid, the oxidizing agent and the release agent, which has a suitable particle size, in a certain proportion. After mixing evenly, put the crucible into melting machine or muffle furnace, which was preheated to 1000 °C ~ 1200 °C for melting. After melting, transfer to the preheated gold platinum mold, to cool and solidify.

7.4 Solution sample preparation method

Carry out chemical treatment of a solid sample, to convert it into a solution. The standard solution and the analytical sample solution shall be similar in terms of composition and pH.

7.5 Thin film sample preparation method

For powder samples, which have a particle size of less than 48 µm, it can be sprayed on the tape; OR sprayed on the supporting material such as filter paper by spraying technology; OR the powder sample can be mixed with an organic reagent to form a jelly, then coated on the supporting material; OR the powder sample is made into a solution, […]