JPS60173448A - Method and device for analyzing surface of moving material - Google Patents

Abstract

PURPOSE:To enable measurement of a characteristic X-ray having >=0.25nm wavelength by providing a fluorescent X-ray analyzing device which contains an X-ray source and a detector for the characteristic X-ray and is evacuated internally to a vacuum or is substd. with He and substituting the air in the space of an X-ray passage with He. CONSTITUTION:The body part of a fluorescent X-ray analyzing device has an X-ray source 1, a detector 5 for a characteristic X-ray and a housing 7 which contains said source and detector, has an X-ray transmission window 6 and is evacuated to a vacuum or substd. with helium in the inside X-ray passage part. A gas substituting chamber 8 having an opened bottom and a preliminary chamber 9 for gas substitution which encloses the circumference of said chamber and has an open bottom are provided. The detector 5 detects the generated characteristic X-ray and the window 6 isolates the vacuum part or helium substd. part in the housing from the outside. The air in the X-ray passage part is substd. with helium and the characteristic X-ray having >=0.25nm wavelength is made measurable in the stage of performing fluorescent X-ray analysis on the surface of a flat plate-shaped material.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method and apparatus for analyzing the surface components of a flat material by fluorescent X-ray analysis. Analysis of the chemical composition and film thickness of the surface of a material subjected to such treatments is often performed by fluorescent X-ray analysis. In general, in fluorescent X-ray analysis, as shown in Figure 1, an X-ray source (X-ray tube or radioisotope) 1
, the sample 3 is irradiated with primary X-rays 2, and the characteristic X-rays 4 emitted from the elements present on the surface of the sample are measured by the detector 5 to quantify the chemical composition and film thickness of the surface. It is. There are two methods of measurement using fluorescent X-ray analysis: one is to cut out a sample piece and load it into a fluorescent X-ray analyzer for analysis (the so-called offline analysis method), and the other is to perform measurements during the production process of metal strips, etc. There are two methods: a method in which a fluorescent X-ray analyzer is installed on such a production line and the moving substance is directly analyzed without cutting out a sample (so-called online analysis method).

For production process control, offline analysis is desirable because it allows for quick feedback of analysis values, but online υ analysis of elements with atomic number 23 or lower has not been carried out so far. This is due to the characteristic X-rays (Kd rays or β-rays) of elements with atomic number 23 or lower, and X-rays with longer wavelengths of tb wavelength 0.25 nm or more, which are largely absorbed by air and cannot be measured in the atmosphere. This is because. Therefore, measurements of these elements have only been performed through off-line analysis. Off-line υ analysis is possible if it is possible to cut out a sample from a semi-finished product that is in the process of being manufactured, but if that is not possible, the sample is cut out and analyzed from the post-process, so it takes a long time to obtain analytical values. Insufficient process control. Conventional methods for fluorescent X-ray analysis of moving substances have the drawbacks mentioned above.
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(Objective of the Invention) The present invention makes it possible to analyze light elements that generate characteristic X-rays with a wavelength of 0.25 nm or more, which has conventionally been impossible to analyze online. The light elements targeted here include titanium, calcium, sulfur, phosphorus, silicon, aluminum, magnesium, and sodium.

(Structure of the Invention) The present invention provides the following features: (1) When performing fluorescent X-ray analysis of a moving flat material r7'':', the air in the X-ray passage space is replaced with helium, and the characteristics of wavelengths of 0.251 m or more are obtained. A method for analyzing the surface of a moving substance, characterized by measuring X-rays.

2. The main body of the fluorescent X-ray analyzer has a built-in X-ray source and a detector for characteristic
A gas exchange chamber is provided with a radiation transmitting window, and a gas exchange chamber with a helium pipe outside the X-ray transmitting window and an open bottom, and a gas exchange preparatory chamber with an open bottom are provided so as to surround the gas exchange chamber, This is an apparatus for analyzing the surface of a moving material, in which the frontage of the replacement chamber and the J1 space replacement preliminary chamber is installed close to the surface of the moving flat material.

The present invention will be explained in detail below.

First, the apparatus according to the present invention consists of a fluorescent X-ray analyzer main body and a gas replacement section. As in the embodiment shown in FIG. 2, the main body of the fluorescent X-ray analyzer includes an
A detector 5 for detecting rays and an X-ray transparent window 6 containing these
and a storage container 7 whose internal X-ray passage is evacuated or replaced with helium. The gas exchange section is composed of a gas exchange chamber 8 which is arranged outside the X-ray transmission window and has an open bottom, and a gas exchange preliminary chamber 9 which is arranged so as to surround this gas exchange chamber and has an open bottom. A device um piping 10 is introduced. In this device, the gas exchange chamber 8 and the gas exchange preparatory chamber 9 are connected to a flat material 1 which is being moved.
placed close to the surface of 1.

The main body of the X-ray fluorescence analyzer, which includes an X-ray source, a detector, an X-ray transmission window, and a storage container, may be an ordinary X-ray fluorescence analyzer for light elements. An X-ray tube is generally used as the X-ray source, and is used to irradiate the surface of a moving flat material to be measured with X-rays to excite existing atoms and generate a characteristic Xm. The detector is for selecting and detecting the generated characteristic XWS. The X-ray transmission window is a vacuum section inside the storage container. It is used to isolate the helium-substituted portion from the outside, and a thin film of a material such as polypropylene or mylar that does not impede the transmission of the characteristic X-rays to be measured is used. The reason why the X-ray passage inside the storage container is vacuumed or replaced with helium is to measure the characteristic X-rays transmitted through the air.

The gas replacement part is provided to prevent the characteristic X-rays from being absorbed by the atmosphere. It is for replacing with helium. Hydrogen is also considered as a replacement gas, and from the viewpoint of X-ray transparency and cost, hydrogen is preferable to helium, but since hydrogen has the risk of explosion, sufficient exhaust gas treatment is required. Hydrogen can also be used as an alternative to helium if exhaust gas safety measures can be taken. In the waste replacement section, the helium pipe introduces helium as a replacement gas, and the gas replacement chamber is a chamber for replacing this part with helium, and the characteristic X-rays to be measured pass through this part. . The gas replacement preliminary chamber, which is installed to surround the gas replacement chamber, is intended to save the amount of helium gas flowing into the gas replacement chamber. Helium gas flows from the waste exchange chamber to the gas exchange preparatory chamber and to the outside. This flow is not necessarily stable, and if the moving flat material moves up and down, a backflow of gas occurs.

Even in that case, the air concentration in the scum replacement chamber can be maintained to a negligible level by causing the gas in the dregs replacement preliminary chamber that has been mostly replaced with helium to flow into the gas replacement chamber.

If there is no preliminary gas exchange chamber, external air flows directly into the gas exchange chamber according to the vertical movement of the moving flat material, and characteristic X-rays that are difficult to penetrate are absorbed by the air and measured. X
11 intensity decreases, resulting in a large error in the analytical value.

Furthermore, the reason why the object to be measured is limited to a flat material is that if the object to be measured has irregularities, it is necessary to maintain the atmosphere in the gas exchange chamber internally.

(Example) An example of the present invention will be described in detail based on the drawings. In this example, the thickness of a film containing magnesium formed on the surface of a steel plate is determined by measuring characteristic X-rays of magnesium.

FIG. 3 shows an example of a manufacturing process in which the present invention is implemented, and this is one process of manufacturing a silicon steel plate. Steel plate in motion 1
2, a liquid containing magnesium oxide is applied using a coating device 13 and an orifice 14, and is fired in a heating furnace 15 to form a film containing magnesium oxide. This film is important in determining the performance of silicon steel sheets, and the film thickness must be controlled. Conventionally, there was no way to measure during the process,
Sample pieces were cut out from the final product after passing through the post-process and measured using a vacuum-type fluorescent X-ray device in the analysis room. With this method, it takes two to three days after processing to obtain analytical values, and the analytical values cannot be used effectively for process control. It was just that.

In this embodiment, an analyzer 16 based on the present invention is installed as shown in FIG. 3, and the film on a steel plate is measured while the steel plate is being passed through. The analyzer 16 has a structure that is movable in the width direction of the steel plate,
It is now possible to analyze any position on the steel plate. In the figure, it is 17idfi and has the role of suppressing vertical vibration of the steel plate. The analyzer 16 has the same structure as shown in FIG. 2, and the embodiment will be explained in more detail with reference to FIG. As the X-ray source 1, an X-ray tube with a Rh target is used. The output of the X-ray tube is 40 mm, 6 or 11 A. The detector 5 detects the MgKa line (wavelength: 0.987), which is the characteristic X-ray of magnesium.
It consists of a spectroscopic crystal ADP and a gas flow type proportional detector to measure the wavelength (nm). X
The line-transmitting window 6 is made of a polyethylene film with a thickness of 1 μm. The X-ray passage space of the storage container 7 is evacuated by a rotary pump. The volume of the gas exchange chamber 8 is 60ml.

The volume of the gas replacement preliminary chamber 9 was set to 180 mA. The flow rate of helium flowing from the helium pipe 10 was set to 11 per minute.

The space between the moving flat plate material 11 (in this case, the steel plate being passed) and the lower ends of each of the gas exchange chamber 8 and the gas exchange preparatory chamber 9 was 4 times. Since the vertical movement of the steel plate is ±2 steps, this interval is set to 4 to ensure that the steel plate surface is not damaged.

Under the above conditions, the helium gas replacement rate in the gas replacement chamber was set to 998 cm, which is a necessary replacement rate for the following reasons. However, slight variations depending on the measurement target should be allowed.

The accuracy of film thickness quantification by MgKα measurement is due to various factors and has a relative error of 5 cm. Therefore, the variation in the measured X-ray intensity only needs to be within 5%, so that the Ii X-ray transmittance is 95% or more. It would be good if it was guaranteed. X-ray path length is 10c
Replacement rate of helium gas and air and MgK in the case of In
The relationship with α-ray transmittance (relative value to the case of complete replacement) is as shown in Figure 4, and in order to obtain a transmittance of 95 cm, it is necessary to maintain the helium replacement rate at 99.8%. .

FIG. 5 shows the relationship between the helium flow rate and the gas replacement rate and the effect of providing a gas replacement preliminary chamber. The effect of the gas replacement preliminary chamber is large, and the helium flow rate may be reduced to about one-tenth in order to obtain the same gas replacement rate. Furthermore, in order to increase the dregs replacement rate, it is effective to provide gas replacement preliminary chambers in multiple stages concentrically. From Fig. 5, when equipped with a gas exchange preliminary chamber, the gas exchange rate is 998 with a helium flow rate of 11 per minute.
% is obtained. The helium flow rate was determined for this reason.

Under the above-mentioned equipment conditions, the film thickness was controlled by performing almost continuous analysis with a fluorescent X-ray measurement time of 10 seconds and feeding back the film thickness of the steel plate in the upper and lower sides. The film thickness was controlled by changing the amount of magnesium oxide solution applied and changing the sheet passing speed, that is, changing the heating time.

The results of this example are shown in Table 1. Conventionally, analysis was not performed during the process, but only by cutting samples from the final product and performing check analysis, so the variation in film thickness was extremely large. By adopting the method of the present invention in the manufacturing process, the variation in film thickness can be reduced to less than +dv2.

Table 1 * Relative change of balata + from the target value of the measured value 111 However
Mechanism: Coil representative value of film thickness measurement value The applicability is clear.

(Effects of the invention) By applying the method of the present invention to processing lines such as Metsu+, painting, and high-temperature oxidation, process control of film thickness and surface composition during processing can be greatly improved, and product quality can be maintained at a high level. Or, the yield rate of the product cannot be improved.

[Brief explanation of the drawing]

Figure 1 is a diagram showing an overview of fluorescent X-ray analysis, Figure 2 is a diagram showing an analysis device according to the present invention, Figure 3 is a diagram showing an example of a manufacturing process in which the present invention is implemented, Figure 4C↓ FIG. 5 is a diagram showing the relationship between the helium gas replacement rate and the transmittance of MgKα rays, and FIG. 5 is a diagram showing the relationship between the helium flow rate and the dregs replacement rate, and the effect of the gas replacement preliminary chamber. 1... X-ray source 2... Primary X-ray 3... Sample 4... Characteristic X-ray 5... X-ray detector 6... X-ray transmission window 7... Storage container 8 ... Gas replacement chamber 9 ... Gas replacement preliminary chamber 10 ... Helium piping 11 ... Flat material 12 ... Steel plate 13 ... Coating device 14 ... Squeezing roll 15 ... Heating furnace 16.
...Analyzer 17...Guide port

Claims (1)

[Claims] 1. When performing fluorescent X-ray analysis on the surface of a moving flat material, in steps 1 to 1, the air in the X-ray passage space is replaced with helium to obtain a wavelength of 0. - A method for analyzing the surface of a moving substance, characterized by measuring characteristic X-rays of 25 nm or more. 2. A fluorescent X-ray analyzer main body that includes a built-in X-ray source and a characteristic X-ray detector, and whose interior is vacuumed or replaced with helium, and an
A gas exchange chamber is provided with a radiation transmitting window, and a gas exchange chamber with a helium pipe outside the X-ray transmitting window and an open bottom, and a gas exchange preparatory chamber with an open bottom are provided so as to surround the gas exchange chamber, An apparatus for analyzing the surface of a moving substance in which the openings of the displacement chamber and the gas exchange preliminary chamber are installed close to the surface of the moving flat substance.