JPS60178340A - Metal or metal-compound analyzing method by using radiation - Google Patents

Abstract

PURPOSE:To obtain data in a sample, by taking the photograph of the cross section of a sample under non-destructive condition by a radiation tomography method, dividing the level of the picture of the tomography according to picture elements, and analyzing the ratio of the numbers of picture elements. CONSTITUTION:A radiation beam 5 is projected on the cross section of a sample 1. Under this state, a radiation projector 3 and a radiation detector 4 are moved as a unitary body along a scanning line 6 from scanning starting points 7 and 7. The amount of radiation (a) transmitted through the sample is continuously detected. At the same time, the amount of radiation (b) from the radiation projector 3 is detected by a monitoring radiation detector 9. The radiations (a) and (b) are inputted to an operating device 12 through an amplifier 10 and an analog to digital converter 11. The signal of the ratio between the radiations (a) and (b), which is recorded in correspondence with the moving distance of the ridiation projector 3, is inversely projected on the cross section 2 of the sample 1 by a central processing unit 15. Thus the components of the sample can be accurately analyzed without contact.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to the non-destructive analysis of components in metals or metal compounds. ) using tomography (CT)
: Computerized Tomography
) has become widespread, and the devices have been installed and utilized in medical institutions with great success. This method makes it possible to observe the inside of the human body from the outside, which was previously impossible, and devices for the head and for the whole body are currently on the market.

On the other hand, in the engineering field, transmission tests using radiation such as X-rays and γ-rays are widely used to detect internal defects in materials such as metals and metal compounds. However, this method was aimed at qualitatively detecting defects, and was not aimed at obtaining cross-sectional images or analyzing components. However, recently, attempts have been made to utilize the medical CT method as it is in the field of engineering.
This method is disclosed in Japanese Patent Application Laid-open No. 846, Japanese Patent Application Laid-open No. 76443/1983, and the like. However, due to the inability to easily obtain high-energy radiation and the lack of suitable detectors, it has not been possible to analyze the components of metals and metal compounds using tomography. Due to these circumstances, currently, the analysis of components such as metals involves cutting the sample, adjusting the sample for analysis, and analyzing the components using various analytical methods and instruments. Not only is it troublesome to prepare, but the sample must be destroyed to prepare it, making it impossible to track changes over time or reanalyzing it, and cutting and processing the sample may cause the object to change in quality.1. There is a problem with gods.

(Object of the invention) The present invention is characterized by taking a tomographic photograph of a sample of a metal or metal oxide, etc., and analyzing the photograph to analyze its components. , non-contact,
The purpose is to obtain internal information in a non-destructive manner.

(Structure and operation of the invention) The present invention uses radiation such as high-17X+W, γ-2, and neutron beams, and uses a highly sensitive detector to extract information about the inside of a sample as an image. By analyzing this image information, the components of the sample are analyzed and displayed in different colors. In other words, the present invention non-destructively photographs a cross section of a sample using radiation tomography, and divides each pixel constituting the obtained tomographic image into two or more levels according to the amount of radiation transmitted. It is characterized by analyzing the target component by dividing the image into 10 pixels, calculating the total number of pixels for each level, and calculating the ratio to the total number of pixels, and displaying the pixels for each level by color. It is something.

The invention will be explained in detail below. FIG. 1 is a schematic diagram showing the method of the present invention, in which 1 is a cylindrical sample made of a metal or metal oxide, and 2 is a cross section thereof.

3 is a radiation irradiation device that can use radioisotopes such as Xfll of 140 KV or higher (in medical use, the voltage is 130 KV or lower), γ rays such as C8 or 110co, neutron beams such as tSt, Ct, etc.

For example, a high voltage X-ray of 420 KV is condensed and a beam 5 having a diameter of 0.5 wm is transmitted through the sample 1 using a slit. 4 is a radiation detector, and a general scintillation counter, G, M (Geiger-Muller) counter, etc. can be used, but for high sensitivity measurement, B, G, 0
It is desirable to use a semiconductor detector such as (Bi-Ge Oxide) or a multi-scintillation detector. Moreover, FIG. 2 is an explanatory diagram showing the general hair according to the method of the present invention,
8 is a radiation source, and 9 is a monitoring radiation detector. 1
0 is an amplifier that amplifies the signals from the radiation detectors 4 and 9, 11 is an analog-to-digital converter connected to the amplifier, 12 is an arithmetic unit, which includes a buffer memory 13, a program store 14, a central processing unit [15, main memory] 16, a reading device 17, and the like. 18 is digital
An analog converter, 19 an amplifier, and 20 a display device.

In order to analyze the components of a metal or metal compound using the method of the present invention, first a tomographic photograph of the sample 1 is taken. As shown in FIGS. 1 and 2, the radiation beam 5 The radiation irradiation device 3 and the radiation detector 4 are set so as to pass through the cross section, and while irradiating the radiation beam 5, they are moved together along the radiation illumination scanning line 6, and the radiation dose a transmitted through the sample 1 is measured. Detect continuously. At this time, the radiation fl'b from the radiation irradiation device 3 is directly detected by the monitoring radiation detector 9. The radiation doses a and b detected by the radiation detectors 4 and 9 are transmitted to the amplifier 10. Via the analog-digital converter 11, it is input to the buffer memory 13 of the arithmetic unit #12, and the ratio of a and b is recorded in correspondence with the moving distance of the radiation 1g4 irradiation device 3 from the running starting point 7.7. Ru. In other words, the intensity distribution of the transmitted radiation along the scanning direction is stored. The signals recorded in the buffer memo IJ13 are further processed in the central processing unit 15 so as to be back-projected onto the cross section 2 of the sample 1. For example, as shown in FIG. 3(a), the detected intensity is uniformly distributed on the cross section 2 along the direction perpendicular to the scanning direction S in proportion to the intensity .

This distributed value represents the shading of the image when the image is reconstructed.

In this way, the first pair of scans 4 on the cross section 2 are rotated around the sample 1 on the cross section 2 (or the sample 1 is rotated), and the same operation as the previous one is performed again. By repeating these operations, the results shown in Figures 3 (a) and (b) are obtained.
, (c) Obtain a back projection image as shown in . This image is composed of, for example, 512×512 pixels, and is displayed in gray scale in proportion to the amount of transmitted radiation. Furthermore, these back-projected images are superimposed by arithmetic processing in the central processing unit 15, and stored in the main memory 1.
The pixels corresponding to the respective addresses are stored in the 6 two-dimensionally arranged addresses. Note that the correspondence between one pixel and the cross section of the sample is, for example, 0.1 m×O, 1 vn (this superimposed and reconstructed image is schematically shown in FIG. 4). At this time, a component F having different radiolucency in the scanned cross section 2 of the sample 1
If , another component image G is generated at that position. Note that the number of times the radiation is scanned must be at least three times, and preferably 30 times or more in order to obtain a clear image. Main memory 1
The image stored in 6 is read out by a reading device 17,
It is converted into an analog signal by a digital-to-analog converter 18. This analog signal is input to a display device 20 via an amplifier 19, and an image of a cross section 2 of the sample 1 is displayed. Note that each of the arithmetic operations described above in the arithmetic unit 12 is executed according to a program read from the program store 14.

Next, the image displayed on the display device 20 is photographed,
The photographed image is put into a known image analysis device, and the amount of radiation transmitted by each pixel is divided into levels, for example, 16 levels, and pixels having the amount of radiation transmitted corresponding to the matrix of the sample are determined.
The pixels are divided into pixels having a radiation transmission amount corresponding to the target component (which may be two or more), and each pixel is counted.

At this time, the target component is analyzed based on the ratio of the number of pixels having the Xm transmission sign corresponding to the target component and the total number of pixels (which becomes the area ratio). Furthermore, when there are two or more target components, the above-mentioned level division may be divided into two or more, and the number of pixels of each level may be determined and the ratio of the number of pixels to the total number of pixels may be determined. In addition, since the analytical value obtained in this case is an area ratio, it is necessary to use a calibration curve method or the like to convert this into a weight ratio.

In addition to the above explanation, for the (most shadow) of the fault of the sample,
The radiation beam is made into a narrow fan shape and the amount of radiation transmitted is measured using multiple detectors, or the radiation beam is scanned onto the sample using only rotational movement by combining a wide fan-shaped radiation beam and multiple detector rows of 300 or more. How to do, even 600
Any method can be used, such as a method in which a large number of detectors are arranged around the entire circumference and only the radiation is rotated, and the fall of these detectors is also included in the scope of the present invention. Next, examples of the present invention will be shown.

(Example 1) Oxide (
SiOz) was analyzed by the method of the present invention.

At this time, the sample was prepared so that the center of the cross section of the central segregation zone was the center of the sample cross section. High-voltage X-ray illumination equipment price (4
Using 20KV, 3mA) and a detector (BGO), rotate the sample at 1/2 of the sample height in 6° increments to obtain a slice 'lVi? It was run 31 times at 0.5 v, I.

The required time was 10 minutes, and the number of pixels was 240 x 240. The obtained image was classified into 16 levels by an image analysis device, and 8 or below levels were classified as oxides. The thus analyzed oxide (Stay) was colored and displayed on a display device. The 0 mark in FIG. 5 is the displayed pixel. This result revealed that there are many oxides in the center of the central segregation zone. Note that this number of pixels is 2
3. The total number of pixels is 57,600. When oxides (0.2 m or more) were included using the calibration curve method, it was 0.04%. The analytical value of oxide (0.2m+ or more) obtained from the same sample by electrolytic method was 0.04%, and both values were in agreement.

(Example 2) Sintered ore used in steel plants [mainly composed of iron oxide (iron ore), mixed with calcium ferrite, slag, etc. Calcium ferrite and slag in a sample having a size of 50 x 40 x 30 vans were analyzed by the method of the present invention. The equipment and conditions used were the same as in Example 1. However, the transmission X a %'' for each pixel is divided into 8 stages,
Each pixel was classified into levels as follows, starting from the one with the least amount of X-ray transmission.

1st stage: Matrix 2nd to 4th stages: Calcium ferrite 5th to 8th stages Nislag These level classifications were carried out based on the X-ray transmittance of each standard sample measured by R.

Calcillano, ferrite, and slag classified into levels as described above were displayed 17 on a display device by color, for example, red and blue. The state is schematically shown in FIG. The colorless part is an iron oxide matrix, the red part (shaded part in FIG. 6) is calcium ferrite, the blue part (checkered part in FIG. 6) is slag, and the black part is pores. According to FIG. 6, there are several small pores throughout the sample, and the distribution of calcium ferrite and slag is still clear. From this 1ii3i (photograph), the number of pixels of each of the iron oxide matrix portion, calcium ferrite portion, and slag portion was scanned using an image analysis device. Iron oxide) The number of pixels in the IJ x section is 11903
The number of pixels in the calcium ferrite portion was 7601, and the number of pixels in the slag portion was 5458. The total number of pixels (the total number of the three parts, excluding the pores) was 24,962. Therefore, the ratio to the total number of pixels is 47.
7%, calcium ferrite 30.4%, slag 21.
It is 9%. These analysis values correspond to the proportions on each screen in FIG. 6, that is, the area ratios. For reference, this sample was cut at the cross-sectional position using X-rays, the cut surface was examined, and the above components were observed and classified using an optical microscope. %, and the slag was 226 cm.

(Effects of the Invention) As explained above, according to the present invention, components of metals and metal oxides can be analyzed with high precision in a non-contact and non-destructive state, and the effects are extremely significant.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating aspects of radiation irradiation and detection according to the present invention, FIG. 2 is an explanatory diagram showing an example of the present invention, and FIG.
The figure is an explanatory diagram showing an example of the image reconstruction method in the present invention, and FIG. 4 is an explanatory diagram explaining the principle of constructing the sho I image by the reconstruction method -fll (back projection method) in FIG. 3. , 5 and 6 are images displayed on a display device in a practical example of the present invention. 1: Sample, 2: Cross section, 3: Radiation irradiation device, 4: Radiation detector, 5 Two radiation beams, 6: Scanning line, 7: Scanning starting point, 8: Radiation source, 9: Monitoring radiation detector, lO
: Amplifier, 11: Analog-digital converter, 12:
Arithmetic unit, 13: Buffer memory, 14 Niprogram store, 15: Central processing unit, 16: Main memory, 17: Reading device #, 18: Digital-to-analog converter, 19:
Amplifier, 20: Display device. Applicant Nippon Steel Corporation Representative Patent Attorney Minoru Aoyagi Figure 1 Figure 3 Figure 2 Figure 5 Figure 6

Claims (2)

[Claims] (1) Non-destructively photographing a cross section of a sample using radiation tomography, and dividing each pixel that makes up the obtained tomographic image into two or more levels according to the amount of radiation transmitted; A method for analyzing metals or metal compounds using radiation, characterized in that a target component is analyzed by calculating the total number of pixels for each level and calculating the ratio to the total number of pixels. (2) A method for analyzing metals or metal compounds using radiation according to claim 1, characterized in that pixels of each level are displayed in different colors.