JPH09257671A - Method for inspecting outer surface defect of ceramic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate a fine crack in a short time by applying a mechanical stress to the outer surface of ceramics. SOLUTION: A plurality of honeycomb structures 1 using cordierite porous material having a diameter of 101.6mm and a length of 127.0mm are introduced into an electric furnace held at 900 deg.C, held for 60min, then removed, and all are conducted by visual and hammering checks. Then, the sample in which the crack is not recognized by the visual check is checked by a 20-times stereomicroscope, and the samples in which the crack is confirmed by the visual and stereomicroscope checks and not confirmed are divided by halves. The end faces of them of the half number are polished at about 1.0mm of sample feeding amount and the specific number of resolutions by an abrasive adhered with diamond grains, and the end faces of the other half number are sandblasted by using nylon or polyplastic for 5 to 10sec in response to the wall thickness separately at 100mm from the end by specific pressure by an air gun having a specific diameter. As a result, the part of fine crack 3 which is impossible to be visually confirmed with polishing and sandblasting is cutout in a V-shape from the end face 2 of the structure 1, and can be sufficiently visually confirmed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic outer surface defect inspection method for detecting fine surface cracks in a ceramic, and particularly to a catalyst carrier filter for purifying exhaust gas and fine particles of an internal combustion engine, and various gases. The present invention relates to a method for inspecting defects on an end surface of a ceramic honeycomb structure used as a combustion gas that uses petroleum as a fuel and / or a deodorizing filter.

[0002]

2. Description of the Related Art Conventionally, a catalyst carrier filter for purifying exhaust gas and fine particles of an internal combustion engine, various gases,
It is necessary to remove defects by inspecting for defects on the outer surface of a ceramic such as a ceramic honeycomb structure used as a combustion gas that uses petroleum as a fuel and / or a deodorizing filter.

The most classical methods for detecting cracks on the outer surface of ceramics, which are currently in practical use, are the most classical methods of visual inspection by the human eye, methods using a magnifying glass or a stereoscopic microscope, pattern recognition methods utilizing image processing, and liquids applied to ceramics. Color check method that recognizes cracks by adding a coloring agent,
Known methods include a fluorescent flaw detection method using a fluorescent agent, and a tapping method that utilizes the fact that a metal without a crack produces a metallic sound when tapped lightly, whereas a metal with a crack has a muddy sound.

[0004]

Among actual cracks, fine surface cracks that cannot be easily detected by visual inspection are generally harmful to ceramics, and it is necessary to detect such cracks. However, in addition to the cost of coloring or fluorescent material and the cost of cleaning after checking, the color check method and the fluorescent flaw detection method require
The porous material has a problem that even minute pores emit color or fluorescence and cannot be distinguished from surface cracks.

Further, in the case of fine surface cracks which cannot be easily detected by visual inspection by the tapping method, there is a problem that even if cracks occur, the sound does not change and the cracks cannot be detected. . Similarly, the pattern recognition method has a problem that it cannot detect fine surface cracks sufficiently. The only method that can detect such cracks is with a stereomicroscope, etc., but this method also narrows the field of view and takes a long time to inspect a wide range if the magnification is increased in order to increase the detection accuracy. There was a problem that the detection accuracy deteriorates if the magnification is reduced in an attempt.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a ceramic outer surface defect detection method capable of accurately detecting fine surface cracks of a ceramic in a short time without using a loupe or a stereoscopic microscope.

[0007]

The method of detecting an outer surface defect of a ceramic according to the present invention is characterized in that a defect is inspected by applying a mechanical stress to the outer surface of the ceramic so as to remove a crack portion on the outer surface. To do.

The present invention utilizes the property that the defective portion of the outer surface of the ceramic is more likely to be chipped by mechanical stress than the defective portion. That is, by forcibly eliminating the defects on the outer surface of the ceramic by applying mechanical stress, the outer surface having the defects causes a chip, and the outer surface having no defects does not have a defect. With, it is possible to easily detect the presence or absence of a defect.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION
There are large cracks with open mouths on the outer surface, and fine cracks that are in close contact with no open mouth. A crack with an open mouth can be easily detected by a visual method or a pattern recognition method without using a microscope. However, cracks with no open mouth cannot be sufficiently detected by any of the methods, and it is particularly difficult to determine whether they are cracks or holes in a porous material. In the present invention,
By forcing these open cracks into a V-shape by applying mechanical stress,
These cracks can be easily identified by visual inspection. Therefore, it is an optimal method for a ceramic honeycomb structure using a porous material.

Surface polishing or sandblasting is preferably used as a method for applying mechanical stress.
In the case of surface polishing, when the continuous surface has cracks, the resistance of the grindstone or the particles of the grindstone are caught in the cracks to form a V-shaped or one-sided V-shaped groove. In the case of the end portion of the honeycomb structure, the partition wall in the cracked portion is in a cantilever state while the other portions are in a beam state in which both ends are fixed, and a V-shaped groove is formed to break with low strength. It is formed.

As for the proper use of the methods, surface polishing is used when the surface is not rough even slightly, and sandblasting is used when the surface is rough. Further, when surface polishing is used, a polishing allowance may be provided in advance due to abrasion by polishing.

[0012]

Embodiments of the present invention will be described below. A honeycomb structure 1 using a cordierite porous material having a shape shown in FIG. 1 was prepared. The honeycomb structure has a diameter of 10
The length was 1.6 mm and the length was 127.0 mm, and various cell structures (partition wall thickness / number of cells) shown in Table 1 below were used. Place the prepared honeycomb structure in an electric furnace maintained at 900 ° C. 6
After holding for 0 minute, it was taken out into the room and checked for cracks.

The cracks were checked first by visual check and tapping sound check. Next, the sample in which no crack was found by visual check was checked with a 20-fold stereomicroscope. After that, divide the sample in which cracks were confirmed with a visual / stereoscopic microscope and the sample in which no cracks were confirmed into half, and polish the end faces of half the honeycomb structure and sandblast the other half face, and visually I checked.

In the polishing process, a grindstone to which diamond grains were adhered was rotated at 2000 times / minute, the sample was fed at 5 mm / minute, and polishing was performed for about 1.0 mm. In the sandblasting process, nylon or polyplus was used as the shot material, and the shot material was sprayed for 5 to 10 seconds at a pressure of 3 kgf / cm ² from an air gun having a diameter of 9 mm at a distance of 100 mm from the end surface of the sample. The reason why there is a difference in the spraying time is that it is necessary to change the spraying time depending on the difference in the mechanical strength of the partition walls. Sample No. 1 having a large material porosity of 43%. It was carried out in 5 seconds for 4 and 10 seconds for others. The results of crack detection are shown in Table 1 below.

[0015]

[Table 1]

As a result, the portion of the fine cracks 3 which could not be visually confirmed by both the polishing process and the sandblasting process,
As shown in FIG. 2, a V-shaped notch was formed from the end surface 2 of the honeycomb structure 1, and the state was sufficiently visible. It was also found that the time required for detection can be shortened in the case of the check after polishing or sandblasting of the present invention, as compared with the conventional visual check, tapping check, and check using a stereoscopic microscope.

The present invention is not limited to the above-described embodiment, but can be variously modified and changed. For example, although a ceramic honeycomb structure having a circular cross-section in the radial direction is used in this embodiment, the present invention is not limited to this, and the present invention is preferably applied to other shapes such as an elliptical shape. It goes without saying that it can be applied. Further, regarding the material, cordierite is used in the present embodiment, but it goes without saying that the material is not limited to this. Furthermore, although the above-mentioned examples show the results for the ceramic honeycomb structure, it is needless to say that the same result can be obtained for other ceramic bodies.
Further, the polishing processing conditions and the sandblasting processing conditions are not limited to the examples because the state of the processed body differs depending on the material and the cell structure.

[0018]

As is apparent from the above description, according to the present invention, the defects on the outer surface of the ceramic are forcibly missing by applying mechanical stress, so that it is difficult to discriminate visually and it is not a stereoscopic microscope. It becomes possible to distinguish minute cracks that are difficult to distinguish in a very short time.

[Brief description of drawings]

FIG. 1 is a perspective view showing a honeycomb structure used in an example of the present invention.

FIG. 2 is an enlarged view of a crack portion of a V-shaped honeycomb structure according to the present invention.

[Explanation of symbols]

 1 honeycomb structure, 2 end faces, 3 cracks

Claims (4)

[Claims] 1. A mechanical stress is applied to an outer surface of a ceramic,
A ceramic outer surface defect method, characterized by inspecting for defects by removing cracks on the outer surface. 2. The method for inspecting an outer surface defect of a ceramic according to claim 1, wherein the outer surface of the ceramic is an end surface of a ceramic honeycomb structure. 3. The method for inspecting outer surface defects of ceramics according to claim 1, wherein the method of applying the mechanical stress is surface polishing. 4. The method for inspecting outer surface defects of ceramics according to claim 1, wherein the method of applying the mechanical stress is sandblasting.