JP2005164428A - Defect inspection method and inspection device of laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a defect inspection method and a defect inspection device of a laminate, capable of detecting a defect of the laminate in a nondestructive/noncontact manner, regardless of the material of the laminate, and utilizable, for example, for deterioration diagnosis of for a solid oxide type fuel cell or process inspection at manufacturing. <P>SOLUTION: Thermal radiation distributions on the inspection body surface generated, when the inspection body 1 is heated from the back side and the surface side respectively by a lower infrared lamp 11; an upper infrared lamp 12 are detected by an infrared camera 20; and data of the change with passage of time of the thermal radiation distributions in the case of back side heating and surface side heating are compared by a data processing means 30, to thereby specify delamination P, based on the difference or the ratio between both data. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides non-destructive, non-contact, and non-destructive, non-destructive, and non-destructive measures for defects in laminates, such as delamination at the solid electrolyte and electrode interface of laminates such as solid oxide fuel cell (SOFC) cells. The present invention relates to a defect inspection method that can be detected without any concern, and a defect inspection apparatus that can be suitably used for such defect inspection.

For example, as a defect inspection method for flat insulating ceramics such as a solid electrolyte for a solid oxide fuel cell, a discharge current generated when a DC high voltage is applied to the sheet by sandwiching both surfaces of the ceramic sheet with electrodes. A method for inspecting whether or not there is a through hole of 2 mm or more by detecting the above is known (see Patent Document 1).
In addition, as a method for inspecting ceramic tubes, there is also known a method for inspecting the presence or absence of defects by illuminating the interior with a light source and photographing the transmitted light from the tube wall with a camera or performing image processing. (For example, see Patent Document 2).

On the other hand, it is also known to use infrared rays for defect inspection, and an inspection apparatus for detecting a potential defect in an unsintered green sheet (metal and organic matter) is disclosed as a process control by transient thermography. (For example, refer to Patent Document 3).
Further, as a non-destructive inspection method for a bonding type bubble sheet, a valve sheet is measured by measuring a change in temperature distribution of the bubble sheet over time when heat is conducted between the cylinder head and the bubble sheet bonded to the cylinder head. It is disclosed to determine whether or not the bonding property to the cylinder head is good (see, for example, Patent Document 4).
JP 2002-90346 A Japanese Patent Laid-Open No. 11-242000 JP-T-2002-502968 JP-A-9-96204

However, among the above-described conventional techniques, the one described in Patent Document 1 applies a high voltage to the ceramic sheet that is the object to be inspected. It is not desirable to use a high voltage for the actual operation.
Moreover, the thing of the said patent document 2 has the problem that it cannot apply, unless a to-be-inspected material is a material which permeate | transmits light to some extent.
The techniques described in Patent Documents 3 and 4 require that the structure of the object to be inspected is relatively simple, have a complicated structure like a fuel cell, and use various materials. There is a problem that it is not always easy to apply the method as it is.

  The present invention has been made in view of such problems of the prior art, and the object of the present invention is to provide nondestructive and non-contacting of defects in the laminated body regardless of the material of the laminated body. An object of the present invention is to provide a defect inspection method and a defect inspection apparatus for a laminated body that can be detected, and can be used for, for example, deterioration diagnosis of a solid oxide fuel cell and process inspection during manufacturing.

  As a result of intensive studies to achieve the above object, the present inventors have achieved the above object by observing changes in the temperature distribution on the surface of the laminate when heat transfer in the stacking direction is given to the laminate. The present inventors have found that the present invention can be accomplished and have completed the present invention.

This invention is based on the said knowledge, Comprising: The defect inspection method of the laminated body of this invention heats or cools the to-be-inspected object which has laminated structure from the surface or back side, and the to-be-inspected surface at this time It is characterized in that a change in temperature distribution is detected to determine the presence or absence of delamination of the object to be inspected.
In another defect inspection method for a laminate according to the present invention, the temperature distribution change on the surface of the object to be inspected when the object to be inspected is heated or cooled from the front side, and the object to be inspected in the case of being heated or cooled from the back side By comparing the temperature distribution change on the body surface, the presence or absence of delamination of the object to be inspected is determined.

  In addition, the defect inspection apparatus for a laminate according to the present invention is suitable for carrying out the defect inspection method, and a heat source or a cooling source for heating or cooling the object to be inspected from the front surface side and the back surface side, and Temperature distribution detection means for detecting the heat radiation distribution on the surface of the object to be inspected that has been heated or cooled, and data processing means for collecting and analyzing the time-dependent data of the heat radiation distribution detected by the temperature distribution detection means. It is characterized by that.

  The inspection apparatus for a solid oxide fuel cell according to the present invention is configured using the defect inspection apparatus for a laminate as described above, and the laminate as an object to be inspected at this time is provided. This is a fuel cell.

According to the first defect inspection method of the present invention, the laminate as the object to be inspected is heated or cooled from the front surface or the back surface side, and the temperature distribution change on the surface of the object to be inspected at this time is detected. When a defect such as delamination occurs in the laminate, heat transfer (conduction) in the part is hindered, and uneven temperature distribution occurs in the part according to the heat transfer direction. By detecting the above, defects in the stacked body can be detected in a non-destructive and non-contact manner regardless of the material of the stacked body, and can be applied to, for example, inspection of a solid oxide fuel cell.
In the second defect inspection method of the present invention, the object to be inspected is heated or cooled from the front surface side and the back surface side, respectively, and the temperature distribution change of the surface of the object to be inspected is heated or cooled from the surface side; Compared with the case of heating or cooling from the side, even if impurities such as impurities other than delamination are mixed, delamination of the object to be inspected can be determined, and the inspection accuracy can be improved. it can.

  Furthermore, the defect inspection apparatus for a laminate of the present invention includes a heat source or a cooling source for heating or cooling a laminate as an object to be inspected from the front surface side and the back surface side, and the heat radiation distribution on the laminate surface at this time. The defect inspection method is smoothly implemented because it includes temperature distribution detection means to detect and data processing means for collecting and analyzing the temporal change data of the thermal radiation distribution detected by the temperature distribution detection means. For example, it can be applied to maintenance such as process inspection of solid oxide fuel cell and deterioration diagnosis after long-term use.

Hereinafter, the principle of the defect inspection method for the laminate of the present invention will be described in detail.
1 to 4 show an example in which the method for inspecting a defect of a laminate according to the present invention is applied to an inspection of a solid oxide fuel cell formed by forming an electrode 3 on an electrolyte 2. 1 shows a case where the object to be inspected is heated from the back surface (lower side in the drawing) of the cell which is the object to be inspected 1 having a laminated structure, that is, the electrolyte 2 side. In this case, the electrolyte 2 and the electrode 3 If delamination P occurs in between, the portion of delamination P functions as a heat insulating layer, so that the heat transfer from the electrolyte 2 to the electrode 3 is suppressed. The temperature rise will be delayed from the surrounding healthy part. Therefore, by observing the temperature distribution of the device under test 1 from the surface side (upper side in the figure), a portion having a temperature lower than the surroundings can be detected as the delamination P.

  FIG. 2 shows the case where the device under test 1 is heated from the surface side, that is, the electrode 3 side. In this case, when delamination P occurs between the electrolyte 2 and the electrode 3, This delamination P hinders heat transfer from the electrode 3 to the electrolyte 2, so that the temperature rise of the delamination portion in the electrode 3 becomes more prominent than the surrounding healthy portion. Therefore, when the temperature distribution of the device under test 1 is observed from the surface side, a portion having a higher temperature than the surroundings can be detected as delamination.

In the above description, the case where the object to be inspected 1 is heated from the back side and the front side has been described as an example. However, when cooled, the heat transfer is reversed. When heated from the side and when cooled from the back side, this is the same as when heated from the front side.
In addition, the electrode 3 side (upper side in the figure) is referred to as the front side, and the electrolyte 2 side (lower side in the figure) is referred to as the back side. Even if the temperature distribution is observed from the electrolyte 2 side, there is no problem.

Examples of the electrolyte 2 used in the above-described solid oxide fuel cell include YSZ (yttria stabilized zirconia), SSZ (scandium stabilized zirconia), SDC (samarium-doped ceria), LSGM (La _0.9 Sr _0.1 Ga _0.83 Mg _0.17 O ₃ ), GDC (gallium-doped ceria), etc. are used, but depending on the constituent materials, the color is considered to be due to the aggregation of impurities in the manufacturing process. Dark spots may be observed.
Even if such spots are present, they can be used as an electrolyte without any problems and cannot be said to be a defect, but because they absorb heat more easily and dissipate heat than the surroundings, the temperature of the surface of the object to be inspected Various effects on distribution.

For example, as shown in FIG. 3, when the device under test 1 is heated from the back side of the device under test 1, that is, the electrolyte 2 side, the spotted portion S due to the aggregation of impurities locally increases in temperature. Since it is observed as a high temperature part, the temperature distribution becomes complicated.
On the other hand, as shown in FIG. 4, even when the device under test 1 is heated from the surface side of the device under test 1, that is, from the electrode 3 side, the thickness of the electrode 3 is small, so Since it will be observed as a high temperature part and behaves in the same tendency as the part where the delamination S occurs, it is difficult to discriminate between the spot S and delamination P due to aggregation of impurities.

As described above, although the presence of the speckled portion S hardly causes a problem in performance, the delamination P is a serious defect that causes a decrease in the performance of the fuel cell. Therefore, it is necessary to distinguish between these and detect only the delamination P. is there.
Therefore, as shown in FIG. 3, the temperature distribution change when the object 1 is heated from the back side of the object 1 to be inspected, and the case where the object 1 is heated from the surface side as shown in FIG. The site where the delamination P is generated can be extracted by comparing the temperature distribution change and detecting the location where the difference in behavior is large.

  For example, by taking the difference or ratio (quotient) of the heat radiation distribution data in the case of the front side heating and the case of the back side heating, the healthy part or the spot part S showing the same behavior in the front side heating and the back side heating. In addition to canceling the data, the data of the portion where the delamination P is generated that exhibits reverse behavior between the front side heating and the back side heating can be expanded, and only the generation site of the delamination P can be detected with high accuracy. it can.

  In addition, when the to-be-inspected object 1 is cooled from the back surface side and the surface side, the spot part S is cooled first as mentioned above, and the said part will be observed as a low-temperature part. Since the speckled portion S exhibits the same behavior in the case of the front side cooling and the back side cooling, the occurrence of delamination P is generated by comparing the temperature distribution change in the case of the front side cooling and the back side cooling as described above. A site can be detected.

In the defect inspection method for a laminate according to the present invention, for example, an infrared lamp can be used as a heat source for heating the object to be inspected 1 from the front surface side or the back surface side. If it can heat, it will not be limited to this, A radiation type heater, a hot air blower, etc. can be utilized.
Further, in the defect inspection method of the present invention, it suffices if heat transfer in the stacking direction can be given to the inspection object 1, and the inspection object 1 can be cooled instead of being heated. Similarly, there is no particular limitation as long as the surface of the object to be inspected can be uniformly cooled in a non-contact manner. For example, an electronic cooler using a Peltier element can be used. When a Peltier element is used as a cooling source, it can be used as a heating source by reversing the direction of the current flowing through the element, so that defect detection can be performed without replacing the heat source.

  In order to detect the temperature distribution on the surface of the inspection object, for example, an infrared camera can be used. However, the temperature distribution is not limited to this as long as the temperature distribution in the inspection region of the inspection object can be detected.

  The surface temperature of the object 1 to be inspected shows a uniform temperature distribution immediately after the start of heating or cooling, and after a certain amount of time has elapsed after the start, the delamination P or the spot portion S due to impurity aggregation exists in the portion. If the temperature change begins to appear and further heating or cooling progresses, the entire object to be inspected becomes a uniform temperature, and the temperature difference distribution is not recognized. It is desirable. Further, as described above, it is also necessary to compare the temperature distribution change when the object 1 is heated (or cooled) from the front surface side and when heated (or cooled) from the back surface side.

  Therefore, it is desirable that the infrared camera has a pixel array and can capture a planar image of the entire inspection area of the object to be inspected, and stores and collects time-dependent data of the amount of radiant heat at each pixel. At the same time, it is desirable to use a microcomputer equipped with an arithmetic function and an image processing function for calculating a difference, a quotient (ratio), etc. between data as the data processing means.

The defect inspection apparatus for a laminate according to the present invention includes a heat source or a cooling source for heating or cooling an object to be inspected from the front surface side and the back surface side, a temperature distribution detection unit, and a data processing unit, and the defect inspection method described above. Can be carried out smoothly and can be practically used for inspection of various laminates.
That is, in the production line, since inspection can be performed in the middle of the process, useless processing for defective products can be avoided, and manufacturing cost can be reduced. For example, in the case of an electrolyte firing process in a solid oxide fuel cell, a potential defect can be detected by performing an inspection before firing, and the firing cost can be reduced.

  In addition, since the defect inspection apparatus of the present invention can be made compact and can be mounted on a vehicle, the defect inspection apparatus can be used for detecting a defect in a fuel cell for an automobile. In addition, by comparing each time with the previous evaluation data, it is possible to diagnose the deterioration over time during long-time use, and use it as an index for cell replacement.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

  FIG. 5 shows an example of a defect inspection apparatus for a laminate according to the present invention, and the defect inspection apparatus shown in the figure serves as a heat source for heating the laminate to be inspected from the front and back sides, respectively. Two infrared lamps 11 and 12, an infrared camera 20 as temperature distribution detecting means for detecting the thermal radiation distribution on the surface of the laminate, and connected to the infrared camera 20, and the detection data from the infrared camera 20 is changed over time. The infrared lamp 11 is composed of an electrolyte substrate 2 made of a solid oxide and an electrode 3 laminated thereon by a printing method. The laminated body 1 (inspected object) is disposed at a position where it can be heated from the front surface side, and the infrared lamp 12 is disposed at a position where the laminated body 1 can be heated from the back surface side.

  The infrared lamps 11 and 12 can almost uniformly heat the inspection target area of the laminate 1 from both surfaces thereof by radiant heat (infrared) H, and the infrared camera 20 is connected to the surface side of the laminate 1 (in this example, Radiation infrared rays h on the electrode 3 side) are detected, and a thermal radiation distribution over the entire surface of the inspection target region, that is, a temperature distribution is detected.

  The microcomputer 30 as data processing means is connected to the infrared camera 20 and includes a memory for storing distribution data of thermal radiation detected by the infrared camera 20 over time, and has an arithmetic function and an image processing function. Provide the display device (not shown) by calculating the difference and ratio between the stored data and emphasizing the temperature distribution on the surface of the laminate at any point in time and the part where delamination occurred by arithmetic processing Output.

Below, the inspection point of the laminated body 1 using the said defect inspection apparatus is demonstrated easily.
First, the position of the laminated body 1 that is an object to be inspected is adjusted to determine the inspection region.

  Next, after shielding between the infrared camera 20 and the laminate 1, a temperature distribution image on the surface side (electrode 3 side) of the laminate 1 before heating is taken by the infrared camera 20, and the thermal radiation distribution in this case Data is stored in the memory of the microcomputer 30.

  Then, the power source of the lower infrared lamp 11 is turned on to start heating from the back side of the laminated body 1, and the temperature distribution image of the laminated body surface is taken every predetermined time by the infrared camera 20, and the heat at that time The radiation distribution data is stored in real time.

Thus, when the collection of the heating data from the back surface side is completed, the power source of the lower infrared lamp 11 is turned off, and the laminated body 1 is radiated and cooled.
Then, the difference between the temperature distribution data collected by the microcomputer 30 for each time and the temperature distribution data before heating is calculated, the temperature distribution image having the most significant temperature difference is obtained, and is used as the temperature distribution data at the time of heating on the back side. .

  When it is confirmed that the heat dissipation of the laminated body 1 is finished and the entire temperature is uniformly reduced, the surface-side temperature distribution image of the laminated body 1 at this time is taken, and the thermal radiation distribution data is similarly stored. .

  Then, the upper infrared lamp 12 is turned on to start heating from the surface side of the laminate 1, and similarly, a temperature distribution image of the laminate surface is taken every predetermined time by the infrared camera 20, and at this time The thermal radiation distribution data is stored in real time.

  In this way, when the collection of the heating data from the surface side is completed, the upper infrared lamp 12 is turned off, the laminate 1 is allowed to cool, and the temperature distribution data collected by the microcomputer 30 for each time The difference of the temperature distribution data before the start of the surface side heating is calculated, the temperature distribution image having the most significant temperature difference is obtained, and is used as the temperature distribution data at the time of the surface side heating.

  Next, by calculating the difference between the temperature distribution data at the time of the back side heating and the temperature distribution data at the time of the front side heating obtained previously, image data other than the delamination P is created, which is not shown By outputting to the display device, it is possible to identify the part where the delamination P occurs from the image.

In the defect inspection method of this invention, it is explanatory drawing which shows the defect detection principle at the time of heating a laminated body from the opposite side of the observation surface of temperature distribution. In the defect inspection method of this invention, it is explanatory drawing which shows the defect detection principle at the time of heating a laminated body from the same side as the observation surface of temperature distribution. In the defect inspection method of this invention, it is explanatory drawing which shows the defect detection principle when the laminated body in which delamination and the speckle part were mixed is heated from the opposite side of the observation surface of temperature distribution. In the defect inspection method of this invention, it is explanatory drawing which shows the defect detection principle when the laminated body in which delamination and the speckle part were mixed is heated from the same side as the observation surface of temperature distribution. It is a block diagram which shows the structure of the defect inspection apparatus of the laminated body of this invention.

Explanation of symbols

1 Laminated body (inspected object)
P Delamination 11 Infrared lamp (heat source)
12 Infrared lamp (heat source)
20 Infrared camera (temperature distribution detection means)
30 Microcomputer (data processing means)

Claims (6)

  A test object having a laminated structure is heated or cooled from the front or back side, and the temperature distribution change of the test object surface during heating or cooling is detected to determine the presence or absence of delamination of the test object. A method for inspecting defects in a laminate.   Change in temperature distribution on the surface of the inspection object when the inspection object having a laminated structure is heated or cooled from the surface side, and temperature distribution on the surface of the inspection object when the inspection object is heated or cooled from the back side A defect inspection method for a laminated body, characterized by comparing the change and determining the presence or absence of delamination of an object to be inspected.   The difference between the heat radiation distribution data from the surface of the inspection object when the object is heated from the surface side and the heat radiation distribution data from the surface of the inspection object when the object is heated from the back side Alternatively, delamination is specified based on the ratio. The method for inspecting a defect of a laminate according to claim 2.   The difference between the heat radiation distribution data from the surface of the inspection object when the inspection object is cooled from the surface side and the heat radiation distribution data from the surface of the inspection object when the inspection object is cooled from the back side. Alternatively, delamination is specified based on the ratio. The method for inspecting a defect of a laminate according to claim 2. A heat source or a cooling source for heating or cooling an object to be inspected having a laminated structure from the front surface side and the back surface side, and
Temperature distribution detecting means for detecting thermal radiation distribution at an arbitrary position on the surface of the object to be inspected;
A defect inspection apparatus for a laminated body, comprising data processing means for collecting and analyzing temporal change data of thermal radiation distribution detected by the temperature distribution detection means.   An apparatus for inspecting a solid oxide fuel cell, comprising the defect inspection apparatus for a laminate according to claim 5, wherein the object to be inspected is a solid oxide fuel cell.

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