JP4873299B2 - Inspection and production method of inorganic insulator and apparatus therefor - Google Patents

Description

  The present invention relates to a firing state inspection method and manufacturing method of an inorganic insulator composed of a ceramic, metal oxide, glass mixture material and the like produced on a substrate surface such as iron or stainless steel, and an apparatus therefor.

An insulator formed of ceramic or the like has a thin film structure and is used for a multilayer ceramic capacitor, an electronic component, a power supply device, an ozone generator, and the like. Since a high voltage is applied to these insulators, it is naturally required to provide a technique capable of forming a uniform layer having excellent voltage resistance.
Conventionally, such an insulator layer is formed by applying a slurry of ceramic or glass mixed with a solvent, water, etc. to a thickness of about 100 to 1000 μm by spraying, spin coating, screen printing, etc. It was sintered in a high temperature sintering furnace at ˜1000 ° C. This slurry may be mixed with metal oxide. As the high-temperature sintering furnace, a batch type electric furnace, a tunnel-type firing furnace, a gas furnace or the like is used.

The insulating layer is composed of one or more layers on a metal substrate such as stainless steel or iron. In addition, a material having good reactivity is used for the layer in contact with the metal substrate in order to improve adhesion to the metal substrate surface. As a material for the layer imparting insulating properties, a material that generates less bubbles and a material that can have a thickness are required.
From this point of view, one or more types of materials are usually applied to the insulator to improve its function, and different materials are used for the base layer in close contact with the substrate and the surface layer that provides insulation. ing.

In Patent Document 1, in a layer that imparts insulation as described above, bubbles in the dielectric layer that become an obstacle to insulation are reduced to obtain high insulation, and a drying step is performed at 100 to 130 ° C. It is described that the firing step is 300 to 600 ° C. and discoloration due to the firing temperature occurs.
Patent Document 2 describes that when the firing temperature is increased, the formation of bubbles cannot be suppressed, so that the temperature at which the glass material is fired is 500 to 650 ° C. from the viewpoint of suppressing the generation of bubbles. .
As described above, conventionally, as a means for maintaining the insulation of the insulator satisfactorily, techniques for firing conditions, bubble states and measurement methods for the surface layer imparting the insulation of the insulator have been provided. .
JP 2002-133947 A Japanese Patent Laid-Open No. 11-345564

In such an insulator, the insulating slurry applied and baked by various coating apparatuses is generated in the insulating layer due to generation of gas (water vapor, carbon dioxide, organic gas, etc.) from the slurry in the process from the start to the end of baking. Air bubbles were often generated. Although some of the generated bubbles are discharged out of the layer in the firing stage, some remain in the insulating layer as they are. This is because bubbles are difficult to escape due to the high viscosity of the slurry, and before the bubbles are completely removed, the firing is completed and the insulating layer is cooled.
The bubbles remaining in these insulating layers generated a discharge inside the bubbles when a high voltage was applied to the insulator, and heat was generated by this discharge, and the insulation layer was destroyed by the heat. . It has been found that such discharges are less likely to occur in dense layers with smaller bubble diameters and fewer bubbles.
When bubbles are generated as described above, the number of bubbles and the bubble volume change depending on the firing temperature of the insulating layer. For this reason, it is important to control the temperature of the firing furnace. However, the temperature inside the furnace and the actual temperature of the insulation layer may vary due to the effects of radiant heat. It was difficult to strictly control and manage.

Conventionally, the following two methods have been taken to grasp the insulating characteristics of the insulating layer. Note that here, the insulating characteristic means a state in which the insulator does not break down when a voltage is applied to the insulator (corresponding to characteristics and withstand voltage).
(1) Actually, a high voltage is applied to the insulating layer, and a confirmation test is performed to determine whether the insulating layer can withstand a target voltage.
(2) The bubbles in the insulating layer are observed with a microscope, and the voltage at which the insulating layer breaks is estimated from the bubble diameter.
However, these two methods require working time, require the collection of a sample (test piece) of the insulating layer, and the test procedure is complicated, and it is not practical as a method for grasping the insulation characteristics of the total number of samples. There wasn't. Further, as described above, since there is a difference between the temperature in the furnace and the temperature applied to the actual insulating layer, even if the set temperature of the furnace is managed, the control and management of bubbles are insufficient.
Furthermore, Patent Document 1 and Patent Document 2 only disclose the relationship between the firing temperature of the insulating layer and the generation state of bubbles in the insulating layer, and the state of mixing of bubbles in the insulating layer can be simplified. There is no disclosure of a method for detecting or a method for suppressing the generation of bubbles.

  The present invention has been made in view of such a situation, and an object thereof is to eliminate the need to collect a sample (test piece) of an insulating layer, and to make a bubble of an insulator in a very simple method and in a short time. It is an object of the present invention to provide a method and apparatus for inspecting the firing state of an inorganic insulator, and a device for the same, which can accurately detect the occurrence state of the inorganic insulator and suppress the generation of bubbles by a simple method.

  The present invention pays attention to the fact that the cause of the generation of bubbles in the insulator is the base insulating layer having a function of improving the adhesion to the metal substrate. It is possible to easily evaluate the performance of the base insulating layer by correlating with the measured value of the reflectance of light to the insulating layer, and to suppress the generation of bubbles in the surface insulating layer that provides withstand voltage laminated on the base insulating layer It is what.

That is, the present invention of claim 1 is an inspection method and a manufacturing method of an inorganic insulator formed by firing an insulating layer made of an inorganic insulator such as ceramic on the surface of a metal substrate, and the method after the firing The reflectance of light on the surface of the insulating layer is measured, the reflectance is related to the state of the bubbles in the insulating layer, and the bubble generated in the insulating layer is determined from the measurement result of the reflectance. The contamination state is estimated.
In the present invention, preferably, the insulating layer is formed of a base insulating layer fired on the surface of the metal substrate and a surface insulating layer fired outside the base insulating layer, and is formed on the surface of the metal substrate. The reflectance of the base insulating layer fired body obtained by firing the base insulating layer is measured at a plurality of locations of the base insulating layer fired body.

In the present invention, the following configuration is preferable.
(1) The relationship between the reflectance and the state of mixing of bubbles in the insulating layer is set with parameters of firing conditions such as the firing temperature and firing time of the insulating layer, and the measurement result of the reflectivity is measured for the bubbles. Corresponding to the set values of the mixing state and the baking conditions, the optimum baking conditions that minimize the mixing of bubbles are calculated, and the insulating layer is fired on the surface of the metal substrate according to the optimum baking conditions.

  (2) The relationship between the reflectivity and the mixed state of bubbles in the insulating layer, with the firing condition as a parameter, the firing temperature under the firing condition is high, and as the firing time becomes longer, the reflectance becomes smaller and A setting table set to reduce the mixing amount is prepared, and the reflectance measurement result is made to correspond to the setting table so that the reflectance is minimized and the mixing amount of the bubbles is minimized. The insulating layer is fired on the surface of the metal substrate under firing conditions.

  (3) A standard illumination light source, a spectral function, a reflectance measurement and calculation function, or a spectrocolorimeter with a built-in calculation function is used for the reflectance measurement.

The invention of claim 6 is an invention of an apparatus for carrying out the method invention,
In an inorganic insulator inspection apparatus for inspecting an inorganic insulator formed by firing an insulating layer made of an inorganic insulator such as ceramic on the surface of a metal substrate, a reference for the reflectance of light on the surface of the insulating layer Means for preliminarily storing the reference reflectance, means for storing the measured reflectance newly measured by the reflectance measuring device, and comparing the reference reflectance with the measured reflectance to determine whether the insulating layer is acceptable or not. And means for judging.

  In this invention, Preferably, the said reflectance measuring apparatus is comprised so that a movement along the surface of the said insulating layer is possible, From the mobile reflectance measuring apparatus which detects the reflectance of the said insulator surface intermittently or continuously. (Claim 7).

The ceramic material that is an insulating layer has features such as improved adhesion to the metal substrate, uniform thermal expansion coefficient with the metal substrate, high heat resistance, and small temperature resistance change.
Such a ceramic material contains glass or alumina as a main component, and also contains trace amounts of metal oxides such as copper oxide, cobalt oxide, nickel oxide, and titanium oxide.
It is known that an insulating material serving as a base for improving adhesion to a metal substrate contains an oxide such as copper oxide or cobalt oxide in order to improve the reactivity with the metal substrate. When the reactivity with the metal substrate is improved in this manner, gas (carbon dioxide or the like) is generated by the reaction at the interface between the metal surface and the insulating layer, and bubbles due to the gas are easily generated in the insulating layer.
The size and volume of bubbles generated in the insulating layer are related to firing conditions such as the firing temperature and firing time of the insulating layer. The firing conditions of the base insulating layer and the generation state of bubbles can be correlated with the reflectance of light to the base insulating layer.

  Based on the above knowledge, the present invention measures the reflectance of light on the surface of the insulating layer after firing, correlates the reflectance with the state of bubbles in the insulating layer, and the reflectance measurement results In particular, it is configured to estimate the mixed state of bubbles generated in the insulating layer. Specifically, the insulating layer includes a base insulating layer fired on the surface of the metal substrate, and an outer side of the base insulating layer. The reflectance in a base insulating layer fired body formed by firing a base insulating layer on the surface of the metal substrate is measured at a plurality of locations of the base insulating layer fired body. (Claims 1, 2, 5, and 6).

Therefore, according to the present invention, the reflectance of light in the insulating layer, specifically the underlying insulating layer fired on the surface of the metal substrate, is measured, and the reflectance is related to the state of bubbles in the insulating layer. By setting the reflectance measurement value to correspond to the setting table prepared in this manner, the bubble generation state in the insulating layer is measured, the light reflectance is measured, and the reflectance and the bubble state are related to each other. It is possible to accurately grasp the reflectance only by corresponding to the measured value.
Thereby, it is not necessary to collect a sample (test piece) of the insulating layer as in the prior art, and it is possible to accurately detect the generation state of the bubbles in the insulator in a very simple method and in a short time.

  Further, according to the present invention, the relationship between the reflectance and the mixed state of bubbles in the insulating layer is set such that the firing temperature is high and the firing temperature is long with the firing conditions such as firing temperature and firing time as parameters. A setting table that is set in advance so that the reflectance is small and the amount of bubbles mixed in is reduced, and the measurement result of the reflectance is made to correspond to the setting table so that the reflectance is minimized. By firing the insulating layer on the surface of the metal substrate at a firing temperature and firing time that minimizes the amount of bubbles mixed in (Claims 3 to 5), the performance of the underlying insulating layer can be simply evaluated and the base It is possible to suppress the mixing of bubbles into the insulating layer to the minimum, and to suppress the generation of bubbles in the surface insulating layer that provides voltage resistance stacked on the base insulating layer.

  Further, if the reflectance measuring device is configured to be movable along the surface of the insulating layer and configured to be a mobile reflectance measuring device that intermittently or continuously detects the reflectance of the insulator surface (claim). 7) The reflectance measurement time can be shortened and the number of evaluation experiment steps can be reduced, and the movable reflectance measuring device can be moved freely in the axial direction and the circumferential direction of the base insulating layer fired body, The reflectance can be measured uniformly over the entire surface of the base insulating layer fired body, and the measurement accuracy of the evaluation experiment can be improved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings and based on experimental results.
FIG. 1 is a configuration diagram of an ozone generator to which an embodiment of the present invention is applied, in which (A) is a cross-sectional view cut in the longitudinal direction of a cylindrical tube, and (B) is a cross-sectional view taken along line AA in (A). FIG.
In FIG. 1 showing a configuration of an ozone generator to which an embodiment of the present invention is applied, reference numeral 1 denotes a cylindrical tube (metal substrate) made of a metal material. An insulating layer made of a ceramic material of two layers of the surface insulating layer 3 outside the base insulating layer 2 is formed.
The ceramic material constituting the base insulating layer 2 and the surface insulating layer 3 has characteristics such as improving adhesion with the cylindrical tube 1 as a substrate, aligning an expansion coefficient with the cylindrical tube 1, and having heat resistance, It contains glass and alumina as the main components, and contains trace amounts of metal oxides such as copper oxide, cobalt oxide, nickel oxide, and titanium oxide.
The ceramic material slurry used for the insulating layer mainly contains soda glass and borosilicate glass powders, and contains oxides such as alumina, copper oxide, nickel oxide, cobalt oxide and titanium oxide. It is melted. This glass may be an inorganic oxide glass mainly composed of silicic acid.
Glass in the ceramic material according to this embodiment accounts for about 60% of the total, alumina is about 10%, metal oxides are about 20% in total, and the remainder is an alkali component such as sodium and potassium.

Moreover, in order to improve the reactivity with the cylindrical tube 1 (metal substrate), the material of the base insulating layer 2 as a base for improving the adhesion to the cylindrical tube 1 (metal substrate) may be copper oxide or Oxides such as cobalt oxide are contained.
Therefore, by adding the above oxide to improve the reactivity, gas (carbon dioxide etc.) is generated by reaction at the interface between the metal surface of the cylindrical tube 1 (metal substrate) and the base insulating layer 2. And it will be in the state where the bubble by this tends to generate.
In the embodiment of the present invention, the cause of generation of bubbles at the interface between the metal surface of the cylindrical tube 1 (metal substrate) and the insulator, that is, the base insulating layer 2 as described above, is in close contact with the cylindrical tube 1 (metal substrate). Focusing on the fact that it is in the base insulating layer 2 having a function of improving the performance, the firing condition of the base insulating layer 2 and the generation state of bubbles are related to the reflectance of light to the base insulating layer 2 to easily perform the performance. This means is used to provide means for suppressing the generation of bubbles in the surface insulating layer 3 that imparts voltage resistance and is laminated on the insulating layer.

In FIG. 1, a metal material such as iron or stainless steel is used for the cylindrical tube 1. On the surface of the cylindrical tube (metal substrate) 1, a base insulating layer 2 having good reactivity is applied and baked for the purpose of improving adhesion to the metal substrate. After the base insulating layer 2 is formed, the surface insulating layer 3 made of a low-reactive material that imparts withstand voltage is applied and baked. At this time, the surface insulating layer 3 may be applied by spraying or dipping. As the substrate on which the insulating layers 2 and 3 are formed, a flat plate, a curved plate, or the like may be used in addition to the cylindrical shape as in the present embodiment. Moreover, the application direction of the layer can be single-sided or double-sided.
Further, since the thickness of the base insulating layer 2 is intended to adhere to the substrate, it is not necessary to increase the thickness, and 10 to 100 μm, preferably 30 to 80 μm is appropriate.
Furthermore, the thickness of the surface insulating layer 3 is 200 to 600 μm, preferably 300 to 500 μm. This is because if the thickness is less than 200 μm in order to provide insulation performance, pinholes are likely to occur in the formation layer, and if the thickness is more than 600 μm, the film thickness unevenness occurs. Is.

After applying the slurry of the ceramic material to the outer peripheral surface of the cylindrical tube 1 (metal substrate) so as to have the dimensions of the base insulating layer 2 and the surface insulating layer 3 as described above, the base insulating layer 2 and the surface insulating layer 3 are It is formed by the following steps.
(1) As shown in FIG. 1, a cylindrical body coated with a slurry of a ceramic material for forming a base insulating layer 2 and a surface insulating layer 3 on a cylindrical tube 1 is preliminarily dried at 100 to 200 ° C. to remove moisture. To do.
(2) The cylinder coated with the slurry is baked for about 1 to 20 minutes in a high temperature furnace at 700 to 1000 ° C.
(3) The fired cylinder is gradually cooled.

2A and 2B are views showing a molded product of the base insulating layer fired body 20 obtained by applying a ceramic material slurry to the cylindrical tube (metal substrate) 1 and firing the base insulating layer 2. FIG. (A) is sectional drawing in alignment with an axial direction, (B) is BB sectional drawing in (A).
As shown in FIGS. 2A and 2B, the base insulating layer 2 is made of a metal substrate during firing of the base insulating layer fired body 20 in which the ceramic material slurry is applied to the cylindrical tube (metal substrate) 1. When gas is generated due to high reactivity with the cylindrical body 1 and firing is completed with insufficient release of the gas, and the surface insulating layer 3 is applied and fired, the base insulating layer 2 reacts again. Gas is generated, which causes a large number of bubbles 4 to be formed.
Therefore, it is desirable that the base insulating layer 2 has a baking temperature of 800 to 1000 ° C. and a baking time of 10 to 20 minutes with a high baking temperature and / or a long baking time so that gas can be released sufficiently.

Here, as described above, when light is irradiated on the surface of the insulator, the reflectance of light from the surface of the insulator changes according to the brightness of the surface of the insulator. When the surface of this insulator is close to white and has high brightness, the reflectance increases, and as the surface becomes a dark color close to black and the brightness decreases, the reflectance decreases.
On the other hand, when the firing temperature of the insulator is low or the firing time is short and firing is insufficient, the gas is not sufficiently released from the inside of the insulator, and the amount of bubbles generated inside the insulator is large. Become.
Table 1 shows the firing conditions and the firing conditions in the base insulating layer fired body 20 obtained by firing the base insulating layer 2 on the cylindrical tube (metal substrate) 1 in the ozone generator (insulator formation product) as shown in FIGS. It is a table | surface which shows the measurement result of the relationship between the reflectance of light, and the bubble volume of the base | substrate insulating layer 2. FIG. 3 is based on Table 1, and is a diagram showing the measurement results of the relationship between the firing time and firing temperature of the base insulating layer fired body 20 and the light reflectance, and FIG. 4 is based on Table 1. It is a diagram showing the measurement results of the relationship between the firing time and firing temperature of the base insulating layer fired body 20 and the bubble volume of the base insulating layer 2.

As shown in Table 1, FIG. 3 and FIG. 4, the firing state of the base surface layer 2 is represented by the bubble volume and is associated with the reflectance.
The reflectivity measurements shown in Table 1, FIG. 3 and FIG. 4 were performed after the base insulating layer 2 was formed as described in the above (1) to (3). The apparatus used for the measurement of the reflectance was a color difference meter (manufactured by Konica Minolta, CR-400), and Y, x, and y were used as the color system. The reflectance is represented by Y (x and y represent chromaticity, which is not used in this embodiment). In addition to these, there are several color systems such as Munsell color system and Hunter Lab color system, each of which has a different numerical value of reflectance, but it has the same use in terms of representing reflectance.
The reflectance measurement is not limited to the color / color difference meter, but a standard illumination light source, a spectral function, a reflectance / measurement function and a color / color difference meter with a built-in calculation function, or a spectral colorimeter can be used.
Further, the bubble volume (cm ³ ) of the base insulating layer 2 was obtained as a numerical value per unit volume (cm ³ ) of the insulating layer based on the bubble diameter and the number of bubbles in the observation field by photographing a cross section with an optical microscope.
FIG. 5 shows an example of imaging of a cross-sectional shape of a void actually recognized in the base insulating layer 2.
As apparent from Table 1, FIG. 3 and FIG. 4, the reflectivity decreases as the firing temperature of the underlying insulating layer 2 increases or the firing time increases, thereby reducing the bubble volume and generating bubbles. The amount is reduced.

In this manner, the base insulating layer fired body 20 is formed, and the base insulating layer fired body 20 is coated and fired in such a manner that the surface insulating layer 3 is laminated on the base insulating layer 2.
The surface insulating layer 3 is made of a low-reactivity material, and the gas of the base insulating layer 2 is sufficiently released by the above-described means to reduce the bubbles 4 so that the firing conditions can be widened. The management of the firing conditions may be performed at a set value. It is desirable that the firing temperature of the surface insulating layer 3 is 700 to 900 ° C. and the firing time is about 3 to 10 minutes.

Table 2 shows that the base insulating layer 2 is fired on the cylindrical tube (metal substrate) 1 while changing the firing conditions, and the surface insulating layer 3 is fired under the same firing conditions to form an insulating layer. This is a table showing the relationship between the firing conditions of the base insulating layer 2, the reflectance, and the breakdown voltage. FIG. 6 is based on Table 2, and the base insulating layer 2 is fired on the cylindrical tube (metal substrate) 1 while changing the firing conditions, and the surface insulating layer 3 is fired under the same firing conditions for insulation. FIG. 3 is a diagram showing a result of a breakdown test performed by forming an ozone generator (insulator formation product) by forming a layer, and is a diagram showing a relationship between a firing condition of the base insulating layer 2, a reflectance, and a breakdown voltage.
As apparent from Table 2 and FIG. 6, the lower the reflectivity of the base insulating layer 2, the higher the voltage leading to the destruction of the entire ozone generator (insulator formation), and the better the insulation. It was.
Therefore, it can be seen from Table 2 and FIG. 6 that when the breakdown voltage is set to 15 kv or more, a reflectance smaller than about 5.0 may be taken as the pass line.

[Example 1]
In the base insulating layer 2 formed of the ceramic material slurry used in the embodiment of the present invention described above, the threshold value of the voltage necessary for insulation is set to 15 kv, and the reflectance of the base insulating layer 2 is measured, and the measurement is performed. Pass / fail was evaluated based on the results.
In this evaluation experiment, the base insulating layer fired body 20 shown in FIGS. 2A and 2B was used. The base insulating layer 2 was fired at 900 ° C. and the firing time was 10 minutes. A comparison was made with a reference value where the acceptance criterion was a reflectance Y = 5.0 or less. The surface insulating layer was formed at a baking temperature of 800 ° C. and a baking time of 5 minutes.
FIG. 7 shows the measurement result of the breakdown voltage of the base insulating layer 2 in this evaluation experiment.
In the measurement of the firing temperature with a thermocouple, the actual temperature ranged from 780 to 820 ° C., but as shown in FIG. 7, all the voltages leading to breakdown satisfied the allowable voltage of 15 kv (threshold) or more. .

[Example 2]
FIG. 8 shows a situation in which the reflectance in Example 1 is measured using a mobile reflectance measuring machine 5 capable of continuous or intermittent measurement, (A) is a cross-sectional view showing an axial measurement situation, (B) is sectional drawing which shows the measurement condition of the circumferential direction.
The mobile reflectivity measuring machine 5 shown in FIG. 8 is preferably provided with a cushioning material such as a rubber sheet at the tip that contacts the base insulating layer 2. In this embodiment, the movable reflectance measuring machine 5 is moved in the axial direction of the base insulating layer fired body 20 as shown in FIG. 8A, or the base insulating layer as shown in FIG. 8B. The reflectance was measured by moving the fired body 20 in the circumferential direction.
By using the mobile reflectance measuring machine 5, the reflectance measurement time can be shortened and the number of evaluation experiment steps can be reduced, and the mobile reflectance measuring machine 5 can be used in the axial direction of the base insulating layer fired body 20 and By freely moving in the circumferential direction, the reflectance can be measured uniformly over the entire surface of the base insulating layer fired body 20, and the measurement accuracy of the evaluation experiment can be improved.

While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made based on the technical idea of the present invention.
For example, in the above-described embodiment, the present invention is applied to a cylindrical ozone generator. However, the present invention is not limited to a cylindrical ozone generator, and a flat plate ozone generator having an insulating layer on a metal substrate. In addition, even in an electronic insulating substrate or the like mounted on an electronic component, the insulating performance can be evaluated and the insulating layer can be formed by the same method as the above-described embodiment.

  According to the present invention, it is not necessary to collect a sample (test piece) of the insulating layer, and it is possible to accurately detect the state of generation of bubbles in the insulator in a very simple method and in a short time, and also by a simple method. It is possible to provide a firing state inspection method and manufacturing method of an inorganic insulator capable of suppressing the generation of bubbles, and an apparatus therefor.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the ozone generator with which embodiment of this invention is applied, Comprising: (A) is sectional drawing cut | disconnected in the longitudinal direction of a cylindrical tube, (B) is AA sectional view taken on the line in (A). . 1 shows a molded article of a base insulating layer fired body obtained by applying a ceramic material slurry to a cylindrical tube and firing the base insulating layer, (A) is a sectional view along the axial direction, and (B) is in (A). It is a BB sectional view. It is based on Table 1, Comprising: It is a diagram which shows the measurement result of the relationship between the baking time and baking temperature of a base insulating layer baking body, and the reflectance of light. It is based on Table 1, Comprising: It is a diagram which shows the measurement result of the relationship between the baking time and baking temperature of a base insulating layer baking body, and the bubble volume of a base insulating layer. It is explanatory drawing which shows an example of the imaging of the cross-sectional shape of the void actually recognized by the base | substrate insulating layer. A diagram showing the relationship between the firing conditions of the underlying insulating layer, the reflectivity, and the breakdown voltage, based on Table 2, which is the result of a destructive test performed by producing an ozone generator (insulator formation). It is. It is a diagram which shows the measurement result of the breakdown voltage of the base insulating layer in the said evaluation experiment. The situation where the reflectance is measured using a mobile reflectance measuring machine capable of continuous or intermittent measurement is shown, (A) is a cross-sectional view showing the measurement situation in the axial direction, and (B) is a measurement in the circumferential direction. It is sectional drawing which shows a condition.

Explanation of symbols

1 Cylindrical tube (metal substrate)
2 Insulating base layer 3 Surface insulating layer 4 Bubble 5 Mobile reflectance measuring machine

Claims (7)

  A method for inspecting and manufacturing an inorganic insulator obtained by firing an insulating layer made of an inorganic insulator such as ceramic on the surface of a metal substrate, wherein the reflectance of light on the surface of the insulating layer after firing is determined. Measure, correlate the reflectance and the state of bubbles in the insulating layer, and estimate the mixed state of bubbles generated in the insulating layer from the measurement result of the reflectance Inspection and production method for inorganic insulators.   The insulating layer is formed by a base insulating layer fired on the surface of the metal substrate and a surface insulating layer fired outside the base insulating layer, and the base insulating layer is fired on the surface of the metal substrate. 2. The method for inspecting and manufacturing an inorganic insulator according to claim 1, wherein the reflectance in the underlying insulating layer fired body is measured at a plurality of locations of the underlying insulating layer fired body.   The relationship between the reflectance and the mixed state of bubbles in the insulating layer is set by setting the baking conditions such as the baking temperature and baking time of the insulating layer as parameters, and the measurement result of the reflectance is mixed with the bubbles and The optimum firing condition that minimizes the mixing of bubbles is calculated in accordance with the set value of the firing condition, and the insulating layer is fired on the surface of the metal substrate according to the optimum firing condition. Inspection and production method of the inorganic insulator described.   Using the firing condition as a parameter, the relationship between the reflectivity and the state of air bubbles in the insulating layer as a parameter, the firing temperature under the firing condition is high, and the reflectance decreases with increasing firing time, and the amount of air bubbles mixed in increases. A setting table set to be reduced is prepared, the measurement result of the reflectance is made to correspond to the setting table, and the baking condition is such that the reflectance is minimized and the amount of bubbles mixed is minimized. The method for inspecting and manufacturing an inorganic insulator according to claim 3, wherein the insulating layer is fired on a surface of the metal substrate.   2. The inorganic insulator according to claim 1, wherein a standard illumination light source, a spectral function, a reflectance measurement and calculation function, or a spectral colorimeter is used for the reflectance measurement. Inspection and production method.   In an inorganic insulator inspection apparatus for inspecting an inorganic insulator formed by firing an insulating layer made of an inorganic insulator such as ceramic on the surface of a metal substrate, a reference for the reflectance of light on the surface of the insulating layer Means for preliminarily storing the reference reflectance, means for storing the measured reflectance newly measured by the reflectance measuring device, and comparing the reference reflectance with the measured reflectance to determine whether the insulating layer is acceptable or not. An inspection apparatus for an inorganic insulator, characterized by comprising:   The reflectance measuring device is configured to be movable along the surface of the insulating layer, and includes a mobile reflectance measuring device that intermittently or continuously detects the reflectance of the insulator surface. The inspection apparatus for an inorganic insulator according to claim 6.

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