JP6475536B2 - Thermally conductive glass lining, thermal conductive glass lining structure and thermal conductive glass lining construction method - Google Patents

Description

  The present invention relates to a glass lining having corrosion resistance, which is used in the chemical industry, the pharmaceutical industry, the food industry and the like, and is excellent in thermal conductivity. Moreover, this invention relates to the construction method made from the heat conductive glass lining comprised from the said heat conductive glass lining, and the construction method of heat conductive glass lining.

A glass layer composed of siliceous (SiO ₂ ) and alumina (Al ₂ O ₃ ) is strongly fired and bonded to the metal surface. Of these, those with particularly excellent acid resistance, alkali resistance and heat resistance This is called glass lining (GL). GL used for GL devices and the like is manufactured by baking an undercoat glaze on a metal substrate such as a low-carbon steel plate or a stainless steel plate, and then baking an overcoat glaze with high corrosion resistance.

  GL equipment usually forms a subbing GL layer on the surface of a metal substrate such as a low carbon steel plate or a stainless steel plate by firing a subbing GL composition to improve adhesion to the substrate surface. On top of this, the overcoat GL composition having various compositions having desired corrosion resistance is fired to form an overcoat GL layer. Generally, the thickness of the undercoat GL layer is about 0.2 to 0.5 mm, and the thickness of the overcoat GL layer is about 1.3 to 2.0 mm. The total thickness of the GL layer including the undercoat GL layer and the overcoat GL layer is about 1.5 to 2.4 mm.

  Since glass lining has high corrosion resistance, various improvements have been made to take advantage of its properties. For example, Patent Document 1 discloses a GL composition that can be thinned and has good thermal conductivity, in particular, a GL composition for an undercoat and a GL composition for an undercoat. The GL composition for the top powder of Patent Document 1 is composed of one or more inorganic refractory powders selected from the group consisting of silica, alumina, and aluminum nitride, and an extra 1 for 100% by mass of the frit. It is characterized by containing ˜20% by mass, and the GL composition for the undercoat is composed of one or more inorganic refractory powders selected from the group consisting of quartzite, alumina and aluminum nitride, and 100% by mass of frit. It is characterized by containing 20 to 120% by mass in an external ratio with respect to%.

  Patent Document 2 discloses a GL composition for lowering and uppering for solving the same problem as Patent Document 1. The GL composition for the under-grinding and the under-grinding of Patent Document 2 has a frit in which the particle diameter of the frit constituting the GL composition is in the range of 0.1 to 250 μm, and the particle diameter is in the range of 0.1 to 1 μm. It is characterized in that the proportion of fine particles is in the range of 1 to 50% by mass, and the normal particle size distribution of the frit is 50% and in the range of 1.5 to 20 μm.

  On the other hand, since GL is easily charged with static electricity, there is a multilayer GL in which a conductive material is added to the overcoat GL layer in order to prevent dielectric breakdown due to electrostatic discharge. Patent Document 3 describes (1) a metal substrate, (2) an undercoating GL layer and an overcoating GL layer that are fired without adding an electroconductive substance to the glass frit, and (3) an electroconductive substance on the glass frit. A conductive GL composed of at least three GL layers of the uppermost conductive GL layer added and baked so that the outermost conductive GL layer covers the metal material at the end. An electrically conductive GL is disclosed in which the outermost layer and the metal base are grounded by construction. This conductive GL is not easily charged with static electricity, is resistant to dielectric breakdown due to electrostatic discharge, and is easy to control quality.

  Patent Document 4 discloses a heat conductive glass lining obtained by pre-treating a heat conductive filler and then mixing and baking it in a glass frit.

JP 2010-195640 A JP 2013-151401 A JP 2010-248632 A JP 2012-111665 A

  In the inventions disclosed in Patent Document 1 and Patent Document 2, it is possible to prevent the generation of bubbles during the construction of the overcoat GL layer, and to make the GL layer thin, but from the undercoat GL layer, There is no consideration for the suppression of bubble loss. Since the undercoat GL layer forms an adhesion layer by a chemical reaction between the glass frit and the steel plate, bubbles are more likely to be generated during construction than the overcoat GL layer due to the progress of the chemical reaction. When coarse bubbles are generated in the undercoat GL layer, bubbles easily escape into the overcoat GL layer, which is the upper layer, and in some rare cases, a part of the undercoat GL layer lowers the bottom of the overdraw GL layer as the bubbles rise. May be mixed in the part. Furthermore, since the metal substrate also generates gas due to the high temperature during firing, the generated gas may rise as bubbles in the undercoat GL layer, and bubbles may escape into the overcoat GL layer.

  In addition, when the overcoat GL layer is fired, bubbles in the undercoat GL layer are bubbled out into the overcoat GL layer, and if such bubbles or bubbles are present in the overcoat GL layer, corrosion resistance may be lowered. Therefore, it is necessary to repair the relevant part. For this reason, it was inevitable that the upper GL layer was repeatedly applied to the layers while repairing. When the thickness of the GL layer is increased, the heat transfer performance of the GL layer portion is lowered. Therefore, it is preferable to thinly apply the overcoat GL layer from the viewpoint of keeping the heat transfer performance good. However, even if it was desired to construct thinly, it was technically difficult for the reasons described above.

  Furthermore, in the invention disclosed in Patent Document 3, it is an object to increase the electrical conductivity of the GL surface, but it is technically necessary to suppress foam removal or repeatedly bak and apply the top GL layer. The problem is not considered.

  Furthermore, in the invention disclosed in Patent Document 4, it is disclosed that the filler is added to the GL layer to increase the thermal conductivity, but when a large amount of filler is added to improve the thermal conductivity, There is a problem that the glossiness of the GL layer surface is lost, the aesthetic appearance is impaired, and the smoothness of the GL layer surface is also lost. There is also a problem that the residual compressive stress of the GL layer is reduced by increasing the amount of filler added.

  An object of the present invention is to provide a GL that prevents bubbles from being removed from the undercoat GL layer during the construction of the overcoat GL layer, and has improved thermal conductivity, and a method for producing the same.

  The present inventors have intensively studied to solve the above problems. As a result, between the undercoat GL layer and the overcoat GL layer, an intermediate is fired by adding a filler (excluding noble metals) to a glass frit that can be constructed as an overcoat GL layer (glass frit for the overcoat GL). It is found that by applying a layer, bubbles can be prevented from being removed from the undercoat GL layer to the overcoat GL layer, and by adding a filler to the intermediate layer, the thermal conductivity can be improved, and the present invention is completed. It came to.

Specifically, the present invention
A metal substrate;
Three GL layers, an undercoat GL layer, an intermediate GL layer, and an overcoat GL layer;
A GL consisting of
The intermediate GL layer is
Thermal conductivity, formed by adding a filler (excluding noble metal) to the glass frit for the overcoat GL, and formed between the undercoat GL layer and the overcoat GL layer Regarding GL.

  The undercoat GL layer is designed to have a composition in which the reaction with the metal base material is likely to proceed in order to ensure adhesion with the metal base material. Moreover, in order to prevent the loss | disappearance of the glass at the time of baking (generally a phenomenon called burnout), many refractory materials etc. are contained. Therefore, the undercoat GL layer has a general feature that the foam content is about 20 to 30%.

  Therefore, in the heat conductive GL of the present invention, as an upper layer of the undercoat GL layer, an intermediate GL layer is formed by adding a filler (excluding noble metals) to the glass frit for the overcoat GL, and the overcoat is formed as the upper layer. A technical feature is to constitute a three-layer GL structure in which a GL layer is formed. As the upper layer of the subbing GL layer, it contains a filler excluding precious metals and forms an intermediate GL layer composed of a glass frit for the subbing GL. It becomes possible to suppress the movement of bubbles from the GL layer. As a result, it is possible to suppress bubble bubbles from the undercoat GL layer to the overcoat GL layer, and to improve the workability of the uppermost GL layer. Moreover, by adding a filler to the intermediate layer, the thermal conductivity can be improved as compared with the case where no filler is added.

The thickness of the three GL layers is 0.6 mm or more and 1.8 mm or less,
The thickness of the undercoat GL layer is 0.1 mm or more and 0.4 mm or less,
The thickness of the intermediate GL layer is preferably adjusted to be 0.1 mm or greater and 1.0 mm or less.

  In the GL of the present invention, the undercoat GL layer is applied with a thickness of 0.1 mm to 0.4 mm, and then the intermediate GL layer is applied with a thickness of 0.1 mm to 1.0 mm. Then, the upper GL layer is applied to the upper layer of the intermediate GL, and the thickness of the three GL layers of the upper GL layer, the intermediate layer, and the lower GL layer is adjusted to 0.6 mm or more and 1.8 mm or less. By providing the intermediate GL layer, it is possible to suppress bubble removal from the undercoat GL layer, and when the thickness of the GL layer is in the above range, the GL is compared with the conventional general GL. It is also possible to sufficiently improve the thermal conductivity of the entire layer.

The filler is one or more of alumina, stannic oxide, magnesium oxide, silicon nitride, silicon carbide, or boron nitride,
The amount of the filler in the intermediate GL layer is preferably 30 volume% 5 volume% or more to the upper coating GL glass frit.

  As the filler added to the glass frit for the GL layer, noble metals such as gold, silver or platinum are also used, but these noble metals are very expensive. Further, since the coefficient of thermal expansion is significantly different from that of the glass frit for GL, it is not possible to make the amount of addition sufficient to enhance the effect of preventing bubble removal. Therefore, although the thermal conductivity of the filler itself is high, improvement in the thermal conductivity of the entire GL layer cannot be expected.

  On the other hand, non-noble metal thermally conductive fillers such as aluminum oxide (alumina) can be effective in improving the workability of GL and practical because they can exhibit the effect of preventing foam loss despite being inexpensive. Furthermore, since the addition amount can be increased by using a non-noble metal thermally conductive filler, it is effective for improving the thermal conductivity of GL.

  However, non-noble metal thermal conductive fillers such as alumina may have a residual compressive stress of the GL layer that is smaller than that of a normal GL layer when the amount added to the glass frit is increased in order to improve the effect of preventing bubble removal. The inventors have discovered that this is the case. Therefore, by providing a glass layer containing no filler on the surface, it is possible to impart gloss to the GL surface and strengthen residual compressive stress.

  The present invention also relates to a GL structure composed of the GL of the present invention.

The present invention also provides
Firing a glass frit for subbing without adding a filler, and applying a subbing GL layer on a metal substrate;
Firing a glass frit for overcoating to which a filler has been added, and applying an intermediate GL layer on the undercoating GL layer;
Firing a glass frit for overcoating without adding a filler, and applying an overcoating GL layer on the intermediate GL layer;
It is related with the construction method of GL characterized by having.

  According to the present invention, the thermal conductivity of the entire GL layer is improved, and a thermal conductive GL excellent in workability is obtained.

Sectional drawing of general GL comprised from a metal base material, undercoat GL layer, and overcoat GL layer is shown. Sectional drawing of the heat conductive GL of this invention is shown. The explanatory view of the instrument used in order to infer the thermal conductivity of a GL test piece is shown.

  Embodiments of the present invention will be described with reference to the drawings as appropriate. The present invention is not limited to the following description.

  FIG. 1 shows a cross-sectional view of a general GL composed of a metal substrate, an undercoat GL layer, and an overcoat GL layer. As the GL metal substrate, low carbon steel or stainless steel is commonly used. First, an undercoat GL layer is formed on the metal substrate. Generally, the thickness of the undercoat GL layer is about 0.2 to 0.3 mm. After firing the undercoat GL layer, a plurality of overcoat GL layers are fired as an upper layer.

  As described above, the subbing GL layer is likely to generate bubbles during construction. When coarse bubbles are generated in the undercoat GL layer during firing of the overcoat GL layer, bubbles are bubbled out from the undercoat GL layer at the bottom of the overcoat GL layer, and pinhole-like defects are generated. The lining surface may be damaged. Therefore, in order to repair defects caused by bubbles, it is common to repeatedly apply the overstretch GL layer a plurality of times to form a complete lining surface without pinholes. For this reason, it is necessary to construct the top GL layer to have a thickness of about 1.2 to 1.8 mm, and the average construction thickness of the entire GL layer is often 1.5 to 2.4 mm. The GL layer is baked by being sprayed a plurality of times. In FIG. 1, the top GL layer is formed as 4 to 6 layers.

  If the bubble removal from the undercoat GL layer can be prevented and the workability can be improved, the thickness of the overcoat GL layer can be reduced. The thermal conductivity of the GL layer of a general GL device is about 1.0 W / m · K, which is very low compared to the thermal conductivity of a metal substrate (the thermal conductivity of iron is 45 W / m · K). ). The GL device adjusts the temperature inside the device by heating or cooling the metal base material of the device with a heat medium flowing in a jacket installed outside the GL device. However, since the thermal conductivity of the GL layer is low, the GL device generally takes more time for heating or cooling than a metal container, has poor responsiveness during temperature control, and is difficult to control.

  Therefore, it is also conceivable to add a filler for increasing the thermal conductivity to the overcoat GL layer in order to increase the thermal responsiveness of the GL device by increasing the thermal conductivity of the GL layer. However, if a thermally conductive filler is added to the glass frit of the overcoat GL layer to the extent that the thermal conductivity of the overcoat GL layer is increased, not only the gloss of the surface of the GL layer is lost and the aesthetic appearance is impaired, GL original smoothness cannot be obtained at the time of conclusion. Moreover, the unevenness | corrugation generate | occur | produces in the GL layer surface, and the problem that a to-be-processed object will adhere easily will generate | occur | produce. Furthermore, the problem that the residual compressive stress of the GL layer becomes small also occurs.

  In addition, when adding a thermal conductive filler to an extent that increases the thermal conductivity of the overcoat GL layer, it is necessary to reconfirm the applicability in the usage environment, and it takes time to determine whether GL can be used in conventional applications. become. On the other hand, in the present invention, since the conventional GL can be used for the surface layer, the present invention can be applied to the same applications as those of conventional devices.

  On the other hand, in the undercoat GL layer, bubbles are intentionally introduced in order to collect a gas such as hydrogen released from the steel plate during firing. In addition to this, bubbles are also formed by the reaction between the glass and the steel plate at the time of firing. Therefore, when firing the overcoat GL layer, these bubbles cannot be prevented from becoming coarse and missing from bubbles. .

<First Embodiment>
FIG. 2 shows a cross-sectional view of an example of the heat conductive GL of the present invention. The metal substrate and the undercoat GL layer are the same as the general GL shown in FIG. 1, but the GL shown in FIG. 2 fires the intermediate GL layer as an upper layer of the undercoat GL layer. It is characterized by that. The intermediate GL layer is a GL layer fired by adding a filler to the same glass frit as that of the overcoat GL layer.

  In the intermediate GL layer, bubbles are bonded in the filler layer (in the intermediate layer) when bubbles are generated in the undercoat GL layer or in the gas generated from the metal substrate due to the addition of filler. In order to inhibit this, it is considered that bubbles do not easily escape to the overcoat GL layer. As a result, in the present invention, bubbles are not removed from the undercoat GL layer compared to the conventional GL, the number of repairs after firing is reduced, and the overcoat GL layer can be applied thinly (in FIG. 2). The overcoat GL layer is fired up to the second layer). Since the thickness of the entire GL layer can be reduced, the thermal conductivity of the entire GL layer can be increased.

  The filler added to the glass frit of the intermediate GL layer (the glass frit for the overcoat GL) is one or more of alumina, stannic oxide, magnesium oxide, silicon nitride, silicon carbide, and boron nitride. The amount added is preferably 5% by volume to 30% by volume. When aluminum oxide is used, it is 10% by volume to 20% by volume. When tin oxide is used, more than 5% by volume and 20% by volume or less. Magnesium oxide More preferably, the volume is 10% by volume or more and 20% by volume or less. In the intermediate GL layer, the filler may be alumina or magnesium oxide from the viewpoint of a high effect of stopping bubbles moving from the undercoat GL layer and a high effect of improving the thermal conductivity of the intermediate GL layer. More preferred.

  The filler added to the intermediate GL layer is at least one of aluminum oxide (alumina), stannic oxide, magnesium oxide, silicon nitride, silicon carbide, and boron nitride, so that the undercoat GL layer is overcoated with the overcoat GL layer. It is possible not only to prevent bubbles from leaking out, but also to provide a heat conductive GL having a high heat conductivity as the entire GL layer as compared with the conventional GL.

  The GL of the present invention has a higher thermal conductivity than the conventional GL by adding a filler to the intermediate layer. From the viewpoint of further improving the thermal conductivity, the undercoat GL layer is 0.1 mm or more. After the construction with a thickness of 0.4 mm or less, the intermediate GL layer is preferably constructed with a thickness of 0.1 mm or more and 1.0 mm or less. And it is preferable to construct an upper GL layer on the upper layer of the intermediate GL and adjust the thickness of the three GL layers of the upper GL layer, the intermediate layer, and the lower GL layer to 0.6 mm or more and 1.8 mm or less.

  The intermediate GL layer is preferably constructed with a thickness of 0.1 mm or more and 1.0 mm or less, and with a thickness of 0.2 mm or more and 0.6 mm or less, in order to prevent bubbles from being removed from the undercoat GL layer to the overcoat GL layer. More preferably. If the thickness of the intermediate GL layer is less than 0.1 mm, the layer is too thin, and a sufficient bubble removal preventing effect may not be obtained. By setting the thickness to 0.2 mm or more, it is possible to more reliably prevent the bubbles from coming out.

  If the thickness exceeds 1.0 mm, the thickness of the entire GL layer (undercoat GL layer + intermediate GL layer + overcoat GL layer) becomes thicker than before, which is not preferable from the viewpoint of thermal conductivity. Further, if the intermediate layer is repeatedly baked to make it thick, the influence of thermal stress is repeatedly received, so that the risk of increased can body distortion may increase.

  The subbing GL layer must be constructed with a thickness of 0.1 mm or more to ensure adhesion, but if it exceeds 0.5 mm, the amount of bubbles present in the GL layer increases and the risk of bubble loss increases. It is not preferable.

  In the present invention, since the defect caused by the bubble loss can be suppressed by suppressing the bubble removal by the intermediate GL layer, it is easy to control the thickness of the overcoat GL layer, and the thickness of the overcoat GL layer. Can be made thinner. To further increase the thermal conductivity of the entire GL layer by reducing the thickness of the entire GL layer, the undercoat GL layer is 0.1 mm to 0.3 mm, the intermediate GL layer is 0.1 mm to 0.6 mm, It is preferable that the thickness of the three GL layers of the upper GL layer, the intermediate layer, and the lower GL layer be 0.6 to 1.2 mm.

[Production example of GL sample]
In the following, the addition of filler to the intermediate GL layer prevents bubbles from being removed, thereby thinning the outermost GL layer and reducing the overall thickness of the GL layer, thereby increasing the thermal conductivity. An example of manufacturing GL will be described.

(Slip production)
Table 1 shows the composition of the glass frit used for producing the thermal conductive GL of the example. The glass frit which can be used for manufacture of each GL layer of the heat conductive GL of this invention is not limited to Table 1, The arbitrary glass frit conventionally used can be used.

  After the glass frit was put into a pot mill, water was further added and the frit was pulverized until it could be glazed. After pulverization, the particle size distribution of the glass particles is measured using Nikkiso Microtrack Series 9200 FRA, and the average particle size of the glass particles (50% of the weight cumulative particle size distribution) is 35 to 55 μm. It was confirmed. If the particle size distribution is within the above range, the slip was completed. The average particle diameter of the glass particles in the slip is preferably 1 to 100 μm from the viewpoint of slip spraying work and GL quality after firing.

  For the intermediate GL layer, the glass frit of the overcoat GL layer and various fillers were added, and then water was added and pulverized with a pot mill. In the case of adding a filler, a slip was produced within the above-mentioned range of the slip standard.

(Glazing and firing on metal substrates)
A GL having the three GL layers shown in FIG. 2 was produced. As the metal substrate, a steel sheet for GL (100 mm × 100 mm, thickness 5 mm) was used. The undercoat GL layer, the intermediate GL layer, and the overcoat GL layer were fired by applying a slip of each layer on the GL steel plate in a predetermined order by a known method using a spray.

  First, an undercoat GL layer was applied to a steel sheet for GL with a spray having a thickness of 0.2 to 0.3 mm, and fired at 920 ° C.

  Next, on the undercoat GL layer, a slip prepared by adding 5 to 30% by mass of filler to the glass frit for overcoat GL is applied by spraying, and is baked at 800 to 850 ° C. The intermediate GL layer was formed with a thickness of 0.4 to 0.5 mm.

  Further, after that, the overcoat GL layer was glazed with a spray with a thickness of 0.3 mm and baked at 800 to 850 ° C. The finally produced GL was used as a GL test piece. For easy comparison, the total thickness of the three layers was adjusted to 1.0 mm for any GL test piece.

  About the produced GL test piece, the foam containing state, GL workability, and thermal conductivity of the intermediate GL layer were evaluated. The bubble-containing state is obtained by observing a cross-section of the GL test piece after firing the intermediate GL layer under a stereomicroscope, and “O” if the generation of bubbles is similar to that at the time of normal overcoat GL layer construction. If it was slightly larger, it was judged as “Δ”, and when bubbles were generated on the entire surface to the extent that it was not seen in the normal overcoat GL layer, it was judged as “x”. For GL workability, a GL test piece is prepared using a steel sheet for GL having a plate thickness difference and an R portion. If there is no occurrence of a hairline defect, “◯”, and if a slight hairline is observed, “△” Was determined.

For thermal conductivity, the GL test piece was attached to the test instrument shown in FIG. Charge a predetermined amount of water to the upper part of the GL test piece, heat the GL test piece with steam from the lower part, and estimate the thermal conductivity W / (m ² · K) of the GL test piece from the rate of temperature rise of the water by calorific value calculation. Was evaluated by The GL layer test piece is fixed to the instrument so that the steel sheet for GL is on the steam side and the GL layer is on the water side, and the use state in an actual reactor is simulated. Laminar film coefficient steam side and ^{5000~10000W / (m 2 · K)} , laminar film coefficient of water side was from stirring blade shape 3000W / and (m ² · K). These film coefficients were confirmed to be reasonable values by preliminarily evaluating the thermal conductivity (0.8 to 1.0 W / m 2 K) of normal GL having no intermediate GL layer added with filler.

  Compared with the normal GL test piece, it is “◯” when the thermal conductivity of the intermediate GL layer is improved by 50% or more, and “△” when it is improved by 10% to less than 50%, and is less than 10%. When it was, it was evaluated as “×”.

  Table 2 shows the evaluation results of the bubble-containing state, GL workability and thermal conductivity of each GL test piece in which the intermediate GL layer contains five types of fillers.

  For all five types of fillers, the foaming state on the surface of the intermediate GL layer was slightly the same as that of the normal overcoat GL layer, but the amount of bubbles increased slightly. Bubble removal to the pulling layer was not a problem. In addition, for all five types of fillers, differences were found in workability, but GL test pieces could be manufactured, workability was not greatly reduced, and there were no GL test pieces that were judged difficult to work. .

Regarding thermal conductivity, when alumina (Al ₂ O ₃ ) or magnesium oxide (MgO) is used as a filler, the thermal conductivity is usually improved to about twice or more that of the GL layer. In combination, it was confirmed that the heat transfer can be improved as a whole GL. In particular, when 30% by volume of magnesium oxide is added to the glass frit, it is confirmed that the thermal conductivity is improved by about 1.9 times compared to the GL layer prepared without adding filler to the glass frit. It was.

<Increase in residual compressive stress>
Undercoat GL layer on SS400 steel plate (150mm × 150mm, thickness 24mm) as above. Thereafter, magnesium oxide was overcoated and 20% by volume was added to the glass frit for GL, and the intermediate GL layer was applied to a thickness of 1.2 mm to prepare a test piece A. On the other hand, after constructing the intermediate GL layer with a thickness of 0.8 mm in the same manner as the test piece A, using the glass frit for the overcoat GL without adding magnesium oxide, construct the glass frit layer for the overcoat GL with a thickness of 0.4 mm. Then, a test piece B was produced.

About the test piece A and the test piece B, the residual compressive stress was compared and evaluated. Since it was difficult to quantitatively evaluate the residual compressive stress (kg / mm ² ) of the GL test piece, an evaluation method using a strain gauge was adopted. As a result, the test piece A had a tendency to reduce the residual compressive stress as compared with the case where no filler was added, but the test piece B had a structure of the test piece B (upward GL layer + intermediate GL layer). In this case, it was found that the residual compressive stress increased by 20% or more from the test piece A, and the strength of the entire GL layer could be improved.

Using the thermal conductivity calculated for a part of the GL test piece, the overall heat transfer coefficient K (kcal / m ² hK), which is an index of heat transfer performance, is calculated by the chemical engineering approach shown in Equation 1. Calculated.

Here, h _out means a can outer film coefficient, h _in means a can inner film coefficient, and h _wall means a can _wall part film coefficient including a glass layer.

The outer canal film coefficient was 5000 kcal / m ² hK, and the inner can film coefficient was 3000 kcal / m ² hK. The wall film coefficient is obtained by Σ (L _i / k _i ). L _i is the thickness of the test piece (base material + GL layer), k _i is the thermal conductivity of the test piece, and these were determined by experiment.

  A GL test piece (comparative test piece) having the structure shown in FIG. 1 was also prepared, and its thermal conductivity was also calculated. And the improvement ratio of the heat conductivity of the GL test piece which has an intermediate | middle GL layer with respect to the heat conductivity of a comparative test piece was computed.

  Table 3 shows the thickness of the GL layer of the test piece, the type and amount of filler added, the thermal conductivity improvement ratio of the intermediate GL layer, the can wall boundary film coefficient improvement ratio, and the overall heat transfer coefficient improvement ratio. The thermal conductivity improvement ratio of the intermediate GL layer means the ratio of the thermal conductivity of the GL test piece to the thermal conductivity of the comparative test piece. The can wall part film coefficient improvement ratio means the ratio of the can wall part film coefficient of the GL test piece to the can wall part film coefficient of the comparative test piece. The overall heat transfer coefficient improvement ratio means the ratio of the overall heat transfer coefficient K of the GL test piece to the overall heat transfer coefficient K of the comparative test piece.

  From Table 3, it was confirmed that when any filler was added, the thermal conductivity of the intermediate GL layer was significantly improved and the overall heat transfer coefficient could be improved.

Second Embodiment
In the first embodiment, the intermediate GL layer is applied, the overcoat GL layer is thinly formed, and the entire GL layer (undercoat GL layer + intermediate layer + overcoat GL layer) is thinned to reduce the thermal conductivity. In this embodiment, the heat conductive GL is described in which the intermediate layer is thicker than the first embodiment and the thickness of the entire GL layer is the same as that of the conventional GL. To do. The second embodiment is the same as the first embodiment except that the thickness of the intermediate GL layer is increased.

  A subbing GL layer was applied with a thickness of 0.2 mm, a glass frit for overcoating to which 30% by volume of magnesium oxide was added as an intermediate GL layer was applied with a thickness of 1.0 mm, and a subbing GL layer was applied with a thickness of 0.6 mm (GL Test piece 5, GL layer thickness 1.8 mm). The overall heat transfer coefficient of the GL test piece 5 was improved to 1.5 times that of the comparative test piece. Similarly, the overall heat transfer coefficient of the GL test piece 6 with the intermediate GL layer thickness of 0.6 mm, the overcoat GL layer with the thickness of 1.0 mm, and the other conditions same as the GL test piece 5 is the comparative test. Improved to 1.3 times that of one piece. In addition, the overall heat transfer coefficient of the GL test piece 6 in which an overcoating glass frit to which 10% by volume of tin oxide is added as an intermediate GL layer was constructed with a thickness of 1.0 mm and an overcoating GL layer was constructed with a thickness of 0.6 mm is It improved 1.3 times compared with the comparative specimen.

  The overall heat transfer system coefficient of the GL test piece 4 of the first embodiment was improved to 1.8 times that of the comparative test piece. From these results, it was confirmed that the thermal conductivity could be sufficiently improved by adding a filler to the intermediate GL layer. Since the presence of the intermediate GL layer suppresses bubble removal from the undercoat GL layer, the thickness of the overcoat GL layer can be controlled to reduce the thickness.

  Although it may be possible to add a noble metal powder such as gold, silver or platinum as a thermal conductive filler to the intermediate GL layer, there is a large difference in thermal expansion coefficient between the noble metal and GL, and the affinity between the two is low. For this reason, it is impossible to add GL glass frit in an amount of 5% by volume to 30% by volume. Furthermore, when noble metal powder is added, the amount added must be made small, so it is considered that the effect of suppressing bubbles by the intermediate GL layer can hardly be expected. As a result, when viewed as the entire GL layer, the effect of improving the thermal conductivity is negligible.

  In the present invention, by providing an intermediate GL layer to which a filler has been added, it is possible to suppress bubble removal from the undercoat GL layer to the overcoat GL layer. As a result, various types of overcoat GL layers that are normally used can be constructed, and thermal conductivity can be improved even if various glasses are used. Furthermore, it is possible to control the thickness of the overcoat GL layer by suppressing bubble removal and to perform thinning.

  In the above example of producing the GL test piece, the filler is added only to the intermediate GL layer. However, in order to further increase the thermal conductivity, the filler may be added to the frit of the undercoat GL layer.

  The construction method of the heat conductive GL, the structure made of heat conductive GL, and the heat conductive GL of the present invention is a chemical industry, etc., as a technology related to a GL product having good surface layer workability and excellent heat conductivity. It is useful in the technical field.

Claims (5)

A metal substrate;
Three glass lining layers, an undercoating glass lining layer, an intermediate glass lining layer, and an overcoating glass lining layer;
A glass lining consisting of
The intermediate glass lining layer is
It contains a glass frit for an overcoating glass lining and a filler, and is formed between the undercoating glass lining layer and the overcoating glass lining layer ,
The filler is at least one of aluminum oxide, stannic oxide, magnesium oxide, silicon nitride, silicon carbide, or boron nitride,
The addition amount of the filler in the intermediate glass lining layer is 5% by volume or more and 30% by volume or less with respect to the glass frit for overcoating glass lining,
The undercoating glass lining layer and the overcoating glass lining layer do not contain the filler,
Thermally conductive glass lining. The thickness of the three glass lining layers is 0.6 mm or more and 1.8 mm or less,
The thickness of the undercoat glass lining layer is 0.1 mm or more and 0.4 mm or less,
The thickness of the intermediate glass lining is 0.1 mm or more and 1.0 mm or less,
The thermally conductive glass lining according to claim 1. The structure made from the heat conductive glass lining of Claim 1 or 2 comprised from the heat conductive glass lining. Firing a glass frit for undercoating glass lining without adding a filler, and applying an undercoating glass lining layer on a metal substrate;
Firing the glass frit for the overlying glass lining to which the filler has been added, and applying an intermediate glass lining layer on the undercoating glass lining layer;
Firing the glass frit for overcoating glass lining without adding a filler, and applying the overcoating glass lining layer on the intermediate glass lining layer;
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The filler is at least one of aluminum oxide, stannic oxide, magnesium oxide, silicon nitride, silicon carbide, or boron nitride,
The addition amount of the filler in the intermediate glass lining layer is 5% by volume or more and 30% by volume or less with respect to the glass frit for the overlying glass lining,
The construction method of the heat conductive glass lining characterized by this. Apply the undercoat glass lining layer with a thickness of 0.1 mm or more and 0.4 mm or less,
The intermediate glass lining layer is applied with a thickness of 0.1 mm to 1.0 mm,
The thermal conductive glass lining construction method according to claim 4 , wherein a total thickness of the undercoating glass lining layer, the intermediate glass lining layer, and the overcoating glass lining layer is 0.6 mm or more and 1.8 mm or less.

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