JPS60187545A - Heat-generating ceramics - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to ceramics, and more particularly to a heat-generating ceramic in which a heating element and a thermally conductive insulating ceramic are closely bonded and integrated into a composite body.

Heat equipment such as heating equipment and cookers that have been traditionally used are
When classified by means of transmitting heat to an object, there are (1) those that primarily use convection or radiation, and (2) those that primarily use conduction. Of these, (1) includes many highly versatile thermal appliances, including near conditioners as well as most electric, gas, and oil stoves and ranges. On the other hand, (2) includes electric blankets, electric carpets, irons, cooking pots, ondo/l/, etc. The bath uses heat conduction from the bathtub to the water and convection of hot water into the bathtub. Due to the differences in these heat transfer means, the trick to obtaining the desired amount of heat at the heat utilization point is (
In the case of 1), high temperature heat generation is required because the heat mixer is located locally, and in the case of 2j, a heat source with a wide area comparable to the heat utilization area is required. Considering this, type (1) has the problem that the characteristics of the heat source gradually deteriorate due to the repeated use of high-temperature heat cycles, resulting in a decrease in thermal efficiency, and the problem that the installation space is required as the thermal equipment becomes larger. On the other hand, type (2), which used to be commonly used in cold regions, has become less commonly used in recent years due to high construction costs and problems with thermal efficiency, and is now mainly used for home use. Electric blankets, electric carpets, foot warmers, etc. are becoming popular.These are a type of panel heater that is used close to the human body, and although they serve their intended purpose even when heating at a relatively low temperature. However, the heater coating has poor heat transfer characteristics and low thermal efficiency.

The heat-generating ceramic of the present invention was developed with the main purpose of eliminating the drawbacks of the conventional heating equipment described above. Another object of the present invention is to disclose ceramics that have new functions beyond those of conventional ceramics in the field of heat cookers and the like.

In order to achieve these objects, the present invention provides a thermally insulating substrate, which is formed by disposing a conductive heating element in close contact with a thermally conductive insulating ceramic plate or inside the ceramic plate, through a heat reflecting plate or by directly insulating it. Disclosed is a panel heater in which the plates are brought into close contact with each other and the heat generated from the conductive heating element is radiated outward from one side of the thermally conductive insulating ceramic plate.

If this panel heater is a fixed type, it can be used by placing it on the wall or floor of the building itself or on the surface of furniture such as desks and chairs, so it not only does not require installation space as a heating device, but also has extremely high thermal efficiency and Highly safe. In addition, since the heat dissipation surface is made of hard ceramic, it has excellent wear resistance, mechanical strength, and long life. Furthermore, when used in mobile products such as heat cookers, we use products that exceed the performance of conventional ceramics, such as clean, high-efficiency heat cookers that do not use gas, etc., and tableware that does not get hot on the outside and does not easily cool down. It can be used as a new product.

The heat-generating ceramic of the present invention originally belongs to the above-mentioned type (2) of thermal equipment, so when applied to heating equipment, the heat source area is large and there is no need to raise the heat generation temperature, so deterioration of the heating element is extremely small. However, even if this is applied to a heat cooker etc. for high temperature heating, (1) the heat transfer plate (thermal conductive insulating ceramic) and the conductive heat generating part are tightly integrated!
0, (II) the heat exchanger plate has high thermal conductivity, (Ill)
Since it has a heat reflection structure and a single-sided heat radiation type, it has a fast thermal response and high thermal efficiency, so the deterioration of the heat generating part is much less than that of conventional thermal equipment.

Household heating appliances that are functionally similar to the heat generating ceramic of the present invention, such as hot plates, electromagnetic frying pans, electric irons, or heat pipes used for heating fluids, have a heat sink surface made of a non-rusting material, such as an insulating material such as Teflon. It is coated with a resin and has poor thermal conductivity.Furthermore, it can only be heated to a relatively low temperature (approximately 250°C) to protect the resin, and its mechanical strength is weak. The performance limits of these products can be easily overcome by the heat generating ceramics of the present invention.

On the other hand, a product that is somewhat similar in structure to the heat generating ceramic of the present invention is a thin film thermal head for printers. The thermal head has a structure in which a so-called glazed alumina substrate whose surface is coated with glass is laminated with a heating element thin film, an insulating antioxidant film, and an abrasion resistant layer in this order. Heat is released from the wear layer side, not the glazed alumina side. Thermal heads are developed for the purpose of rapidly (1-10 msec), high temperature (~500°C), and repeated heating of small area areas (wear-resistant layers) for printing, so they are designed to prevent deterioration due to oxidation of the conductive heating element. Therefore, unlike the case of the present invention, an anti-oxidation film (insulating film) is placed on the heating element at the expense of thermal conductivity.
Furthermore, in consideration of the already formed low-melting point glaze layer and electrode layer, SiC or 5102, which can be formed at low temperature, is used as a heat dissipating part, that is, a wear-resistant layer, at the expense of thermal conductivity. Due to these poor thermal conductivities, the heating element must be heated to an even higher temperature in order to obtain the desired temperature on the surface of the wear-resistant layer (printed area), and the heat is transferred to the glaze layer on the bottom surface of the heating element. Heat is radiated from the alumina substrate directly below.
However, it is inevitable that the life of the heating element will be shortened.

On the other hand, the heat-generating ceramic of the present invention is fundamentally different in that the heat-radiating surface is formed of a ceramic with good thermal conductivity, with the above-mentioned heat-radiating properties as the most important consideration.

The present invention will be described in detail below based on embodiments.

(Example 1) This example is shown in FIG.

As the material of the thermally conductive insulating ceramic 1 that forms the heat dissipation part, 96-chi HT2O5 clay is used with a thickness of 1 cm and an area of 30×
It is formed into a shape with a serpentine groove about 3 m deep and 1.2 m wide on one side with a pitch of 4, and the distance between the turning points is about 29.5 cm.
rn), and then fired at a high temperature of 1400°C or higher and then taken out.

A Kanthal wire (circular cross section) with a wire diameter of 1 piece is placed in close contact with the meandering groove as the conductive heating element 2, as shown in FIG. ) x 30cd 92% ht2o 3 clay plates are stacked and crimped, and again 130
Fire at 0°C to form a laminated tile. When using a linear heating element as in this example, it is important from the viewpoint of thermal conductivity and impact resistance that the heating element 2 be embedded and fixed in a thermally conductive insulating ceramic l. It is. Next, copper alloy metal fittings 5 and 9 are attached to both ends of the Kanthal wire embedded in the laminated tile. That is, by using a notch with a width of 5 m and a length of 1 crn previously made in the 92% At205 clay plate, a cylindrical hole 52 with an inner diameter of about 2 holes made of copper alloy was made at one end at a depth of about 1 cm in the tile. The other end is made of a prepared alloy rod 51 having a diameter of about 2 mm (thick enough to fit tightly into the cylindrical hole 52) and protruding about 1 tyn outside the tile. This diagram is shown in FIG. 1 (b). 51 and 52 constitute the copper alloy fitting 5. Then the 96%
Glaze 7 is applied to the At205 ceramic surface and heated to 900℃.
Fire it with Thereafter, a copper plate having a thickness of approximately 1 wm is adhered to the 92% Ht2O5 ceramic plate as a heat reflecting plate so as not to come into contact with the copper alloy fitting 5, and the heat reflecting plate 3 is
A heat-generating ceramic is completed by adhering an isolite brick with a thickness of about 5 mm on top as a heat insulating material 4.

When a plurality of these heat generating ceramics are connected and energized, it is useful as a large panel heater. For example, when pasting on a wall surface of 3 x 3 m, 10 pieces of the heat-generating ceramic are placed in the copper alloy cylindrical hole 5 of the ceramic adjacent to the prepared alloy rod 51.
Arrange them in a row horizontally so that they are inserted and fixed inside the
If you repeat 0 stages, you can fill the wall surface. The gap between the adjacent heat-generating ceramics is fixed by applying meji as in conventional tiling. The series connection resistance value of each horizontal row was about 420 at room temperature. Each stage is connected in parallel and connected to an AC slideac 2 with a primary side of 200 V and a capacity of 15 KVA.
This is the load on the next side. After drying, when the voltage on the secondary side is increased, a voltage of about 2.5 at 100V is applied to the series-connected ceramic group in each row horizontally.
A, a current of nearly 200V-r5A flows. Room temperature 18
℃.

In the case of indoor air natural convection, 100V is applied to this wall ceramic.
When the voltage is applied, the wall surface temperature reaches 22℃ after 5 minutes and 3℃ after 100 minutes.
After 4.155 minutes, the temperature reached 48.degree. C. after 20 minutes, and the temperature was saturated at 4.155 minutes. On the other hand, when 200V is applied, 45
℃, reached 74℃ after 100 minutes and 91℃ after 15 minutes, almost 10℃.
It was saturated at 5°C. When forced convection was used to draw indoor air down from the ceiling along the wall, the wall temperature saturated at 55°C under strong wind speed even when 200V was applied. Under these conditions, the temperature in the room having a volume of 3 x 3 x 10ff/ reaches approximately 32°C after 10 minutes from the initial 18°C. This can be said to be a very efficient thermal defoaming device.

Although not mentioned in the above example, well-known temperature sensors and SC
Of course, it is also possible to adjust the temperature to a constant temperature in combination with R. In addition, when combined with a thermister or the like, it is possible to adopt an efficient energization method that heats the entire wall surface up to a predetermined temperature in a short time.

Although this is a large panel heater, since it forms part of the wall or floor surface, it does not take up much space to install, and the temperature of the heating element itself is low, and it is completely covered with ceramics. Therefore, it is possible to maintain high thermal efficiency for an extremely long period of 10 years or more without the adhesion of dirt, dust, etc.

(Example 2) This example is shown in FIG. As a raw material for thermally conductive insulating ceramics 1, clay containing 92% activated alumina with excellent sinterability was prepared with a thickness of 5 mm and a size of 31×50.
Form into a plate shape (d) and fire at 1400°C to make a porcelain plate. One side was polished to make it slightly smooth, and the polished surface was marked with the image shown in Figure 2 (
As shown in a), a striped conductive film In2O5-5nO2-5b203 having a width of 16 DEG C. and a gap of 1 crn is formed to a thickness of several micrometers by a chemical spray method. In this heating ceramic, this striped conductive film becomes the heating element 2. A through hole 10 is provided at the end of the heat insulating film 4 formed right above the surface of the conductive film. This through hole 10 has a configuration in which a hole with a diameter of 5 mm is penetrated near both ends in the longitudinal direction in accordance with the striped conductive film pattern as shown in FIG. 2 (b).
(The position of the hole is on the conductive film). The insulation film 4 has a thickness of 1 cm.
It is made of isolite bricks with an area of 31 x 50 m and is glued as a heat insulating material, and the surrounding area is molded with resin to prevent moisture.

Next, Snni2 with a diameter of 3 and a length of 1 an is placed on the copper strip plate 11.
are vertically soldered to the isolite brick holes at intervals of 1 tyn, and an In pellet is pasted 9 on the tip of each Sn wire 12.

This Sni-coated copper plate strip 11 is placed near both ends of the isolite brick, and each 5nal 12 is inserted into the hole of the isolite brick to bring the In pellet into contact with the striped conductive film. When heated to about 200[deg.] C., the In pellet at the Sn tip melts and adheres to the striped conductive film as an In--Sn alloy. When coated conductive wires are soldered to the copper strips 11 at both ends, the 16 striped conductive films are connected in parallel to each other. The entire surface of the inrite brick including the copper strip 11 is molded with resin to provide a waterproof and insulating structure. Thereafter, this heat-generating ceramic is turned over, and the surface of the thermally conductive insulating ceramic 1 is turned into soil and laid on the floor. The resistance value of the striped groove N1 film varies depending on the film composition, manufacturing conditions, thickness, etc., but usually one stripe has a resistance of 3 to 10 Ω.

Apply voltage between the above covered conductors and apply 0.5 to each stripe.
When a current of ~IA is applied, the temperature in the room, which was initially 18℃ without forced convection, is reduced to thermally conductive insulating ceramics (
The surface of the alumina porcelain plate) 1 is heated to a saturation temperature of approximately 70°C. In the case of this heat generating ceramic, a plurality of each ceramic can be connected in series and parallel to each other and used as in the previous embodiment. In fact, if these heat-generating ceramic panels (series-parallel connections) are installed on streets after waterproofing, they can be used for heating in winter and for preventing snow from accumulating on roads in cold regions.

(Example 3) 96% alumina was selected as the raw material for the thermally conductive insulating ceramic 1 for a heat sink, and a flat clay dough having a thickness of about 1+mm was made. On top of this, a Ta-8i cermet clay fabric with a thickness of about 1 tone is layered as the heating element 2, and on top of that, a zircon (ZrO2.5iO2) clay fabric with a thickness of about 1 meter is layered, and the top layer is a heat reflective insulation layer. As material 4, cordierite (2Mg0, 2At203, 5Si02) with a thickness of about 1
) Layer the clay dough and roll it to a thickness of about 2 mm, and then make a bottom diameter of 20 cm with the 96 chialumina clay inside.
, machined into a pan shape with a depth of 5 crn, and
After firing at 100° C., the product is slowly cooled and taken out to form a heat-generating ceramic pot as shown in FIG. Fill this pot with water, put it on an electromagnetic cooking table (equipped with an electromagnetic oscillation tube), and turn on the power. As a result, eddy currents are generated in the Ta-8t-based methane layer, resulting in Joule heating. Heat conducts well to the alumina porcelain side inside the pan, but the thermal conductivity of cordierite porcelain is about y2o compared to alumina porcelain, so heat conduction is inhibited. Zircon porcelain has thermal conductivity and coefficient of thermal expansion that are between those of alumina and cordierite, which alleviates the occurrence of thermal distortion when ceramics are heated. Now, as mentioned above, cordierite porcelain works as a heat insulating material 4, but at the same time, the optical refractive index is about half that of alumina, so that heat is reflected by the cordierite surface, so it also works as a heat reflecting plate 3. In a laminated ceramic pot with the above functions, even if the water inside the pot boils, the outer wall of the pot can be heated to about 55℃ (6 J) with bare hands.This is also due to the extremely high thermal efficiency of this heat-generating ceramic. This means that the cooking time is shorter, and the finished food does not cool down easily.

If you make a teacup using this heat-generating ceramic and compare it to a regular porcelain teacup of the same size, if you pour the same amount of hot water at 85℃ into it, it will take about 5 times longer for the former to cool down to 50℃ than the latter. It was confirmed.

(Example 4) This example is shown in FIG. The figure (A) is a cross-sectional view in the radial direction, and the figure (B) is a cross-sectional view taken along the line AA'.

95q6 alumina is selected as a raw material for thermally conductive insulating ceramics 1, and the clay is shaped into a cylindrical rod with a diameter of 10 mm. This is the heating element 2, which has an inner diameter of 10.5 mm and an outer diameter of 14.
Insert into a 5-tone StC sintered body cylinder. Both ends of the SiC sintered body are treated with metal Sl,9 and the resistivity of the middle part is lowered by about two orders of magnitude. After pressing 80 thialumina clay with a thickness of about 21+lI+1 on the outside of the hollow cylinder of the SiC sintered body, excluding both ends of the low-resistance SIC,
Place it in a cylindrical mold with an inner diameter of 16.5 mm.

A through hole with a diameter of 6 holes is made in the center of the 95% alumina clay layer inside the stc cylinder. After being removed from the mold, this hollow multilayer cylinder is fired at 1400°C. Seven taps were placed in the hollow part of the resulting composite ceramic tube, and the surface of the outer 95-dialumina tube was plated with copper to a thickness of more than 10 μm by electroless plating. A hollow Pyrex glass tube with an inner diameter of 17 pieces is placed on top of this, heated to about 900°C, welded while softening, and slowly cooled. As a result, from the inside, 95% At20
5 / SiC / 80%Az2o5 / Cu /
A laminated ceramic tube called Pyrex is produced. sic
When Sn electrodes are attached to both ends of the tube (where the resistance has been lowered by metal Si treatment) and electricity is applied, the SIC tube generates heat. Heat is conducted to the alumina porcelain side, but the heat conducted to the alumina outside the SiC is reflected by the Cu surface and returns to the inside. That is, Cu functions as a heat reflecting plate 3. In addition, the outermost layer of Virex exhibits a good heat insulating effect and is suitable for the heat insulating board 4. Fluid inside the hollow part of this heat pipe,
For example, by passing water through it, it can heat much more efficiently than conventional heat pipes, contributing to energy savings. In addition, this porcelain heat pipe has excellent acid and alkali resistance, and is also stable against corrosive gases such as 1 (28), making it ideal for heating chemicals (fluids) and extremely durable.

As described in the examples above, the heat generating ceramic of the present invention has an all-solid laminated structure of (1) heat sink - heat generating plate - (heat reflecting plate) - heat insulating plate and has excellent mechanical strength and earthquake resistance.

■ The heat sink is made of insulating ceramics with high thermal conductivity.
It has excellent heat radiation properties and wear resistance.

■ High single-sided heat dissipation efficiency from the radiation plate due to the use of heat reflectors and heat insulating plates.

■ Due to its ceramic structure, it can generate heat at high temperatures, has a long life, and can be processed into any shape before firing.

■ The resistance heating type can be made larger by connecting single panels in series and parallel to form a large-area heating plate, and can be used as a heating device with excellent installation ease.

It has excellent advantages.

In the above embodiments, only the case where the heating element in the heat generating ceramic of the present invention is an electric heating element has been described. However, as is clear from the structure of the heat-generating ceramics described above, it is also possible in principle to construct the heat-generating body part with a hollow heat transfer pipe, and to pass heated fluid inside and utilize the heat generated from the fluid.

Furthermore, as a material for the heat sink, nitrides such as aluminum nitride, silicon nitride, boron nitride, etc. can be used in addition to alumina. In addition to metal, materials for the heat reflecting plate include calcium fluoride, glass, asphalt, glasstic, and the like.

The heat-generating ceramic of the present invention achieves a highly efficient, clean, noiseless, long-life heating device that only requires wall and floor heating.
Chairs, benches, beds, hot water tank.

It can be applied to a wide range of products such as flower pots, roof tiles, dryers, and cooking utensils.

[Brief explanation of the drawing]

1 to 4 are diagrams for explaining other embodiments of the present invention, respectively. In the figure, 1 is a thermally conductive insulating ceramic, 2 is a heating element, 3 is a heat reflecting plate, 4 is a heat insulating material, 5 is a copper alloy fitting, 6 is a copper strip, and 7 is a glaze (glass). Patent applicant: Polytronics Co., Ltd. Agent: Tadashi Akimoto Actual Figure 1 (a) (b) 7 Second cause (o) Figure 3, 4N A' (b)

Claims (1)

[Claims] 1. A heat insulating plate is closely attached to a heat emitting substrate formed by closely arranging a conductive heating element on or inside a thermally conductive insulating ceramic plate, either through a heat reflecting plate or directly. A heat-generating ceramic, characterized in that heat generated from the conductive heating element is radiated outward from one direction of the ceramic plate. 2. The heat-generating ceramic described in claim 1, wherein the ceramic is provided with a connection terminal for supplying power to the conductive heating element, and a plurality of heat-generating ceramics are connected in series and parallel.