JPH0238355A - Electrically conductive ceramic heating unit emitting far infrared rays - Google Patents

Abstract

PURPOSE:To obtain an electrically conductive ceramic heating unit capable of emitting far infrared rays by adding a binder to a material consisting of a ceramic material containing a far infrared ray emitting ceramic and a ceramic material containing carbon and directly passing a current through the resultant mixture. CONSTITUTION:An electrically conductive ceramic heating unit obtained by adding a binder to an electrically conductive ceramic material consisting of one or plural ceramic materials containing one or plural far infrared ray emitting ceramics and a ceramic material containing carbon. A metallic oxide-based ceramic (e.g., alumina), siliceous ceramic (e.g., silica), etc., are cited as the far infrared ray emitting ceramics used. Quartzite, agalmatolite, bauxite, carborundum, etc., are used as the ceramic materials containing the far infrared ray emitting ceramics. Graphite, coke, charcoal, carbon black, etc., are cited as the ceramic material containing the carbon.

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial Application Field" The present invention relates to a ceramic heating element that is heated by supplying electricity to the heating element itself and emits far-infrared rays.

"Conventional technology" Far-infrared radiant energy is used to dry automobile paint films,
It is widely used in fields ranging from food processing, heating, and cooking to medical and measurement fields.

Ceramics are used as far-infrared heating elements, but in order to cause the ceramic heating elements to emit far-infrared rays, it is necessary to supply thermal energy from the outside to heat them.

Examples of heating means include those in which a heater is built into a ceramic heating element (Japanese Patent Publication No. 56-26081, Japanese Patent Publication No. 57-41794, etc.), or those in which a ceramic heating element is installed in heated air or liquid (Japanese Patent Publication No. 56-26081, Japanese Patent Publication No. 57-41794, etc.). Kosho 50-24
21, Special Publication No. 52-26613, etc.).

[Problems to be Solved by the Invention] Therefore, in order to radiate far-infrared rays, it is necessary to supply thermal energy from the outside, which causes a large loss of thermal energy. In addition, the provision of the heating means has the disadvantage that the overall structure of the far-infrared radiation device becomes complicated. Furthermore, there was also the problem that the shape and structure of the heating element were limited.

"Means for Solving the Problems" This invention solves the drawbacks of the conventional far-infrared heating elements using ceramics as described above, and makes the ceramic heating element conductive so that it can be connected to the heating element itself. Its main purpose is to radiate far-infrared rays by directly energizing it, and its gist is as follows.

That is, the conductive ceramic heating element that emits far infrared rays according to the present invention is a conductive ceramic heating element made of one or more ceramic materials containing one or more far infrared ray emitting ceramics and a ceramic material containing carbon. It is characterized by adding a binder to the ceramic material.

To explain in more detail, examples of far-infrared emitting ceramics include aluminum oxide (metal oxide ceramic)
Examples include, but are not limited to, silicon-based ceramics such as silicon dioxide (silica), silicon carbide, and silicon nitride. isn't it.

Ceramic materials containing one or more of these far-infrared emitting ceramics include silica, waxite, A-chamotte, silica shale, cordierite, flint clay synthetic mullite, bauxite, which are commercially available as raw materials for refractory bricks. Fused alumina, chromite, chromium oxide, magnesia, spinel, zircon, zirconia, carborundum, etc. can be used. All of these materials are preferably used in powder form with a particle size of about 0.3 fins or less.

Ceramic materials containing carbon for imparting electrical conductivity include, for example, graphite, coke, charcoal, carbon black, etc., and preferably have a particle size of about 0.5 fi or less.

The reason why the far-infrared emitting ceramic material and the carbon-containing ceramic material are made into powders having the above-mentioned particle sizes is to mix the materials evenly.

As the binder, in addition to synthetic resins such as liquid phenol resin and powdered melamine resin, sodium silicate and the like can be used, but the binder is not limited thereto.

The combination ratio of each of these materials varies depending on the purpose of use, conditions, and form. In experiments, 5 to 25% of a binder was added externally to a conductive ceramic material consisting of 30 to 98% far infrared emitting ceramic material and 2 to 30% of carbon-containing ceramic material. However, this mixing ratio is not limited to this.

Next, the molding method will be explained.

A conductive ceramic material consisting of a far-infrared emitting ceramic material, a carbon-containing ceramic material, and a binder having the above weight ratio are thoroughly kneaded, placed in a mold, and pressed. Alternatively, it can be made into a paste and poured into a mold to be molded, or applied to the surface of a pipe or the like to be molded, and then heat treated to strengthen it.

Therefore, where it can be shaped freely according to the purpose of use,
There is one major feature of this invention.

The heat treatment is performed at a temperature of, for example, 120°C to 30°C in order to remove moisture and volatile components of the resin, dry it, solidify it, and give it strength.
Low-temperature treatment at 0°C and e.g. 1400°C in a non-oxidizing atmosphere
There is a high temperature treatment of ~1700°C. In the former case, heat treatment may be possible without energizing.

When sintering is required for high-temperature processing, as a sintering material,
For example, a combination of one to three of ferrosilicon, metal silicon, metal aluminum, kaolin clay, etc. is added, preferably in an amount of 2 to 30% by weight.

The conductive ceramic heating element according to the present invention can be used in a wide temperature range and can be energized with either direct current or alternating current.

In addition, the far-infrared radiation characteristics of this conductive ceramic heating element are extremely close to those of a standard black body, as will be described later, and it can be used for heating, drying, room heating, cooking, medical treatment, etc. by effectively utilizing electrical energy. It is widely available.

Furthermore, this conductive ceramic heating element has a practically sufficient coefficient of thermal expansion, thermal conductivity, and strength, and as long as it is not handled carelessly, such as by passing an excessive current or dropping it on a hard floor, it will not work. There is no risk of damage.

Example 1 In this example, a conductive ceramic heating element was used as the heat source of a yakiniku pot.

Its composition is by weight: Carborundum: 70% Ferrosilicon: 15% Silicon: 5% Graphite: 10% and Phenol resin liquid: 25% (external coating) ), and these materials are kneaded for 60 minutes using a kneader.

Next, the kneaded materials were heated to 60°C using a fluidized fluid dryer.
Dry for 30 minutes.

The dried material is put into a mold and press-molded at 500 kg/cffl using a 250t press.

The molded product after pressure molding is kept at a temperature of 150° C. and dried by hot air drying for 24 hours.

Furthermore, the dried molded product is stored in a square heat-resistant container,
Fill the periphery of the molded product with finely pulverized coke powder,
It is fired for 4 hours in a tunnel kiln in a temperature atmosphere of 00°C.

FIG. 1 shows a conductive ceramic heating element 1 for a yakiniku pot formed in this way. 2 is a connecting fitting, and 3 is a cord. The heating element 1 is made by bending a rod-shaped body with a width of 10 mm and a thickness of 10 mm, and an overall length of 300 mm and a width of 16 mm.
It is 4R.

The results of applying 100 V AC to this heating element 1 are as follows.

Current after 5 minutes of energization (8) Electrical resistance (Ω) Surface temperature ('C) 9.6
10.4 290 Current after 10 minutes (Δ) Electrical resistance (Ω) Surface temperature (°C) 9.8
10.2 When meat was placed directly on the 370 heating element 1 and grilled, unlike a general yakiniku machine that uses a commercially available gas burner and nichrome wire, there was no smoke from the meat juices, and the meat had a very good texture and texture. was. Also, there was no carbonization on the meat surface. These effects are due to far-infrared radiation.

FIGS. 2 and 3 show far-infrared radiation characteristics at a surface temperature of 370° C. when an alternating current of 100 square meters is applied to the heating element 1. FIG. 2 shows the radiant heat energy, and FIG. 3 shows the emissivity, and the dotted lines each show that of a standard black body.

The conductive ceramic heating element formed as in this example can be used not only in cooking devices but also in a wide variety of applications such as space heaters, dryers, heaters, and the like.

Example 2 An example using a conductive ceramic heating element as the heat source for moxibustion is shown below.

The composition (weight ratio) is Zircon...50% Zirconia...15% Alumina...15% Silica...5% Graphite...15% as well as, Phenol resin liquid: 25% (external).

After kneading these materials in a kneading machine for 60 minutes, as shown in Fig. 4, they were placed in a cylindrical mold 12 with an inner diameter of 201 m, and the pressure rod 13 was hit with a hammer to form a mold with a diameter of 20 m and a height of 20 m. It is formed into a cylindrical shape 11' having a diameter of 10 mm.

14.14 is the outer diameter 1 for forming the hole for inserting the conductor
It is a heavy piano wire.

After forming, the piano wire 14.14 was pulled out and heated at 260℃ for 2 hours.
Dry with hot air for 4 hours.

Finally, the conducting wire 15 and a conducting wire fixing base l-16 having the following composition are inserted into the hole of this molded product 11', and the conducting wire 15.
A current of 0.3 A is applied to the paste 15 to slowly dry the paste 16 so as not to reach a high temperature.

FIG. 5 shows the moxibustion heating element 11 formed in this manner.

Composition of conductor fixing paste (weight ratio) Zirconia (44μ or less)...50% graphite
...50% and liquid phenol resin applied externally...30 to 35% A handle is attached to the heating element 11 for moxibustion thus formed, and it is used while maintaining an appropriate temperature with a thermoswitch.

When a direct current of 3.5V and 0.5A is applied to this heating element 11 for moxibustion, the surface temperature is 96°C, 4. OV, 0.7A
The surface temperature in this case is 123°C.

When DC 6V is applied to the above-mentioned moxibustion heating element 11,
Figure 6 shows the far infrared radiation characteristics at a surface temperature of 122°C.
It is shown in FIG. FIG. 6 shows thermal energy, and FIG. 7 shows emissivity, and the dotted lines are those of a standard blackbody.

Example 3 This example shows a conductive ceramic heating element used as a heat source for keeping the handles of motorcycles, motorized bicycles, etc. warm.

As shown in Fig. 8, two grooves 33.33 with a length of 80 fins and a width of 5 fins are provided in a rubber plate 32 measuring 100+n in length and width and 2 fins in thickness. The conducting wire fixing pastes 31' and 31' shown in Example 2 are thoroughly kneaded and applied. 34 is a conductor, and 35 is a large group of strings.

If a direct current of 6V is applied to the conductor wire 34 to dry the material, it will become the heating element 31.31 for keeping the handle warm.As shown in Fig. 9, the protective rubber plate 36 of the O05 crane is provided with 35 groups of string holes. .36 are pasted on the front and back sides of the rubber plate 32. In addition, the protective rubber plate 36 is not provided with the 35 groups of string holes in advance.
．． 36 may be attached to the rubber plate 32 and then provided at once.

This is wrapped around the handle, and the string is passed through the string hole 35 and fixed. The power source uses a 6v battery from a motorcycle.

The surface temperature of this heating element 31 for heating the handle is 60°C to 8°C.
It is 0°C. Note that, if the thickness of the heating element 31 for heat retention of the handle is made thinner, the current used will be reduced and the surface temperature will increase.

Example 4 A paste having the composition of Example 2 is applied to the surface of a pipe coated with a heat-resistant and insulating coating using a spray gun. A hot water pipe can be formed by attaching conductive wires and drying with electricity.

Example 5 By applying the same paste as in Example 4 to a heat-resistant and insulating coated iron plate with a spray gun, attaching conductive wires and drying with electricity, a planar conductive ceramic heating element is formed. , can be used as a heater.

Example 6 Similar to Example 5, a tile capable of melting snow can be formed by providing a conductive ceramic heating element on the surface of the tile.

Example 7 If a conductive ceramic heating element is provided on a small piece of cloth, nonwoven fabric, etc. in the same manner as in Example 5 and applied to the affected area, it can be used for moxibustion. Also, if it is provided on the lining of clothing, it can form a heat retaining layer.

Example 8 If a conductive ceramic heating element is provided on the inner surface of a plant cultivation pot in the same manner as in Example 5, it will be effective in keeping the roots warm next season.

"effect" The effects of this invention are listed below.

(1) Since the heating element has conductivity, electricity can be directly applied to the heating element, so energy efficiency is extremely high compared to conventional far-infrared radiation heating elements that supply thermal energy from the outside.

(2) Therefore, since there is no need for means for supplying thermal energy from the outside, the structure of the far-infrared radiation device or instrument becomes simple.

(3) Since the heating element can be formed into any shape, it can be used in a wide range of applications.

(4) High radiation efficiency of far infrared rays.

(5) Since firebrick material can be used, it can be provided at low cost.

[Brief explanation of the drawing]

Figure 1 is a plan view of a conductive ceramic heating element formed as a heat source for a yakiniku pot, Figure 2 shows the relationship between its far-infrared radiant heat energy and wavelength, and Figure 3 shows the relationship between far-infrared emissivity and wavelength. FIG. Figure 4 is a cross-sectional view of a device for forming a conductive ceramic heating element as a heat source for moxibustion, Figure 5 is an enlarged cross-sectional view of the heating element for moxibustion, and Figure 6 shows the relationship between far-infrared radiant heat energy and wavelength. , and FIG. 7 are far-infrared radiation characteristic diagrams showing the relationship between far-infrared radiation weight and wavelength, respectively. FIG. 8 is a perspective view showing a state in which a handle heat insulating device for a motorcycle or the like is formed using a conductive ceramic heating element, and FIG. 9 is a partially cutaway front view of the finished product.

Claims (1)

[Claims] 1. 1 containing one or more far-infrared emitting ceramics
Alternatively, a conductive ceramic heating element that emits far infrared rays is characterized in that a binder is added to a conductive ceramic material made of a plurality of ceramic materials and a ceramic material containing carbon. 2. The conductive ceramic heating element that radiates far infrared rays according to claim 1, characterized in that a sintered material is added to the conductive ceramic material.