JPS5848794Y2 - Ceramic hatsnet tie - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a ceramic heating element that can be suitably used for heating objects, particularly for rapid heating, igniting combustible gas, and the like.

It is known that ceramics are formed into a long piece and electrodes are provided near both ends of the piece to serve as a heating element.

This type of ceramic heating element is used by holding and fixing its two ends, but when heated to a high temperature of 1000°C or higher, the electrode parts may melt and peel off, or the electrodes may separate between the holding parts due to thermal expansion. It has drawbacks such as distortion and, in some cases, breakage.

In addition, even if the ceramic is not damaged, the strain is repeatedly applied each time it is heated and cooled, which inevitably deteriorates the quality of the ceramic material and reduces its durability.

In order to prevent the electrodes provided at both ends from melting and peeling off due to high temperatures, it has been proposed that both ends have a larger cross-sectional area than the middle part to diffuse heat and lower the temperature. It is not possible to prevent damage or material deterioration due to distortion.

The inventors of the present invention have worked hard to overcome these drawbacks of conventional ceramic heating elements and to develop a durable ceramic heating element suitable for heating objects, especially rapid heating, and igniting combustible gases. As a result of repeated research, we have made the cross-sectional area of both ends larger than the middle part, formed the whole into a U-shape, and fixed both ends with a single holder made of heat-resistant insulating ceramics. We found a way to accomplish this purpose, and based on this knowledge, we came up with the present invention.

The structure of the present invention will be explained with reference to the accompanying drawings. Figure 1 is a plan view showing one example of the shape of the heating element body of the present invention, and Figure 2 shows the body of a different shape than that in Figure 1, which is separated by a holder. FIG. 2 is a plan view showing a state in which the heat generating portion 1 is approximately U-shaped and has a constant cross-sectional area, and two base portions 2 having a larger cross-sectional area than the heat generating portion are integrally formed at both ends of the heat generating portion 1. The materials for the heat generating part and the base part in the present invention are as follows: 10
Heat-resistant ceramics having a conductivity of about -4 to 100h are preferred, and examples of such materials include silicon carbide, molybdenum silicide, zirconia, and lanthanum chromite.

The main body, which is separated from the heat generating part and the base part, is manufactured, for example, by molding a ceramic raw material mixture or a calcined product thereof into a U-shape using a predetermined mold and firing it according to a conventional method.

Next, the electrodes of the present invention are made by applying electrodes to the surface of ceramics such as aluminum metallicon, baking silver, or molybutton-magan metallizing in hydrogen at appropriate places on the peripheral base of the main body manufactured as described above. It is provided by means commonly used in providing.

Next, as the material for the holder of the present invention, heat-resistant ceramics having heat shielding properties and electrical insulation properties are preferable, such as high melting point ceramics such as alumina-based, magnesia-based, spinel-based, and zirconia-based ceramics. , sponge lumen, coryptite, aluminum titanate, cordierite, nurite, and zircon-based low thermal expansion ceramics.

This holder is configured, for example, as a pair of plate-shaped bodies having grooves in which the heating element base part is fitted in one or both of the lids on the opposing surfaces, and is held between the circumferential base parts, and is made of alumina, zirconia, etc. It is attached by adhesion using alumina-based or alumina-silica cement or water glass.

At this time, if necessary, heat-resistant fibers or the like may be interposed between the main body and the holder.

Alternatively, the holder may be formed as a single rectangular block having recesses on the opposite surface into which the respective base portions fit.

The present invention has the above-mentioned configuration, and since the thermal expansion during heating is not hindered by the fixing means, there is no distortion in the heating element body, and the cross-sectional area of the base part is larger than the heating part. Since the heat is diffused through the holder, the temperature rise in the base part is alleviated, and damage caused by strain, material deterioration, and melting of the electrode due to overheating of the base part are prevented. It has the advantage of suppressing peeling and oxidation and providing strength.

Next, the effects of the present invention will be explained with reference to examples.

Using Mo5t2A1203 ceramics, a U-shaped main body with a heat generating part having a cross-sectional area of 2 mm2, a base part having a cross-sectional area of 20 mm2, and a total length of 30 mm was fabricated, and electrodes were provided at both ends with aluminum metallicon.

Next, using spodiumene-based ceramics, a holder was made with a structure consisting of two plate-like bodies of the same shape and size, with grooves on both opposing surfaces into which the main body could fit, and alumina cement was used. Attach this to the heating element body using
A ceramic heating element as shown in the figure was manufactured.

When electricity was applied to the ceramic heating element thus obtained, the heating part began to become red hot after about 1 second, and the temperature reached about 1150°C after about 10 seconds.

However, the temperature of the base portion at this time was approximately 110° C., and no peeling of the electrode was observed.

Further, this heating element experienced thermal expansion of approximately 0.32 mm, but this was due to free expansion and no distortion occurred.

For comparison, we used the same ceramics with a cross-sectional area of 2 mm.
2. A rod-shaped body with a length of 60 mm was prepared, and electrodes were provided at both ends of the rod-shaped body using aluminum metallicon, thereby manufacturing a linear ceramic heating element.

When I held this thing by one end and turned on electricity, it turned out to be about 1
After 0 seconds, the temperature of the heat generating part reached approximately 1150°C.

The temperature of the electrode portion at this time was as high as approximately 850° C., and when electricity was continued, the aluminum melted after 2 minutes and the electrode disappeared.

In addition, when the thermal expansion length was measured at this time, it was approximately 0.48
mm, it can be seen that if both ends were fixed, considerable distortion would occur.

As described above, the present invention is durable and has no risk of damage due to thermal expansion unlike conventional ceramic heating elements.
In addition to being capable of frequent rapid heating, there is no deterioration of the electrodes because the rise in temperature of the base is moderated, and furthermore, since the positions of the electrodes are biased to one side, wiring is convenient.

[Brief explanation of drawings]

Figure 1 is a plan view showing one example of the heating element main body of the present invention;
The figure is a plan view showing another example of the present invention. In the figure, reference numeral 1 indicates a heat generating portion, 2 a base portion, 3 an electrode, and 4 a holder.

Claims (1)

[Scope of utility model registration request] A U-shaped heat generating part having a substantially constant cross-sectional area, two base parts continuous to both ends of the heat generating part, each integrally formed with a larger cross-sectional area than the heat generating part, provided on the base part. A ceramic heating element comprising a holder made of heat-resistant insulating ceramic that clamps and fixes the electrodes and both base parts.