JPS5932875B2 - far infrared radiation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a far infrared ray radiating device which is suitable for heating and insulating heating rooms for dry foods with baked paint and is excellent in design.

In general, far-infrared radiation devices are required to have the following properties.

l) In order to emit strong far-infrared rays, the emissivity of the radiating material should be close to l in the wavelength range of 4 to 50 μ.

2) The radioactive substance must be thermally stable at high temperatures of 500 to 700°C.

3) It has great adhesion to the heat radiator and does not cause peeling or cracking during use in cooling and heating cycles.

4) Strong against mechanical stress.

5) The radioactive material is colorful and has a good design.

On the other hand, conventional far-infrared radiation devices include quartz tube heaters, ceramic tube heaters, and thermal spray heaters. Quartz tube heaters and ceramic heaters have a structure in which a nichrome wire is coiled in a quartz tube or a ceramic tube, and a thermal spray heater has a structure in which a nichrome wire is coiled in a quartz tube or a ceramic tube, and a thermal spray heater is a sheathed heater shown in Fig. A heating element having a structure in which a spiral heating element 3 having electrode terminals 2 at both ends is pushed through, filled with a heat-resistant insulating filler 4 such as M90, and both ends sealed with an airtight material 5, and the surface of a heat radiating element 1. to Fe2o3CoO, N
It consists of a radiation layer 6 lined with an oxide such as iO or MnO by plasma spraying. However, the above-mentioned quartz tube heater has an emissivity of 0.5 or less at wavelengths of 4 μ or more, so it has poor performance as a far-infrared radiating device, is weak against the stress of aircraft stock, and has heat-generating rays exposed to the air. Because of this, there were drawbacks such as wire breakage due to oxidation.

Ceramic tube heaters have a high emissivity in the range of 6μ to 15μ, and while they have excellent characteristics, they are weak against mechanical stress.Also, since the heating wire is exposed to the air, there is a problem of wire breakage due to progressing oxidation, which shortens the lifespan. had a short flaw. Furthermore, thermal spray heaters have an emissivity of 4 to 50μ, and are resistant to mechanical stress.
It has the advantage of long life, but the emissive layer is Fe2O3, CoO,
Because it is a radioactive substance such as NiO or MnO, only a black color tone can be obtained, and it is unsuitable for applications where a black color is undesirable in terms of design, such as food heating and insulation, space heating, etc.

The present invention was made in consideration of the above-mentioned drawbacks, and combines a blue radioactive material with a spinel structure obtained by firing a mixed powder of alumina and cobalt carbonate with at least 3 weight axes or more and other ceramics. By lining the surface of the heat radiator with the mixed powder by thermal spraying, it has a high emissivity in the wavelength range of 4 to 50μ, is stable at 500 to 700℃, has good adhesion to the heat radiator, and has good mechanical impact resistance. It is possible to provide a far-infrared ray radiating device with strong color and beautiful color tone.

An embodiment of the present invention will be described below with reference to the drawings.

The spinel compound of alumina and cobalt carbonate used as a radioactive material is made as follows. First, 100-30
A mixed powder of 0 mesh alumina powder and 250 to 500 mesh cobalt carbonate has a weight ratio of approximately 6:4.
3 to 10% by weight of M9O or a stabilizer such as CaO is added to the mixed powder, mixed uniformly, and then calcined at a temperature of 1000 to 1400°C for 1 to 5 hours to form cobalt carbonate. It changes to B3 cobalt oxide and undergoes a solid phase reaction between alumina and cobalt oxide. Through a solid-state reaction, cobalt oxide diffuses into alumina, creating a type of solid solution. After firing, excess cobalt oxide that does not participate in the solid phase reaction is dissolved and removed by immersing it in an acidic solvent, such as hydrochloric acid.
The dissolved and removed solid solution of alumina and cobalt oxide is neutralized or washed with water and then dried. In addition, the temperature suitable for the solid phase reaction between alumina and cobalt oxide to proceed is as follows:
The temperature during firing was limited to 1000 to 1400°C. Further, the mixed powder after firing does not necessarily need to be treated with an acidic solvent, and the present invention is not limited thereto. B5 has the feature B5 that a clearer blue or cobalt blue color can be obtained by performing an acidic solvent treatment. The obtained solid solution contains Al, CO,
It was found that each O atom forms a ceramic spinel structure, which is thermally stable and has an emissivity superior to that obtained by simply mechanically mixing alumina and cobalt oxide in the range of 4 to 50 μm. Next, a method of lining the surface of the thermal radiator with a radiation material, which is an aluminum-cobalt oxide, by thermal spraying will be described.

First, as a pretreatment, the surface of the heat radiator is blasted with 40 to 80 mesh alumina steel, silicon carbide, or the like. Next, 150-300 mesh N
The base layer is lined with i-Cr alloy to a thickness of 50 to 150 μm by thermal spraying. In the pretreatment mentioned above, the purpose of blasting is to remove oil and dirt from the surface of the heat radiator and to mechanically roughen it, thereby improving the projection effect of Nl-Cr and improving the adhesion of Ni-Cr. do. Ni-C
The surface treatment of r is necessary for the following reasons. Ceramic, which is lined as a radiation layer, has a low coefficient of thermal expansion, so
If it is deposited on the surface of a thermal radiator without Ni-Cr intervening, the radiant material may peel off during cold use. but,
The provision of the Ni--Cr intermediate layer serves to absorb thermal stress caused by the thermal expansion coefficients of the heat radiator and the radiation layer.
The emissive layer is obtained by lining the Ni--Cr underlayer with, for example, the following ceramic powder by thermal spraying.

The mixture of the above example was heated in a sheathed heater (length 500m7n).
3 on the surface of a pipe with a diameter of 12 mm (1100, 500 W)
Thermal spray lining was applied to a thickness of 0 to 100μ, and the radiation characteristics were investigated by applying electricity.

As shown in Figure 2, the radiation characteristics are measured by the specific radiation energy at 25 to 50 μ using an infrared spectrophotometer, and the radiation characteristics are worse than that of the conventional ceramic tube heater, which is the main component of COO. has. Furthermore, the effects of drying the paint were investigated, and the results shown in Table 1 were found to be worse than the conventional product examples. In addition, taking into consideration the conditions of use of cold and heat, we conducted a cold and heat test between the operating temperature of 600℃ and room temperature, and the results showed that there was no peeling or crack BS after over 1000 cycles, and there was no problem with the service life. There was found.
The mechanical impact strength of the emissive layer is excellent due to its spinel structure. The reason why the amount of ceramics having a spinel structure of Al2O3-COO in the emissive layer is set at 3% by weight or more is as follows.
It is as follows. Ceramics B33 weight with spinel structure? If it is less than that, the radiation characteristics will be poor and there will be no pigment effect, making it unsuitable for applications requiring a good color tone. Preferably 5 weight? The above is preferable, and ceramics having a 100% spinel structure may also be used. As described above, we are particularly pleased to be able to provide a unique radiating device that has excellent radiation characteristics, thermal characteristics, lifespan, mechanical strength, etc. that a far-infrared ray radiating device should have, and also has a cobalt blue color tone in terms of design. has.

Claims (1)

[Claims] 1 Mixed powder of alumina and cobalt carbonate from 1000 to
1. A far-infrared radiation device characterized in that the surface of a heat radiator is lined with at least 3% by weight or more of aluminum-cobalt oxide powder having a spinel structure obtained by firing at 1400° C. by thermal spraying.