JPS6113353B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an infrared radiation device used for drying and baking paint, keeping food warm, heating, and the like. In general, organic and inorganic substances that make up paints and foods have natural vibrations of their constituent molecules at a temperature of 4 to 50μ, regardless of temperature, so if you irradiate them with infrared rays that have the same vibration as their natural vibrations, you can eliminate the resonance phenomenon. and generate violent molecular vibrations. It is well known that the constituent molecules generate self-heating due to the friction of the molecules caused by the molecular vibrations, which not only makes it possible to dry and bake paints and keep food warm, but also to heat the room using the same principle. be. Therefore, the above-mentioned infrared emitting device is suitable for use in the infrared region of 0.75 to 50μ, especially in the range of 4 to 50μ.
It is preferable to efficiently radiate infrared rays in the far infrared region. Conventional infrared radiation devices of this type include:
There are so-called thermal spray heaters and infrared lamps in which the surface of a metal heat radiator is lined with ceramic powder such as ZrO ₂ or Al ₂ O ₃ by thermal spraying. While the above infrared lamps have excellent emissivity in the near-infrared region of 0.75 to 3μ, their emissivity drops significantly in the far-infrared region of 4 to 50μ, making them unsuitable for drying paint, keeping food warm, heating, etc. Not only that, but they also have the disadvantage of being inferior in terms of impact resistance and lifespan. Further, although the ceramic-lined thermal spray heater has good mechanical impact resistance, service life, and emissivity in the range of 8 to 50μ, it has the disadvantage of poor emissivity in the range of 0.75 to 8μ. As is clear from the spectral radiant energy distribution characteristics of known blanks, the operating temperature of the radiator is 300~
Spectral radiant energy at 700℃ is 0.75~8μ
, especially in the 3-8 μm range, the thermal spray heater with low emissivity in this range is unsuitable as a radiating device. In view of the above, the present invention aims to provide an infrared radiation device with excellent radiation characteristics.
On the base layer formed on the surface of the heat radiator, FeO
The radiation layer is formed by welding ceramic powder containing at least 5% of natural magnetite powder containing at least 50% of Fe ₂ O ₃ . Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a heat radiator made of metal;
For example, pipes made of iron, stainless steel, etc.
is a heat-resistant insulating filler, such as MgO, filled in the heat radiator 1. 3 is a linear heating element embedded in the filling material 2, 4 is a terminal connected to the heating element 3, and 5 is an airtight material for sealing both ends of the heating element 3. 6, after blasting the surface of the heat radiator 1 with a blasting material such as alumina or silicon carbide,
The base layer 7 is formed by lining a metal such as Ni-Cr or Ni-Al to a thickness of 50 to 100 μ by plasma spraying, and 7 is a layer containing at least FeO/Fe ₂ O ₃ .
The radiation layer is formed by lining the base layer 6 to a thickness of 30 to 100 microns by plasma spraying with ceramic powder containing at least 5% of natural magnetite powder. The purpose of blasting the heat radiator 1 as described above is to remove oxides and dirt on the surface of the heat radiator,
In addition, by roughening the surface, the surface energy is increased and the adhesion between the heat radiator 1 and the base layer 6 is improved. The reason for lining the base layer 6 is that this type of infrared radiating device is used at a surface temperature of 300 to 800°C, and the radiation layer 7 has a linear expansion coefficient different from that of the thermal radiator 1. Heat radiator 1 may cause peeling and cracking.
This is because it is necessary to provide a thermal shock layer between the radiation layer 7 and the radiation layer 7. Metals such as Ni-Cr and Ni-Al have excellent adhesion and oxidation resistance with the heat radiator 1 made of iron and stainless steel, and the base layer 6 formed by thermal spray lining is porous and has a large surface area, so the radiation layer It is well known that it is convenient to form 7. Therefore, the base layer 6 such as Ni--Cr or Ni--Al is provided in order to increase the adhesion strength between the heat radiator 1 and the radiation layer 7 and to obtain a heat cycle. Since the natural magnetite powder mainly composed of FeO.Fe ₂ O ₃ that composes the radiation layer 7 consists of the components shown in the table below, in the present invention, FeO.Fe ₂ in the natural magnetite powder is _O3 content at least 50
% or more, and because it has thermal sprayability, that is, each component is in a solid solution state and is a round powder, compared to ceramic powder made by artificially pulverizing and mixing each component. The fluidity of the powder during thermal spraying and the uniformity of the radiation layer coating formed by thermal spraying are extremely excellent, and the radiation layer and heat cycle resistance are excellent. Also, as mentioned above, magnetite whose main component is FeO.Fe ₂ O ₃ may be used alone, but it can also be used with ZrO ₂ .
It has been found that the use of SiO ₂ or a mixture with ZrO ₂ or Al ₂ O ₃ improves thermal sprayability, radiation properties, heat cycle resistance, etc.

[Table] The reason why the amount of natural magnetite powder was limited to 5% (weight ratio) or more in this example is as follows. For example, when the radiation layer was lined with Al ₂ O ₃ and FeO.By changing the blending ratio of natural magnetite powder whose main component is _{Fe 2} O ₃ , the total radiant energy was measured, and the results are shown in Figure 5. It is. From this diagram
This is because it is clear that if the content of natural magnetite powder containing FeO.Fe ₂ O ₃ as a main component is 5% or more, there will be no problem in terms of properties. Further, in this embodiment, the radiation layer 7 was formed by welding the radiation layer containing natural magnetite powder onto the base layer 6 provided on the surface of the sheathed heater by the plasma spraying method, but the plasma spraying method is not limited to this method. isn't it. Furthermore, the same effect can be obtained by mixing the natural magnetite with clay or the like and firing the mixture to form a ceramic radiation layer. Next, an experimental example of the present invention will be explained. Experimental example After blasting the surface of a SUS sheathed heater (100V, 600W) with a diameter of 12 mm and a length of 500 mm with 40 mesh SiC,
A base layer was formed by lining Ni-Cr powder to a thickness of 0.05 to 0.01 mm by plasma spraying. Next, 100 to 200 mesh layers are applied to the base layer.
A radiation layer was formed by lining to a thickness of 0.05 to 0.07 mm using a natural magnetite powder plasma spraying method containing FeO.Fe ₂ O ₃ as the main component. Experimental example The same sheathed heater as in the experimental example was subjected to the same blasting treatment and after lining with the base layer,
ZrO ₂ , SiO ₂ with particle size of 100-300 mesh
Natural magnetite powder containing FeO.Fe ₂ O ₃ as the main component was mixed in equal proportions and lined by plasma spraying to form a radiation layer. Experimental example After applying the same blasting treatment to the same sheathed heater as in the experimental example and lining the base layer,
Al ₂ O ₃ and FeO with particle size of 100-300 mesh.
Natural magnetite powder whose main component is Fe ₂ O ₃ at 1:3
A radiation layer was formed by lining by plasma spraying. The infrared radiation device configured as above was energized and the specific radiation energy in the wavelength range of 2.5 to 50μ was measured using an infrared spectrophotometer.
A characteristic curve as shown in FIG. 4 was obtained. That is, the solid lines indicate the characteristic curves of the experimental examples, and the broken lines indicate the characteristic curves of the conventional example corresponding to each experimental example. From these figures, it is clear that the emissive layer of the experimental example exhibits better radioactivity characteristics than the conventional example. Next, as a result of a heat cycle test at 700℃ and room temperature for experimental example ~,
No peeling or cracking occurs even after 1000 cycles or more, extending the service life. Furthermore, since the emissive layer is very hard, there is no risk of it being damaged by mechanical impact. As explained above, according to the present invention, the
Since the amount of infrared radiation in the infrared region, especially up to 8 μm, is significantly larger than that of the conventional example, the radiation characteristics are excellent. Furthermore, since the adhesion between the radiation layer and the heat radiator is strong, the heat cycle resistance can be significantly improved. Furthermore, since the emissive layer has a high hardness, it can withstand mechanical shock sufficiently, thereby extending its life.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway cross-sectional view showing an embodiment of the infrared radiation device of the present invention, FIGS. 2 to 4 are diagrams showing specific radiant energy characteristics of the embodiment of the present invention and the conventional example, and FIG. FIG. 2 is a diagram showing the relationship between magnetite powder content and total radiant energy characteristics of the present invention. 1... Heat radiator, 6... Base layer, 7... Radiation layer.

Claims (1)

[Claims] 1 A base layer is formed on the surface of a heat radiator made of metal, which has a linear heating element and a heat-resistant insulating filler inside, and ceramic powder is welded on the base layer to form a radiation layer. In the infrared radiation device, the radiation layer 7 is made of at least 50% FeO.Fe ₂ O ₃ .
Natural magnetite powder containing at least 5%
An infrared radiation device characterized in that it is formed from ceramic powder containing % or more.