JPS5836820B2 - Manufacturing method of far-infrared radiating element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a far-infrared radiating element that has excellent emissivity for far-infrared radiant energy and excellent durability.

In general, the conditions that an excellent far-infrared radiating element should meet are: 1) The radiation layer must be in strong contact with the substrate, 2) The emissivity of the radiation layer must be close to 1, and 3) The surface of the radiation layer must be rough. It is required to have a large surface area.

If the radiation layer is in strong contact with the base, the heat generated from the heating element will be efficiently conducted to the radiation layer, increasing the amount of radiant energy.

Moreover, even when the heater is used in a cold/hot cycle state, the radiation layer does not peel off or crack, resulting in a far-infrared radiation element with excellent durability.

If the emissivity of the emissive layer is close to 1, heat loss due to convection will be reduced, resulting in an efficient far-infrared radiating element.

Far infrared rays are emitted from the surface of the emissive layer, so the larger the surface area, the more radiant energy.

Conventionally, methods for manufacturing far-infrared radiation elements include: 1) a method of thermally spraying a radiation material such as a metal oxide, carbide, or nitride onto the surface of a substrate to form a radiation layer;

2) A method in which a heat-resistant paint containing a radioactive material such as a metal oxide, carbide, or nitride is applied to the surface of the substrate by spraying or brushing to form a radiation layer. 3) Alumite treatment is performed on the aluminum substrate to form an A I
There is a method of forming a 203 radiation layer of 10 to 40 μm.

When forming a radiation layer by thermal spraying, the surface area of the radiation layer can be increased, but in order to improve the adhesion between the substrate and the radiation material, the surface of the substrate must be blasted with steel grids or glass beads, or self-fusing metal , for example N i
It is necessary to carry out a process called a pound coat, in which metals such as -Cr, Ni-AI, Mo, etc. are thermally sprayed in advance, or a blast process and a bond coat process, which complicates the manufacturing process and has the drawback of poor productivity.

Considering the heat resistance of the paint binder, the radiant layer coated with heat-resistant paint can only be used at temperatures below 500°C, and cannot be used in applications where the radiant layer surface temperature is 600 to 700°C and generates strong radiant energy. Another drawback was that the surface area of the emissive layer could not be increased by roughening it.

Even in the case of an alumite-treated emissive layer on the surface of an aluminum substrate, it cannot be used unless it is heat resistant to 400°C or lower, so it cannot be used as a far-infrared emitting element for high temperatures, and it also has the disadvantage that the surface of the emissive layer cannot be roughened to increase the surface area. .

The present invention has been made in consideration of the above points, and involves lining the surface of a steel heating element base with aluminum or an aluminum alloy, such as an AI-Si system, by thermal spraying, heating it at a high temperature, and then coating the thermally sprayed surface. By forming the emissive layer through alumite treatment, it is possible to (1) improve the emissivity, (2) improve the adhesion between the substrate and the emissive layer, and (2) obtain a far-infrared radiating element with a large radiation surface area.

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

In Figure 1, aluminum or aluminum alloy 2 is lined with a thickness of 50 to 200 μm on the surface of a steel heating element base 1 by thermal spraying, and then the surface of aluminum or aluminum alloy 2 is coated with sulfuric acid or organic acid for 10 to 200 μm. A 30μ thick alumite layer 3 is applied.

The reason why the adhesion between the thermal spray-lined aluminum or aluminum alloy 2 and the heating element base 1 is improved by this S is the following phenomenon.

When aluminum is thermally sprayed onto steel and then heated, mutual diffusion occurs at the joint between the steel and aluminum, and an iron-aluminum alloy layer 4 is formed there.

The alloy layer 4 reaches a thickness of 50 to 80 microns when heating is maintained at about 800 DEG for 1 to 2 hours in the air.

Therefore, if heated by external heating or self-heating of the heating element, the aluminum of the sprayed lining layer will form a strong bond with the heating element, and there will be no fear of peeling or falling off, and the heat conduction will be good.

It is preferable to perform heating before the alumite treatment in order not to destroy the alumite layer.

The aluminum alloy that can be used for the thermal spray lining layer 2 is easily alumite-treated and has an emissivity of 0.88 to 0.94 A.
I-Si type is suitable.

The alumite treatment may be carried out using generally widely used sulfuric acid or an organic acid capable of blackening, and the thickness of the alumite layer is preferably 10 to 30 μm from the viewpoint of performance and economy.

As described above, the present invention involves lining the surface of a steel heating element with aluminum metal or its alloy by thermal spraying, heating the lining layer at a high temperature of about 800°C for 1 to 2 hours, and then anodizing the lining layer. As a result, the adhesion with the heating element base is good and the emissivity is 0.88.
A strong far-infrared radiation element can be provided by having a large particle diameter of ~0.94 and having a rough surface of the radiation layer.

The tests shown in Table 1 were conducted on the radiating element obtained by the method of the present invention and the paint application method as a conventional example.
The radiant energy in the 0μ wavelength region is measured using an infrared spectrophotometer, and the emissivity at that time is calculated from the results, and the result is shown in FIG. 2.

As can be seen from Figure 2, when the cooling and heating cycles are repeated, the emissivity of the conventional example decreases significantly from the initial level due to peeling.
The examples of the present invention retain their initial characteristics even after long-term use.

For this reason, it can be said that it is a far-infrared radiating element with excellent durability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a far-infrared radiation element of the present invention, and FIG. 2 is an emissivity characteristic diagram of the present invention and a conventional example. 1... Heating element base, 2... Aluminum or its alloy, 3... Alumite layer.

Claims (1)

[Claims] 1. A method for manufacturing a far-infrared radiating element, characterized in that the surface of a steel heating element base is lined with aluminum metal or its alloy by a thermal spraying method, then heated to a high temperature, and then the thermally sprayed surface is subjected to an alumite treatment.