JPS607095A - Far infrared ray heater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a far-infrared heater that is used as a heat source for drying, heating, cooking, heating, etc., and that efficiently radiates far-infrared rays.

Conventional configurations and their problems Conventional far-infrared heaters include (1) infrared lamps, (11) those in which a heating element is embedded in ceramic and fired, (iii) those in which a far-infrared radiation layer is formed on the surface of a sheathed heater, etc. However, from the viewpoint of radiation characteristics 2 mechanical strength and lifespan, sheathed heaters with a far-infrared radiation layer formed on the surface are often used.

In this sheathed heater type far infrared heater, generally, as shown in FIG.
is filled with electrically insulating powder 4 such as electrofused magnet 7a,
A far-infrared emitting layer γ is formed on the surface of the metal pipe 3 of a conventional sheathed heater in which both ends of the metal pipe 3 are sealed with glass or heat-resistant resin 6 as necessary.
As the far-infrared radiation layer 7, a material whose main component is zirconium oxide, which has excellent radiation characteristics on the long wavelength side of about 1 o/im, is mainly used.

However, far-infrared heaters containing zirconium oxide as a main component have the disadvantage that they cannot be used at high temperatures of 500'C or higher due to intermittent energization, and the actual temperature range in which they can be used is limited.

OBJECTS OF THE INVENTION The present invention solves these conventional drawbacks and provides a stable far-infrared heater whose far-infrared radiation layer does not peel off even when used at high temperatures of SOO°C or higher.

Components of the Invention The present invention is characterized in that the surface of a metal pipe made of stainless steel, iron-based alloy, or nickel-based alloy U-heat steel is coated with a material such as nickel oxide, which has a thermal expansion coefficient equal to that of the metal pipe and the heat of a far-infrared emitting layer. By providing a base layer made of a material with an intermediate value of expansion coefficient, and further providing a far-infrared emitting layer containing zirconium oxide as a main component, the base layer is made of stainless steel, iron-based material, and nickel. It acts to alleviate the difference in thermal expansion between the base alloy heat-resistant steel and the zirconium oxide far-infrared radiation layer, and prevents the far-infrared radiation layer from peeling off at high temperatures of 500°C or higher.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to FIG. In the drawings, the same members as in the conventional example are designated by the same reference numerals as in the conventional example, and the description thereof will be omitted.

The metal pipe 3 blasts the surface of a sheathed heater (diameter 11M, length 5oOM) made of iron-based alloy NCF300 (trade name Incoloy 800) with molten alumina (#60) abrasive, and then blasts the surface. Underlayer 11 coated with nickel oxide by plasma spraying and having a thickness of 50 μm.
was formed.

Furthermore, zirconium oxide (stabilized zirconia) was coated on the base layer 11 by the same method to a thickness of 50 mm.
Form a far infrared radiation layer 12 of 1 oov-50 μm.
We have completed a 0W far-infrared heater shown in Figure 2.

On the other hand, for comparison, a conventional far-infrared heater was also completed in which the metal pipe 3 was coated with the above-mentioned zirconium oxide by plasma spraying without forming the base layer 11 of nickel oxide.

Each completed far infrared heater was heated to 500"C, 6
00″G, 700″C, aoooC (7) The voltage was adjusted to each temperature, and an intermittent energization test was conducted with one cycle of 20 minutes on and 10 minutes off, and the far infrared emitting layer 12
The peeling degree of 0, which was tested, was 100.500 and 1000.

Measured after 5000 cycles.

The results are shown in the table.〇In this table, ○ marks indicate that no peeling is observed at all, ∆ marks indicate that the phenomenon is observed in several places, and X marks indicate that more than half of the heaters A peeling phenomenon was observed, indicating a situation that could not be used in actual use.

As is clear from the table, the conventional far-infrared heater without the nickel oxide base layer 11 can be used in practice at 500° C., but peeling occurs at temperatures higher than that.

However, in the far-infrared heater of the present invention having the nickel oxide base layer 11, no peeling occurred at temperatures up to 800°C.

This is because the base layer 11 of nickel oxide is an iron-based alloy.
Thermal expansion coefficient of CF300 170-180x 1o-'
(Room temperature ~ 1o○0℃) and zirconium oxide rhamnothermal expansion coefficient 50~60X10-' (g temperature ~ 1oQO℃). It is estimated that this acts to alleviate the difference in thermal expansion between the two.

Furthermore, it is presumed that Nisoquerl oxide has the effect of increasing adhesion with the chromium element, which is a component element of NCF300, through some kind of chemical bond.

For the above reasons, the far-infrared heater having the structure of the present invention does not cause a peeling phenomenon even when used at high temperatures, and has excellent characteristics.

As another example, the surface of the metal pipe 3 is a 5US321 7-mm pipe (diameter: 6.6 mm, length: 600 rhymes), which is blasted in the same manner as in the above-mentioned example. The far-infrared heater of the present invention shown in the figure was completed. When the completed far-infrared heater was subjected to an intermittent energization test of 20 minutes on and 10 minutes off at 700° C., no peeling of the zirconium oxide far-infrared emitting layer 12 was observed up to 500 cycles.

As is clear from the above embodiment, a base layer 11 made of nickel oxide, which has a coefficient of thermal expansion between the two and forms a chemical bond with the metal pipe 3, is provided between the metal pipe 3 and the far-infrared emitting layer 120. By providing this, the actual operating temperature of a conventional far-infrared heater using zirconium oxide can be increased.

Note that the base layer 11 of the present invention is not limited to nickel oxide, and may be any material having a thermal expansion coefficient that is intermediate between the thermal expansion coefficient of the metal pipe and the thermal expansion coefficient of the far-infrared emitting layer. The purity of the nickel oxide used is also limited to the examples as long as it does not contain impurities (alkaline IJ-j or alkaline earth metals or oxides thereof, etc.) that adversely affect the metal vibe 3. It's not fi.

5US32 shown in the example as the metal pipe 3.
1. Stainless steel other than NCF300.

Any heat-resistant steel of iron-based alloy or nickel-based alloy may be used.

Effects of the Invention As is clear from the above explanation, according to the far-infrared heater of the present invention, there is a gap between the metal pipe and the far-infrared radiation layer mainly composed of zirconium oxide. By providing a base layer with a thermal expansion coefficient intermediate to that of the radiation layer, the far-infrared radiation layer does not peel off, making it possible to use it at high temperatures of 500°C or higher, and its industrial effects. is a dog.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional far-infrared heater, FIG. 2 is a sectional view of a far-infrared heater according to an embodiment of the present invention, and FIG. 3 is an enlarged view of section A in FIG. 2. 3...metal pipe, 11--base layer, 12-far-infrared radiation layer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (2)

[Claims] (1) A far-infrared radiation layer mainly composed of zirconium oxide is provided on the surface of a metal pipe made of heat-resistant steel via a base layer, and the thermal expansion coefficient of this base layer is the thermal expansion coefficient of the metal pipe and the far-infrared radiation. A far-infrared heater with a thermal expansion coefficient intermediate to that of the layer. (2) The far-infrared heater according to claim 1, wherein the base layer is mainly composed of nickel oxide.