JPS603884A - 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 Industrial Application The present invention relates to a far-infrared heater that is used as a heat source for drying, heating, cooking, space heating, etc. and that efficiently emits far-infrared rays. Examples of configurations and their problems Traditionally, far-infrared heaters include (1) an infrared lamp, (4) a heater in which a heating element is embedded in ceramic and fired, and (iii) a sheathed heater with a far-infrared radiation layer formed on the surface. However, from the viewpoint of radiation characteristics 2 mechanical strength and lifespan, many sheathed heaters with a far-infrared radiation layer formed on the surface are used.

This sheathed heater type far-infrared heater has a far-infrared radiation layer formed on the surface of a metal pipe of the sheathed heater.

On the other hand, as the far-infrared radiation layer, a material mainly composed of zirconium oxide, which has excellent radiation characteristics on the longer wavelength side of about 10 μm, is mainly used.

However, far-infrared heaters whose main component is zirconium oxide have the disadvantage that their radiation layer tends to peel off during heating and cooling cycles of 500"C or higher, and they cannot be used at high temperatures of Boo"C or higher. The reality is that it 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 500° C. or higher.

Structure of the Invention The present invention provides a far-infrared radiation layer made of zirconium oxide on the surface of a metal pipe, and this far-infrared radiation layer contains at least one selected from the group of silicon carbide and silicon nitride whiskers, and the content thereof is is 1 to 10% by weight, and the silicon carbide whiskers or silicon nitride whiskers act to reduce the difference in thermal expansion between the zirconium oxide and the metal pipe. This can prevent the peeling phenomenon.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 1, a heating wire 2 made of a coiled nichrome wire with terminal rods 1 at both ends is NCFao.

Insert it into the metal pipe 3 of (product name Incoloy 800),
This metal pipe 3 is filled with electrical insulating powder 4 made of fused magnesia powder, and both ends of the metal pipe 3 are sealed with glass 5 and heat-resistant resin 6. It was a sheathed heater.

Next, the surface of this sheathed heater is coated with molten alumina (SSO).
) was blasted with an abrasive.

Thereafter, zirconium oxide containing silicon carbide whiskers or silicon nitride whiskers in the proportions shown in the table is coated by plasma spraying to form a far-infrared emitting layer 7 of 50 μm. Sample No. 2 shown in the table below.
~25 far infrared heaters have been completed.

On the other hand, for comparison, a conventional far-infrared heater of Sample No. 1 was completed by coating conventional zirconium oxide containing no silicon carbide whiskers or silicon nitride whiskers in the same manner.

Each of the completed far-infrared heaters was subjected to an intermittent energization test at temperatures of 500°C and 800'C' (7), with one cycle of 20 minutes on and 10 minutes off, to determine whether the far-infrared radiation layer 7 would peel off. , 01. Regarding peeling, 100, E500, 10.
After 00°5ooo cycles, the results are shown in the table (-).

(Margins below) In the table, the ○ mark indicates that no peeling is observed at all, and the X mark indicates that one or more places of peeling are observed.

As is clear from this coating, Sample No. 1, which has a far-infrared emitting layer made of conventional tungsten zirconium, and silicon carbide whiskers or silicon nitride whiskers, have a total content of less than 1%, and Sample No. 1, which has a far-infrared emitting layer made of conventional tungsten zirconium zirconium, has a total content of less than 1%. Sample number 2 with a far-infrared emitting layer made of zirconium chloride,
Each far infrared heater of 3, 4, 19.20 is 6
At 00″C, no peeling was observed, but at SOO″C,
It can be seen that peeling occurred by 5oo cycles.

However, sample number 6゜6 has a far-infrared emitting layer 7 made of zirconium oxide containing at least one selected from the group of silicon carbide whiskers and silicon nitride whiskers, with a total content of 1 to 10%. .7,8,9,1
0,11.12,13,14゜15.16,17.18
The far infrared heater has not only 500"C but also 8oo
Even with "C", no peeling occurred at all.

On the other hand, with zirconium oxide containing 20% or more of silicon carbide whiskers and silicon nitride whiskers, thermal spraying is impossible, and a far-infrared emitting layer cannot be uniformly formed.

Next, for the far infrared heaters of sample numbers 1 and 10, the emissivity at each wavelength of 2.5 μm to 30 μm was measured using an infrared spectrometer, and the results are shown in FIG. In FIG. 2, a indicates the measurement results of sample number 1, and b indicates the measurement results of sample number 1o.

As is clear from FIG. 2, it can be seen that the far-infrared heater of sample number 10 of this example exhibits excellent far-infrared radiation characteristics as well as the conventional far-infrared heater of sample number 1.

In this way, by providing zirconium oxide containing at least one selected from the group of silicon carbide whiskers and silicon nitride whiskers, with a total content of 1 to 10% by weight, on the surface of the metal pipe, it is possible to improve the conventional method. This can increase the actual operating temperature of far-infrared heaters that use zirconium oxide.

It has been found that the metal pipe exhibits a sufficient effect with any heat-resistant steel such as stainless steel, iron-based metal, or nickel-based metal, other than the 1'' JCF800 shown in the example.

Effects of the Invention As is clear from the above explanation, the far-infrared heater of the present invention contains at least one selected from the group of silicon carbide whiskers and silicon nitride whiskers, and the total amount thereof is 1 to 10% by weight. By providing a far-infrared radiation layer made of zirconium oxide with 50%
It can be used at high temperatures of 0°C or higher, and its industrial value is significant.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a far-infrared heater according to an embodiment of the present invention, and FIG. 2 is a graph showing emissivity versus wavelength of a conventional far-infrared heater and a far-infrared heater of the embodiment. 3.--Gold pipe, 7. Far-infrared radiation layer. Figure 1 Figure 2 z5510 2θ 3° Wave 5 (Crab, 1

Claims (1)

[Claims] A far-infrared radiation layer made of zirconium oxide is provided on the surface of the metal pipe, and this far-infrared radiation layer contains at least one selected from the group of silicon carbide whiskers and silicon nitride whiskers, with a total content of 1 to 10% by weight. Far infrared heater as %0