JPH01184257A - Far infrared radiator and its production - Google Patents

Abstract

PURPOSE:To prevent deterioration in radiation characteristics of the title radiator by subjecting a stainless steel in which respective contents of C, Si, Mn, Cr, Al, Y, Nd, Gd, and N are specified to heating under the prescribed conditions and forming a layer containing Al2O3 on the surface. CONSTITUTION:A stainless steel having a composition consisting of, by weight, <=0.1% C, <=1% Si, 3% Mn, 8-30% Cr, 1-8% Al, 0.001-0.1% of one or more elements among Y, Nd, and Gd, <=0.05% N, and the balance Fe is refined. Then, a sheet of the above stainless steel is heated in an oxidizing atmosphere, by which a layer containing acicular or cylindrical Al2O3 can be formed on the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a far-infrared radiator and a method for manufacturing the same, and particularly provides a radiator whose radiation characteristics do not deteriorate even after repeated heating and cooling.

[Prior art 1] Conventionally, far-infrared radiators have generally been coated with a far-infrared radiator material on a stainless steel substrate by thermal spraying or the like. Moreover, peeling and cracking were likely to occur unless the coating thickness was limited. Furthermore, even if the density is limited and the thickness is controlled, the bond between the far-infrared paint and the substrate is weak if it is applied on the surface, so it is important to avoid peeling due to repeated use over a long period of time. I can't. This is because no matter what method such as thermal spraying is applied to the substrate, the resistance to peeling in the coating method depends only on the bonding force between the coating and the substrate.

On the other hand, the radiation characteristics of far infrared rays depend on the characteristics of the material being painted,
This is due to the surface area effect, that is, there are many irregularities and the effective radiation area is large. In the case of painting, if a porous coating is applied to increase the surface area, the interfacial strength will decrease.

Therefore, it is basically impossible to improve the radiation characteristics and increase the peel resistance at the same time using the coating method.

The present applicant proposed Japanese Patent Application No. 61-169422 in order to solve these problems at the same time.

[Problems to be Solved by the Invention] Through subsequent research, the present inventors obtained new knowledge regarding rare earth elements Y, Nd, and Gd other than Ce and La.

An object of the present invention is to provide a radiator having high radiation characteristics, a stable coating layer, and high resistance to peeling, and a method for manufacturing the same.

[Means for Solving the Problem] As a result of extensive experiments, the present inventors formed an acicular or rod-shaped alumina film on the surface of stainless steel having the following composition by oxidizing it in an oxidizing atmosphere. This led to the invention of a radiator with excellent far-infrared radiation characteristics.

That is, C: O, 10 wt% or less Si: 1.0 wt% or less Mn: 3.0 wt% or less Cr: 8 wt% or more and 30 wt% or less Aff: 1 wt% or more and 8 wt% or less Y, Nd, One or more of Gd: O, OO1
Weight% or more, i Weight% or lessN: 0.05% by weight
The following is a far-infrared radiator characterized in that a film having needle-shaped or rod-shaped 8β203 is formed on the surface of stainless steel, the balance of which is Fe and unavoidable impurities. Further, the total amount of rare earth elements such as Y and La and/or Ce may be o, ooi weight % or more and 0.1 weight % or less.

Furthermore, if various processing is required as a radiator,
A far-infrared radiator is obtained by adding one or more selected from Ti, Nb, Zr, (2), and Ta to the above components. The amount added is at least 3 times the total of C and N and at most 0.7% by weight. A far-infrared radiator is obtained by forming a film having needle-shaped or rod-shaped Al2203 on the surface of stainless steel to which one or more selected from Ti, Nb, Zr, V, and Ta are added.

These stainless steels produce needle-shaped or rod-shaped alumina crystals by heating in an oxidizing atmosphere of 500° C. or more and 1200° C. or less.

This alumina crystal is basically composed of Aff, but
Actually, Fe, Cr, Mn, and rare earth metals are included, and when an element selected from Ti, Zr, Nb, V, and Ta is added, these elements are also included.

In the present invention, a coating with excellent far-infrared radiation properties is produced, and even if these elements are mixed into alumina as impurities, the surface crystal shape becomes needle-like or rod-like and has a surface area effect. If it is, there will be no effect on the radiation characteristics.

Furthermore, if the surface of stainless steel is subjected to a blasting process to give processing strain, acicular or rod-shaped crystals can be effectively generated by the oxidation process.

[Function] The coating layer of the far-infrared radiator according to the present invention is produced by reaction from the substrate, and is crystallized with the substrate. Therefore, peeling resistance is high. Furthermore, the outermost surface of the coating layer is made of needle-shaped or rod-shaped alumina crystals, and has a large effective radiation area.

Here, the reasons for limiting the components of the present invention are as follows.

C hardens stainless steel and reduces ductility, so it needs to be low. As a far-infrared radiator, it is possible to use the plate as is without any complicated processing.
The upper limit was set to 0.10% by weight.

Sl: Si concentrates at the interface between the oxide film and the substrate, becomes an interfacial oxide, and increases the peeling resistance of the film, but if it is too high, it forms a thick 5i02 layer at the interface, which actually impairs the peeling resistance.
The upper limit needs to be 1.0% by weight.

Mn/Mn has a high diffusion rate in oxides, has the effect of thickening the oxide film, and is effective for growing needle-shaped or rod-shaped crystals, and through these enhances far-infrared characteristics, but too much Since the oxidation resistance itself deteriorates, the upper limit is limited to 3.0% by weight.

CF=C,r is the basic composition of stainless steel, and 8% by weight or more is required to form an effective oxide film.

If it exceeds 30% by weight, the toughness decreases, and if high AI2 is added as a far-infrared radiator material, manufacturing problems will occur.

Al1: A°C is an essential element for forming an alumina film on the stainless steel surface, but if it is less than 1% by weight, an alumina film cannot be obtained. If it exceeds 8% by weight, the toughness will decrease even if the C content is about 8% by weight, causing manufacturing problems.

Y, Nd, Gd - These rare earth elements have the effect of improving the adhesion of the oxide film, and for that purpose it is desirable to add a large amount, but 0.1
If it exceeds % by weight, it will segregate at grain boundaries and impair hot workability.

These rare earth elements are effective in making the alumina crystals needle-like, and this effect is exhibited at 0.001% by weight or more, and is effective in improving the radiation characteristics. Furthermore, similar effects can be obtained even if the total amount of one or more of these rare earth elements plus Ce or/and La is within the range of 0.1% by weight or less and 0.001% by weight or more. be able to.

N.

Like C, N makes stainless steel brittle. In particular, in the steel of the present invention having a high A.2, the A° C.N becomes coarse and the cleanliness deteriorates. Considering the use as a flat plate, the upper limit is limited to 0.05% by weight.

Ti, Nb, Zr, V, Ta: T1, Nb, Zr, V, and Ta fix C and N and improve the workability of stainless steel. The effect is at least (C
10N), but if it exceeds 0.7% by weight, it will actually make the steel brittle.

In order to effectively form an oxide film on the above stainless steel surface, it is necessary to heat it at a temperature of 500°C or higher; however, if the heating temperature exceeds 1200°C, needle-shaped or rod-shaped oxides cannot be obtained. , heating temperature range is 500℃ or higher1
Limited to 200°C or less.

When processing strain is applied to the stainless steel surface by blasting, needle-like crystals are likely to form. The greater the degree of blasting, the better. However, needle-shaped crystals can be formed even if there is no such substance.

[Example 1] A material having the composition shown in Table 1 was rolled to a thickness of 1.5 mm and bright annealed at 950°C. These materials were treated under the oxidation treatment conditions shown in Table 2, and their far-infrared radiation characteristics were measured. Further, after heating to 500°C, water quenching was performed, and the peeling resistance of the film was examined. These results are shown in Table 2.

As is clear from Tables 1 and 2, the radiation material according to the present invention has excellent far-infrared radiation characteristics and film peeling resistance, and such a material can be produced by the method of the present invention.

Table 2 (Note) *Radiation characteristics: Ratio to black body at wavelengths of 3 to 10μ at 400°C *2: After heating to 500°C, +2-336 depending on the presence or absence of peeling due to water cooling [Effects of the invention] This book The far-infrared radiator of the invention has excellent film peeling resistance even in applications that are subject to sudden thermal stress, and has high far-infrared radiation characteristics, so it can be used in various heating devices, drying furnaces, and mortar furnaces. The range of applications is wide (the energy saving effect and penetration effect of far infrared rays can be effectively used, and Ti, Nb
, Zr, V, and Ta provide excellent workability.

According to the method of the present invention, a film having needle-like or rod-like Aff203 can be easily formed, and if blasting is performed before heat treatment, a -layer can be easily formed.

Claims (1)

[Claims] 1 C: 0.10 wt% or less Si: 1.0 wt% or less Mn: 3.0 wt% or less Cr: 8 wt% or more and 30 wt% or less Al: 1 wt% or more and 8 wt% One or more of the following Y, Nd, and Gd: 0.001% to 0.1% by weight N: 0.05% by weight or less The remainder is stainless steel consisting of Fe and unavoidable impurities, and the surface A far-infrared radiator characterized in that a film having needle-like or rod-like Al_2O_3 is formed on the material. 2 The total amount of one or more of Y, Nd, and Gd and La and/or Ce is 0.001% by weight or more.0.
The far-infrared radiator according to claim 1, wherein the amount is 1% by weight or less. 3 In addition, Ti, Nb, Zr, V, Ta are included as components.
The far-infrared radiator according to claim 1 or 2, wherein the far-infrared radiator contains at least 3 times the total amount of C and N and at most 0.7% by weight of one or more selected from the following, and the remainder is Fe and unavoidable impurities. 4 Stainless steel heated to 500℃ or higher in an oxidizing atmosphere12
Claim 1 characterized in that the heating is performed at a temperature of 00°C or less.
A method for producing a far-infrared radiator according to items 3 to 3. 5. The manufacturing method according to claim 4, wherein the stainless steel surface is heated after being subjected to a blasting process to give processing strain.