JPH02230683A - Manufacture of far infrared radiative material - 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] [Industrial Application Field] The present invention has a surface that emits far infrared rays, which is made of ceramic material, and can be used for a long period of time without peeling even due to rapid heating or cooling from a part of the internal heater. The present invention relates to a method for manufacturing a far-infrared radiation material that is durable and has a high emissivity.

[Conventional technology]

In recent years, demand for heaters that emit far-infrared rays has been increasing.

These heaters have their surfaces coated with ceramic materials with high far-infrared emissivity, such as zirconia (Z'02) and cordierite (2MgO.2AllO5S).
1 0 2 ), alumina (Ag203), etc., among which aluminum oxide (hereinafter referred to as Ag2
03) is utilized as the preferred material.

Generally, Ag20 is placed on a metal substrate processed into a desired shape.
Heaters that are coated with Ceramic Sox, which has a high far-infrared emissivity such as No. 3, by coating, spraying, or thermal spraying, are heated using various heat sources.

Among these heaters, there is a demand for a heater with excellent thermal efficiency in which the space between the heater and the metal base material is coated without any gaps.

Conventionally, as a far-infrared heater that meets the above requirements, the surface of a metal heating element is coated with Afi metal, which is easy to coat, and the Aj7 metal surface is further coated with A,020s, which has a high far-infrared emissivity. things are used.

[Problem to be solved by the invention]

Conventionally, as a method for manufacturing the above-mentioned type of far-infrared heater, a method was used in which A1203 powder was coated on AI metal by coating or spraying.
The difference in thermal expansion coefficient between 203 and Aj7 metal is the cause,
There was a problem in that it was easy to peel off due to thermal cycles of rapid heating and cooling.

On the other hand, in order to solve this problem, the AN metal matrix is oxidized using a means of high temperature heating in an oxidizing atmosphere, so that A, l! When 203 is formed, the adhesion is improved I7 and no peeling occurs. However, the thickness of the formed Ag203 layer cannot be obtained sufficiently, and the specific surface area of the coated surface of the A1203 layer formed on a smooth surface that has been cold-worked such as wire drawing is small. There was a problem that high emissivity could not be obtained because of the small size.

The present invention has been made to solve the above problems,
The purpose of this is that the surface conventionally used is Ag2.
The present invention relates to a method for producing a far-infrared radiating material that has even better peeling resistance than the far-infrared radiating material made of No. 03 and has a higher far-infrared emissivity.

[Means to solve the problem]

The present inventors conducted various experiments to examine the peeling resistance, and found that A,1720s obtained by oxidizing the surface of Ag metal itself as a starting material is the same as that of the H-based AI metal. Since the results showed that the adhesion was excellent,
Various methods were tried for oxidizing the Aff metal surface.

As a result, A1203, which is produced by anodizing the i-metal surface under appropriate electrolytic conditions, can form an AI203 layer with the desired thickness, and has excellent adhesion to the base material A [metal and is easily peeled off. I found out something difficult.

Furthermore, this anodic oxidation treatment is applied to Af
A I! obtained by applying it to the J metal surface. It was also discovered that the specific surface area of the 20s layer increases and the emissivity of far infrared rays also increases, leading to the present invention.

That is, the present invention provides a method for manufacturing a far-infrared radiating material in which the core portion is formed of a metal heating element, the intermediate portion is formed of aluminum metal, and the outer surface coating portion is formed of aluminum oxide, including: (1) Intermediate portion aluminum (2) The roughened aluminum metal surface is subjected to an anodizing treatment process by electrolysis at a current density of 5OA/drrr or less in a dilute acid aqueous solution to form an outer surface coating part. This is a method for producing a far-infrared radiating material, characterized in that aluminum oxide is formed on the material.

In order to manufacture a radiant oil in which the core is made of a metal heating element, the middle part is made of aluminum metal, and the outer covering part is made of aluminum oxide, first, the adhesion between the metal heating element and the aluminum metal is strengthened. need to be kept. For this purpose, it is possible to immerse the metal heating element in molten aluminum and plate it with molten aluminum, but the easiest method is A.
9 It is preferable to fill the rod of the metal heating element in the vibrator and then wire-draw the rod. This eliminates the gap between the metal heating element and the metal base material.

The surface of the intermediate aluminum metal can be roughened by subjecting the surface to shot blasting, sandblasting, etc., but it can also be achieved by rolling with a roll that has a roughened surface.

For anodizing the roughened metal surface of aluminum, a dilute acid aqueous solution such as dilute sulfuric acid, dilute chromic acid, or oxalic acid is used.

In this anodizing treatment, the current density is 50A/drrf
If it exceeds the desired thickness, the desired thickness of Ag203 can be obtained in a short time, but the adhesion with Al metal deteriorates.

〔Example〕

EXAMPLES The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to these Examples.

(Example 1) After filling the Ag vibe with nichrome alloy rods, the Al
The wire was drawn to a wire with a wall thickness of 0.5 wua and an outer diameter of 2.6 m+*. After roughening the surface of this wire by shot blasting, it was anodized in a 25 volume % sulfuric acid aqueous solution at 1-0°C or lower at a current density of 50 A/drrf, and the wire surface was coated with a thickness of 80 μm. AfI20
Three layers were formed.

The measurement results of the AR20a releasability and far-infrared emissivity of this far-infrared emitting material are shown in Table 1 together with other examples and comparative examples.

(Example 2) Current density was 30 A/d, thickness of Ag203 layer was 70 μm.
The procedure was the same as in Example] except that.

(Comparative Example 1) After filling the AfI vibe with nichrome alloy rods,
The wires of AIl with a wall thickness of 0.2 mm and outer diameters of 2 and 6 stops were processed. An appropriate amount of water was added to a mixed powder of 1095% Kibushi clay and 5% Kibushi clay to form a slurry of an appropriate viscosity, which was sprayed onto the wire rod, dried, and coated with Ag203 powder.

(Comparative Example 2) After filling the AI vibe with nichrome alloy rod, AN
The wire was drawn to a wire with a wall thickness of 0.2 mm and an outer diameter of 2.6 mm. The obtained wire was heated in the atmosphere at 620°C for 1 hour to oxidize the metal surface and achieve Ai! 203 layers were formed.

(Comparative Example 3) Except that AΩ roughening treatment on the wire surface was not performed.
The procedure was the same as in Example 1.

(Comparative Example 4) Current density 55A/d resistance, A. 17203 layer thickness 90μ
The procedure was the same as in Example 1 except that m was used.

Thermal cycle test shown below was conducted on the far-infrared radiating materials produced in the Examples and Comparative Examples.

Room temperature - heating (25 minutes) - radiation material temperature 500°C (5 minutes) - cooling (30 minutes) one room temperature As a result, Comparative Example 1
Comparative Example 4 caused peeling after 45 cycles, but all the others even after 50 cycles or more! I didn't do IM.

In addition, for Example 2, 2 and Comparative Example 2.3, 30
Far-infrared emissivity at a wavelength of 4 to 20 μm at 0° C. was measured. Emissivity is expressed as a ratio to the far-infrared output from a blackbody furnace at the same temperature.

〔Effect of the invention〕

According to the method of the present invention, Ag
The surface of the metal base material is roughened and the current density is 5 in a dilute acid solution.
By anodic electrolytic oxidation below O A/dd
By forming the 17203 layer, a radiant material with excellent peeling resistance of the A II 2 O s layer and high far-infrared emissivity can be obtained.

Claims (1)

[Claims] A method for manufacturing a far-infrared radiating material in which the core portion is formed of a metal heating element, the intermediate portion is formed of aluminum metal, and the outer surface coating portion is formed of aluminum oxide, comprising: (1) intermediate portion aluminum; (2) The roughened aluminum metal surface is subjected to an anodizing process by electrolysis at a current density of 50 A/dm^2 or less in a dilute acid aqueous solution to obtain an outer surface. A method for producing a far-infrared radiating material, comprising forming aluminum oxide on a covering portion.