JPH10158096A - Far infrared ray radiator and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a tough and inexpensive far IR radiator more excellent in radiating characteristics than the conventional ceramic radiator by forming at least the surface part of a substrate with a metal as a simple substance selected from among Ti, Al, Mg, Zr, Ta and Nb or an alloy contg. such a metal and then forming an oxidized coating film having a spinel structure contg. such a metal on the surface of the substrate. SOLUTION: An oxidized coating film 3 having a spinel structure, e.g. an MgCr2 O4 coating film is formed on the surface of a substrate 2 made of a metal as a simple substance selected from among Ti, Al, Mg, Zr, Ta and Nb or an alloy contg. such a metal, e.g. an Mg-Mn alloy by electrochemical reaction or chemical reaction preferably using a water-soluble compd. contg. one or more selected from among Cr, Fe, Co, Zn, Mn, Ni, Ti, Al, Zr, Mg and Ta, e.g. by electrolysis using Na2 Cr2 O7 .2H2 O.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a far-infrared radiator capable of effectively utilizing infrared rays and far-infrared rays in a field utilizing radiant heating, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, most of heat utilization forms mainly use convection (hot air) and conduction (direct fire), and radiate 193 heat.
It has been applied to the coating and drying technology of automobiles since the 0's, but was not generalized due to cost restrictions. However, when the far-infrared boom began on the market around 1978, the use and application of far-infrared rays were tried in various fields, and far-infrared heating systems also appeared. However, due to lack of physical knowledge and misunderstanding, they were widely spread. Has not been reached. However, in recent years, as industrial products have become finer, the radiant heating method has been reviewed again due to the development of near / mid infrared radiators in which halogen gas is sealed. In particular, for heating and drying metal painted objects,
Attention has been focused on a system that uses near-mid infrared and hot air together.

[0003]

In such a background, attention has been paid to heating means using far infrared rays. This kind of far infrared rays is attributed to the development of ceramic radiators. It is said. Conventionally, many far-infrared radiators are made of ceramics.However, the manufacturing process of far-infrared radiators made of ceramics involves granulating and mixing raw material powders, calcining them, and pulverizing them. Using the pulverized material as a raw material for sintering and further mixing a binder,
Since a large number of steps such as forming into a desired shape, and further manufacturing through a calcination step, a processing step, and a sintering step are performed, there is a problem that the step is not at least a simple step. In addition, as a problem of the ceramic far-infrared radiator, there is a problem that it is very fragile and fragile,
There is a problem that it is almost impossible to finish a complicated shape. Furthermore, there is a problem that many of them are not technically established when considering the quality, economy and film forming technology comprehensively.

[0004] The present invention has been made in view of the above-mentioned circumstances, and is intended to easily obtain a high-quality material easily and economically at a lower cost than conventional ceramic far-infrared radiators. It is an object of the present invention to provide a far-infrared radiator and a method for producing the same.

[0005]

According to the present invention, in order to solve the above-mentioned problems, a single metal or alloy selected from Ti, Al, Mg, Zr, Ta, and Nb is formed on at least a surface portion. An oxide film having a spinel structure containing the single metal is formed on a surface of the base material. The film having the above-described configuration may be configured to be attached to the surface of a substrate.

Further, the present invention relates to a method for producing a far-infrared radiator, wherein an electrochemical reaction or a chemical reaction is carried out on the surface of a substrate made of a single metal or alloy selected from Ti, Al, Mg, Zr, Ta and Nb. It is characterized in that an oxide film having a spinel structure is formed by a chemical reaction. Further, as a reaction solution for performing the electrochemical reaction or the chemical reaction, Cr, Fe, Co, Zn, Mn, Ni, Al, T
A water-soluble compound containing at least one of i, Zr, and Mg can be used.

[0007]

FIG. 1 shows a first example of a far-infrared radiator according to the present invention. In this example, a far-infrared radiator 1 covers the entire surface of a plate-shaped base material 2. 3. The substrate 2 is made of Al, Ti, Mg, Zr, T
It is composed of a single metal or an alloy selected from a and Nb. Specifically, it is composed of a single metal of these elements or an alloy of these elements. These elements are
It is an element that can exhibit a rectifying effect that allows current to flow in one direction, and is a metal that can generate an anodic oxide film that can perform rectifying action by anodic oxidation. In addition, as the base material 2, a material in which the coating layer of the single metal or alloy is coated on the surface of another metal base material or a nonmetallic base material can be used as the base material. The film 3 is an oxide of a metal element constituting the substrate 2 or a double oxide containing the element constituting the substrate 2, that is, a film of a spinel structure. In the spinel structure, the metal elements A and B are AB ₂ O ₄
Is a double oxide represented by the following chemical formula: More specifically, MgCr ₂ O ₄ , MgAl ₂ O ₄ , ZnAl ₂
O ₄ , MnAl ₂ O ₄ , FeAl ₂ O ₄ , CoAl ₂ O ₄ , N
iAl ₂ O ₄ , Mg (TiMg) O ₄ , ZnFeO ₄ , Fe
(CuFe) O ₄ , FeCr ₂ O _{4 and the} like can be exemplified.

In order to obtain the above-mentioned far-infrared radiator 1, for example, a substrate 2 made of a Mg—Mn alloy, Mg, Al, an Al alloy containing Mg, Ti and Zr, a Ti foil, a mild steel plate, or the like is treated with an electrolytic bath. And subjected to anodizing treatment. Examples of the type and treatment of the electrolytic bath include the following. Further, the composition of the spinel oxide generated when each electrolytic treatment is performed is also exemplified. Electrolysis example 1: 20 to 30% NH ₄ HF, 7 to 10% H ₃ PO
_{4, 6~12% Na 2 Cr 2} O 7 · 2H 2 at O mixed bath of Mg-
Electrolyze Mn alloy or Mg base. Spinel oxide: MgCr ₂ O ₄ Electrolysis Example 2: Ammonium sulfate (30 g / l), sodium bichromate (30 g / l) and aqueous ammonia (28%:
Electrolysis of Al-Mg alloy substrate in a mixed bath of 2.5 ml / l). Spinel oxide: MgAl ₂ O ₄

Electrolysis Example 3: 0.5% chromic acid in an electrolytic bath
% MgSO _4, electrolysis Al base with mixing bath was added _{0.5% Na 2 Cr 2 O 7} · 2H 2 O. Spinel oxide: MgAl ₂ O ₄ , MgCr ₂ O ₄ Electrolysis Example 4: 4Mg-1 in a sulfuric acid bath containing 0.5% nickel sulfate
Electrolysis of Ti-1Zr-Al alloy. Spinel _{oxides: MgAl 2 O 4, Mg (} TiMg) O 4 electrolytic Example 5: 2.5% phosphoric acid, 3.5% sulfuric acid, 1% hydrogen _{peroxide, 2% Na 2 Cr 2 O} 7 · 2H 2 O Electrolysis of Ti foil in mixed bath. Spinel oxide: TiCr ₂ O ₄ Electrolysis Example 6: 0.5% Mg (OH) ₂ , 0.5% Zn (O
H) ₂ , 0.5% copper hydroxide, 0.5% chromium hydroxide, 15
% Electrolysis in a mixed bath of NaOH. Spinel oxide: ZnFeO ₄ , Fe (CuFe) O ₄ ,
FeCr ₂ O ₄ electrolysis example 7: 0.5% Na ₂ Cr ₂ O _7.
Immerse in a hot bath containing 2H ₂ O and 2% NaOH. Spinel oxide: MgAl ₂ O ₄ , MgCr ₂ O ₄

The film 3 can be formed on the surface of the base material by performing the electrolytic treatment or the immersion treatment as described above.
As the current waveform at the time of electrolysis, DC, AC, AC / DC superposition, AC / DC combined use, incomplete rectified waveform, pulse waveform, rectangular wave, and the like are used. As an electrolysis method, a constant current, a constant voltage, a constant power method, a high-speed anodic oxidation method using continuous, intermittent, or current recovery can be used. In the above, a nonuniform anodic oxide film is generated using pulse waveforms or incomplete rectification waveforms, or a multi-layer anodic oxide film is formed by intermittent electrolysis or current recovery method, and a higher emissivity is obtained. You can also.

If the far-infrared radiator 1 is provided with the coating 3 having the spinel-structured double oxide, excellent heat resistance can be obtained and practically effective 3 to 30 μm.
With respect to the total emissivity in the wavelength region of, a stable emissivity of 70% or more, which has conventionally been difficult to achieve without using a special alloy, can be obtained with an extremely thin film. For this reason, various materials suitable for the purpose of use, such as workability and strength, can be used.

In the above-described example, the coating 3 is provided on the entire surface of the base material 2. However, as shown in FIG. Of course. Further, the film having the spinel-structured double oxide is pulverized to obtain a powder, and by attaching the powder to a substrate or a base material, a far-infrared radiator can be obtained. By doing so, it is possible to form a film on a desired portion of a free-form base material regardless of the shape and material of the base material and to obtain a film having a desired thickness. A shape is obtained. Further, in this case, a material that is difficult to be subjected to anodic oxidation or chemical conversion treatment can be used as the substrate, so that a far-infrared radiator can be obtained without selecting a substrate.

[0013]

【Example】

 (Example 1) Mg-Mn alloy (Mn: 0.82% by weight (hereinafter
The percentage indicating the composition of the lower alloy is expressed by weight%. ), Fe: 0.
005%, Si: 0.003%, Zn: 0.014%, C
u: 0.001%, Ni: 0.001%, Al: 17 pp
m, extruded material sample of the balance Mg) was treated with ammonium acid fluoride (N
H_FourHF 200-300 g / l), phosphoric acid (H_ThreePO _Four
 70-100 g / l), sodium bichromate (Na
_TwoCr_TwoO₇・ 2H_TwoO60-120 g / l)
Anodize at ~ 100V in electrolytic bath at ~ 90 ° C
To form an anodic oxide film about 25 μm thick
Sample 1 was obtained. For sample 1 having this coating, 3
Black at 250 ° C. in the far infrared wavelength region of ３０30 μm
Performs measurement of total emissivity and color tone based on body, and X-ray
The product was identified by diffraction.
The results and the X-ray diffraction chart shown in FIG. 3 were obtained.

For comparison, a sample 2 obtained by subjecting an extruded material sample having the same composition as that of the Mg-Mn alloy to an anticorrosion treatment (anodizing treatment) in accordance with five types of JIS H8651, and the Mg-Mn alloy Extruded material samples of the same composition
651 and an extruded sample having the same composition as the Mg-Mn alloy and a sample 4 obtained by chemical conversion treatment with chromic acid. An equivalent test was performed.

[0015]

[Table 1]

The above-mentioned five kinds of anticorrosion treatments of JIS are defined as ammonium sulfate (30 g / l), sodium dichromate (30 g / l) and aqueous ammonia (28%: 2.5 ml / l).
1) using a mixed bath, a bath temperature of 55 ° C. and a current density of 0.6 A
/ Dm ² and an electrolysis time of 20 minutes. The JIS 6 kinds of anticorrosion treatment include caustic soda (240 g / l) and ethylene glycol (83 ml /
l), using a mixed bath of sodium oxalate (2.5 g / l), performing a first treatment at a bath temperature of 75 ° C., a current density of 1.5 A / dm ² , and an electrolysis time of 20 minutes. Sodium chromate (50 g / l), sodium acid fluoride (50 g
/ L), the sample is immersed in the mixed bath, neutralized, washed thoroughly with water and hot water, and dried.

As is clear from the results shown in Table 1, Sample 1 having a double oxide film composed of an oxide and a spinel structure on the surface has an extremely high emissivity of 88%. Obtained. On the other hand, in Samples 3 and 4 in which the double oxide composed of the oxide and the spinel structure does not exist on the surface, the emissivity is 18 or 25%, which is significantly higher than that of Sample 1 of the present invention. It was a low value. It should be noted that, as a result of performing a test equivalent to the above on a sample obtained by performing the same treatment as above by changing the sample from an Mg-Mn alloy to an extruded material sample of Mg alone, it is possible to obtain the same result as above. Was completed.

(Embodiment 2) The same processing as that performed on the sample 1 of the embodiment 1 is performed on an Mg substrate to form an anodic oxide film having a thickness of 25 μm, and then this sample is immersed in a 10% nitric acid solution. Then, the Mg substrate was melted, sufficiently washed and dried to take out only the anodic oxide film, which was finely pulverized with a ceramic ball mill to a particle size of 300 mesh or less to obtain a powder. Using this powder as a binder, about 2% was dispersed in a solution of water and alcohol containing 1% of PVA (polyvinyl alcohol) to obtain a treatment liquid. A mild steel plate as a substrate was immersed in the treatment solution, and electrophoretic deposition was performed at a constant voltage of 500 V to form an electrodeposition film having a thickness of 15 μm on the substrate surface. The substrate was taken out of the processing solution and heated to enhance the binder effect of PVA, and then the far-infrared spectral emissivity was measured again at 250 ° C. in the far-infrared wavelength region of 3 to 30 μm. The X-ray diffraction and color tone of the coating were also investigated. As a result, the film showed a dark green color, the emissivity was about 82%, and the X-ray diffraction image of the product was the same as that of the sample 1 of Example 1 described above.

A sample of an Al alloy containing 4% of Mg and 1% of Ti was prepared.
Anodizing treatment is performed in an aqueous sulfuric acid solution containing 5%,
An oxide film having a thickness of 20 μm was formed on the surface. For this sample, 250 in the far infrared wavelength range of 3 to 30 μm.
Measurement of the spectral emissivity at ° C. gave an emissivity of 87%. The color of this film was yellowish beige. Also, according to the X-ray diffraction results, Al ₂ O ₃ , MgAl
The presence of ₂ O ₃ , Mg (TiMg) O ₄ , NiO, etc. could be confirmed.

Example 4 A mild steel sheet was subjected to constant voltage electrolysis in a 15% aqueous sodium hydroxide solution containing 0.5% magnesium hydroxide, 0.5% copper hydroxide and 0.5% chromium hydroxide. As a result, a brown anodized film of iron having a thickness of 10 μm was obtained. The emissivity of the anodized film at 250 ° C. was 90%. As a result of X-ray diffraction of this anodized film, Fe ₂ O ₃ , ZnFe ₂ O ₄ , Fe (CuFe) O ₄ ,
The presence of Fe (MgFe) O _{4 and the} like could be confirmed.

Example 5 An A5052 aluminum plate containing Mg was prepared by using sodium bichromate 5% and sodium hydroxide 2
% In a hot bath at 95 ° C. for 30 minutes to a thickness of 5%.
A μm chemical conversion coating was produced. 250 ° C of this film
Has a far-infrared radiation characteristic of 90%, and the presence of Al ₂ O ₃ , MgAl ₂ O ₄ , MgCr ₂ O _{4 and the} like can be identified from the results of the X-ray diffraction test. Also, the color of this film exhibited national defense color.

(Example 6) A plurality of pure Ti foils were prepared, and these were anodized in an electrolytic bath of phosphoric acid (25 g / l), sulfuric acid (35 g / l), and hydrogen peroxide (10 g / l). The anodic oxide films having a thickness of 4 μm and 8 μm, respectively, were obtained as comparative materials. Further, as an example of the present application, the above-mentioned electrolyte solution was added to sodium dichromate (Na ₂ Cr ₂ O ₇ : 2).
(0 g / l) was added to form an electrolytic bath. Using the electrolytic bath, anodic oxide films having a thickness of 4 μm and 8 μm were formed in the same manner as described above to obtain samples. At 250 ° C., the spectral far-infrared emissivity of each sample in the electromagnetic wavelength range of 3 to 30 μm was determined and compared with the total emissivity. Further, both products were identified by X-ray diffraction of each sample. The results are summarized in Table 2.

[0023]

[Table 2]

As shown in Table 2, it was found that the use of sodium bichromate as the electrolyte solution produced a far-infrared radiator having an excellent total emissivity as compared with the case where sodium bichromate was not used. Further, when the electrolyte was treated with sodium dichromate, the result of X-ray diffraction revealed that a double oxide could be formed.

Example 7 An A1050 aluminum plate was anodized in a 3% chromic acid electrolytic bath to form an anodized film having a thickness of 5 μm on the surface of the aluminum plate to obtain a comparative material sample. Next, as a material of the present invention, magnesium sulfate (MgSO ₄ : 5 g / l) and sodium dichromate (Na ₂ Cr ₂ O ₇ : 5 g / l) were added to the above electrolytic solution to form an electrolytic bath. A sample of the present invention was formed by forming an anodized film having a thickness of 5 μm on the surface of an A1050 aluminum plate using an electrolytic bath. For each of these samples, the spectral far-infrared emissivity in the electromagnetic wavelength range of 3 to 30 μm was determined at 250 ° C. and compared with the total emissivity. Further, both products were identified by X-ray diffraction of each sample. Table 3 shows the results
Are shown together.

[0026]

[Table 3]

As shown in Table 3, the sample of the present invention exhibited an excellent total emissivity as compared with the comparative sample, and the result of the X-ray diffraction test confirmed the presence of the double oxide.

[0028]

As described above, Ti, Al, M
An excellent far-infrared radiator having a spinel-structured oxide film on the surface of a base material having a single metal or alloy selected from g, Zr, Ta, and Nb formed on at least a surface portion thereof is excellent. In addition to providing heat resistance, stable emissivity of 70% or more, which was difficult to achieve without using special alloys and ceramics, even in the total emissivity in the wavelength range of 3 to 30 μm, which is practically effective. It can be obtained with a very thin oxide film. Therefore, it can be used for various materials suitable for the purpose of use such as workability and strength.

Next, the film having the spinel-structured double oxide is pulverized to obtain a powder, and the powder is attached to a substrate or a base material to obtain a far-infrared radiator. By doing so, it becomes possible to form an oxide film on a desired portion of a free-form substrate irrespective of the shape and material of the substrate, so that the desired thickness can be obtained. Is obtained.

In order to manufacture the far-infrared radiator having the above structure, an electrochemical reaction or a chemical reaction is applied to the surface of a substrate made of a single metal or alloy selected from Ti, Al, Mg, Zr, Ta and Nb. To produce an oxide film having a spinel structure. As a reaction liquid used at this time, Cr, Fe, Co, Zn, Mn,
By using a material having at least one of Ni, Al, Ti, Zr, Mg, and Ta, an oxide film can be surely generated in the film.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first example of a far-infrared radiator according to the present invention.

FIG. 2 is a sectional view showing a second example of the far-infrared radiator according to the present invention.

FIG. 3 is a view showing an X-ray diffraction chart of a sample of the present invention.

[Explanation of symbols]

 1 ... far-infrared radiator, 2 ... substrate, 3, 4 ... coating.

Claims (4)

[Claims] 1. A spinel structure including a single metal or an alloy selected from Ti, Al, Mg, Zr, Ta, and Nb is formed on at least a surface of a base material having the single metal or alloy selected from the group consisting of Ti and Al. A far-infrared radiator comprising an oxide film formed thereon. 2. A far-infrared radiator, wherein the film according to claim 1 is adhered to a surface of a substrate. 3. An oxide film having a spinel structure is formed on the surface of a substrate made of a single metal or an alloy selected from Ti, Al, Mg, Zr, Ta, and Nb by an electrochemical reaction or a chemical reaction. A method for producing a far-infrared radiator, comprising: 4. The reaction solution for performing the electrochemical reaction or the chemical reaction includes Cr, Fe, Co, Zn, M
The method for producing a far-infrared radiator according to claim 4, wherein a water-soluble compound containing at least one of n, Ni, Al, Ti, Zr, Mg, and Ta is used.