JP3195020B2 - Far infrared radiator - Google Patents

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 such as heating and cooking.

[0002]

2. Description of the Related Art Conventionally, heaters utilizing infrared rays have a high emissivity of a radiator, a relatively low surface temperature of 100.degree. Alumina, which satisfies such required characteristics relatively well as a radiator,
2. Description of the Related Art A heater is made of various ceramic materials such as cordierite and zirconia.

[0003]

However, conventional ceramic materials have mechanically fragile properties,
Since it is difficult to produce a complicated shape or a thin product, and it is also difficult to produce a heavy product, there is a problem that the use is naturally limited. Also,
A radiator sprayed with ceramic on the surface of a metal substrate has also been put into practical use, but this radiator has problems that the production cost is high and it is difficult to obtain a thin plate or a radiator having a complicated shape.

On the other hand, there has been an attempt to form an alumite film on the surface of Al or an Al alloy by anodic oxidation and utilize it as a far-infrared radiator, taking advantage of the good workability and light weight of Al. It has been done. However, the conventional method has the following problems. Al far infrared radiators are easily deformed by heating,
There is a problem that cracks are generated in the alumite film due to stress concentration due to deformation. The far-infrared radiator made of Al has a problem that the total emissivity in the far-infrared region is low because the spectral emissivity in the wavelength region of 3 to 7 μm is low. In the above problem, the emissivity in a specific wavelength region can be improved by coloring the alumite film with an organic dye.However, in this method, when the alumite film is heated to 200 ° C. or more, the organic dye becomes There is a fundamental drawback of discoloration and discoloration, and there is a problem of poor heat resistance.

Therefore, as a result of various studies on far-infrared radiators excluding such disadvantages, the present inventors found that a far-infrared ray formed by forming an alumite film by anodizing on the surface of a special Al alloy containing Mn or the like. Developed the radiator and applied for patents (Japanese Patent Application Nos. 3-15229 and 3
No. 301018). According to these methods, deformation due to heating and generation of cracks at high temperatures can be prevented, and the spectral emissivity in the wavelength range of 3 to 7 μm can be considerably improved. A radiator with excellent characteristics was obtained.

[0006] In this case, since the base material is an Al alloy, the heat conductivity is also excellent. Therefore, various applications utilizing these characteristics are expected. However, even in the far-infrared radiator of the patent application, this
When applied to a substrate in the shape of
As a result, cracks and warpage occurred, and it was found that there were still insufficient characteristics. Regarding this point, for example,
Japanese Patent Application Laid-Open No. 54-024330 also discloses an aluminum substrate.
In the case of a heat dissipation layer whose surface has been anodized,
Since it cannot be used unless it is below 0 ° C, it emits far infrared rays for high temperatures.
In addition to being unusable as a radiation element, the surface of the radiation layer is roughened
There was a disadvantage that the product could not be increased. ''
As a solution, thermal spraying of Al or its alloy on the surface of steel substrate
For lining with alumite treatment
Propose a law. However, by this spraying method, Al or A
The method of forming the coating layer of the alloy is based on the pinhole of the coating layer.
Anodizing treatment is almost impossible to prevent
In this case, the steel melts at this pinhole and the lining
It is almost impossible to form an oxide film on the Al surface
In addition, there is a problem that
There was a disadvantage.

The present invention has been made in view of the above circumstances, and is particularly a plate-like far-infrared radiator, which has a high spectral emissivity in a wavelength region of 3 to 7 μm without using a special alloy, and It has excellent far-infrared radiation characteristics and is resistant to deformation due to heating. Even if it is used at a high temperature of 400 ° C. or more, it can select a material according to the intended use without causing cracking or warping. It is intended to provide an infrared radiator.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive studies and experiments on a far-infrared radiator based on the anodized Al or Al alloy. As a result, by using a radiator in which an anodic oxide film having fine irregularities on the surface of Al or an Al alloy material is formed to a specific thickness or more, various characteristics are remarkably improved as compared with those simply subjected to anodizing treatment. This led to the present invention.

In order to solve the above-mentioned problems, the far-infrared radiator according to claim 1 contains 0.3 to 4.3% by weight of Mn, the balance being Al and unavoidable impurities, and a particle size of 0.3. An anodic oxide film having fine surface irregularities is formed to a thickness of 4 μm or more on the surface of a plate-like substrate made of an Al alloy in which Al-Mn-based intermetallic compound precipitates of 0.1 to 3 μm are dispersed. The surface roughness of the anodic oxide film is in the range of 1.5 to 3.0 μm in average roughness and 5 to 30 μm in maximum roughness.

[0010] For the second aspect of the invention to solve the above problems, in the far-infrared radiator according to claim 1, Al
As an alloy, Al-Mn containing 0.3 to 4.3% by weight of Mn and 0.05 to 6.0% by weight of Mg, the balance being Al and unavoidable impurities, and having a particle size of 0.01 to 3 µm.
An Al alloy system intermetallic compound precipitates are dispersed
It is characterized by using a plate-shaped substrate .

In order to solve the above-mentioned problems, the far-infrared radiator according to claim 3 contains 3 to 15% by weight of Si, the balance consisting of Al and unavoidable impurities, and is composed of primary crystal Si, eutectic Si or precipitated silicon. Among metal Si particles made of Si,
The maximum diameter of a circle which can be drawn in a region where no metal Si particles having a particle size of 0.05 μm or more is present is 30 μm or less, and a circle having a diameter of 15 μm can be drawn in a region where no metal Si particles having a particle size of 0.05 μm or more exist. the total area of the region, Al alloy is 30% or less an area ratio with respect to total area Tona
Oxidation with fine surface irregularities on the surface of the plate-shaped substrate
The coating is formed to a thickness of 4 μm or more.
The surface roughness of the film is 1.5-3.0 μm in average roughness, maximum roughness
Characterized in that the range is 5 to 30 μm.

According to a fourth aspect of the present invention, there is provided a far-infrared radiator according to the third aspect, wherein
The alloy contains 3 to 15% by weight of Si, 0.05 to 2.0% by weight of Fe, 0.05 to 2.0% by weight of Mg,
0.05 to 6.0% by weight of Cu, 0.05 to 2.0% by weight of Mn, 0.05 to 3.0% by weight of Ni, 0.05 to 3.0% by weight of Cr
0.5% by weight, V: 0.05 to 0.5% by weight, Zr: 0.0%
5 to 0.5% by weight, Zn more than 1.0% by weight to 7.0% by weight or less, and the balance consists of Al and inevitable impurities. Crystal Si,
Among the metal Si particles composed of eutectic Si or precipitated Si, the maximum diameter of a circle drawn in a region where there is no metal Si particle having a particle size of 0.05 μm or more is 30 μm or less, and the metal Si particle having a particle size of 0.05 μm or more is used. Al alloy having a total area of 30% or less of a total area of a region in which a circle having a diameter of 15 μm can be drawn among regions where no particles exist.
Characterized by using a plate-shaped substrate made of

According to a fifth aspect of the present invention, there is provided a far-infrared radiator according to the third or fourth aspect , wherein the Al alloy contains 3 to 15% by weight of Si and 0.1 to 0.1% of Ti. 005-0.2% by weight and P
0.005 to 0.1% by weight, 0.005 to 0.1% by weight of Na, 0.005 to 0.3% by weight of Sb, and 0.00% of Sr.
5 to 0.1% by weight, the balance being Al and unavoidable impurities, and among the metallic Si particles composed of primary crystal Si, eutectic Si or precipitated Si, The maximum diameter of a circle which can be drawn in a region where no metal Si particles having a particle size of 0.05 μm or more is present is 30 μm or less, and a circle having a diameter of 15 μm can be drawn in a region where no metal Si particles having a particle size of 0.05 μm or more exist. A in which the total area of the regions is 30% or less in area ratio with respect to the entire area
characterized by using a plate-shaped substrate made of l alloy.

[0014] For the invention of claim 6, wherein to solve the above problems, in the far infrared radiator of claims 1 to 5, wherein,
The surface roughness of the anodic oxide film is 1.5 to 2.6 μm in average roughness
m, and a maximum roughness in a range of 11 to 27 μm.

[0015]

[0016]

The far-infrared radiator according to the present invention is made of Al-S
i-type or Al-Mn-type alloy
i-particles or those in which Al-Mn intermetallic compounds are dispersed and precipitated are used as plate-like substrates . Further, as an example, the anodic oxide film having fine irregularities formed on the surface of these plate-like substrates has a predetermined range by a mechanical roughening method such as blasting or liquid honing treatment on the surface of the substrate. After the surface is roughened to a roughness, the substrate is obtained by anodizing. The anodic oxide film has a surface roughness of 1.5 to 3.0 μm in average roughness and 5 to 3 in maximum roughness.
It is preferable that the thickness is in the range of 0 μm, and the surface roughness of the anodic oxide film is 1.5 to 2.6 μm in average roughness.
More preferably, the maximum roughness is in the range of 11 to 27 μm.

[0017] Then, the far-infrared radiator of the present invention that the anodic oxide film having such fine irregularities are formed, the total emission characteristics of far infrared in the wavelength region of 3~30μm which is practically effective, A high characteristic of 70% or more can be obtained, and the heat resistance is 200% with conventional pure Al.
Although the temperature is limited to ° C., excellent characteristics are obtained in which no warping or deformation occurs even with a thermal heat cycle up to 500 ° C. and no cracks that can be observed with the naked eye are generated.

The reason why such unexpectedly excellent characteristics are obtained is not clear, but the reason is that regarding the radiation characteristics of far infrared rays, the apparent surface area increases due to the fine irregularities on the surface. It is conceivable that film growth becomes uneven due to surface roughening, complex irregularities and complicated branched pores are formed, and the scattering and absorptivity of incident light increases. Further, regarding the heat resistance, it is considered that the complicatedly branched pores alleviate the stress due to the thermal cycle and prevent the occurrence of cracks and the like.

Further, in this case, the Al—S particles in which Si particles and Al—Mn-based intermetallic compound particles described later are dispersed and deposited.
When a heat-resistant alloy such as an i-based alloy or an Al-Mn-based alloy is used as a base material, Si particles or Al-Mn
Since the intermetallic compound particles are taken into the anodic oxide film and the anodic oxide film grows to avoid these particles, the pores in the anodic oxide film have a more complicated and branched structure, and the thermal stress Resistance is increased, and a material having more excellent heat resistance is obtained.

Further, since Si particles and Al-Mn intermetallic compound particles are dispersed and present in the anodic oxide film, their presence further increases the scattering and absorptivity of incident light, and Even better radiation characteristics can be obtained.

Hereinafter, the present invention will be described in more detail. As a method of roughening the surface of the base material or the anodic oxide film, blast treatment or liquid honing treatment using a powder having a grinding action such as alumina, silicon carbide, silica sand, or the like, or Such as a method in which a grinding wheel in which corundum-containing nylon fiber or a piano wire having a diameter of about 0.1 to 1.0 mm is implanted is rotated at a high speed, or a method in which the grinding wheel is sharpened by emery paper (cloth). The surface may be roughened by a chemical method such as electrolytic etching, or the like, but in the case of the present invention, the surface is formed to have an average roughness of 0.5 to 0.5 using a mechanical method. By adjusting the average roughness to a range of 5.0 μm and a maximum roughness of 5 to 50 μm, more excellent characteristics can be obtained.

The reason why this mechanical method is excellent is not clear, but in the mechanical surface roughening method, a large force is locally applied to cause plastic flow of the aluminum base metal or impairment of the metal structure due to work hardening. It is presumed that this was due to the homogenization and forcibly complicating the uneven shape due to the scraping of the metal, and further anodizing in this state caused a partial anodization due to the difference in the metallographic structure. An anode with a complex pore structure that branches off with very uneven asperities due to differences in the quality and growth rate of the film, and the growth of the anodic oxide film in random directions due to the complex unevenness. An oxide film is formed, which increases the absorptivity of incident light scattering, improves the far-infrared radiation characteristics, and also increases the relaxation effect of thermal cycling. It is believed to be an excellent thing.

The thickness of the film formed by the anodic oxidation treatment is preferably 4 μm or more, and if it is less than this, a sufficient far-infrared emissivity cannot be obtained.
As the anodic oxidation method, various kinds of commonly used methods can be used. In addition, as the electrolytic bath, not only an acidic bath but also an alkaline bath or a non-aqueous bath such as a formamide type and a boric acid type can be used.

For example, examples of the acidic electrifying bath include sulfuric acid, phosphoric acid, chromic acid, oxalic acid, sulfosalicylic acid, pyrophosphoric acid, sulfamic acid, phosphomolybdic acid, boric acid, malonic acid, succinic acid, maleic acid, citric acid, and the like. An aqueous solution in which one or more kinds of tartaric acid, phthalic acid, itaconic acid, malic acid, glycolic acid and the like are dissolved can be used.

As the alkaline electric field bath, an aqueous solution in which one or more kinds of caustic soda, caustic potash, sodium carbonate, potassium phosphate, aqueous ammonia, etc. are dissolved can be used.

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 alumite method using continuous, intermittent, or current recovery can be used. In the above, a heterogeneous 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 to achieve higher emissivity. You can also.

The post-treatment after forming the film by the anodic oxidation treatment includes, for improving corrosion resistance, boiling water immersion,
The sealing treatment may be performed by an ordinary method such as a hot water immersion method containing a metal salt. In addition, when non-adhesiveness is required as in cooking utensils, the surface may be coated with a fluororesin such as polytetrafluoroethylene. In this case, since the surface after the anodizing treatment is rough, primer treatment or the like is required. Excellent adhesion can be obtained without doing so. In addition, Ni, Cu, Co, Sn, P
After depositing a metal such as b or Cd, the deposited metal is oxidized in an oxidizing atmosphere, or is alternately immersed in an aqueous silicate solution or zirconium salt water bath with an acid or an alkali to deposit silicon in the fine pores. Acid salts or zirconium hydroxides may be deposited. By including a metal oxide having excellent far-infrared radiation characteristics in the micropores of the anodized film by these methods, a far-infrared radiator having a higher emissivity can be obtained.

Next, the Al—Mn alloy used in the present invention will be described. In an Al-Mn alloy containing an appropriate amount of Mn, an Al-Mn intermetallic compound is formed,
If the precipitation state of the l-Mn intermetallic compound is appropriate, it contributes to far-infrared radiation characteristics and also contributes to improvement of heat crack resistance. Examples of the Al-Mn intermetallic compound include Al ₆ Mn, Al ₆ (MnFe), and αAlMn.
(Fe) Si, and those in which a small amount of Cr, Ti, or the like are dissolved in solid solution, are available. Anodizing treatment is performed on the surface of an aluminum alloy in which such an Al-Mn intermetallic compound is dispersed and precipitated. Is applied, the Al-Mn intermetallic compound particles are contained in the anodic oxide film in a dispersed state.

The incident light is easily scattered and absorbed by the intermetallic compound particles dispersed in such an anodic oxide film, and the radiation characteristics of far infrared rays are improved. Since visible light is also absorbed, the visual color tone becomes black. Furthermore, in the process of growing the anodic oxide film during the anodic oxidation treatment,
The pore has a branched structure. Such a branched pore structure promotes scattering and absorption of incident light in the anodic oxide film, and further improves far-infrared radiation characteristics.

Further, the Al-Mn intermetallic compound particles dispersed and present in the anodic oxide film also function as a stress relaxation point, and the branched structure of the pore as described above has a strain absorbing ability. As a result, cracks are unlikely to occur, and even if cracks occur, their propagation is prevented.

Here, if the diameter of the Al—Mn intermetallic compound precipitate is less than 0.01 μm, the above-described effect due to the dispersion of the Al—Mn intermetallic compound precipitate cannot be obtained.
Since coarse Al-Mn based intermetallic compound precipitates exceeding 3 µm deteriorate the formability, those having a particle size of 0.01 to 3 µm are preferably dispersed. In addition, the particle size is 0.
Al-Mn intermetallic compound precipitates of 01 to 3 µm
It is preferable that the particles are dispersed at a density of × 10 ⁵ particles / mm ³ or more.

Next, the reasons for limiting the component composition in the Al-Mn-based alloy as described above will be described.

Mn: Mn forms an Al-Mn intermetallic compound precipitate and contributes to the improvement of far-infrared characteristics and the improvement of heat crack resistance as described above. If the Mn content is less than 0.3% by weight, good far-infrared radiation characteristics cannot be obtained. On the other hand, when the content exceeds 4.3% by weight, continuous casting from an alloy to a thin plate becomes difficult, which is not practical. That is, in order to obtain the precipitation state of the Al-Mn intermetallic compound precipitate as described above, the cooling rate during casting is set to 5 ° C / sec or more, and Mn is sufficiently dissolved in solid form.
Thereafter, it is preferable to perform a heat treatment for the precipitation of the intermetallic compound. However, in order to cast at a cooling rate of 5 ° C./sec or more, it is practical to apply a continuous casting method of a thin plate (continuous casting and rolling). Optimal. However, when the amount of Mn is 4.
If it exceeds 3% by weight, continuous casting of a thin plate becomes difficult. Therefore, the Mn content is preferably in the range of 0.3 to 4.3% by weight.

Mg: Mg is not necessarily an essential element, but promotes precipitation of Al—Mn intermetallic compound precipitates,
It contributes to achieving the above-mentioned precipitation state. Especially Mn
In a range where the amount is relatively small, increasing the amount of added Mg is effective for promoting the precipitation of Al-Mn-based intermetallic compound precipitates and improving the far-infrared radiation characteristics.
However, if the amount of Mg exceeds 6.0% by weight, continuous casting of a thin sheet becomes difficult, which is not practical. On the other hand, the Mn content is 0.1.
If the amount is less than 05% by weight, the above-mentioned effects due to the addition of Mg cannot be obtained. Therefore, the addition amount of Mg is preferably in the range of 0.05 to 6.0% by weight.

Fe: Fe has some influence on the precipitation of Al—Mn intermetallic compound precipitates, but has essentially no effect on far-infrared radiation characteristics. From the viewpoint of castability, the Fe content is preferably as small as possible. If it exceeds 0.5% by weight, continuous casting may be difficult.

Although Si has some influence on the precipitation of Al—Mn based intermetallic compound precipitates, it has essentially no effect on far-infrared radiation characteristics. From the viewpoint of castability, the amount of Si is preferably small, and if it exceeds 2.0% by weight, continuous casting may be difficult.

Further, in a normal Al alloy, a small amount of Ti may be added alone or in combination with a small amount of B in order to refine the crystal grains of the ingot.
Ti may be added to the n-based alloy in the range of 0.003 to 0.15% by weight alone or in combination with B of 1 to 100 ppm.

That is, Ti has the effect of refining the crystal grains of the ingot to prevent streaks and texture of the rolled sheet.
If i is less than 0.003% by weight, the effect cannot be obtained.
If i exceeds 0.15% by weight, a TiAl ₃ -based coarse intermetallic compound is generated. B is an element that coexists with Ti and promotes grain refinement. However, if the B content is less than 1 ppm, the effect cannot be obtained. On the other hand, if the B content exceeds 100 ppm, the effect is saturated, and coarse TiB ₂ particles Are generated and linear defects occur.

In addition, in an aluminum alloy containing Mg, a small amount of Be has been conventionally added to prevent oxidation of the molten metal.
There is no particular problem in adding Be of about 0 ppm or less.

In an Al—Mn alloy, Ni, Z
r, V, Cu, Zn, and the like may be included. Of these, Ni, Zr, and V do not essentially affect the far-infrared radiation characteristics, but Ni is 1.0% by weight or more, Zr is 0.3% by weight or more, and V is 0.3% by weight or more. Since continuous casting becomes difficult, it is desirable to suppress Ni to less than 1.0% by weight, Zr to less than 0.3% by weight, and V to less than 0.3% by weight. Further, although Cu and Zn slightly change the color tone of the anodic oxide film, they do not essentially affect far-infrared radiation characteristics, but Cu is not less than 1.0% by weight and Zn is not less than 2.0% by weight. In this case, continuous casting of a thin plate becomes difficult.
It is preferred that the content be less than 0% by weight and Zn be less than 2.0% by weight.

Next, the process conditions for producing a rolled plate made of the above Al-Mn alloy will be described. As described above, in order to achieve the far-infrared radiation characteristics obtained by obtaining an appropriate precipitation state of the Al-Mn intermetallic compound, the casting speed and the heat treatment for the precipitation are important. As for casting, by increasing the casting speed and sufficiently dissolving Mn, it is possible to precipitate the Al-Mn intermetallic compound in an appropriate precipitation state in the subsequent precipitation treatment. C./sec or higher casting rates are preferred. In order to obtain a cooling rate of 5 ° C./sec or more, especially in the case of manufacturing a large plate, a thin plate continuous casting method (continuous casting and rolling method) which can easily obtain a thin plate having a thickness of about 5 to 10 mm is applied. Is preferred.

On the other hand, the heating for the precipitation is preferably performed at a temperature of 300 ° C. or more and 600 ° C. or less for 0.5 hours or more. If the temperature is lower than 300 ° C., the precipitate is too small to obtain excellent far-infrared radiation characteristics, while if it exceeds 600 ° C., the color tone after the anodic oxidation treatment deteriorates and the crystal grains become coarse. Also, the time is kept from the heating process,
The time during which the temperature is 300 ° C. or higher throughout the cooling process is set to 0.
If it is 5 hours or more, the time during which the temperature is 300 ° C. or more is less than 0.5 hour, and good far-infrared characteristics cannot be obtained after anodizing.

The heating for the precipitation may be performed on the ingot as it is, during the rolling, or after the rolling. Therefore, this precipitation treatment is a homogenization treatment for the ingot, or a heat treatment for hot rolling, furthermore, an intermediate annealing performed as necessary after hot rolling or in the middle of cold rolling, and further cold rolling. This can be performed together with final annealing performed as needed later. Further, the heating and annealing for hot rolling and pressure welding may be performed together. In addition, hot rolling, cold rolling, and, if necessary, intermediate annealing or final annealing may be performed according to a conventional method.

Next, the reasons for limiting the component composition in the Al-Si alloy will be described. Si: Si is crystallized as primary crystal eutectic and eutectic Si according to the added amount during casting, and the shape of the crystallized Si changes due to heat treatment and composition processing performed as necessary. In addition, when heat treatment is performed as necessary, metal Si is also precipitated from the Al matrix. These primary crystal Si, eutectic Si and precipitated Si are taken into the anodic oxide film as metal Si particles during the anodic oxidation treatment as described above, and contribute to the improvement of far-infrared radiation characteristics through scattering and absorption of incident light. In addition, it contributes to the prevention of cracks. Further, as described above, the metal Si particles contribute to the formation of a branched structure in the pores in the anodic oxide film, which also contributes to the improvement of the far-infrared radiation characteristics and the prevention of cracks. If the amount of Si in the base aluminum alloy is less than 3% by weight, the number of metallic Si particles is small, and radiation of far infrared rays becomes insufficient. On the other hand, if the Si content exceeds 15% by weight, the volume ratio of the metal Si particles in the anodic oxide film is too large, so that the strength and corrosion resistance of the anodic oxide film are reduced, and the rolling property is also reduced. Therefore, the amount of Si is preferably in the range of 3 to 15% by weight.

The Al—Si alloy may be basically Al and unavoidable impurities other than the above-mentioned Si. In addition to Si, for improving strength, Fe, Mg, C
One, two or more of u, Mn, Ni, Cr, V, Zn, and Zr may be contained. The amounts of these additives are as follows.

Fe: Fe is effective for improving strength and refining crystal grains. If the Fe content is less than 0.05% by weight, the effect cannot be obtained, and if it exceeds 2.0% by weight, the strength and corrosion resistance of the anodic oxide film decrease. When the amount of Fe is 2.
If it exceeds 0% by weight, Si combines with Fe to form Al-Fe-
The amount of the Si-based intermetallic compound increases, and the far-infrared radiation characteristics decrease. Therefore, the amount of Fe when Fe is added is
The range is preferably 0.05 to 2.0% by weight.

Mg: Mg also contributes to improvement in strength. If the Mg content is less than 0.05% by weight, the effect cannot be obtained.
If it exceeds 2.0% by weight, Mg and Si combine to form Mg ₂ Si.
And the far-infrared radiation characteristics decrease. If the Mg content exceeds 2.0% by weight, castability and plastic workability are also reduced. Therefore, when Mg is added, the amount of Mg is 0.1.
It is preferably in the range of 0.5 to 2.0% by weight.

Cu: Addition of Cu also contributes to the improvement in strength.
If the Cu content is less than 0.05% by weight, the effect cannot be obtained.
If the content exceeds 6.0% by weight, castability, plastic workability, and corrosion resistance deteriorate. Therefore, the amount of Cu when Cu is added is 0.0.
A range of 5 to 6.0% by weight is preferred.

Mn: Mn contributes to the improvement of strength, the refinement of crystal grains, and the improvement of heat resistance. If the Mn content is less than 0.05% by weight, these effects cannot be obtained. On the other hand, if the Mn content exceeds 2.0% by weight, Mn bonds to Si and Al-
The generation amount of the Mn-Si based intermetallic compound increases, and the far-infrared radiation characteristics improve. If the amount of Mn exceeds 2.0% by weight, casting becomes difficult. Therefore, when Mn is added, the Mn content is preferably in the range of 0.05 to 2.0% by weight.

Ni: Ni also contributes to improving the strength and heat resistance. If the Ni content is less than 0.05% by weight, these effects cannot be obtained, while if it exceeds 3.0% by weight, casting becomes difficult. Therefore, when Ni is added, the amount of Ni is preferably in the range of 0.05 to 3.0% by weight.

Cr, Zr, V: These elements contribute to the improvement of strength and also to the refinement of crystal grains. In any case, if the content is less than 0.05% by weight, the effect cannot be obtained. On the other hand, if the content exceeds 0.5% by weight, a coarse intermetallic compound is generated, and the strength is rather lowered. Therefore, when one or more of Cr, Zr and V are added, the added amount is preferably in the range of 0.05 to 0.5% by weight as a single amount. When rolling, extrusion, or casting of a slab, a billet, or the like is applied, the single addition amount of these elements is 0.3.
If the content is more than 10% by weight, the plastic workability decreases and casting becomes difficult.

Zn: Zn is an element that is inevitably mixed when scrap is used as a raw material for melting, but contributes to an improvement in strength when more than 1% by weight is positively contained. If Zn is less than 1.0% by weight, the effect cannot be obtained.
On the other hand, if it exceeds 7.0% by weight, castability deteriorates. Therefore, when Zn is positively added, the amount of Zn is set to exceed 1.0% by weight and 7.0% by weight or less. Further, in the case of an Al-Si based alloy, Ti, P, Na, S
One or more of b and Sr are contained. The reasons for limiting these components are as follows.

Ti: Ti contributes to refinement of the structure through refinement of ingot crystal grains. If the amount of Ti is less than 0.005% by weight, the effect cannot be obtained. If the amount exceeds 0.2% by weight, a coarse intermetallic compound is generated, which is not preferable. Therefore, when Ti is added, the amount of addition is 0.005 to 0.5.
2% by weight is preferred. In order to refine the ingot crystal grains, it is effective to make B coexist with Ti.
In this case, if the amount of B added is less than 1 ppm, the effect cannot be obtained, and if it exceeds 100 ppm, the effect is saturated. Therefore, when B is added together with Ti, the amount added is 1 to 10 ppm.
A range of 0 ppm is preferred.

P: P contributes to miniaturization of primary crystal Si. Therefore, the addition amount of P is effective in the case of an alloy containing about 10% by weight or more of Si such that primary crystal Si first appears.
If the amount of P is less than 0.005% by weight, the effect of miniaturizing the primary crystal Si cannot be obtained, and if it exceeds 0.1% by weight, the effect is saturated. Therefore, when P is added,
0.005 to 0.1% by weight is preferred.

Na, Sb, Sr The elements Na, Sb, and Sr contribute to the refinement of eutectic Si. In any case, if less than 0.005% by weight, the effect cannot be obtained. When the content of Na and Sr exceeds 0.1% by weight, the effect is saturated, and when the content of Sb exceeds 0.3% by weight, the effect is saturated. Therefore, the amount of addition when Na is added is 0.0.
0.5 to 0.1% by weight, when Sb is added, the amount of addition is 0.1.
The amount of Sr added is preferably 0.005 to 0.1% by weight. Note that Nb, S
When b and Sr coexist with P, it is desirable not to coexist with P because the effect of miniaturization of primary crystal Si by P is lost.

In addition to the above elements, there is no particular problem in adding about 1 to 100 ppm of Be to prevent oxidation during dissolution. Also, other elements do not particularly adversely affect far-infrared radiation characteristics as long as the total amount is about 1% by weight or less.

Next, a description will be given of the microstructure of the rolled sheet using the Al-Si alloy as described above, in particular, the dispersion of metal Si particles.

As described above, an Al alloy containing a considerable amount of Si is crystallized as primary crystal eutectic Si and eutectic Si at the time of casting, depending on the amount of Al added. When heat treatment is performed after casting, metallic Si is also precipitated from the Al matrix. These crystallized Si (primary crystal Si, eutectic Si) and precipitated Si remain in the anodic oxide film as metal Si particles as they are even after the anodic oxidation treatment. The metal Si particles in the anodic oxide film have a great effect on far-infrared radiation characteristics and crack resistance of the anodic oxide film.

Here, in order to obtain good radiation characteristics of far infrared rays, the size (particle size) and distribution of the metal Si particles are important. That is, when the diameter of the metal Si particles is less than 0.05 μm, the scattering and absorption of visible light and far-infrared rays are insufficient, and good radiation characteristics cannot be obtained. Therefore, it is essential that metal Si particles having a particle size of 0.05 μm or more exist. For this reason, it is necessary to control the distribution state of the metal Si particles having a size of 0.05 μm or more by dropping.

In a region where no metal Si particles are present, or where only metal Si particles having a particle size of less than 0.05 μm are present, absorption of visible light and far infrared rays is poor.
Therefore, if such a region exists more than a certain degree, the far-infrared radiation characteristics deteriorate. Further, since the region has no or very few points for relaxing the stress, the anodic oxide film in the region is liable to crack. Therefore, a region where the metal Si particles are absent, or even if they are present, are only particles having a particle size of less than 0.05 μm (hereinafter abbreviated as “particle-free region”) is regulated by the following two conditions. (A) The maximum diameter of a circle that can be drawn in the particle-free region is 30 μm or less. (B) In the particle-free region, the total area of the area where a circle having a diameter of 15 μm can be drawn is 30% or less in terms of the area ratio with respect to the entire area.

Here, the condition (A) means that the size of each particle-free region is small, and the condition (B) means that the total area of the particle-free region having a certain size or more is small. However, the conditions (A) and (B) will be specifically described with reference to the drawings.

The ingot structure of the Al alloy generally has a dendrite structure (dendritic structure) as shown in FIG. The periphery of the dendrite portion composed of the α solid solution 1 is a eutectic region 2, that is, a region where the α phase and the metal Si coexist alternately. Therefore, in this case, it can be said that the region of the α solid solution 1 in the dendrite portion is a particle-free region.

In general, in a hypereutectic Al—Si alloy, primary crystal Si is crystallized, and in the ingot structure, as shown in FIG. In this case, the portion of the α solid solution 1 around the primary crystal Si3 can be referred to as a particle-free region.

Further, in the case of a decooled structure having a slow cooling rate during casting, as shown in FIG. 3, Si4 in the eutectic structure becomes coarse and irregular needle-like, and the boundary of dendrite may become unclear. is there. In this case, it may be necessary to consider all the portions between Si4 in the eutectic structure as a particle-free region.

On the other hand, when heat treatment is performed after casting, for example, as shown in FIG. 4, metal Si particles precipitate in the α solid solution of the dendrite portion, and therefore, the original dendrite portion 1 ′
Are often not in the particle-free region. Then, when plastic working such as pressing, casting, and rolling is performed on the ingot, for example, as shown in FIG. The shape and dimensions change. In the present invention, the conditions (A) and (B) are applied so that the width and the area ratio of the particle-free region can be defined commonly in all the cases described above.

Here, regarding the condition (A), FIG.
FIGS. 6, 7 and 8 show the state of drawing the largest diameter circle 5 in the particle-free region for each of the tissues shown in FIGS.
The condition of the above (A) is that the maximum circle 5 is 30 μm.
m or less means good. In addition, (B)
1, 3 and 5 (however, the tissue on the right side of FIG. 5) has a diameter of 1 in the particle-free region.
FIGS. 9, 10 and 11 show a state in which a circle 6 of 5 μm is drawn. In these figures, the thick solid line 7 is 15 μm in diameter.
Indicates an outer peripheral line of a region where a circle can be drawn. The condition (B) means that the area of the region surrounded by the outer peripheral line (7) may be 30% or less of the entire area.

When the above condition (A) is not satisfied, that is, when there is a particle-free region having a diameter of more than 30 μm, cracks are easily formed in the anodic oxide film, and the far-infrared radiation characteristics are deteriorated. On the other hand, when the condition (B) is not satisfied, that is, when the total of the particle-free regions having a diameter of 15 μm or more exceeds 30% of the total area, the far-infrared absorption region in the coating decreases, and the far-infrared radiation is reduced. The characteristics deteriorate.
In addition, in a region where only a small circle having a diameter of less than 15 μm can be drawn, even if the total area exceeds 30% of the entire area, the crack resistance of the anodic oxide film is not particularly impaired, and good far-infrared radiation characteristics are obtained. Is obtained.

Next, the conditions (A) and (B) as described above will be described in more detail in relation to the production process of the rolled Al—Si diameter alloy sheet.

If an Al—Si alloy having the above composition is cast, eutectic Si and primary Si
Are crystallized together with the primary Al-α dendrite. The dendrite branches are in a solid solution as cast, and metal Si does not exist in this portion.

The thickness of the α-dendrites is affected by the cooling rate during casting. If the cooling rate is low, the interval between branches increases, and the thickness of the branches also increases. The faster the cooling rate, the narrower the dendrite spacing and the smaller the thickness of the branches. Therefore, when the casting speed is relatively low as in sand casting, the thickness of the dendrite trunk tends to be 30 μm or more, and the area of a circle with a diameter of 15 μm or more is also increased. The distribution of metal Si is (A),
In many cases, the condition (B) is not satisfied. Conversely, when the cooling rate is high, such as in die casting or roll casters, the intervals between dendrites are close and the thickness of the dendrite trunk is also small. For this reason, the aforementioned (A) and (B)
Is often satisfied as cast, and in this case, good far-infrared radiation characteristics can be obtained even as cast.

As described above, when the dendrite is coarse in the casting stage and a structure satisfying the conditions (A) and (B) cannot be obtained, the ingot is heated to remove the metal Si in the dendrite.
May be precipitated. The precipitated Si particles are generally smaller than the size of the crystallized Si particles at the time of casting, but if the temperature conditions are appropriately selected, the Si particles of 0.05 μm or more are contained in the α phase of the dendrite. Precipitates. Thus, even in the case where the dendrite structure is coarse and the particle-free region is wide in the casting stage, the structure satisfying the above conditions (A) and (B) is obtained by performing the precipitation treatment, whereby the far-infrared radiation characteristic is obtained. Can be improved.

The temperature of the precipitation treatment in this case varies depending on the composition of the alloy, but is usually about 300 to 550 ° C., and the time is usually about 0.5 to 24 hours. If the temperature is lower than 300 ° C., the size of the precipitated Si particles is small and tends to be less than 0.05 μm. If the temperature exceeds 550 ° C., local melting occurs or the amount of Si precipitated is reduced, and the ratio of the area of a circle having a diameter of 15 μm or more to the ingot structure may exceed 30%. is there. If the precipitation time is less than 0.5 hours, there is no effect.
Beyond 24 hours is economically useless.

When performing hot working such as hot rolling,
Irrespective of the dendrite structure, it is necessary to heat the ingot before hot working, and the heat treatment before hot working can also serve as the above-described precipitation treatment. Of course, before the heat treatment before the hot working, or after the hot working, and at any time after the middle of the cold working or after the hot working, the Si having the size described above is precipitated. Such heat treatment can be performed alone or in combination with annealing. Furthermore, it can also be performed together with heating and annealing before hot rolling for pressure welding in the manufacturing process. When performing hot rolling, care must be taken so that cracks do not occur during hot rolling. Si content is 15
If the content exceeds 10% by weight, cracks tend to occur during hot rolling.

In some cases, cold rolling is performed directly on the cast material. That is, in the method of continuously casting a thin plate, a thin plate of 5 to 20 mm is continuously produced between the cold rolls.
In this case, the cast plate is often subjected to direct cold rolling. In the case of such continuous casting and rolling, since the cooling rate is remarkably high, the structure becomes fine. Therefore, the above conditions (A) and (B) are often satisfied as they are without performing any precipitation treatment. . That is, it exhibits excellent far-infrared characteristics as it is in continuous casting rolling or cold rolling. However, even when performing cold rolling as described above,
In the casting stage, if the conditions (A) and (B) are not satisfied as the structural conditions, heat precipitation treatment is performed as necessary to precipitate metal Si particles of 0.05 μm or more in the particle-free region, What is necessary is to satisfy the conditions of A) and (B).

When a forging process such as hot rolling or cold rolling is performed, a non-particle region such as dendrite is made uniform by the working. And the total processing rate is 7
If it exceeds 0%, the trace of the original dendrite almost disappears, and the distribution of the metal Si particles becomes uniform. Therefore, when hot rolling or cold rolling with a high degree of work is performed, even if the conditions (A) and (B) are not satisfied in the casting stage, the conditions should be easily satisfied by subsequent working. Can be.

Next, if the surface of the Al-Mn-based or Al-Si-based Al alloy substrate as described above is subjected to anodic oxidation treatment, the anodic oxide film exhibits excellent far-infrared characteristics, Shows excellent heat crack resistance. That is, at the time of the anodizing treatment, in the case of the base material of the Al-Mn-based Al alloy, precipitated particles of the Al-Mn-based intermetallic compound, and in the case of the Al-Si-based Al alloy, the metal Si particles are all contained in the film. An anodic oxide film grows as it is on the surface. Therefore, the growth of the pores in the film is hindered by the Al-Mn intermetallic compound particles or the metal Si particles, and a porous film having branched fine pores is generated. Further, fine pores that remain and disperse as they are in the anodic oxide film scatter and absorb incident light, and radiation characteristics of far infrared rays are also improved. Further, the above-mentioned branched fine pore structure and Al-Mn-based intermetallic compound particles or metal Si particles dispersed in the film function as a relaxation point of thermal stress, so that cracks hardly occur in the film, and
It can be used without cracks up to a high temperature of about 0 ° C.

By the way, when a substrate made of Al or Al alloy is subjected to mechanical surface roughening treatment and then subjected to anodic oxidation treatment, the value of the surface roughness of the substrate surface is directly changed to the surface roughness of the anodic oxide film. It will be manifested in. Therefore, the surface of the base material has an average roughness of 0.5 to 5 μm,
m, the surface roughness of the obtained anodic oxide film is also 0.5 to 5 μm in average roughness and 5 to 50 μm in maximum roughness.
m.

Further, the inventors of the present invention disclosed in Japanese Patent Application No. 3-15522.
In the far-infrared radiator for which a patent application is made in the specification of Japanese Patent No. 9, particularly effective far-infrared radiation characteristics and heat crack resistance characteristics are obtained when the thickness of the anodic oxide film is 10 μm or more. In the case where the surface is mechanically roughened, excellent radiation characteristics and heat crack resistance can be obtained even with an anodic oxide film having a thickness of 4 μm or more. Since good properties can be exhibited even with such a thin anodic oxide film, the thickness of the anodic oxide film required at the time of manufacturing can be reduced, so that a wider range of manufacturing conditions can be selected and plastic processing of a thin plate can be easily performed. Become like

[0079]

【Example】

(Example 1) JIS defined 1050 material (pure aluminum)
A 50 × 100 × 1 mm plate made of was used as a sample plate, and the surface of the plate was blasted at a pressure of 4 kg / cm ₂ using # 100 and # 180 alumina particles. Then, in a 20% by weight sulfuric acid bath at 20 ° C., anodizing treatment was performed at a current density of 3 A / dm ² for 5 minutes, 10 minutes, and 30 minutes, respectively. This sample was placed in a muffle furnace, heated from room temperature, heated at 500 ° C. for 30 minutes, and then subjected to a heat cycle test in which 10 heat cycles for returning to room temperature were performed. Thereafter, the sample temperature was increased to 250
A test for measuring the total emissivity of far infrared rays in a wavelength region of 3 to 30 μm was performed by setting the temperature to 500 ° C. Table 1 shows the results. Further, in the above test, a sample not subjected to only the blast treatment was also prepared, and the same test as above was performed on this sample. Table 2 shows the results.

[0080]

[Table 1]

[0081]

[Table 2]

As is clear from the results shown in Tables 1 and 2, the sample of the present invention in which a pure aluminum material was subjected to a surface roughening treatment to form an anodic oxide film having fine irregularities was subjected to the surface roughening treatment. It was found that the emissivity was remarkably improved as compared with the sample not subjected to. And especially, a wavelength of 3 to 7 μm
The total emissivity at 500 ° C. at which the spectral emissivity greatly decreases in the m band has a large difference depending on whether or not blasting is performed. In addition, large differences were also observed in heat resistance properties such as the occurrence of cracks and the occurrence of warpage, and all of the samples according to the present invention shown in Table 1 showed good values.

(Example 2) The same test as in Example 1 was performed using 5052 and 6063 JIS-specified Al alloys. Table 3 shows the results.

[0084]

[Table 3]

As is evident from the results shown in Table 3, any of the materials subjected to the blast treatment exhibited excellent characteristics. (Example 3) As Al alloys having the composition ranges described in claims 2 to 6 as shown in Table 4, the same tests as in Example 1 were performed. The test results are shown in Tables 5, 6, and 7.

[0086]

[Table 4]

[0087]

[Table 5]

[0088]

[Table 6]

[0089]

[Table 7]

As shown in Tables 5 to 7, the alloys according to the present invention were subjected to the method of the present invention using Tables 1 and 3
The emissivity was higher than in the case where a normal Al material such as 1050 material, 5052 material and 6063 material shown in FIG. 3 to 7 μm with large property deterioration especially at high temperatures
, Excellent characteristics close to the total emissivity at 250 ° C. were obtained even at the total emissivity at 500 ° C. Before the heat cycle, needless to say, 5
After 10 heat cycles of 00 ° C for 30 minutes
No cracks or warpage, showing excellent heat resistance
Was. Further, in this example, the results of an example in which both the film thicknesses of 5 μm and 10 μm are thin as the anodic oxide film are shown, but it is clear that higher emissivity can be obtained by increasing the film thickness. When performing bending or other processing on a sheet material after anodizing, the thinner the film thickness, the better the workability. Therefore, high emissivity can be obtained while maintaining high thermal stability even when thin. The benefits are great. When a higher emissivity is required and mechanical properties such as excellent wear resistance are required, a thick film may be formed, and a hard alumite treatment may be performed as necessary.

[0091]

As described above, according to the present invention, A
An anodic oxide film having a thickness of 4 μm or more having fine irregularities is formed on a plate-shaped base material of an alloy, and the surface roughness of the anodic oxide film is 1.5 to 3.0 μm in average roughness, and the maximum roughness. Now 5-3
0μm range, or the surface roughness of the anodic oxide film,
1.5 to 2.6 μm in average roughness, 11 to 27 μm in maximum roughness
far infrared radiator comprising a range of m is, the far infrared radiation
Cracks and warpage even when using a high temperature of 400 ° C or more as a plate
In addition to obtaining excellent heat resistance that does not cause cracking, the total emissivity in the wavelength region of 3 to 30 μm, which is considered to be practically effective, is 70% or more, which was difficult to achieve without using a special alloy in the past. A stable emissivity is obtained with a very thin coating. For this reason, far-infrared radiation that requires heat resistance
It can be suitably used for the use of a shooting plate .

[0092] In the case where an anodic oxide film having fine irregularities is formed on the surface of an Al-Mn-based or Al-Si-based Al alloy substrate, extremely excellent far-infrared characteristics are exhibited. In addition, it shows excellent characteristics in heat resistance such as heat shock. That is, at the time of the anodizing treatment, in the case of the base material of the Al-Mn-based Al alloy, the precipitated particles of the Al-Mn-based intermetallic compound, and in the case of the Al-Si-based Al alloy, the metal Si particles are all contained in the coating. An anodic oxide film is formed while remaining as it is. Therefore, the growth of pores in the anodic oxide film is hindered by the Al-Mn-based intermetallic compound particles or the metal Si particles, and a porous anodic oxide film having branched fine pores is formed. As a result, the fine pores formed in the anodic oxide film in a complicatedly branched manner further improve the scattering and absorptance of incident light and improve the radiation characteristics of far infrared rays.

Further, the above-described branched fine pore structure and Al-Mn intermetallic compound particles or metal Si particles dispersed in the film also function as a relaxation point of thermal stress. Is less likely to occur 5
It can be used without causing cracks up to a high temperature of about 00 ° C. Therefore, the far-infrared radiator according to the present invention can also be used for applications that require strict dimensional restrictions and high characteristics, such as when incorporated in precision equipment and the like.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a first example of an ingot structure of an aluminum alloy.

FIG. 2 is a schematic view showing a second example of an ingot structure of an aluminum alloy.

FIG. 3 is a schematic view showing a third example of an ingot structure of an aluminum alloy.

FIG. 4 is a schematic diagram showing an example of a structural change when a heat treatment is performed on an aluminum alloy ingot.

FIG. 5 is a schematic diagram showing an example of a structural change when an ingot of an aluminum alloy is subjected to rolling.

FIG. 6 shows a grain size of 0.05 μm among the texture conditions of the present invention.
FIG. 4 is a diagram for describing a maximum diameter of a circle that can be drawn in a region where the metal Si particles do not exist, and is a schematic diagram corresponding to the structure illustrated in FIG. 1.

7 is a diagram for explaining the maximum diameter, and is a schematic diagram showing the tissue shown in FIG. 3;

8 is a view for explaining the maximum diameter, and is a schematic view showing a tissue shown on the right side of FIG. 5;

FIG. 9 shows a grain size of 0.05 μm among the texture conditions of the present invention.
The diameter 15 in the region where the above metal Si particles do not exist
FIG. 2 is a diagram for explaining a region where a circle of μm can be drawn, and is a schematic diagram corresponding to the tissue shown in FIG. 1.

10 is a diagram for explaining a region where a circle having a diameter of 15 μm can be drawn, and is a schematic diagram corresponding to the tissue shown in FIG. 3;

11 is a diagram for explaining a region where a circle having a diameter of 15 μm can be drawn, and is a schematic diagram corresponding to the tissue shown in FIG. 5;

[Explanation of symbols]

 1 α solid solution (dendrite), 2 eutectic region, 3 primary crystal Si, 4, Si, 5, 6 yen, 7, solid line (outer line).

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masatake Maejima 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (72) Inventor Sadayoshi Nishiyama 1-5-1, Kiba, Koto-ku, Tokyo Fujikura (72) Inventor Shuichi Matsumoto 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (72) Inventor Noriyoshi Baba 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (72) Inventor Mamoru Matsuo 4-3-1-18 Nihonbashi Muromachi, Chuo-ku, Tokyo Inside Sky Aluminum Co., Ltd. (56) References JP-A-2-230683 (JP, A) JP-A-54-13028 (JP, A) JP-A-1-180937 (JP, A) JP-A-59-56559 (JP, A) JP-A-48-72015 (JP, A) JP-A-49-67807 (JP, A) -116639 (JP , B2)

Claims (6)

(57) [Claims] 1. Mn content of 0.3 to 4.3% by weight, balance of Al and unavoidable impurities, and particle size of 0.01
An anodic oxide film having fine surface irregularities is formed to a thickness of 4 μm or more on the surface of a plate-like substrate made of an Al alloy in which Al-Mn-based intermetallic compound precipitates of up to 3 μm are dispersed. The surface roughness of the anodic oxide film is 1.5 on average.
A far-infrared radiator characterized in that the far-infrared radiator has a maximum roughness in a range of 5 to 30 μm. 2. The far-infrared radiator according to claim 1 , wherein the Al alloy contains 0.3 to 4.3% by weight of Mn and 0.05 to 6.0% by weight of Mg, with the balance being Al and A consisting of unavoidable impurities and having a particle size of 0.01 to 3 μm
Al alloy in which l-Mn intermetallic compound precipitates are dispersed
A far-infrared radiator characterized by using a plate-shaped substrate made of: 3. An alloy containing 3 to 15% by weight of Si and the balance of A
1 and unavoidable impurities, and primary crystal Si, eutectic S
Among the metal Si particles composed of i or precipitated Si, the maximum diameter of a circle drawn in a region where no metal Si particle having a particle size of 0.05 μm or more is present is 30 μm or less, and the metal Si particle having a particle size of 0.05 μm or more is among non-existent area, the total area of the region draw a circle with a diameter of 15 [mu] m, an Al alloy is not more than the area ratio of 30% to the total area
Anodized skin with fine surface irregularities on the surface of the plate-shaped substrate
The film is formed to a thickness of 4 μm or more, and the anodic oxide film
Has an average roughness of 1.5 to 3.0 μm and a maximum roughness of
A far-infrared radiator characterized by having a range of 5 to 30 μm . 4. The far-infrared radiator according to claim 3 , wherein the Al alloy contains 3 to 15% by weight of Si, 0.05 to 2.0% by weight of Fe, and 0.05 to 2% of Mg. .0
% By weight, 0.05 to 6.0% by weight of Cu, and 0.05% of Mn.
2.0% by weight, Ni 0.05 to 3.0% by weight, Cr 0.05 to 0.5% by weight, V 0.05 to 0.5% by weight, Z
r of 0.05 to 0.5% by weight and Zn of more than 1.0% by weight to 7.0% by weight or less, with the balance being Al and unavoidable impurities. And the maximum diameter of a circle that can be drawn in a region where no metal Si particles having a particle diameter of 0.05 μm or more is present among the metal Si particles composed of primary crystal Si, eutectic Si, or precipitated Si is 30 μm or less. A plate-shaped substrate made of an Al alloy having an area ratio of 30% or less with respect to the total area of a region where a circle having a diameter of 15 μm can be drawn out of a region where no metal Si particles of 0.05 μm or more was present was used . A far-infrared radiator, characterized in that: 5. The far-infrared radiator according to claim 3 , wherein the Al alloy contains 3 to 15% by weight of Si, 0.005 to 0.2% by weight of Ti, and P 0.005 to 0.1% by weight, 0.005 to 0.1% by weight of Na
0.1% by weight, 0.005 to 0.3% by weight of Sb, and 0.005 to 0.1% by weight of Sr, with the balance being Al and inevitable impurities And the maximum diameter of a circle that can be drawn in a region where no metal Si particles having a particle diameter of 0.05 μm or more is present among metal Si particles composed of primary crystal Si, eutectic Si or precipitated Si is 30 μm or less, A plate-like substrate made of an Al alloy having a total area of 30% or less with respect to the total area of a region in which a circle having a diameter of 15 μm can be drawn among regions where no metal Si particles having a diameter of 0.05 μm or more is present is used. A far-infrared radiator, characterized in that: 6. The far infrared radiator according to claim 5, wherein the surface roughness of the anodic oxide film, 1.5 at average roughness
A far-infrared radiator characterized in that it has a range of 2.6 μm and a maximum roughness of 11 to 27 μm.