JP3048086B2 - Far-infrared radiator and manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention relates to heating, cooking, drying,
The present invention relates to a member that emits far-infrared rays for heat treatment of materials and other various radiant heating, and more particularly to a far-infrared radiator having an anodized film formed by using an aluminum alloy as a base material and a method of manufacturing the same. .

[0002]

2. Description of the Related Art Generally, in heaters utilizing far-infrared rays, the radiator has a high far-infrared emissivity,
At a relatively low surface temperature of 0 ° C. or higher, radiation in the visible region is small, but radiation in the far infrared region is large.
As a radiator satisfying such demands, a radiator made of various ceramic materials such as alumina, graphite, and zirconia has been put to practical use. Among these materials, it is known that alumina has excellent performance as compared with other ceramic materials in terms of far-infrared radiation characteristics.

[0003] However, the far-infrared radiator made of the conventional ceramic material has a large weight, is easily broken, and it is difficult to produce a thin one. There were problems such as poor efficiency.

Therefore, a radiator in which ceramic is sprayed on the surface of a metal substrate has been put to practical use. However, in this case, a high cost is required for production, and it is difficult to obtain a thin plate or a radiator having a complicated shape. There are problems such as.

[0005] By the way, with respect to alumina among ceramic materials, a layer made of alumina can be easily formed on the surface of an aluminum substrate by forming an anodized film (anodized film) by anodizing the surface of aluminum. Can be. In this case, since the base material is aluminum, the thermal conductivity is good, and since the anodic oxide film on the surface is alumina, the far-infrared radiation characteristics are also good. Can be satisfied. Therefore, recently, a far-infrared radiator in which the surface of an aluminum substrate is anodized as described above has been attempted.

[0006]

However, conventional radiators in which the surface of an aluminum base material is subjected to anodizing treatment are limited due to the following drawbacks (1) to (3). There is a problem that it can be applied only to the intended use. (1) At a temperature of 200 ° C. or higher, cracks tend to occur in the alumite film, so that the emissivity becomes unstable and the corrosion resistance also deteriorates. (2) The emissivity in the wavelength range of 3 to 7 μm is low. (3) It is difficult to obtain a member having a complicated shape by casting or various types of plastic working.

[0007] Among the above problems, the problem (1) can be solved by using an aluminum alloy that can form an anodic oxide film that does not easily crack even at a high temperature of 200 ° C or higher. Aluminum alloys are not currently known as far-infrared radiators.

[0008] Regarding the problem described in the above (2),
It is known that the emissivity in the above wavelength range can be improved by coloring the anodic oxide film on the aluminum substrate surface of the infrared radiator with a dye. However, in these methods, the number of coloring steps is increased, resulting in higher cost. Further, at a high temperature of 200 ° C. or more, dyes and the like are decomposed or cracks are generated in the film, and the emissivity in the wavelength band becomes unstable. However, there is a problem that the radiation characteristics are deteriorated.

The problem (3) can be solved by using an aluminum alloy that can be cast or subjected to various types of plastic working. However, plastic working such as casting, extrusion, and forging can be performed, and the problem is stabilized by anodizing. The fact is that aluminum alloys that can be turned black to obtain good far-infrared radiation characteristics have not been known so far.

The present invention has been made in view of the above circumstances. Even at a high temperature of 200 ° C. or more, cracks due to thermal strain hardly occur in the anodic oxide film, and far infrared radiation characteristics are excellent, and casting, forging, and extrusion are performed. It is an object of the present invention to provide a far-infrared radiator based on an aluminum alloy, which can be manufactured by various processing methods such as those described above to obtain a member having a complicated shape.

[0011]

The present inventors have SUMMARY OF THE INVENTION As a result of extensive experiments and studies to solve the problems described above, the aluminum alloy base material, a component system containing a small amount of Si
In addition , the present inventors have found that the aforementioned problems can be solved by appropriately adjusting the dispersion state of precipitated Si particles, and have accomplished the present invention.

Specifically, the far-infrared radiator according to the first aspect of the invention is based on an alloy containing 1 wt% or more and less than 3 wt% of Si, with the balance being Al and unavoidable impurities.
Material and the total precipitated Si particles on the substrate
That is, the size of the precipitated Si particles in number of 80% or more is
0.05 μm or more and the amount of residual solid solution Si
Depending on the content, the Si content is 1 wt% or more and 1.5 wt%
%, The residual solid solution Si amount (wt%) ≦ Si content (wt%) −
0.5 , and the Si content is 1.5 wt% or more and 3 wt%
If less than 1 , the amount of residual solid solution Si (wt%) ≦ 1 is satisfied, and the surface of the base material has a thickness of 10 μm.
It is characterized in that the above black anodic oxide film is formed.

Further, the far-infrared radiator according to the second aspect of the present invention contains 1 wt% or more and less than 3 wt% of Si, 0.05 to 1.5 wt% of Fe, and 0.05 to 1.0 wt% of Mg.
t%, Cu0.05-1.0wt%, Mn0.05-
1.0 wt%, Ni 0.05 to 1.0 wt%, Cr0.
05-0.5wt%, V0.05-0.5wt%, Zr
0.05-0.5wt%, Ti 0.005-0.2wt
% Or more, and the balance is made of an alloy consisting of Al and inevitable impurities.
Of the total precipitated Si particles in the substrate
% Or more of precipitated Si particles is 0.05 μm or more.
And the amount of residual solid solution Si depends on the Si content.
When the content is 1 wt% or more and less than 1.5 wt%, the amount of residual solid solution Si (wt%) ≦ Si content (wt%) −
0.5 , and the Si content is 1.5 wt% or more and 3 wt%
If less than 1 , the amount of residual solid solution Si (wt%) ≦ 1 is satisfied, and the surface of the base material has a thickness of 10 μm.
It is characterized in that the above black anodic oxide film is formed.

[0014]

The method for producing a far-infrared radiator according to the third aspect of the present invention contains Si in an amount of 1 wt% or more and less than 3 wt%, and further contains 0.05 to 1.5 wt% of Fe as needed.
%, 0.05-1.0 wt% of Mg, 0.05-1.
0 wt%, Mn0.05-1.0 wt%, Ni0.05
1.0 to 1.0 wt%, Cr 0.05 to 0.5 wt%, V0.
0.5 to 0.5 wt%, Zr 0.05 to 0.5 wt%, T
i An alloy containing one or more of 0.005 to 0.2 wt%, the balance being Al and unavoidable impurities is cast, and if necessary, hot working and / or cold working are performed. To obtain a base material of a predetermined size, and then to perform anodizing treatment to form an anodic oxide film of 10 μm or more on the surface, after the casting, after hot working, or in the middle of cold working or Later, 250-5
By heating to a temperature in the range of 50 ° C., the Si
Is 80% or more of the precipitated Si particles out of all the precipitated Si particles is 0.05 μm or more and the residual solid solution S
The i content is 1 wt% according to the Si content.
If the content is less than 1.5 wt%, the amount of residual solid solution Si (wt%) ≦ Si content (wt%) −
0.5, and the Si content is 1.5 wt% or more 3
When the content is less than wt%, the precipitation is performed so as to satisfy the amount of residual solid solution Si (wt%) ≦ 1.

[0016]

The far-infrared radiator of the present invention is basically 1 watt.
Metallic Si particles containing at least t% and less than 3 wt% of Si
The base material is an Al-Si-based aluminum alloy whose precipitation state is appropriately controlled, and a black anodic oxide film is formed on the surface thereof.

As described above, in an aluminum alloy containing 1 wt% or more and less than 3 wt% of Si, metal Si particles are dispersed and precipitated in the structure by performing an appropriate heat treatment, as will be described later. Is subjected to anodic oxidation treatment, the precipitated Si particles are taken in the anodic oxide film as metal Si particles. And metal Si in the anodic oxide film
Since the particles are dispersed, the incident light is scattered and absorbed, and the radiation characteristics of far infrared rays are improved. In addition, since visible light is also absorbed, the visual color tone becomes black. Further, in the process of growing the anodic oxide film (porous layer) during the anodic oxidation treatment, the pores grow so as to avoid the metal Si particles, so that the pores in the film have a branched structure. The pore structure improves the scattering and absorption of the incident light in the anodic oxide film, and the radiation characteristics of far infrared rays are further improved.

Further, the metal Si particles dispersed and present in the anodic oxide film also function as stress relaxation points, and the above-described branched structure of the pore has a high strain absorbing ability.
Therefore, cracks are unlikely to occur, and even if cracks occur, their propagation is prevented.

Here, the reason for limiting the component composition in the base aluminum alloy of the far-infrared radiator of the present invention will be described.

Si: Si is a fundamentally important alloy component in the present invention. Si forms a solid solution in accordance with the added amount during casting, and the solid solution Si precipitates as metal Si by heat treatment. As described above, the precipitated Si particles form the metal S during the anodic oxidation treatment.
It is taken into the anodic oxide film as i-particles, and contributes to the improvement of far-infrared radiation characteristics through scattering and absorption of incident light, and also to the prevention of cracks. Further, the metal Si particles contribute to the formation of a branched structure in the pores in the film as described above, and also function as a stress relaxation material, thereby also contributing to improvement of far-infrared radiation characteristics and prevention of crack generation. Substrate aluminum alloy Si
If the amount is less than 1 wt%, less volume of the metal Si particles in the anodized film, the far-infrared radiation characteristics and resistance to clutch
Insufficient workability . On the other hand, if the amount of Si is 3 wt% or more, the number of eutectic Si particles at the time of casting increases, and the corrosion resistance of the anodic oxide film decreases. Therefore, the amount of Si is 1w
It was set within the range of t% or more and less than 3 wt%.

As the component elements of the aluminum alloy of the base material, in addition to the above-mentioned Si, basically, Al and unavoidable impurities may be used. That is, even if the elements other than Al and Si are treated as inevitable impurities and are less than the lower limit specified in claim 2, the intended object of the present invention can be achieved.

However, in order to improve the strength, Fe, Mg, Cu, Mn, Ni, Cr,
One, two or more of V, Zr, and Ti may be contained. The reasons for these additions are as follows.

Fe: Fe is effective for improving strength and refining crystal grains. If the Fe content is less than 0.05 wt%, the effect cannot be obtained, and if it exceeds 1.5 wt%, the strength and corrosion resistance of the anodic oxide film decrease. If the amount of Fe exceeds 1.5% by weight, Si combines with Fe to increase the amount of Al-Fe-Si-based intermetallic compound, and the far-infrared radiation characteristics deteriorate. Therefore, when Fe is added, the amount of Fe is 0.05
To 1.5 wt%.

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 0 wt%, Mg and Si are combined to increase the amount of Mg ₂ Si generated, and the far-infrared radiation characteristics are reduced. Therefore, when adding Mg, the amount of Mg is 0.05 to 1.0 wt.
%.

Cu: The addition of Cu also contributes to the improvement in strength.
If the Cu content is less than 0.05 wt%, the effect cannot be obtained, while if it exceeds 1.0 wt%, castability, corrosion resistance, and plastic workability deteriorate. Therefore, when Cu is added, the amount of Cu is set in the range of 0.05 to 1.0 wt%.

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 wt%, these effects cannot be obtained, while if it exceeds 1.0 wt%, Mn is bonded to Si and Al-Mn
The generation amount of the -Si-based intermetallic compound increases, and the far-infrared radiation characteristic decreases. Therefore, when Mn is added, M
The n content was in the range of 0.05 to 1.0 wt%.

Ni: Ni also contributes to the improvement of the strength and the heat resistance. If the Ni content is less than 0.05 wt%, these effects cannot be obtained, while if it exceeds 1.0 wt%, the corrosion resistance decreases. Therefore, when adding Ni, the amount of Ni is set in the range of 0.05 to 1.0 wt%.

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, Cr, Zr, V
In the case where one or two or more of the above are added, the added amount is in the range of 0.05 to 0.5 wt% in a single amount. When rolling, extrusion, or forging of slabs, billets, etc. is applied, the single addition amount of these elements is 0.3 wt.
%, The plastic workability is reduced and the production becomes difficult.

Ti: Ti contributes to refinement of the structure through refinement of ingot crystal grains. If the Ti content is less than 0.005 wt%, the effect cannot be obtained, while if it exceeds 0.2 wt%, coarse intermetallic compounds are generated, which is not preferable. Therefore, the amount of Ti when Ti is added is 0.005 to 0.2 wt.
%. 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 is less than 1 ppm, the effect cannot be obtained.
If the content exceeds 00 ppm, the effect is saturated. Therefore, when B is added together with Ti, the amount of B is preferably in the range of 1 to 100 ppm.

In addition to the above elements, there is no particular problem in adding Be in an amount of about 1 to 100 ppm for preventing oxidation during dissolution. Zn is an element inevitably mixed when scrap is used as a raw material.
Need not be positively added, but if it is about 1.0 wt% or less, there is no adverse effect on characteristics such as far-infrared radiation characteristics. 1wt% of other elements in total
A trace amount of less than about 10 does not particularly adversely affect far-infrared radiation characteristics.

Next, the structure state of the base aluminum alloy of the far-infrared radiator of the present invention, in particular, the dispersion state of metal Si particles will be described.

As described above, in an aluminum alloy containing 1% by weight or more and less than 3% by weight of Si, Si forms a solid solution at the time of casting in accordance with the added amount. When heat treatment is performed after casting, the solute Si precipitates as metallic Si from the Al matrix. The precipitated Si particles remain in the film as metal Si particles even after the anodizing treatment. And metal Si in this anodic oxide film
The particles have a significant effect on the infrared radiation characteristics and the crack resistance of the anodic oxide film.

That is, since the metal Si particles are dispersed in the anodized film, the incident light is scattered and absorbed, the radiation characteristics of far infrared rays are improved, and the visible light is also absorbed.
The visual color also becomes black. Furthermore, during the pore growth process during the anodizing treatment, the pores grow so as to avoid the metal Si particles, so that the pores have a branched structure, which facilitates the scattering and absorption of incident light in the anodized film, thereby increasing the distance. The infrared radiation characteristics are further improved.

On the other hand, the metal Si particles in the anodic oxide film also function as stress relaxation points, and the branched structure of the pores has a high ability to absorb strain, so that cracks are unlikely to occur, and if cracks occur, Is also prevented from propagating.

Here, in order to obtain good far-infrared radiation characteristics, the size (particle size) of the precipitated metal Si particles and the amount of the precipitated metal Si particles are important. That is, first, of the total precipitated Si particles, those having a number of 80% or more are 0.05 μm
It is necessary to have the above particle size. When the diameter of the precipitated Si particles is less than 0.05 μm, the scattering and absorption of visible light and far-infrared light are insufficient, good radiation characteristics cannot be obtained, and the yellowness becomes strong visually. Not black
In addition, good crack resistance cannot be obtained .
Even if precipitated Si particles of 0.05 μm or more are present, the same problem as described above occurs if the number ratio is less than 80%. Therefore, in order to achieve the intended object of the present invention, it is essential that precipitated Si particles having a particle size of 0.05 μm or more account for 80% or more of the total number of precipitated Si particles.

Further, not only the particle size of the precipitated Si particles,
The amount of precipitation is also important. In an Al-Si alloy, S
i is a form of crystallized Si generally generated at the stage of casting,
The form of precipitated Si deposited by the subsequent heat treatment and the solid solution S
exists in the form of i. At the stage of casting, it exists in a state of crystallized Si and solid solution Si, and metallic Si is precipitated from the solid solution Si by a subsequent heat treatment. The amount of Si that forms a solid solution at the time of casting is approximately 0.5 wt% or more. On the other hand, according to the study by the present inventors, it is necessary to effectively radiate far-infrared rays and to obtain a precipitate S which has good crack resistance.
It has been confirmed that the amount of i is approximately 0.5 wt % or more . Therefore, the amount of the precipitated metal Si particles may be determined so as to be 0.5 wt% or more based on the total weight of the alloy. However, it is difficult to directly determine the amount of precipitated Si particles in an actual alloy. That is, the total amount of metallic Si in the alloy can be determined by analyzing hydrochloric acid-insoluble Si as shown in FIG.
i not only a large crystallization Si during the casting is also included, this large crystallized Si is far-infrared radiation characteristics and crack resistance
Do not contribute to the improvement of metal Si farmland crystallized Si is required to be excluded. Therefore, the metal S
If i is analyzed to determine the amount of crystallized Si, and then heat treatment for Si precipitation is performed, and if the analysis of metal Si is performed again, the amount of precipitated Si can be determined by determining the difference. It is believed that there is. However, in general, it is difficult to perform analysis at the same place in the stage after casting and the stage after heat treatment. Therefore, the amount of precipitated Si obtained as described above should be used as a standard for direct far-infrared radiation characteristics. Can not. Therefore, the present inventors tried to estimate the amount of precipitated Si from the amount of residual solid solution Si after Si deposition. As a result, the residual solid solution Si
When the amount satisfies a certain relationship, the amount of precipitated Si is approximately 0.5
become a wt% or more, Oyo enough excellent far-infrared radiation characteristics
And crack resistance were obtained.

That is, in the Al-Si alloy, attention is paid to the fact that eutectic Si is crystallized when the Si content is approximately 1.5 wt% or more, and the added Si
The relationship between the amount (total Si content), the amount of residual solid solution Si, and the amount of precipitated Si was studied. Here, the amount of residual solid solution Si is
The total Si content (the amount of Si added) was determined by subtracting the amount of metallic Si (for example, by the method shown in FIG. 1) and the amount of Si in the total intermetallic compound (for example, by the method shown in FIG. 2).
This is because Si crystallizes and precipitates as metallic Si, and F
Usually, a compound is formed with e, Mn, Mg, etc.
Therefore, an error occurs between the value obtained by subtracting the amount of metallic Si from the total Si content and the amount of residual solid-solution Si by an amount corresponding to the amount of Si in the total intermetallic compound.

As described above, the amount of the residual solid solution Si and the total Si
As a result of examining the relationship with the content, first, the Si content was 1 wt.
% Or more and less than 1.5 wt%, the amount of residual solid solution Si (wt%) ≦ the total content of Si (wt%) −
0.5, and the Si content is 1.5 wt% or more and 3.0 wt% or more.
If it is less than wt%, if they meet the residual solute Si content (wt%) ≦ 1.0, the total amount of precipitated Si becomes 0.5 wt% or more, excellent far-infrared radiation characteristics and crack resistance Was obtained. That is, if that does not meet these relations, precipitation Si amount is less than 0.5 wt%, even size far-infrared radiation characteristics and crack resistance even 0.05μm or more precipitation Si particles not It will be enough.

In order to obtain the precipitated state of the precipitated Si particles as described above, it is necessary to perform a precipitation treatment after casting or at a later stage. That is, in the method for producing a far-infrared radiator of the present invention, the base material is formed by casting an alloy having the above-described component composition, or after forging, if necessary, hot forging, hot extrusion, hot rolling, or the like. Can be obtained by performing hot working and / or cold working such as cold rolling. Precipitation treatment can be performed at a stage after casting in the production process of the base material, or hot working and / or Alternatively, in the case of performing cold working, the precipitation treatment may be performed after hot working, in the middle of cold working, or after cold working.

This deposition treatment may be performed by heating at a temperature within the range of 250 to 550 ° C. for 0.5 to 24 hours. If the temperature of the precipitation treatment is lower than 250 ° C., the size of the precipitated Si particles tends to be smaller and smaller than 0.05 μm, while
If the temperature exceeds 100 ° C., the precipitated solid will be dissolved again.
Absolute amount of precipitation is insufficient. In addition, the time of the precipitation treatment is 0.
If the time is less than 5 hours, it is difficult to sufficiently precipitate the metal Si from the solid solution Si. On the other hand, if the time exceeds 24 hours, it is only economically useless. Note that such a precipitation treatment may be performed independently or may be performed together with another heat treatment. That is, when hot working is performed after casting, precipitation treatment can be performed also as ingot heating before the hot working, or between hot working and cold working or in the middle of cold working. In the case of performing intermediate annealing, the precipitation treatment can be performed also as the intermediate annealing, and when performing the final annealing after cold working, the precipitation treatment can be performed also as the final annealing. In this case, the heat treatment may be performed under such conditions that the precipitation state of the precipitated Si particles is obtained as described above.

Next, the anodic oxidation treatment applied to the aluminum alloy substrate will be described.

When anodizing is performed on an aluminum alloy substrate having the above-mentioned chemical components and metal structure, a black anodic oxide film is formed, and excellent far-infrared radiation characteristics are exhibited. That is, during the anodic oxidation treatment, the anodic oxide film grows in a state where the metal Si particles remain in the film as it is.
Therefore, the growth of pores in the coating is hindered by the metal Si particles, and a porous coating having branched fine pores is generated. Further, the metal Si particles existing as they are in the anodic oxide film and the above-described branched fine pores scatter and absorb the incident light, and as a result, the color tone becomes black visually, and the radiation characteristics of far infrared rays are also improved. . In addition, the above-described branched fine pore structure and the metal Si particles in the film function as relaxation points of thermal stress, so that cracks are less likely to occur in the film, and cracks are generated up to a high temperature of about 500 ° C. It can be used without it.

Here, the thickness of the anodic oxide film needs to be 10 μm or more. That is, in order to exhibit a blackness with a lightness of 4.5 or less in the Munsell value, the film thickness needs to be 10 μm or more. When the film thickness is 10 μm or more, a stable high blackness can be obtained, so that stable far-infrared radiation characteristics can be obtained in a wide wavelength range.

The conditions of the anodic oxidation treatment are not particularly limited, and an electrolytic bath such as an inorganic acid such as sulfuric acid or oxalic acid, or an organic acid, or a mixed acid thereof may be used.
The anodic oxidation treatment may be performed using an arbitrary waveform such as a direct current, an alternating current, a combined AC / DC, and a superimposed AC / DC waveform. However,
From the viewpoint of economy and work efficiency, it is preferable to use a direct current in a sulfuric acid bath. Before anodic oxidation, degreasing,
It is common to perform pretreatment such as caustic etching,
When caustic etching is performed, it is general to subsequently perform desmut treatment with an acid such as nitric acid. In addition, as a matter of course, it is needless to say that cutting, acid cleaning, chemical polishing, hairline processing, mechanical pretreatment such as shot blasting or the like may be performed.

[0045]

【Example】

Example 1 For alloys having the component compositions shown in alloy numbers 1 to 3 in Table 1, 2
It was sand-cast into a shape of 0 mm x 200 mm x 200 mm. Prior to casting, degassing was performed in advance. A part of the obtained castings was a material as cast, and the remaining ones were subjected to a heat treatment at 400 ° C. or 150 ° C. for 5 hours and then gradually cooled at a cooling rate of 10 ° C./hr.

After mechanically cutting the surface of each material, it was etched with 10% caustic soda at 60 ° C. for 5 minutes.
After washing with water, desmutting was performed using 30% nitric acid. Then, using a 15% sulfuric acid bath, the current density was 1.5 A / dm.
^2. Anodizing treatment was performed at an electrolysis temperature of 20 ° C.

For each material after the anodizing treatment, the Munsell lightness was measured and the spectral emissivity at 300 ° C. was measured. Here, as far-infrared radiation characteristics of a conventional general anodic oxide film, since the spectral emissivity at a wavelength of 3 to 7 μm is usually inferior, the spectral radiation at a typical wavelength of 6 μm within that range is considered. The rate was measured. In addition, Si of each material
The precipitate size and the amount of solute Si were examined. The size of the Si precipitate was first determined using an optical microscope, and when a precipitate close to 0.05 μm, which is difficult to determine with an optical microscope, appears to have precipitated, it was determined using a transmission electron microscope.
The amount of solid solution Si was analyzed by analyzing the amount of metallic Si in the material by the method shown in FIG. 1, and the amount of Si in all the intermetallic compounds was analyzed by the phenol residue method shown in FIG.
The amount of the former metal Si and the latter amount of the Si in the intermetallic compound were subtracted from i). These results are shown in Table 2. Here, when the value of the Munsell lightness is 4.5 or less, it can be determined that the color has a sufficient black color. When the spectral emissivity at a wavelength of 6 μm is 0.7 or more, it can be determined that the device has good far-infrared radiation characteristics.

[0048]

[Table 1]

[0049]

[Table 2]

In Example 1, the alloy Nos. 1 and 2
The temperature of the 0 ° C. heating material satisfies the conditions for Si satisfying the condition range specified in the present invention.
In the case of 29 μm or 32 μm exceeding μm, it is understood that the Munsell brightness and the spectral emissivity satisfy predetermined values, that is, the visual color tone is sufficiently black and the far-infrared radiation characteristics are excellent. 400 ° C. for alloy numbers 1 and 2
Among the heating materials, the material having an anodic oxide film thickness of more than 10 μm showed no crack even when heated to 500 ° C. after the anodic oxidation treatment and the surface was visually observed.

However, as-cast materials of Alloy Nos. 1 and 2, 7 μm of anodized film thickness of less than 10 μm among 400 ° C. heating materials of Alloy No. 1, and each of Alloy No. 3 were anodized. When the surface was observed after heating to 500 ° C. after the treatment, many cracks were visually observed. Among the 400 ° C. heating materials of Alloy No. 1, the material having an anodized film thickness of 7 μm satisfies the conditions regarding Si, but the far-infrared radiation characteristics were inferior. The 150 ° C. heating material of alloy numbers 1, 2, and 3 has a slightly darker color tone than the as-cast material when visually observed after anodizing, but as far as observed with an optical microscope, No precipitated Si was observed in the dendrite portion. Then, when this part was observed with an electron microscope, the presence of fine precipitated Si particles of 0.01 to 0.03 μm or 0.01 to 0.02 μm was recognized. Since these fine precipitated Si particles do not work as a far-infrared absorption point even if they are precipitated,
Far-infrared radiation characteristics have not improved.

Example 2 An alloy having a component composition shown in Alloy No. 4 in Table 1 was prepared.
A 400 mm × 1000 mm × 3500 mm ingot for rolling (slab) was DC cast. After chamfering the obtained slab, 4
After being heated to 00 ° C. for 2 hours, hot rolling was performed. After performing hot rolling to a thickness of 4 mm, cold rolling was performed to a thickness of 1 mm, and this was annealed at 350 ° C. for 2 hours, and anodized in the same manner as in Example 1.

Example 1 about the material after the anodizing treatment
The same measurement and structure observation as described above were performed. The results are shown in Table 2.

As shown in Table 2, the case of Example 2 is a rolled plate that has been annealed after slab heating and hot rolling / cold rolling. The conditions of the heat treatment (slab heating or annealing) during the manufacturing process are as follows. By making the heat treatment appropriate, these heat treatments also served as the precipitation treatment, and a proper Si precipitation state could be obtained. Also in this case, the far-infrared radiation characteristics were excellent, and no crack was observed when the surface was visually observed after heating to 500 ° C. after the anodizing treatment.

Example 3 An alloy having a component composition shown in Alloy No. 5 in Table 1 was heated between water-cooled rolls to cast a continuous thin-rolled coil having a thickness of 7 mm and a width of 900 mm. The coil was subsequently cold-rolled to a thickness of 2 mm and heated at 390 ° C. × 2 hours for final annealing.
The obtained material was anodized in the same manner as in Example 1. For each material after the anodizing treatment, measurement and structure observation were performed in the same manner as in Example 1. The results are shown in Table 2.

In the case of the third embodiment, the final annealing after the cold rolling also serves as the precipitation treatment.
A precipitation state was obtained. And 500 ° C after anodizing
After the heating, the surface was visually observed, and no crack was observed. In this case, FIG.
Spectral emissivity curves for wavelengths up to 5 μm are also shown. As is clear from FIG. 3, good spectral emissivity was obtained over the entire wavelength range, and no decrease in the emissivity was observed in the wavelength range of 3 to 7 μm, which is typical of ordinary anodic oxide films.

As can be seen from the above examples, alloys within the component composition range specified in the present invention exhibit excellent far-infrared radiation characteristics only if the above-mentioned Si precipitation conditions are satisfied. It is clear that even when heated to 500 ° C., cracks do not occur in the anodic oxide film, and thus it is clear that the anodic oxide film is effective as a far-infrared radiator at high temperatures up to about 500 ° C. Further, it is clear that a material having excellent far-infrared radiation characteristics can be produced by any production means such as casting, forging, rolling, and extrusion.

[0058]

According to the far-infrared radiator of the present invention, excellent far-infrared radiation characteristics can be obtained, and in particular, radiation characteristics in a wavelength range of 3 to 7 .mu.m, which is considered to be inferior to a conventional aluminum anodic oxide film. It is excellent, and cracks due to thermal strain do not occur in the anodic oxide film up to a high temperature of about 500 ° C., so that the heat resistance is good and 500 ° C.
Effective as a far infrared radiator at high temperatures up to
Further, since excellent far-infrared radiation characteristics are given by appropriate dispersion of the precipitated Si particles in the anodic oxide film, there is no possibility that the far-infrared radiation characteristics deteriorate with time. And the far-infrared radiator of the present invention is cast, forged, rolled,
It can be manufactured by any manufacturing means such as extrusion, so that it is possible to obtain a far-infrared radiator of any shape depending on the application and place of use, and also easily obtain a radiator of a complicated shape. . As described above, the far-infrared radiator of the present invention has various excellent advantages. Therefore, the far-infrared radiator can be used in an extremely wide range, in addition to the advantage of lightness due to the light weight of the base aluminum alloy. Can be put to practical use.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an example of a method for analyzing the amount of metallic Si in an aluminum alloy.

FIG. 2 is a flowchart showing an example of a method for analyzing the amount of Si in all intermetallic compounds in an aluminum alloy.

FIG. 3 is a graph showing a spectral emissivity curve for a material of alloy number 5 in Example 3.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mamoru Matsuo 4-3-1-18 Nihonbashi Muromachi, Chuo-ku, Tokyo Inside Sky Aluminum Co., Ltd. (72) Inventor Masatake Maejima 1-5-1 Kiba, Koto-ku, Tokyo (56) References JP-A-54-13028 (JP, A) JP-A-1-180937 (JP, A) JP-A-51-99610 (JP, A)

Claims (3)

(57) [Claims] 1. A contained less Si1wt% or more 3 wt%, the alloy group the balance of Al and unavoidable impurities
Material and the total precipitated Si particles on the substrate
That is, the size of the precipitated Si particles in number of 80% or more is
0.05 μm or more and the amount of residual solid solution Si
Depending on the content, the Si content is 1 wt% or more and 1.5 wt%
%, The residual solid solution Si amount (wt%) ≦ Si content (wt%) −
0.5 , and the Si content is 1.5 wt% or more and 3 wt%
If less than 1 , the amount of residual solid solution Si (wt%) ≦ 1 is satisfied, and the surface of the base material has a thickness of 10 μm.
A far-infrared radiator comprising the above black anodic oxide film. 2. The composition contains 1 wt% or more and less than 3 wt% of Si, and contains 0.05 to 1.5 wt% of Fe and 0.05 to 0.05 wt% of Mg.
1.0 wt%, Cu 0.05-1.0 wt%, Mn0.
05-1.0 wt%, Ni 0.05-1.0 wt%, C
r0.05-0.5wt%, V0.05-0.5wt
%, Zr 0.05-0.5 wt%, Ti 0.005-
An alloy containing one or more of 0.2 wt% and the balance consisting of Al and unavoidable impurities is used as the base material.
Of the total precipitated Si particles on the substrate
The size of 80% or more of precipitated Si particles is 0.05 μ
m or more and the amount of residual solid solution Si depends on the Si content.
If the Si content is 1 wt% or more and less than 1.5 wt%,
If the residual solid solution Si content (wt%) ≤ Si content (wt%)-
0.5 , and the Si content is 1.5 wt% or more and 3 wt%
If less than 1 , the amount of residual solid solution Si (wt%) ≦ 1 is satisfied, and the surface of the base material has a thickness of 10 μm.
A far-infrared radiator comprising the above black anodic oxide film. 3. It contains not less than 1 wt% of Si and less than 3 wt%, and if necessary, 0.05-1.5 wt% of Fe.
Mg 0.05-1.0 wt%, Cu 0.05-1.0 w
t%, Mn0.05-1.0 wt%, Ni0.05-
1.0 wt%, Cr 0.05-0.5 wt%, V0.0
5 to 0.5 wt%, Zr 0.05 to 0.5 wt%, Ti
An alloy containing one or more of 0.005 to 0.2 wt%, the balance being Al and unavoidable impurities is cast, and if necessary, hot working and / or cold working are performed. To obtain a base material of a predetermined size, and then to perform anodizing treatment to form an anodic oxide film of 10 μm or more on the surface, after the casting, after hot working, or in the middle of cold working or Later, 250-55
By heating to a temperature in the range of 0 ° C.,
80% or more of precipitated Si in total Si particles
When the particle size is 0.05 μm or more and the residual solid solution Si content is 1 wt% or more and less than 1.5 wt% according to the Si content, the residual solid solution Si content (wt%) ≦ Si content (wt%)
0.5, and the Si content is 1.5 wt% or more 3
A method for producing a far-infrared radiator, wherein precipitation is performed so as to satisfy a residual solid solution Si amount (wt%) ≦ 1 when the content is less than wt%.