JPH05255890A - Coating material with excellent far-infrared radiation - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a material that has excellent far-infrared emissivity and can be manufactured easily and inexpensively even in a high temperature environment of over 350 ° C. [Composition] Non-equilibrium Al-Mn alloy phase on the substrate in volume ratio of 20
% Or more, and an Al-Mn alloy layer with an Mn content of 5 to 50% by weight is provided, and a pore diameter is formed on the surface by anodizing treatment.
An Al-Mn oxide film having a thickness of 0.01 to 2.0 μm, a porosity of 10 ³ to 10 ¹² pieces / cm ² , an Mn / Al weight ratio of 0.001 to 2.0, and a film thickness of 0.1 to 100 μm is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Al-Mn-based coating material, and more particularly to an Al-Mn-based coating material having a porous Al-Mn-based oxide film and excellent in far infrared radiation. The Al-Mn-based coating material of the present invention can be used for various heating or drying applications, and not only exerts an effect on energy saving by improving heating / drying efficiency, but is also easy to process and light in weight. Application to new uses is also possible.

[0002]

2. Description of the Related Art Far infrared rays are electromagnetic waves in the wavelength range of 3 to 1000 μm. Far-infrared rays are absorbed by water and organic substances to generate a thermal effect, which is effective for efficient heating and drying. Further, it is said that the action effect of far infrared rays has an action of facilitating the movement of water, in addition to a thermal action.

The latter action is similar to the action of microwaves (wavelengths next to far infrared rays) used in microwave ovens on water molecules. For example, aluminum foil without water does not become warm even if put in a microwave oven, but when an object with water (e.g. food) is put in, the water molecules vibrate and are converted into heat energy. As a result, the temperature rises, the temperature is further transmitted, and the whole becomes warmer.

Far infrared rays do not vibrate water molecules violently like microwaves used in microwave ovens,
It has the function of facilitating the movement of water. Therefore, the evaporation of water is activated even if the temperature is not raised so much, and the heat of evaporation is taken away by vigorous evaporation of water, so that the surface temperature does not rise so much.

In order to actually apply the thermal effect of far infrared rays and the effect of facilitating the movement of water, a material having excellent far infrared radiation is required. An example of such a material is a porous Al-Mn oxide film. Conventional porous Al
-Mn-based oxide film is produced by following the steps of solidification, rolling, and annealing of molten metal-about 2% Mn-about 0.5% Mg-about 0.1% Fe Al-
Anodizing a Mn-based alloy plate by constant current electrolytic treatment in a well-known sulfuric acid solution, the surface of the alloy plate was about 30
It is formed with a film thickness of μm and is excellent in far infrared radiation, so that it is applied to heating and drying.

However, this porous Al-Mn oxide film is
It has the drawback of poor far-infrared emissivity in the high temperature range where the operating environment temperature exceeds 350 ° C. In FIG. 2, the above-mentioned Al
-About 2% Mn-About 0.5% Mg-About 0.1% Fe Al-Mn-based oxide film formed on the surface by electrolytic treatment of Al-Mn-based alloy plate, its environmental temperature and far-infrared radiation of wavelength 15μm The relationship with the rate is shown as the prior art. As can be seen from this figure, the far-infrared emissivity is significantly reduced when the operating environment temperature exceeds 350 ° C.

However, since drying and heating are often performed at 350 ° C. or higher, the use of the conventional Al-Mn oxide film as a far-infrared radiation material is extremely limited. .. Therefore, there has been a demand for a material that does not significantly reduce the far infrared emissivity even at a temperature higher than 350 ° C.

[0008]

DISCLOSURE OF THE INVENTION The object of the present invention is 350
Excellent far-infrared emissivity even in high temperature environments above ℃,
It is an object of the present invention to provide a new material that has long-term durability and can be manufactured easily and inexpensively. The specific object of the present invention is to
The surface is covered with a porous Al-Mn-based oxide film that maintains a far-infrared emissivity of 0.9 or higher even in a high-temperature environment of 350 ° C or higher, and it can be easily and inexpensively manufactured and has excellent long-term durability.
An object is to provide an Mn-based coating material.

[0009]

The above object can be achieved by the present invention having the following constitution. Here, the present invention has a porous Al-Mn oxide film having an average pore diameter of 0.01 to 2.0 μm and a porosity of 10 ³ to 10 ¹² particles / cm ² as an outermost layer on at least a part of the surface of the substrate. , The Mn / Al weight ratio of this oxide film is 0.001
.About.2.0 and a film thickness of 0.1 to 100 .mu.m, which is an Al-Mn coating material excellent in far infrared radiation.

The above porous Al-Mn-based oxide film may be present directly on the surface of the base material, or an Al-Mn-based alloy layer having an Mn content of 5 to 50% by weight may be formed as a lower layer on the surface of the base material. The porous Al-Mn-based oxide film may be present as an upper layer. In the latter case, the lower Al-Mn alloy layer is a non-equilibrium Al-
It is preferable to contain the Mn-based alloy phase in a volume ratio of 20% or more, and such an Al-Mn-based alloy layer can be easily formed by plating means, for example, electrolytic plating of a molten salt containing aluminum chloride. it can.

The Al-Mn-based coating material of the present invention comprises a non-equilibrium Al-Mn-based alloy phase in a volume ratio of 20% on at least a part of the surface of the substrate.
By forming an Al-Mn-based alloy layer having an Mn content of 5 to 50% by weight, which is contained as described above, and subjecting the alloy layer to electrolytic treatment to oxidize it completely or incompletely, it can be simply and inexpensively produced.

[0012]

The present invention has been completed on the basis of the following findings found as a result of repeated studies by the present inventors.

(1) When the Al-Mn oxide film has a small average pore diameter and a dense porous film having a high pore density (porosity), far-infrared radiation becomes high. However, adjusting the porosity alone does not improve far-infrared radiation at high temperatures above 350 ° C.

(2) Increasing the Mn content in the base material Al-Mn-based alloy to form an Al-Mn-based oxide film formed by electrolytic treatment
When the Mn / Al weight ratio is increased, high temperatures exceeding 350 ° C
Far infrared emissivity at (eg 400-600 ℃) is improved.

(3) However, when the Al--Mn alloy obtained by the melting method is used as the base metal as in the prior art, even if the Mn content in the base alloy is increased, the Mn in the oxide film is increased. Since the / Al weight ratio cannot be increased so much, there is a limit to the improvement of far-infrared emissivity at high temperature.

(4) In contrast, on the surface of a suitable metal substrate
Al-Mn alloy plating is performed, and this plating layer is used as a mother layer,
When an oxide film is formed by electrolytically treating and oxidizing this, the Mn / Al weight ratio in the oxide film can be easily increased.

(5) The Mn / Al weight ratio in the oxide film formed from the Al-Mn alloy plating film can be increased because the proportion of the non-equilibrium Al-Mn alloy phase in the plating film is high. Because.

(6) The Al-Mn alloy plating layer which is the mother layer may be completely anodized by electrolytic treatment to convert the entire layer into an oxide film, but the anodization is not performed completely. When the unoxidized Al-Mn alloy plating layer is left under the oxide film, the corrosion resistance of the base material can be improved due to the excellent corrosion resistance inherent in this alloy plating layer.

1 (a) and 1 (b) schematically show an example of the constitution of the Al--Mn type coating material of the present invention. That is, the Al-Mn of the present invention
The coating material may have a porous Al-Mn oxide film directly on the surface of the base material as shown in FIG. 1 (a), or, as shown in FIG. 1 (b), Al-Mn alloy layer on the substrate
(For example, an Al-Mn-based alloy plating layer), and a porous Al-Mn-based oxide film may be provided on the alloy layer. In addition,
When the Al-Mn alloy layer 3 is as thin as 0.05 μm or less, this layer can be ignored and it should be regarded as having a structure consisting essentially of the base material and oxide film shown in FIG. 1 (a). You can

The "Al-Mn coating material" of the present invention is not limited to the illustrated constitutional example. That is, any material may be used as long as it has the above-described Al-Mn-based oxide film as the outermost layer on the surface of the base material, and the presence or absence of the lower layer of the oxide film, the type of the lower layer, and the number of layers are not limited.

The material of the base material is not particularly limited, and a suitable inorganic or organic material may be used depending on the application. The shape of the base material is a plate material, a pipe material, a bar material, a profile material, a molded product, or the like.
It is appropriately selected depending on the application.

Suitable base materials include steel materials, stainless steel materials, various plated steel materials such as zinc or zinc alloy plated steel materials and Al or Al alloy plated steel materials; and various non-ferrous materials such as aluminum, titanium, zirconium, nickel and alloys thereof. A metal material can be mentioned. Furthermore, ceramics, plastics, glass, etc. can be used as the substrate.

When the base material does not have conductivity, if a metallizing process such as electroless plating or vapor deposition plating is performed as a base treatment, a base layer of Al-Mn alloy is formed on the surface of the base material by electrolytic plating. You can Alternatively, the Al—Mn based alloy mother layer may be formed on the surface of the base material by applying vacuum deposition plating by a sputtering method, an ion plating method or the like without performing the base treatment.

The base material is an Al-layer which becomes a mother layer which undergoes anodization.
It may be an Al-Mn alloy having the same composition as the Mn alloy layer.
In this case, depending on the conditions, the Al—Mn-based coating material of the present invention can be manufactured by anodizing the base material itself.

In order to improve the adhesion between the substrate and the Al-Mn-based oxide film or Al-Mn-based alloy layer coated thereon,
The surface of the base material may be subjected to an appropriate undercoating (eg, pre-plating with Ni, Fe, Co, etc.).

According to the present invention, at least a part of the surface of the base material (eg, the outer peripheral surface in the case of a pipe material) has an average pore diameter of 0.01 to 2.0 μm and a porosity of 10 ³ to 10 ¹² pieces / cm 2. ² ,
It is covered with a porous Al-Mn-based oxide film having a Mn / Al weight ratio of 0.001 to 2.0 and a film thickness of 0.1 to 100 μm, and this oxide film constitutes the outermost layer of the coating.

Here, the Mn / Al weight ratio in the oxide film is
The abundance ratio of all Mn elements and all Al elements contained as oxides in the oxide film is expressed by a weight ratio. This weight ratio is measured directly by EPMA or XPS or dissolved by an alkali or the like to prepare an aqueous solution. It can be measured by atomic absorption spectrometry.

Although the rationale that this Al-Mn oxide film can retain excellent far infrared radiation even at high temperature is not yet clear, the mixing ratio of Al oxide and Mn oxide in the film (that is,
If the (Mn / Al weight ratio) is within the appropriate range of 0.001 to 2, the stability of the composite oxide at high temperature increases, and the far infrared rays emitted from the composite oxide of Al and Mn are separated from each other. It may be related to resonance amplification. Therefore, as shown in the present invention in FIG. 2, the far-infrared emissivity is maintained at around 0.9 or more even in a temperature range exceeding 350 ° C., and the far-infrared emissivity at high temperature hardly decreases.

If the Mn / Al weight ratio in the oxide film is less than 0.001, the Mn content is small and the far infrared emissivity at high temperature deteriorates to be lower than 0.9. On the other hand, if the Mn / Al weight ratio exceeds 2.0, the workability of the oxide film deteriorates, making it difficult to process the Al-Mn coating material. The preferred range of Mn / Al weight ratio is 0.01
˜1.5, more preferably 0.01 to 1.0.

The porosity of the above-mentioned porous oxide film, that is, the pore diameter and the porosity, are the main controlling factors of the far-infrared emissivity, and by adjusting it within an appropriate range, excellent far-infrared emissivity can be obtained. Can be secured. The porosity of the outermost layer of the porous oxide film is the controlling factor of the far infrared ray emissivity, the far infrared rays radiated from the pore wall and the bottom of the pore of this film are reflected, absorbed, and diffracted in a myriad of pores. This is considered to be because the amount of far-infrared rays emitted as a whole from the entire outermost oxide film to the outside of the film is controlled by causing complicated interference and the like.

Specifically, as shown in FIGS. 3 and 4, fine pores having an average pore diameter of 0.01 to 2.0 μm have a diameter of 10 ³ to
When existing with a porosity (pore density) of 10 ¹² pieces / cm ² , a high far-infrared emissivity with a far-infrared emissivity of 0.9 or more can be obtained, and when the pore diameter or porosity deviates from this range, Far infrared radiation deteriorates. Preferably, the average pore diameter is 0.05 to 1 μm and the porosity is 10 ⁸ to 10 ¹¹ pieces / cm ^2.
Is.

The pore diameter and porosity of this oxide film are
It can be measured by directly observing the surface of the oxide film with a scanning electron microscope (SEM).

The thickness of the outermost Al-Mn oxide film is 0.1 to
Within the range of 100 μm. If it is less than 0.1 μm, sufficient far infrared radiation cannot be obtained, and if it exceeds 100 μm, the effect is saturated,
It is uneconomical. The thickness of the oxide film is preferably 1 to 100 μm, more preferably 5 to 50 μm.

The Al-Mn oxide film having the above Mn / Al weight ratio and porosity is an Al-containing Mn content of 5 to 50% by weight containing 20% or more by volume of the non-equilibrium Al-Mn alloy phase. It can be formed by oxidizing the -Mn-based alloy layer. That is, the Al-Mn-based oxide film is formed by first forming the Al-Mn-based alloy layer as an oxidation mother layer on the surface of the substrate and then oxidizing the mother layer.

At this time, if the Al-Mn alloy layer, which is the base layer, is completely oxidized, the Al-Mn-based alloy layer on the substrate as shown in FIG.
An Al-Mn-based coating material directly coated with the oxide coating is obtained. However, in reality, it is difficult to completely oxidize the mother layer, and it is inevitable that a trace amount of Al-Mn alloy remains. When the remaining Al-Mn alloy layer has a thickness of 0.05 μm or less, it can be considered that the mother layer is completely oxidized. On the other hand, if the oxidation of the alloy layer is incomplete and only the surface layer of the alloy layer becomes an oxide film, and the Al-Mn alloy layer in the lower part remains with a thickness of more than 0.05 μm, the As shown in b), the lower layer on the substrate
Al having an Al-Mn alloy layer and an upper Al-Mn oxide film
-Mn-based coating material is obtained.

In a severe environment where the environment of use is exposed to a hot and humid atmosphere in the presence of salt water, an Al-Mn-based oxide film is formed under the Al-Mn-based oxide film as shown in FIG. 1 (b). It is preferable to use a coating material having an alloy layer. Lower layer Al
This is because the -Mn alloy layer has excellent corrosion resistance, so that the base material can be effectively protected even in a harsh environment, and the product life can be extended.

When the Mn content of the Al-Mn alloy layer of the base layer is less than 5% by weight or more than 50% by weight, Mn /
When it becomes difficult to obtain an oxide film having an Al weight ratio of 0.001 to 2.0, and at the same time, when a part of the mother layer remains to form an underlying Al-Mn-based alloy layer, the resulting coating material has poor corrosion resistance.
When the Mn content of the lower Al-Mn-based alloy layer is in the range of 20 to 40% by weight, the workability is good, so that the mother layer (hence,
The lower layer) preferably has a Mn content of 20 to 40% by weight.

In this Al-Mn alloy layer, other than Al and Mn, 1
It may contain one or more additional alloying elements. Such additional alloying elements include Cu, Ag, Fe, Co,
Ni, Mg, Ca, Sr, Ba, Zn, Cd, In, Tl, Si, Ge, Sn, P
b, As, Sb, Bi, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo,
There are W and Re.

The non-equilibrium Al-Mn-based alloy phase in the Al-Mn-based alloy layer means a crystal phase that is an equilibrium phase [for example, Al ₆ Mn, Al ₃ Mn,
fcc-Al (face-centered cubic Al, etc.), and specifically includes quasi-crystalline and amorphous Al-Mn alloy phases. In the present invention, it is preferable that the Al—Mn alloy layer serving as the base layer and the lower layer of the oxide film contains the non-equilibrium Al—Mn alloy phase in a volume ratio of 20% or more. Thus non-equilibrium
When the Al-Mn-based alloy layer containing a large amount of Al-Mn-based alloy phase is used as the base layer for the oxidation treatment, the Mn / Al weight ratio in the obtained oxide film is increased and the far infrared radiation at high temperature is improved.

Each phase existing in the Al-Mn type alloy layer can be easily identified by observing the alloy layer with a transmission electron microscope (TEM). Therefore, nonequilibrium in the alloy phase
The volume fraction of the Al-Mn alloy phase can be directly measured by TEM observation, but the volume fraction of each equilibrium phase (Al ₆ Mn, Al ₃ Mn, fcc-Al) obtained by measurement by TEM observation, X-ray scattering intensity (integrated intensity of diffraction peak) measured by X-ray diffraction method is
Since there is a linear correlation as shown in FIG. 6, the volume ratio of the equilibrium phase can be relatively easily obtained by the X-ray diffraction method using this as a calibration curve. By subtracting the total volume ratio of each equilibrium layer thus obtained from 100%, the volume ratio of the remaining non-equilibrium phase can be obtained.

It is generally known that the plating film is thermally non-equilibrium as it is (without heat treatment), and the proportion of the non-equilibrium phase is very high. Therefore, the Al-Mn alloy layer containing the non-equilibrium Al-Mn alloy phase in a volume ratio of 20% or more is formed by a known Al-Mn alloy electrolytic plating method such as molten salt electrolytic plating and non-aqueous solvent electrolytic plating. It can be easily formed. The formation of such a thermally non-equilibrium Al-Mn alloy layer can be performed by a dry plating method such as a sputtering method or an ion plating method in addition to the electrolytic plating, and further, a melt quenching method, an ion beam method. The mixing method or the mechanical alloying method of fine powder can be used, and thus these methods may be adopted.

However, the simplest and cheapest method is currently the molten salt electrolytic plating method using a chloride molten salt bath containing aluminum chloride. An example of a suitable molten salt bath is AlCl _3-
Examples include KCl-NaCl-MnCl ₂ system and AlCl ₃ -ethyl methyl imidazolium chloride (EMIC) -MnCl ₂ system. In other film forming methods, a non-aqueous system or a high vacuum system is used, so that the apparatus cost is high, or the film forming rate is low and the productivity is low, so that the manufacturing cost is high.

When the volume ratio of the non-equilibrium Al-Mn phase in the Al-Mn alloy layer of the base layer is less than 20%, it is difficult to form an oxide film having a high Mn / Al ratio by the oxidation treatment. result,
The obtained Al-Mn-based coating material has a low far-infrared radiation property at high temperatures. Since the Al-Mn alloy material obtained by the melting method is generally in a thermal equilibrium state, the volume ratio of the non-equilibrium Al-Mn alloy phase is usually 20% or less even on the surface. Therefore, even when the base material is an Al-Mn-based alloy obtained by the melting method, the surface of the Al-Mn-based alloy layer containing the non-equilibrium alloy phase in a volume ratio of 20% or more by the plating or other method as described above. To be formed separately. Alternatively, it is possible to increase the volume ratio of the non-equilibrium Al—Mn alloy phase on the surface of the base material to 20% or more by subjecting the base material to a non-equilibrium treatment such as an argon sputtering method.

As described above, the cause of the far-infrared emissivity of the Al-Mn-based coating material of the prior art being deteriorated in the high temperature region exceeding 350 ° C. is that the surface of the base material of the Al-Mn-based alloy obtained by the melting method is used. It is considered that this is because the non-equilibrium Al-Mn alloy phase is less in proportion and the Mn / Al weight ratio in the oxide film formed on the surface by the oxidation treatment of the base material is low.

As described above, when the proportion of the non-equilibrium Al—Mn alloy phase in the Al—Mn alloy layer that is the oxidation mother layer is small (in other words, the proportion of the equilibrium phase is large), the oxide film formed is Mn
The reason why the / Al weight ratio decreases is considered as follows.

For example, an Al--Mn alloy in a substantially thermal equilibrium state obtained by the melting method has a two-phase mixed state in which an Al ₆ Mn crystal phase is dispersed in an Al phase in which Mn is dissolved. To take. However, since the Al ₆ Mn crystal phase is more inert to anodic oxidation than the Al phase, it is less susceptible to oxidation during the electrolytic treatment, and the Al ₆ Mn crystal phase remains finely dispersed in the oxide film as it is.
Therefore, even if the Mn content in the base alloy is increased, Al ₆ Mn
It only increases the amount of crystalline phase and does not lead to an increase in the Mn / Al weight ratio in the oxide film.

Further, since a large amount of the Al ₆ Mn crystal phase remains without being oxidized, the porous structure of the porous oxide film formed by the electrolytic treatment becomes inhomogeneous, and the Al ₆ Mn crystal phase is distant. Since it does not contribute to the improvement of the infrared radiation effect, the far infrared radiation emissivity at a temperature of 350 ° C or lower does not increase.

On the other hand, like the Al-Mn alloy plating film,
The thermally nonequilibrium Al-Mn-based alloy layer consisting of quasicrystals or amorphous Al-Mn system alloy phase containing no or very little crystalline phase, Al ₆ Mn crystalline phase precipitation is suppressed, the Mn Most of the metal Mn becomes a solid solution in the mother layer very uniformly, and this Mn easily undergoes anodization at the same level as Al, so Mn / Mn in the oxide film formed after electrolytic treatment
Higher Al weight ratio.

Further, since the Al ₆ Mn crystal phase is small, the resulting oxide film has a small average pore diameter, a high porosity, and a dense porous structure. Therefore, far infrared rays at a temperature of 350 ° C. or less are used. Radioactivity is also high. Therefore, it is possible to obtain an Al-Mn-based oxide film having a high far-infrared radiation property and capable of retaining the high far-infrared radiation property even at a high temperature.

The thickness of the Al-Mn-based alloy layer serving as the base layer is not particularly limited, and is determined by the thickness of the oxide film to be formed and the thickness of the Al-Mn-based alloy layer to be left as a lower layer if necessary. Good. However, when this alloy layer is formed by electroplating, if the film thickness exceeds 100 μm, the surface roughness of the plating film increases and it becomes dendrite-like or powder-like. Is preferably 100 μm or less. Even when the Al-Mn alloy layer is formed by another method, a thick film having a thickness of 100 μm or more leads to an increase in cost, so that the thickness is preferably 100 μm or less.

The formation of the Al-Mn-based oxide film by the oxidation of the Al-Mn-based alloy layer can be carried out by any known oxidation treatment as long as the oxide film having the above Mn / Al weight ratio and porosity is formed. It can also be done by. For example, chemical oxidation treatment using an appropriate oxidizing agent (eg, high temperature steam, alkali, chromic acid) is also possible, but considering economic efficiency, electrochemical oxidation, that is, anodization by electrolytic treatment Al
It is preferable to form a -Mn oxide film.

In order to control the Mn / Al ratio in the oxide film within a predetermined range, the chemical oxidation treatment is carried out by Mn in the Al-Mn alloy base layer.
It is better to change the content. In the case of electrolytic treatment, the Mn / Al ratio in the oxide film can be controlled within a predetermined range by adjusting the current frequency on the anode side between 1 and 1000 Hz. Also, to adjust the surface pore diameter and porosity to the proper range, the duty cycle of the current on the anode side should be adjusted.
Adjust the (duty cycle) in the range of 20-80%. The film thickness of the oxide film can be adjusted by the time of the oxidation treatment. In order to electrochemically oxidize an Al-Mn-based alloy layer having a high Mn content as in the present invention, a current reversal method of occasionally reversing the polarity is used.
The electrolytic treatment by (Periodically Reverse Current) is most suitable. To prepare an electrolytic solution used for electrolytic treatment, sulfuric acid,
Various known electrolytes used for electrolytic oxidation treatment of Al or Al alloys such as oxalic acid, chromic acid, phosphoric acid, aromatic sulfonic acid, sodium phosphate, sodium fluoride and the like can be used.

[0053]

Example As the base material, an aluminum plate, an aluminum alloy plate, a titanium plate, a titanium alloy plate, a stainless steel plate, an alloyed hot dip galvanized steel plate, a hot dip aluminum alloy plated steel plate, and a vapor deposited aluminum plated steel plate were used.
All the metal materials of the base material were manufactured by the melting method. Al-Mn alloy plating was applied to both surfaces of these base materials by either of the following methods to form an Al-Mn alloy plating layer which was a mother layer for forming an oxide film.

Formation of Al-Mn System Alloy Plating Layer by Molten Salt Electrolysis Method (Test Nos. 4 to 26) (a) Using an AlCl ₃ -KCl-NaCl-MnCl ₂ system molten salt bath,
The temperature was maintained between 100 and 280 ° C, and constant current electrolysis with a current density of 50 A / dm ² was performed. The film thickness is adjusted by changing the energization time,
The Mn content in the plating film was adjusted by the amount of MnCl ₂ added to the bath.

(B) AlCl ₃ -EMIC-MnCl ₂ as another molten salt bath
A constant temperature electrolysis with a current density of 20 A / dm ² was performed by using a molten salt bath of the system and keeping the bath temperature at 10 to 80 ° C. The film thickness and the Mn content in the plating film were adjusted in the same manner as above. It was confirmed that the Al-Mn-based alloy plating layer obtained by electrolysis in this molten salt bath was substantially the same as that obtained by electrolysis in the molten salt bath of (a) above. The plated material obtained by the method (a) was used for the next electrolytic treatment.

Formation of Al-Mn Alloy Plating Layer by Sputtering Method (Test No. 27 to 31) Al-Mn Alloy Plate (5 to 50% by Weight Mn) Produced by Melting Method
Was used as a target material, and a sputter film was formed on the surface of the base material at an output of 150 W in a vacuum container having a vacuum degree of 10 ⁻⁶ to 10 ⁻⁷ torr. The thickness of the Al-Mn alloy plated layer was controlled by adjusting the sputtering time. Generated plating layer
The Mn content was adjusted by changing the Mn content in the target material.

The Mn content of the Al-Mn alloy plating layer thus formed on the substrate was measured by an atomic absorption method by film dissolution.
The volume fraction of non-equilibrium Al-Mn alloy phase was determined by TEM.

This Al-Mn alloy plating base material was then subjected to electrolytic treatment to convert at least the surface layer portion of the surface Al-Mn alloy plating layer into an oxide film by anodic oxidation. The electrolytic solution used for the electrolytic treatment is an aqueous solution containing 5 to 20 g / l of phosphoric acid and 10 to 30 g / l of ammonium dichromate (pH 3 to 5).
Met. In this electrolyte, the plating base material is 10 to 100 V, 10
Electrolytic treatment was performed at -100 Hz to anodize the Al-Mn alloy plating layer on the surface. The electrolytic treatment was carried out using the current reversal method using Al-Mn.
The pore diameter and porosity were adjusted by appropriately reversing the polarities of the base alloy-plated substrate and the counter electrode (carbon) and adjusting the duty cycle of the current on the anode side within the range of 20 to 80%.

The thickness of the outermost Al-Mn-based oxide film formed in this way and the remaining Al-Mn-based alloy plating layer as well as the average pore diameter and porosity of the oxide film were
It was measured by direct observation of the surface coating by SEM. The Mn / Al weight ratio in the oxide film was measured by XPS.

The above measurement results are summarized in Table 1 together with the type of the substrate. The lower Al-Mn alloy layer is 0.05
A very thin film having a thickness of less than μm corresponds to that shown in FIG. 1 (a), and substantially all of the Al-Mn alloy layer is an oxide film. The far-infrared radiation characteristics of the outermost Al-Mn-based oxide film of the Al-Mn-based coating material produced as described above were evaluated in the following manner. The results are also summarized in Table 1.

Measurement of far-infrared emissivity IR-810 manufactured by JASCO Corporation while maintaining the test material at 500 ° C
Type infrared spectrophotometer. The emissivity was measured in the wavelength range of 4 to 30 μm and evaluated by the average value of the emissivity for each wavelength. An emissivity of 0.9 or higher was passed.

Test of Wood Drying Performance A test material was attached to a heating plate of a dryer, and 10 pieces of sea lion pine wood (35 mm thickness, 100 mm width, 2000 mm length) were dried at 60 to 70 ° C. to obtain a wood moisture content. We measured the number of days that the wood fell from 45% to 15% and inspected the wood for cracks and warpage after drying.

Tasting evaluation test of cooked rice Using an Al-Mn coating formed on the inner surface of an aluminum pot in the same manner as in the example, and using a pot without this coating, the same results were obtained. Standard rice was cooked under the conditions, and 50 people sampled and compared. 45 people answered that it is better to cook rice in a pot with the oxide film of the present invention.
The number of people was ◯, 35 or more was △, and 25 or less was X.

Measurement of Far-Infrared Emissivity After Corrosion Test Considering the case of use in a severe corrosive environment, the far-infrared emissivity after corrosion test was measured in the same manner as. As a corrosion test, salt spray (5% saline, 35 ℃) → wet (40 ℃, RH75
%) → indoor corrosion → dry (50 ℃, RH20%) complex corrosion test
(Each treatment is 1 hour, 1 cycle is 4 hours), and 200 cycles were carried out. When the difference between the far-infrared emissivity after this test and the far-infrared emissivity before corrosion was within 5%, ◯ was evaluated, 5-10% was evaluated as Δ, and 10% or more was evaluated as x.

[0065]

[Table 1]

FIGS. 3 to 5 show the results of the above example as the pore diameter,
It is a graph which shows collectively about porosity and Mn / Al weight ratio. Figures 3 and 4 show the emissivity with respect to changes in pore diameter and porosity, respectively. When the pore diameter is 0.01 to 2.0 µm and the porosity is 10 ³ to 10 ¹² particles / cm ² , the emissivity is 0.9 or more. I understand. Figure 5 also shows the change in emissivity with respect to the Mn / Al weight ratio in the oxide film. The Mn / Al ratio 0.001 to 2.
It can be seen that the emissivity is 0.9 or more when 0. Further, the emissivity of Al-Mn-based coating material of the present invention of 0.9 or more shows good drying performance and heating performance in both Todo pine drying test and rice cooking test, and is useful as a far-infrared radiation material. It was proven.

[0067]

According to the present invention, it is possible to obtain an Al-Mn-based coating material which is excellent in far-infrared emissivity even in a high temperature environment of more than 350 ° C. and is useful as a far-infrared emitting material which can be produced easily and inexpensively.

[Brief description of drawings]

FIG. 1 is a structural conceptual diagram of an aspect of the present invention.

FIG. 2 is a graph showing a relationship between a use environment temperature and a far infrared ray emissivity in the related art and the present invention.

FIG. 3 is a graph showing the results of the examples of the present invention.

FIG. 4 is a graph showing the results of the examples of the present invention.

FIG. 5 is a graph showing the results of the examples of the present invention.

FIG. 6 is a graph showing the relationship between the scattered X-ray diffraction peak integrated intensity of the Al—Mn alloy plating layer and the volume fraction of each crystal phase.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hirohisa Seto 4-53-3 Kitahama, Chuo-ku, Osaka City Sumitomo Metal Industries, Ltd. (72) Kunihiro Fukui 4-53-3 Kitahama, Chuo-ku, Osaka Sumitomo Metal Industries, Ltd. (72) Inventor Shinya Hikino 4-53, Kitahama, Chuo-ku, Osaka City Sumitomo Metal Industries, Ltd.

Claims (4)

[Claims] 1. A porous Al—Mn oxide film having an average pore diameter of 0.01 to 2.0 μm and a porosity of 10 ³ to 10 ¹² pores / cm ² is provided as an outermost layer on at least a part of the surface of the substrate. Mn / Al weight ratio of oxide film is 0.001 to 2.0, film thickness is 0.1 to 100 μm
Al-, which has excellent far-infrared radiation, characterized by
Mn-based coating material. 2. An Mn content of 5 as a lower layer of the oxide film
The method according to claim 1, further comprising an Al-Mn alloy layer of about 50% by weight.
The Al-Mn-based coating material described. 3. The Al according to claim 2, wherein the Al—Mn alloy layer contains a nonequilibrium Al—Mn alloy phase in a volume ratio of 20% or more.
-Mn-based coating material. 4. The Al—Mn according to claim 3, wherein the Al—Mn alloy layer is formed by molten salt electrolytic plating.
System coating material.