JP2006242390A - Heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger using a photocatalyst capable of stably exhibiting an anti-fouling property and corrosion resistance over a long period irrespective of a refrigerant. <P>SOLUTION: A multifunctional layer composed of titanium oxide or titanium alloy oxide doped with carbon, is arranged in at least a part of an inner surface of at least a small diameter tube 103a for circulating seawater serving as the refrigerant therethrough. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat exchanger, and is particularly useful as a heat exchanger or the like used for a condenser of a power plant.

  Heat exchangers are used in many applications, and one of them is a power plant condenser. In such a condenser, seawater is usually used as the refrigerant. Therefore, the inner peripheral surface of the conduit through which the refrigerant flows is easily soiled and foreign matter is also likely to adhere. Therefore, periodic cleaning is required, but at present, such maintenance requires a great deal of cost. That is, the running cost is increased.

  On the other hand, miscellaneous germs are mixed in the flush water used for toilets in large and medium-sized buildings and toilets in public facilities (flushing) during flushing (water between rainwater and other sewage). In many cases, when the temperature is high, bad odors and odors may be generated and sometimes discolored. Therefore, it is important to make the temperature as low as possible. A device for cooling the air has also been developed.

  However, in such an apparatus, the surface of the heat exchanger is immediately soiled due to various germs in the water, or the apparatus itself is severely deteriorated.

  In addition, the bioreactor heat exchanger may be held not only at a low temperature but also in a certain temperature range. In this case, since viable bacteria are activated actively, the surface of the heat exchanger used and the entire apparatus are immediately contaminated.

  Furthermore, since the hot spring heat exchanger using hot spring heat is used in an environment where the concentration of a toxic gas such as hydrogen sulfide is high, it is particularly necessary to have excellent corrosion resistance.

On the other hand, photocatalysts are attracting attention as those that exhibit extremely good antifouling properties and corrosion resistance. For example, 1) a photocatalytic heat exchanger in which a fin surface made of a heat conductive metal material is coated with a photocatalyst, an inorganic antibacterial agent and an organic binder, and 2) a fin surface made of a heat conductive metal material is oxidized. Photocatalyst heat exchanger with a structure coated with an organic binder and photocatalyst particles coated with an inert ceramic film as a photocatalyst having fine pores on the surface of titanium particles, 3)
In a heat exchanger in which hydrophilic fins are formed by arranging a large number of aluminum thin plates in parallel with a predetermined gap, a hydrophilic binder containing a photocatalyst is applied to the entire surface of the aluminum thin plate and the photocatalyst is applied to the binder. A photocatalyst heat exchanger or the like is proposed in which hydrophilic fins are formed that increase the hydrophilicity by irradiating the photocatalyst with ultraviolet light.

  However, the photocatalyst products according to the prior art have poor durability and are difficult to use for a long period of time due to peeling of the photocatalyst layer, etc., and it is necessary to irradiate with sufficient ultraviolet light to exert the photocatalytic function It had a big problem in practical use. That is, the advent of a heat exchanger excellent in antifouling properties and durability is awaited.

Japanese Patent Laid-Open No. 2002-071298 Japanese Patent Application Laid-Open No. 2002-071297 Japanese Patent Laid-Open No. 2001-033190

  An object of the present invention is to provide a heat exchanger using a photocatalyst that can stably exhibit antifouling property, corrosion resistance, etc. over a long period of time regardless of the refrigerant.

  The first aspect of the present invention that achieves the above object is characterized in that a multifunctional layer made of carbon-doped titanium oxide or titanium alloy oxide is provided on at least a part of the inner surface of a conduit through which refrigerant flows. And

  According to a second aspect of the present invention, in the first aspect, the multi-functional layer is integrally formed on the surface of the substrate, and the carbon is doped in a Ti-C bond state. At least the surface layer of the substrate is titanium, a titanium alloy, a titanium alloy oxide, or titanium oxide.

  According to a third aspect of the present invention, in the second aspect, the base body includes a surface portion forming layer made of titanium, titanium alloy, titanium alloy oxide, or titanium oxide, and a core material. It is a material other than an alloy, titanium oxide, and titanium alloy oxide.

  According to a fourth aspect of the present invention, in the second or third aspect, the multi-functional layer has a Vickers hardness of 300 or more.

  According to a fifth aspect of the present invention, in the second or third aspect, the multi-functional layer has a Vickers hardness of 1000 or more.

  The sixth aspect of the present invention has a large number of protrusions made of titanium oxide or titanium alloy oxide on at least a part of the surface of the base made of titanium, titanium alloy, titanium alloy oxide or titanium oxide at least on the surface side. And a multi-functional layer in which the protrusion is carbon-doped is provided at least on the inner surface of the conduit through which the refrigerant flows.

  According to a seventh aspect of the present invention, in the sixth aspect, the multi-functional layer is characterized in that fine columns are erected and the inside of the fine is carbon-doped.

  The eighth aspect of the present invention is characterized in that, in the sixth or seventh aspect, doped carbon is contained in a Ti-C bond state.

  According to a ninth aspect of the present invention, in any one of the sixth to eighth aspects, the substrate includes a surface portion forming layer made of titanium, a titanium alloy, a titanium alloy oxide, or titanium oxide, and a core material. The core material is a material other than titanium, titanium alloy, titanium oxide, and titanium alloy oxide.

  According to a tenth aspect of the present invention, in the heat exchanger according to any one of the first to ninth aspects, a light source that irradiates visible light or ultraviolet light to the multifunctional layer is provided inside the conduit. It is characterized by doing.

  First, a multifunctional material having a multifunctional layer that can be used in the present invention will be described.

  The first multifunctional material used in the present invention has a surface layer made of titanium, a titanium alloy, a titanium alloy oxide, or a titanium oxide at a high temperature using a combustion flame of a gas mainly composed of hydrocarbon. It is obtained by heat treatment, carbon is doped in a Ti-C bond state, and has excellent durability (high hardness, scratch resistance, abrasion resistance, chemical resistance, heat resistance) and It has a multifunctional layer composed of a carbon-doped titanium oxide layer that functions as a visible light responsive photocatalyst as a surface layer.

  That is, the first multifunctional material used in the present invention has at least a surface layer composed of a carbon-doped titanium oxide layer and is doped with the carbon in a Ti-C bond state, and has excellent durability and a visible light response type. It has a multi-functional layer that functions as a photocatalyst.

  The first multifunctional material used in the present invention uses, for example, a gas combustion flame mainly composed of hydrocarbons on the surface of a substrate whose surface layer is made of titanium, titanium alloy, titanium alloy oxide or titanium oxide. And can be produced by heat treatment at a high temperature. In other words, this results in a structural member in which a carbon-doped titanium oxide layer is integrally formed on the surface of titanium, titanium alloy, titanium alloy oxide or titanium oxide, which is the surface layer of the substrate, and the surface is excellent in durability and visible. It becomes the 1st multifunctional material which functions as a photoresponsive photocatalyst. The substrate whose at least surface layer is made of titanium, titanium alloy, titanium alloy oxide or titanium oxide may be composed of titanium, titanium alloy, titanium alloy oxide or titanium oxide as a whole, or It is comprised by the surface part formation layer and core material which consist of titanium, a titanium alloy, a titanium alloy oxide, or a titanium oxide, and those materials may differ. That is, in this case, a structural member in which a carbon-doped titanium oxide layer is integrally formed on the surface of titanium, titanium alloy, titanium alloy oxide, or titanium oxide, which is the surface layer of the composite material substrate, is formed on the surface. However, it is good also as a 1st multifunctional material which is excellent in durability and functions as a visible light responsive photocatalyst.

  If at least the surface layer is made of titanium, titanium alloy, titanium alloy oxide or titanium oxide and the surface portion forming layer and the core material are different from each other, the thickness of the surface portion forming layer The thickness may be the same as the thickness of the carbon-doped titanium oxide layer to be formed (that is, the entire surface portion forming layer becomes a carbon-doped titanium oxide layer) or may be thick (that is, the thickness of the surface portion forming layer). Part of the direction becomes a carbon-doped titanium oxide layer, and part remains as it is). The material of the core is not particularly limited as long as it does not burn, melt, or deform during the heat treatment in the manufacturing method of the first invention. For example, iron, iron alloy, non-ferrous alloy, ceramics, other ceramics, high temperature heat resistant glass, etc. can be used as the core material. Examples of the substrate composed of such a thin film-like surface layer and a core material include, for example, a method of sputtering, vapor deposition, thermal spraying, etc., on a surface of the core material made of titanium, titanium alloy, titanium alloy oxide, or titanium oxide. Or a film formed by applying a commercially available titanium oxide sol on the surface of the core material by spray coating, spin coating or dipping.

  Various known titanium alloys can be used as the titanium alloy, and are not particularly limited. For example, Ti-6Al-4V, Ti-6Al-6V-2Sn, Ti-6Al-2Sn-4Zr-6Mo, Ti-10V-2Fe-3Al, Ti-7Al-4Mo, Ti-5Al-2.5Sn, Ti- 6Al-5Zr-0.5Mo-0.2Si, Ti-5.5Al-3.5Sn-3Zr-0.3Mo-1Nb-0.3Si, Ti-8Al-1Mo-1V, Ti-6Al-2Sn-4Zr- 2Mo, Ti-5Al-2Sn-2Zr-4Mo-4Cr, Ti-11.5Mo-6Zr-4.5Sn, Ti-15V-3Cr-3Al-3Sn, Ti-15Mo-5Zr-3Al, Ti-15Mo-5Zr, Ti-13V-11Cr-3Al or the like can be used.

  In the production of the first multifunctional material, a gas combustion flame mainly composed of hydrocarbons, particularly acetylene can be used, and it is particularly desirable to use a reducing flame. When using a fuel with a low hydrocarbon content, the carbon doping amount is insufficient or none, resulting in insufficient hardness and insufficient photocatalytic activity under visible light. It becomes. In the production of the first multifunctional material used in the present invention, the hydrocarbon-based gas means a gas containing at least 50% by volume of hydrocarbon, for example, containing at least 50% by volume of acetylene, As appropriate, it means a gas mixed with air, hydrogen, oxygen or the like. In the production of the first multifunctional material used in the present invention, the gas containing hydrocarbon as a main component preferably contains 50% by volume or more of acetylene, and the hydrocarbon is most preferably 100% of acetylene. When unsaturated hydrocarbons, especially acetylene having a triple bond, are used, in the process of combustion, especially in the reducing flame part, the unsaturated bond part decomposes to form an intermediate radical substance. It is considered that carbon doping is likely to occur because of its high activity.

  In the production of the first multifunctional material of the present invention, when the surface layer of the substrate to be heat-treated is titanium or a titanium alloy, oxygen that oxidizes the titanium or titanium alloy is necessary, and air or It needs to contain oxygen.

  In the production of the first multifunctional material used in the present invention, the surface of the substrate whose surface layer is made of titanium, titanium alloy, titanium alloy oxide or titanium oxide is used with a gas combustion flame mainly composed of hydrocarbons. In this case, the surface of such a substrate is mainly composed of hydrocarbons even if it is heated at a high temperature by directly applying a combustion flame of a gas mainly composed of hydrocarbons to the surface of the substrate. Heat treatment may be performed at a high temperature in a combustion gas atmosphere of a component gas, and this heat treatment may be performed in a furnace, for example. When heat treatment is performed at a high temperature by directly applying a combustion flame, the above-described fuel gas may be burned in a furnace and the combustion flame may be applied to the surface of the substrate. When heat treatment is performed in a combustion gas atmosphere at a high temperature, the above fuel gas is burned in a furnace and the high-temperature combustion gas atmosphere is used. In addition, when at least the surface layer is made of titanium, titanium alloy, titanium alloy oxide or titanium oxide in a powder form, such powder is introduced into the flame and heated by being retained in the flame for a predetermined time. By treating or maintaining such powder in a fluidized hot combustion gas in a fluidized bed for a predetermined time, the entire particle is carbon doped titanium oxide doped with carbon in Ti-C bonds. Alternatively, a powder having a carbon-doped titanium oxide layer in which carbon is doped in a Ti—C bond state can be obtained.

  As for the heat treatment, the surface temperature of the substrate becomes 900 to 1500 ° C., preferably 1000 to 1200 ° C., and a carbon-doped titanium oxide layer doped with carbon in a Ti—C bond state is formed as the surface layer of the substrate. It is necessary to heat-treat. In the case of the heat treatment in which the surface temperature of the substrate ends below 900 ° C., the durability of the substrate having the carbon-doped titanium oxide layer obtained is insufficient and the photocatalytic activity under visible light is also insufficient. On the other hand, in the case of heat treatment in which the surface temperature of the substrate exceeds 1500 ° C., the ultrathin film peels off from the surface of the substrate during cooling after the heat treatment, and the durability (high hardness, (Scratch resistance, abrasion resistance, chemical resistance, heat resistance) effect cannot be obtained. Moreover, even in the case of the heat treatment in which the surface temperature of the substrate is in the range of 900 to 1500 ° C., if the heat treatment time becomes long, the ultrathin film is peeled off from the surface of the substrate during cooling after the heat treatment, Since the effect of durability (high hardness, scratch resistance, abrasion resistance, chemical resistance, heat resistance), which is an important function of the first multifunctional material, cannot be obtained, its substrate during cooling after heat treatment It is necessary that the time is such that peeling does not occur on the surface portion. That is, the heat treatment time is sufficient to make the surface layer a carbon-doped titanium oxide layer doped with carbon in a Ti-C bond state. It must be a time that does not result in peeling of the thin film. This heat treatment time is correlated with the heating temperature, but is preferably about 400 seconds or less.

  In the production of the first multifunctional material used in the present invention, carbon containing 0.3 to 15 at%, preferably 1 to 10 at% of carbon is Ti—C bond by adjusting the heating temperature and heat treatment time. A carbon-doped titanium oxide layer doped in a state can be obtained relatively easily. When the carbon doping amount is small, the carbon-doped titanium oxide layer is transparent, and as the carbon doping amount increases, the carbon-doped titanium oxide layer becomes translucent and opaque. Therefore, by forming a transparent carbon-doped titanium oxide layer on a transparent plate-shaped core material, it has excellent durability (high hardness, scratch resistance, abrasion resistance, chemical resistance, heat resistance) and visible light response A transparent plate that functions as a mold photocatalyst can be obtained, and durability (high hardness, scratch resistance, abrasion resistance) can be obtained by forming a transparent carbon-doped titanium oxide layer on a plate having a colored pattern on the surface. , A decorative plate that is excellent in chemical resistance and heat resistance) and functions as a visible light responsive photocatalyst. In the case where at least the surface layer is made of titanium, titanium alloy, titanium alloy oxide or titanium oxide, and the substrate is composed of the surface portion forming layer and the core material, and the thickness of the surface portion forming layer is 500 nm or less. When heated to the vicinity of the melting point of the surface portion forming layer, a large number of small island-like undulations floating in the sea are generated on the surface and become translucent.

  In the first multifunctional material having a carbon-doped titanium oxide layer doped with carbon in a Ti—C bond state, the thickness of the carbon-doped titanium oxide layer is preferably 10 nm or more, and has high hardness and scratch resistance. In order to achieve the properties and wear resistance, the thickness is more preferably 50 nm or more. When the thickness of the carbon-doped titanium oxide layer is less than 10 nm, the resulting multifunctional material having the carbon-doped titanium oxide layer tends to be insufficient. The upper limit of the thickness of the carbon-doped titanium oxide layer is not particularly limited, although it is necessary to consider the cost and the effect achieved.

  The carbon-doped titanium oxide layer of the first multifunctional material used in the present invention is a conventional chemically modified titanium oxide or a titanium compound Ti—O—X doped with various conventionally proposed atoms or anions X. Unlike titanium oxide containing, the carbon is contained in a relatively large amount, and doped carbon is contained in a Ti-C bond state. As a result, it is considered that mechanical strength such as scratch resistance and abrasion resistance is improved and Vickers hardness is remarkably increased. Moreover, heat resistance is also improved.

  The carbon-doped titanium oxide layer of the first multifunctional material used in the present invention has a Vickers hardness of 300 or more, preferably 500 or more, more preferably 700 or more, and most preferably 1000 or more. A Vickers hardness of 1000 or more is harder than that of hard chrome plating. Therefore, the first multifunctional material of the present invention can be significantly used in various technical fields in which hard chrome plating has been conventionally used.

  The carbon-doped titanium oxide layer, which is a multifunctional layer of the first multifunctional material used in the present invention, responds not only to ultraviolet rays but also to visible light having a wavelength of 400 nm or more, and functions effectively as a photocatalyst. Therefore, the first multifunctional material used in the present invention can be used as a visible light responsive photocatalyst and exhibits a photocatalytic function not only outdoors but also indoors. The carbon-doped titanium oxide layer of the first multifunctional material used in the present invention exhibits super hydrophilicity with a contact angle of 3 ° or less.

  The carbon-doped titanium oxide layer of the first multifunctional material used in the present invention has excellent chemical resistance, and after being immersed in an aqueous solution of 1M sulfuric acid and 1M sodium hydroxide for one week, the film hardness and abrasion resistance When the photocurrent density was measured and compared with the measured value before the treatment, no significant change was observed. Incidentally, with respect to commercially available titanium oxide films, generally, the binder dissolves in acid or alkali depending on the kind thereof, so that the film peels off, and there is almost no acid resistance and alkali resistance.

  Furthermore, the carbon-doped titanium oxide layer of the first multifunctional material used in the present invention can be used as a catalyst that also responds to radiation such as gamma rays. That is, the inventors have previously invented that a thermal spray film such as titanium oxide suppresses stress corrosion cracking, scale adhesion, etc. of the nuclear reactor structural member in response to radiation, but the first used in the present invention. Similarly, when the carbon-doped titanium oxide layer of the multifunctional material 1 is used as such a radiation-responsive catalyst, the potential of the substrate can be lowered to suppress pitting corrosion, overall corrosion, and stress corrosion cracking, There is an effect that scales and dirt can be decomposed by oxidizing power. It is simpler than other radiocatalyst film-forming methods, and is excellent from the viewpoint of durability such as chemical resistance and wear resistance.

  In addition, the second multifunctional material has a specific condition in which a combustion flame of unsaturated hydrocarbon, particularly acetylene, is directly applied to the surface of a substrate having at least a surface layer made of titanium, titanium oxide, titanium alloy or titanium alloy oxide. Or by heating the surface of the substrate in a combustion exhaust gas atmosphere of an unsaturated hydrocarbon, particularly acetylene, under specific conditions, and the surface layer is made of titanium oxide or a titanium alloy oxide. A layer in which fine columns are erected is formed, and the layer in which the fine columns are erected is cut in a direction along the surface layer so that at least a part of the titanium oxide or titanium alloy oxide is formed on the substrate. A member in which a layer in which a fine pillar made of is exposed is exposed, a large number of continuous narrow protrusions made of titanium oxide or titanium alloy oxide on a thin film, and a fine pillar standing on the protrusion But Both of which have a large number of protrusions made of titanium oxide or titanium alloy oxide on at least a part of the surface, both of which are useful multifunctional materials. Being a fine column that is a projection made of the titanium oxide or titanium alloy oxide, and a continuous narrow projection is carbon-doped, so that the photocatalytic activity is high and functions as a visible light responsive photocatalyst, Furthermore, VOC can be easily adsorbed, has high hardness, and has excellent peel resistance, wear resistance, chemical resistance, and heat resistance.

  That is, the second multifunctional material used in the present invention has a large number of protrusions made of titanium oxide or titanium alloy oxide on at least a part of the surface. A layer in which fine columns made of titanium alloy oxide are forested is exposed, or a large number of continuous narrow projections made of titanium oxide or titanium alloy oxide on a thin film and forested on the projections Fine columns are exposed, and the protrusions, for example, the fine columns and the narrow protrusions are carbon-doped.

  The second multifunctional material used in the present invention is obtained by subjecting the surface of a substrate having at least a surface layer made of titanium, titanium oxide, a titanium alloy or a titanium alloy oxide to a heat treatment with a combustion flame of, for example, an unsaturated hydrocarbon, particularly acetylene. In the surface layer, a layer in which fine columns made of titanium oxide or titanium alloy oxide are erected is formed, and then, for example, thermal stress, shear stress, tensile force is applied, and the tiny columns are erected The layer is cut in a direction along the surface layer, and a layer in which fine columns made of the titanium oxide or the titanium alloy oxide are forested is formed on at least a part of the substrate, usually on a large part of the substrate. By obtaining an exposed member, and a member in which a large number of continuous narrow protrusions made of titanium oxide or titanium alloy oxide on the thin film and fine columns standing on the protrusions are exposed Can be manufactured, ie A multifunctional material Both have a number of projections of at least a portion of titanium oxide or titanium alloy oxide on the surface, both these two is a second multifunctional material used in the present invention.

  The substrate whose at least surface layer is made of titanium, titanium oxide, titanium alloy or titanium alloy oxide, the entire substrate may be composed of titanium, titanium oxide, titanium alloy or titanium alloy oxide, Or you may be comprised by the core part which consists of a surface part formation layer which consists of titanium, a titanium oxide, a titanium alloy, or a titanium alloy oxide, and another material.

  At least the surface layer is made of titanium, titanium oxide, a titanium alloy or a titanium alloy oxide, and the substrate is composed of a surface portion forming layer made of titanium, titanium oxide, a titanium alloy or a titanium alloy oxide and a core material made of other materials. The thickness (amount) of the surface portion forming layer is equal to the amount of the layer in which fine columns made of titanium oxide or titanium alloy oxide are formed ( That is, the entire surface portion forming layer is a layer in which fine columns made of titanium oxide or titanium alloy oxide are erected), or may be thicker (that is, a part of the surface portion forming layer in the thickness direction is A fine column made of titanium oxide or titanium alloy oxide becomes a forested layer, and the rest remains unchanged.) The material of the core material is not particularly limited as long as it does not burn, melt or deform during the heat treatment in the production of the second multifunctional material used in the present invention. For example, iron, iron alloy, non-ferrous alloy, glass, ceramics, or the like can be used as the core material. Examples of the substrate composed of such a thin film surface layer and a core material include, for example, a method of sputtering, vapor deposition, thermal spraying, etc., on a surface of the core material made of titanium, titanium oxide, titanium alloy or titanium alloy oxide. Or a film formed by applying a commercially available titanium oxide sol on the surface of the core material by spray coating, spin coating or dipping. The thickness of this surface layer is preferably 0.5 μm or more, more preferably 4 μm or more.

  Various known titanium alloys can be used as the titanium alloy, and the titanium alloy is not particularly limited and can be the same as the first multifunctional material.

  In the production of the second multifunctional material used in the present invention, for example, it is desirable to use a combustion flame of a gas mainly containing an unsaturated hydrocarbon, particularly acetylene, and particularly to use a reducing flame. In the production of the multifunctional material of the present invention, a gas containing at least 50% by volume of unsaturated hydrocarbon, for example, a gas containing at least 50% by volume of acetylene and appropriately mixed with air, hydrogen, oxygen or the like is used. preferable. In the production of the second multifunctional material used in the present invention, the fuel component is most preferably 100% acetylene. When unsaturated hydrocarbons, especially acetylene having a triple bond, are used, in the process of combustion, especially in the reducing flame part, the unsaturated bond part decomposes to form an intermediate radical substance. Has a strong activity, and carbon doping is likely to occur, and doped carbon is contained in a Ti-C bond state. Thus, when carbon dope arises in a micro pillar, the hardness of a micro pillar will become high, As a result, mechanical strength, such as hardness of a multifunctional material and abrasion resistance, will improve, and heat resistance will also improve.

  In the production of the second multifunctional material used in the present invention, the surface layer is subjected to heat treatment by directly applying a combustion flame to the surface of the substrate made of titanium, titanium oxide, titanium alloy or titanium alloy oxide, or the substrate. The surface is heated in a combustion exhaust gas atmosphere. This heat treatment can be carried out, for example, by a gas burner or in a furnace. When the combustion flame is directly applied and heat treatment is performed at a high temperature, the combustion flame may be applied to the surface of the substrate by a gas burner. When heat treatment is performed in a combustion exhaust gas atmosphere at a high temperature, the above fuel gas may be burned in a furnace and an atmosphere containing the high-temperature combustion exhaust gas may be used.

  For the heat treatment, at least the surface layer is made of titanium, titanium oxide, a titanium alloy or a titanium alloy oxide, and a layer in which fine columns made of titanium oxide or a titanium alloy oxide stand is formed inside the surface layer. For example, applying a thermal stress, a shear stress, or a tensile force to cut the layer in which the fine pillars are erected in a direction along the surface layer, so that at least a part of the titanium oxide or titanium alloy oxide is formed on the substrate. A member in which a layer in which a fine pillar made of is exposed is exposed, a large number of continuous narrow protrusions made of titanium oxide or titanium alloy oxide on a thin film, and a fine pillar standing on the protrusion It is necessary to adjust the heating temperature and the heat treatment time so as to obtain the exposed member. This heat treatment is preferably performed at a temperature of 600 ° C. or higher.

  By performing the heat treatment under such conditions, the height of the layer in which the fine pillars stand is about 1 to 20 μm, and the thickness of the thin film thereon is about 0.1 to 10 μm. Intermediates having an average thickness of about 0.2 to 3 μm are formed. Thereafter, for example, by applying a thermal stress, a shear stress, or a tensile force to cut the layer in which the fine pillars are erected in a direction along the surface layer, at least a part of the titanium oxide or the substrate is formed on the substrate. A member in which a layer with fine columns made of titanium alloy oxide is exposed (that is, all or most of the thin film existing on the layer with fine columns on the substrate is peeled off) However, a part of the thin film existing on the layer where the fine pillars are erected may remain without being peeled) and a large number of continuous narrow widths made of titanium oxide or titanium alloy oxide on the thin film It is possible to obtain a protrusion and a member in which a fine pillar standing on the protrusion is exposed.

  In the case of cutting a layer in which fine columns are erected by applying thermal stress in a direction along the surface layer, for example, either the surface or the back surface of the substrate is cooled or heated to heat the surface of the substrate. A temperature difference is provided between the back surface and the back surface. As this cooling method, for example, either the surface or the back surface of the hot intermediate is brought into contact with a cooling object, such as a stainless steel block, or cold air (room temperature air) is applied to either the surface or the back surface of the hot intermediate. Spray. Even if the hot intermediate is allowed to cool, thermal stress is generated, but the degree is low.

  When shearing stress is applied and the layer in which the fine pillars are erected is cut in a direction along the surface layer, for example, a relatively reverse force is applied to the front and back surfaces of the intermediate by frictional force. In addition, when a layer in which fine columns are erected is cut in a direction along the surface layer by applying a tensile force, for example, the surface and the back surface of the above intermediate body are removed from those surfaces using a vacuum suction disk or the like. Pull in the opposite direction in the vertical direction. When using only a member in which a layer in which fine columns made of titanium oxide or titanium alloy oxide are forested is exposed on at least a part of the substrate, oxidation is performed on the intermediate thin film. A portion corresponding to a member in which a large number of continuous narrow protrusions made of titanium or a titanium alloy oxide and fine columns standing on the protrusions are exposed can be removed by polishing, sputtering, or the like.

  In a member in which a layer with fine columns made of titanium oxide or titanium alloy oxide is exposed on at least a part of the substrate obtained as described above, the layer with fine columns is set Although the height of the layer in which the fine column stands is changed depending on the height position of the fine column cut in the direction along the surface layer, the height of the layer in which the fine column stands is generally 1 to The average thickness of the fine columns is about 0.5 to 3 μm. This member can easily adsorb VOC, has a large surface area, has a high activity as a photocatalyst, and also has a high film hardness, a second multi-layer excellent in peeling resistance, abrasion resistance, chemical resistance, and heat resistance. It is a functional material.

  On the other hand, on the thin film obtained as described above, a large number of continuous narrow protrusions made of titanium oxide or titanium alloy oxide and members with exposed fine columns standing on the protrusions are small. The height of the protrusion on each small piece is about 2 to 12 μm, and the height of the fine column is the height of the fine column obtained by cutting the layer in which the fine column stands in the direction along the surface layer. Although the height varies depending on the position, the height of the layer in which the fine pillars stand is generally about 1 to 5 μm, and the average thickness of the fine pillars is about 0.2 to 0.5 μm. However, a layer in which the fine columns are erected is cut in a direction along the surface layer, and depending on the conditions, there are cases where a large number of continuous narrow protrusions are exposed without the presence of the fine columns. This member can also adsorb VOCs and has a large surface area, so it has high activity as a photocatalyst. Further, this member can be used as it is or after being pulverized, and the pulverized product can easily adsorb VOC and has a large surface area, so it has high activity as a photocatalyst.

  In the second multifunctional material used in the present invention, carbon-doped fine columns made of titanium oxide or titanium alloy oxide, a large number of continuous narrow projections, and fine columns standing on the projections are carbon-doped. Therefore, it responds not only to ultraviolet rays but also visible light having a wavelength of 400 nm or more, works particularly effectively as a photocatalyst, and can be used as a visible light responsive photocatalyst, and exhibits a photocatalytic function not only outdoors but also indoors. .

  The shape of each fine column of the layer in which the fine column made of titanium oxide or titanium alloy oxide constituting the second multifunctional material used in the present invention stands is judged from the micrographs of FIGS. As described above, a prismatic shape, a cylindrical shape, a pyramid shape, a conical shape, an inverted pyramid shape, or an inverted conical shape, etc., which extends straight or perpendicular to the surface of the substrate, is curved or bent There are those that extend, those that branch and extend, and those that are complex. Moreover, as the whole shape, it can show by various expressions, such as a frost column shape, a raising carpet shape, a basket shape, a row column shape, and the column shape assembled with blocks. In addition, the thickness and height of the fine columns, the size of the base (bottom surface), and the like vary depending on heating conditions and the like.

  A number of continuous narrow protrusions made of titanium oxide or titanium alloy oxide and fine columns standing on the protrusions are exposed on the thin film, which is the second multifunctional material used in the present invention. As can be seen from the photomicrograph of FIG. 12, the member can be viewed as having a number of consecutive narrow protrusions appearing outside the walnut shell, pumice. It can be seen that the narrow-width protrusions are bent in the shape of a water bath or a stagnation. In addition, the shape of the fine column standing on the protrusion is the same as the shape of each fine column in the layer where the fine column on the base is standing, but the junction between the fine column and the thin film Therefore, the density of the fine columns standing on the protrusion is generally smaller than the density of the fine columns in the layer where the fine columns on the base are standing.

  The third multifunctional material used in the present invention is provided with a multifunctional layer containing titanium oxide or titanium alloy oxidized powder (hereinafter referred to as carbon-doped titanium oxide powder) doped with carbon by a technique such as coating on the surface of the substrate. It is a thing. The multifunctional layer in this case is formed by a coating agent containing carbon-doped titanium oxide and an inorganic binder. Here, examples of the inorganic binder include alkoxysilanes such as ethyl silicate, partial condensates of alkoxysilanes, and silica sols.

  The carbon-doped titanium oxide powder used for such a third multifunctional material uses a titanium powder as a substrate and, as in the first multifunctional material production method, a gas containing hydrocarbon, particularly acetylene as a main component. It can be formed by heat treatment using a combustion flame or the like. In this case, when the particle size of the powder is small, it is possible to make the entire particle carbon-doped titanium oxide by heat treatment as described above. However, in this application, only the surface layer needs to be carbon-doped titanium oxide. Therefore, the particle size of the powder is not limited at all. However, considering the ease of heat treatment and the ease of production, it is preferably 15 nm or more.

  The carbon-doped titanium oxide powder can be obtained by pulverizing the fine columns of the second multifunctional material or the thin film having fine columns.

  In any case, the carbon-doped titanium oxide powder is particularly preferably one in which carbon is doped in a Ti—C bond state, and the effect thereof is as described above.

  Below, the function of the multifunctional material used by this invention is demonstrated in detail based on an Example and a comparative example.

Examples 1 to 3 (first multifunctional material)
Carbon dope in which carbon is doped in a Ti—C bond state as a surface layer by heat-treating a titanium plate having a thickness of 0.3 mm using an acetylene combustion flame so that its surface temperature is about 1100 ° C. A titanium plate having a titanium oxide layer was formed. By adjusting the heat treatment time at 1100 ° C. to 5 seconds (Example 1), 3 seconds (Example 2), and 1 second (Example 3), respectively, the amount of carbon doping and the thickness of the carbon-doped titanium oxide layer were reduced. Titanium plates with different carbon doped titanium oxide layers were formed.

The carbon content was calculated | required with the fluorescent-X-ray-analysis apparatus about the carbon dope titanium oxide layer with which the carbon formed in this Example 1-3 was doped in the state of Ti-C bond. Assuming the molecular structure of TiO ₂ -xCx based on the carbon content, the carbon content of Example 1 is 8 at%, TiO _1.76 C _0.24 , the carbon content of Example 2 is about 3.3 at%, and TiO _1.90. Regarding C _0.10 and Example 3, the carbon content was 1.7 at% and TiO _1.95 C _0.05 . In addition, the carbon-doped titanium oxide layer in which the carbon formed in Examples 1 to 3 was doped in a Ti—C bond state was superhydrophilic with a contact angle of about 2 ° with water droplets.

Comparative Example 1
A commercially available titanium oxide sol (STS-01 manufactured by Ishihara Sangyo Co., Ltd.) was spin-coated on a titanium plate having a thickness of 0.3 mm, and then a titanium plate having a titanium oxide film whose adhesion was improved by heating was formed.

Comparative Example 2
A commercially available product in which titanium oxide was spray-coated on a SUS plate was used as the substrate having the titanium oxide film of Comparative Example 2.

Test Example 1 (Vickers hardness)
The carbon-doped titanium oxide layer doped with the carbon of Example 1 in a Ti—C bond state and the titanium oxide film of Comparative Example 1 were subjected to indenter: Belkovic using a nanohard nesting tester (NHT) (manufactured by CSM Instruments, Switzerland). When the film hardness was measured under the conditions of type, test load: 2 mN, load unloading speed: 4 mN / min, the carbon-doped titanium oxide layer doped with carbon in the state of Ti-C bond in Example 1 had a Vickers hardness. Was a high value of 1340. On the other hand, the Vickers hardness of the titanium oxide film of Comparative Example 1 was 160.

  These results are shown in FIG. For reference, the literature values of the Vickers hardness of the hard chromium plating layer and nickel plating layer (Tomono, “Practical Plating Manual”, Chapter 6, Ohmsha (1971)) are also shown. It is clear that the carbon-doped titanium oxide layer doped with the carbon of Example 1 in a Ti—C bond state has higher hardness than the nickel plating layer and the hard chromium plating layer.

Test Example 2 (Scratch resistance)
For the carbon-doped titanium oxide layer doped with the carbon of Example 1 in a Ti—C bond state and the titanium oxide film of Comparative Example 1, a microscratch tester (MST) (manufactured by CSM Instruments, Switzerland) was used as an indenter: Rockwell. The scratch resistance test was performed under the conditions of (diamond), tip radius 200 μm, initial load: 0 N, final load: 30 N, load speed: 50 N / min, scratch length: 6 mm, stage speed: 10.5 mm / min. A “peeling start” load at which a small film peels off within the scratch mark and an “overall peel” load at which the film peels across the scratch mark were determined. The results were as shown in Table 1.

Test Example 3 (Abrasion resistance)
The carbon-doped titanium oxide layer doped with the carbon of Example 1 in a Ti—C bond state and the titanium oxide film of Comparative Example 1 were tested at a test temperature using a high-temperature tribometer (HT-TRM) (manufactured by CSM Instruments, Switzerland). A wear test was performed under the conditions of: room temperature and 470 ° C., ball: SiC sphere having a diameter of 12.4 mm, load: 1 N, sliding speed: 20 mm / sec, rotation radius: 1 mm, test rotation speed: 1000 rotations.

  As a result, for the titanium oxide film of Comparative Example 1, peeling occurred at both room temperature and 470 ° C., but for the carbon-doped titanium oxide layer in which the carbon of Example 1 was doped in a Ti—C bond state, No significant trace wear was detected under both room temperature and 470 ° C conditions.

Test Example 4 (Chemical resistance)
After immersing the titanium plate having the carbon-doped titanium oxide layer doped with the carbon of Example 1 in a Ti—C bond state in a 1M sulfuric acid aqueous solution and a 1M sodium hydroxide aqueous solution for 1 week at room temperature, When the wear resistance and the photocurrent density described below were measured, no significant difference was observed in the results before and after immersion. That is, it was confirmed that the carbon-doped titanium oxide layer in which the carbon of Example 1 was doped in a Ti—C bond state had high chemical resistance.

Test Example 5 (Structure of carbon-doped titanium oxide layer doped with carbon in a Ti-C bond state)
For the carbon-doped titanium oxide layer in which the carbon of Example 1 was doped in a Ti—C bond state, the acceleration voltage was 10 kV, the target was Al, and Ar ion sputtering was performed for 2700 seconds using an X-ray photoelectron spectrometer (XPS). Done and started the analysis. If this sputtering rate is 0.64 Å / s corresponding to the SiO ₂ film, the depth is about 173 nm. The result of the XPS analysis is shown in FIG. The highest peak appears when the binding energy is 284.6 eV. This is judged to be a C—H (C) bond commonly found in Cls analysis. The next highest peak is seen when the binding energy is 281.7 eV. Since the bond energy of the Ti—C bond is 281.6 eV, it is determined that C is doped as a Ti—C bond in the carbon-doped titanium oxide layer of Example 1. As a result of XPS analysis at 11 points at different positions in the depth direction of the carbon-doped titanium oxide layer, similar peaks appeared in the vicinity of 281.6 eV at all points.

  Ti-C bonds were also confirmed at the boundary between the carbon-doped titanium oxide layer and the substrate. Accordingly, the hardness is increased due to the Ti—C bond in the carbon-doped titanium oxide layer, and the film peeling strength is significantly increased due to the Ti—C bond at the boundary between the carbon-doped titanium oxide layer and the substrate. Is expected.

Test Example 6 (wavelength response)
The wavelength responsiveness of the carbon-doped titanium oxide layer in which the carbons of Examples 1 to 3 were doped in a Ti—C bond state and the titanium oxide films of Comparative Examples 1 and 2 were measured using an Oriel monochromator. Specifically, a voltage of 0.3 V was applied to each layer and film between the counter electrode in a 0.05 M aqueous sodium sulfate solution, and the photocurrent density was measured.

  The result is shown in FIG. FIG. 3 shows the obtained photocurrent density jp with respect to the irradiation wavelength. The wavelength absorption edge of the carbon-doped titanium oxide layer in which the carbons of Examples 1 to 3 are doped in a Ti—C bond state extends to 490 nm, and the photocurrent density increases as the carbon doping amount increases. Was recognized. Although not shown here, it has been found that when the carbon doping amount exceeds 10 at%, the current density tends to decrease, and when the carbon doping amount exceeds 15 at%, the tendency becomes remarkable. Therefore, it was recognized that the carbon doping amount has an optimum value of about 1 to 10 at%. On the other hand, in the titanium oxide films of Comparative Examples 1 and 2, it was confirmed that the photocurrent density was extremely small and the wavelength absorption edge was about 410 nm.

Test example 7 (light energy conversion efficiency)
For the carbon-doped titanium oxide layer in which the carbons of Examples 1 to 3 are doped in a Ti—C bond state and the titanium oxide films of Comparative Examples 1 and 2, the formula η = jp (Ews−Eapp) / I
The light energy conversion efficiency η defined by Here, Ews is the theoretical decomposition voltage of water (= 1.23 V), Eapp is the applied voltage (= 0.3 V), and I is the irradiation light intensity. The result is shown in FIG. FIG. 4 shows the light energy conversion efficiency η with respect to the irradiation light wavelength.

  As is clear from FIG. 4, the carbon-doped titanium oxide layer in which the carbons of Examples 1 to 3 are doped in a Ti—C bond state has extremely high light energy conversion efficiency, and the conversion efficiency in the vicinity of a wavelength of 450 nm is a comparative example. It was recognized that the conversion efficiency in the ultraviolet region (200 to 380 nm) of the 1 and 2 titanium oxide films was superior. Further, the water decomposition efficiency of the carbon-doped titanium oxide layer in which the carbon of Example 1 is doped in a Ti—C bond state is about 8% at a wavelength of 370 nm, and an efficiency exceeding 10% can be obtained at 350 nm or less. I understood.

Test Example 8 (Deodorization test)
A deodorizing test was performed on the carbon-doped titanium oxide layer in which the carbons of Examples 1 and 2 were doped in a Ti-C bond state and the titanium oxide film of Comparative Example 1. Specifically, after acetaldehyde generally used in deodorization tests is enclosed in a 1000 ml glass container together with a substrate having a carbon-doped titanium oxide layer, the influence of concentration reduction due to initial adsorption can be ignored. Visible light was irradiated with a fluorescent lamp with a UV cut filter, and the acetaldehyde concentration was measured by gas chromatography at every predetermined irradiation time. The surface area of each film was 8.0 cm ² .

  The result is shown in FIG. FIG. 5 shows the acetaldehyde concentration with respect to the elapsed time after irradiation with visible light. The acetaldehyde decomposition rate of the carbon-doped titanium oxide layers of Examples 1 and 2 is higher than the acetaldehyde decomposition rate of the titanium oxide film of Comparative Example 1, and the carbon doping amount is large. It was found that the carbon-doped titanium oxide layer of Example 1 having a higher energy conversion efficiency has a higher decomposition rate than the carbon-doped titanium oxide layer of Example 2.

Test example 9 (antifouling test)
An antifouling test was carried out on the carbon-doped titanium oxide layer of Example 1 and the titanium oxide film of Comparative Example 1. Each coating was placed in a smoking room in the Central Research Institute of Electric Power Co., Ltd., and surface contamination after 145 days was observed. There is no direct incidence of sunlight in the smoking room.

  A photograph showing the results is shown in FIG. Fat was attached to the surface of the titanium oxide film of Comparative Example 1 and had a pale yellow color, but the surface of the carbon-doped titanium oxide layer of Example 1 was not particularly changed and was kept clean. It was confirmed that the antifouling effect was sufficiently exhibited.

Examples 4 to 7 (first multifunctional material)
By using an acetylene combustion flame in the same manner as in Examples 1 to 3, a titanium plate having a thickness of 0.3 mm was heated at the surface temperature shown in Table 2 for the time shown in Table 2, thereby forming a surface layer. A titanium plate having a carbon-doped titanium oxide layer was formed.

Comparative Example 3
Using a natural gas combustion flame, a 0.3 mm thick titanium plate was heat-treated at the surface temperature shown in Table 2 for the time shown in Table 2.

Test Example 10
The Vickers hardness (HV) of the carbon-doped titanium oxide layers of Examples 4 to 7 and the film of Comparative Example 3 was measured in the same manner as in Test Example 1 above. The results are shown in Table 2. Moreover, the carbon dope titanium oxide layer formed in Examples 4-7 was super hydrophilicity whose contact angle with a water droplet was about 2 degrees.

  As is apparent from the data shown in Table 2, when the heat treatment was performed with the combustion gas of natural gas so that the surface temperature became 850 ° C., only a film having a Vickers hardness of 160 was obtained, but the surface temperature was 1000 ° C. In Examples 4 to 7 where heat treatment was performed using acetylene combustion gas as described above, a carbon-doped titanium oxide layer having a Vickers hardness of 1200 was obtained.

Test Example 11
For the carbon-doped titanium oxide layers of Examples 4 to 7 and the titanium oxide films of Comparative Examples 1 and 3, as in Test Example 6, a voltage of 0.3 V was applied between the counter electrode in a 0.05 M sodium sulfate aqueous solution. The photocurrent density was measured by irradiating with light of 300 nm to 520 nm. The result is shown in FIG. FIG. 7 shows the obtained photocurrent density jp with respect to the potential ECP (V vs. SSE).

  The carbon-doped titanium oxide layers of Examples 4 to 6 obtained by heat treatment using an acetylene combustion gas so that the surface temperature becomes 1000 to 1200 ° C. have relatively high photocurrent density and are excellent. all right. On the other hand, the titanium oxide of Comparative Example 3 obtained by heat treatment so that the surface temperature becomes 850 ° C. and the carbon-doped titanium oxide layer of Example 7 obtained by heat treatment so that the surface temperature becomes 1500 ° C. It was found that the current density was relatively small.

Example 8 (first multifunctional material)
A titanium alloy whose surface layer contains carbon-doped titanium oxide by heat treatment of a Ti-6Al-4V alloy plate having a thickness of 0.3 mm using an acetylene combustion flame so that its surface temperature is about 1100 ° C. An alloy plate made of The heat treatment time at 1100 ° C. was 60 seconds. The layer containing carbon-doped titanium oxide thus formed is superhydrophilic with a contact angle with water droplets of about 2 °, and has the same photocatalytic activity as that of the carbon-doped titanium oxide layer obtained in Example 4. showed that.

Example 9 (first multifunctional material)
A titanium thin film having a thickness of about 500 nm was formed on the surface of a stainless steel plate (SUS316) having a thickness of 0.3 mm by sputtering. A stainless steel sheet having a carbon-doped titanium oxide layer as a surface layer was formed by heat treatment using an acetylene combustion flame so that the surface temperature was about 900 ° C. The heat treatment time at 900 ° C. was 15 seconds. The carbon-doped titanium oxide layer thus formed is superhydrophilic with a contact angle with water droplets of about 2 °, and exhibits the same photocatalytic activity as the carbon-doped titanium oxide layer obtained in Example 4. It was.

Example 10 (first multifunctional material)
A titanium oxide powder having a particle size of 20 μm is supplied into an acetylene combustion flame, and is retained in the combustion flame for a predetermined time, and heat-treated so that the surface temperature is about 1000 ° C. A titanium powder having a layer was formed. The heat treatment time at 1000 ° C. was 4 seconds. The titanium powder having the carbon-doped titanium oxide layer formed as described above showed the same photocatalytic activity as that of the carbon-doped titanium oxide layer obtained in Example 4.

Examples 11 to 12 (first multifunctional material)
A titanium thin film having a thickness of about 100 nm was formed by sputtering on the surface of a 1 mm thick glass plate (Pyrex (registered trademark)). A glass plate having a carbon-doped titanium oxide layer as a surface layer is obtained by heat treatment using an acetylene combustion flame so that the surface temperature is 1100 ° C. (Example 11) or 1500 ° C. (Example 12). Formed. The heat treatment time at 1100 ° C. or 1500 ° C. was 10 seconds. The carbon-doped titanium oxide layer thus formed was transparent as shown in the photograph in FIG. 8A when the surface temperature was 1100 ° C., but when the surface temperature was 1500 ° C., FIG. As shown in FIG. 8, many small island-like undulations floating in the sea are generated on the surface, and it became translucent as shown in FIG.

Examples 13 to 16 (second multifunctional material)
The surface of the titanium plate having a thickness of 0.3 mm was subjected to heat treatment with an acetylene combustion flame at the surface layer temperature shown in Table 3 for the time shown in Table 3. After that, when the surface to which the flame is applied is brought into contact with a flat surface of a stainless steel block having a thickness of 30 mm and cooled, a layer in which fine columns made of white titanium oxide stand on the most part of the titanium plate surface is exposed. And a small piece member in which a large number of continuous narrow protrusions made of white titanium oxide on the thin film and fine columns standing on the protrusions are exposed. That is, the layer in which the fine columns made of titanium oxide formed in the surface layer by heat treatment are erected is cut in the direction along the surface layer by the subsequent cooling. Thus, the 2nd multifunctional material of Examples 13-16 was obtained.

  FIG. 10 is a photomicrograph of the second multifunctional material obtained in Example 13, in which the layer 2 in which fine columns made of white titanium oxide stand on the titanium plate surface 1 is exposed, A state in which a small piece member 3 in which a large number of continuous narrow protrusions made of white titanium oxide on a thin film and fine columns standing on the protrusions are exposed remains on a part of the layer 2 Is shown. In addition, in the manufacturing method of Examples 13-16, although the titanium plate surface 1 is not exposed, the micrograph of FIG. 10 has shown the state which removed a part of layer 2 in which the fine pillar stands. FIG. 11 is a photomicrograph showing the state of the surface on the thin film side of the small piece member 3 in which a large number of continuous narrow protrusions made of white titanium oxide and thin columns standing on the protrusions are exposed on the thin film. FIG. 12 shows a number of continuous narrow widths of small piece members 3 in which a large number of continuous narrow-width projections made of white titanium oxide are exposed on a thin film and fine columns standing on the projections are exposed. FIG. 13 is a photomicrograph showing the state of the surface of the protrusion and the surface on which the fine pillars standing on the protrusion are exposed, and FIG. 13 shows the layer 2 where the fine pillars made of white titanium oxide stand. It is a microscope picture which shows a state.

Example 17 (second multifunctional material)
The surface of a Ti-6Al-4V alloy plate having a thickness of 0.3 mm was heat-treated with an acetylene combustion flame at the surface layer temperature shown in Table 3 for the time shown in Table 3. After that, when the surface to which the flame is applied is brought into contact with a flat surface of a stainless steel block having a thickness of 30 mm and cooled, a layer in which fine columns made of titanium alloy oxide stand on most of the surface of the titanium alloy plate is exposed. And a small piece member in which a number of continuous narrow protrusions made of titanium alloy oxide on the thin film and fine columns standing on the protrusions are exposed.

Example 18 (second multifunctional material)
A titanium thin film having a thickness of about 3 μm was formed on the surface of a stainless steel plate (SUS316) having a thickness of 0.3 mm by electron beam evaporation. The surface of the thin film was heat-treated with an acetylene combustion flame at the surface layer temperature shown in Table 3 for the time shown in Table 3. After that, when the surface to which the combustion flame is applied is brought into contact with a flat surface of a 30 mm thick stainless steel block and cooled, a layer in which fine columns made of white titanium oxide are forested is exposed on the majority of the surface of the stainless steel plate. And a small piece member in which a large number of continuous narrow protrusions made of white titanium oxide on the thin film and fine columns standing on the protrusions are exposed.

Comparative Example 4
A commercially available titanium oxide sol (STS-01 manufactured by Ishihara Sangyo Co., Ltd.) was spin-coated on a titanium plate having a thickness of 0.3 mm, and then a titanium plate having a titanium oxide film whose adhesion was improved by heating was formed.

Test Example 12 (Scratch hardness test: pencil method)
Mitsubishi Pencil Co., Ltd., based on JIS K 5600-5-4 (1999), on the surface of the fine column side of the member in which the layer in which the fine column is grown is exposed on the substrate surface obtained in Examples 13 to 18 A pencil scratch hardness test was carried out using Uni 1H-9H pencils. The results were as shown in Table 3. That is, no damage was observed when a 9H pencil was used for all the test pieces.

Test Example 13 (Chemical resistance test)
The members having exposed layers with fine pillars exposed on the substrate surfaces obtained in Examples 13 to 18 were immersed in 1M sulfuric acid aqueous solution and 1M sodium hydroxide aqueous solution for 1 week at room temperature, washed with water and dried. Then, the above scratch hardness test: the pencil method was carried out. The results were as shown in Table 3. That is, even when a 9H pencil was used for all the test pieces, no damage was observed, and it was confirmed that the test pieces had high chemical resistance.

Test example 14 (heat resistance test)
A member in which a layer in which fine columns are erected is exposed on the surface of the substrate obtained in Examples 13 to 18 is placed in a tubular furnace, and the temperature is raised from room temperature to 500 ° C. in an air atmosphere over 1 hour. After holding at a constant temperature of 500 ° C. for 2 hours and further allowing to cool to room temperature over 1 hour, the above-described scratch hardness test: pencil method was performed. The results were as shown in Table 3. That is, no damage was observed even when a 9H pencil was used for all the test pieces, and it was confirmed that the specimen had high heat resistance.

Test Example 15 (Anti-fouling test)
As a sample, an 8 cm ² surface area member having a surface area of 8 cm ² exposed from the surface of the substrate obtained in Example 16 and a layer having fine pillars and a titanium oxide film having a surface area of 8 cm ² obtained in Comparative Example 4. A deodorization test was conducted using Specifically, each of these samples was immersed in 80 mL of an aqueous methylene blue solution adjusted to a concentration of about 12 μmol / L, and the influence of concentration reduction due to initial adsorption became negligible. Matsushita Electric Industrial Co., Ltd. Visible light was irradiated with a fluorescent lamp with a UV cut filter manufactured, and the absorbance of the methylene blue aqueous solution at a wavelength of 660 nm was measured with a water quality inspection apparatus DR / 2400 manufactured by HACH at every predetermined irradiation time. The result was as shown in FIG.

  From FIG. 14, the member in which the layer with the fine pillars exposed on the surface of the substrate obtained in Example 16 is exposed to methylene blue as compared with the titanium plate having the titanium oxide film obtained in Comparative Example 4. It can be seen that the decomposition speed of is high and the antifouling effect is high.

Test Example 16 (Crystal structure and bonding state)
As a result of performing X-ray diffraction (XRD) on the sample obtained from the fine column of the member in which the layer in which the fine column is erected on the substrate surface obtained in Example 15 is exposed, it has a rutile-type crystal structure. It has been found.

Further, with respect to the fine column portion of the member in which the layer with the fine columns grown on the surface of the substrate obtained in Example 15 is exposed, an X-ray photoelectron spectrometer (XPS) is used to accelerate voltage: 10 kV, target: Al was used for Ar sputtering for 2700 seconds, and analysis was started. If this sputtering rate is 0.64 Å / s corresponding to the SiO ₂ film, the depth is about 173 nm. The result of the XPS analysis was as shown in FIG. The highest peak appears when the binding energy is 284.6 eV. This is judged to be a C—H (C) bond commonly found in Cls analysis. The next highest peak is seen when the binding energy is 281.6 eV. Since the bond energy of the Ti—C bond is 281.6 eV, it is determined that C is doped as a Ti—C bond in the fine column of Example 15. As a result of XPS analysis at 14 points at different heights of the fine columns, similar peaks appeared in the vicinity of 281.6 eV at all points.

  As described above, the first multifunctional material is excellent in durability (high hardness, scratch resistance, abrasion resistance, chemical resistance, heat resistance) and functions as a visible light responsive photocatalyst. Not only can it be used as a photoresponsive photocatalyst, it can also be used significantly in various technical fields where hard chrome plating has been used. In addition, it can be expected to be applied to products aimed at reducing the potential of the base material to prevent pitting corrosion, overall corrosion, stress corrosion cracking, and the like. In addition, it is used as a radiation-responsive catalyst that responds to not only ultraviolet rays but also γ-rays, etc. to suppress stress corrosion cracking and scale adhesion of reactor structures, etc. Therefore, the film can be easily formed and the durability can be improved.

  In addition, the second multifunctional material has high photocatalytic activity, functions as a visible light responsive photocatalyst, and can easily adsorb VOC, has high hardness, peel resistance, wear resistance, chemical resistance, and heat resistance. Is excellent.

  Furthermore, the third multifunctional material has a high photocatalytic activity and functions as a visible light responsive photocatalyst.

  Hereinafter, an example of the heat exchanger to which the multifunctional material described above is applied will be described. FIG. 16 is an explanatory diagram conceptually showing a power plant having a heat exchanger according to an embodiment of the present invention. As shown in the figure, the steam that has driven the high-pressure turbine 100 and the low-pressure turbines 101 and 102 is condensed by returning heat to seawater in the condensers 103 and 104 and returns to the liquid. That is, the condensers 103 and 104 function as a heat exchanger using seawater as a refrigerant. Here, seawater is taken in through the water intake by the circulating water pump 105, flows into the condensers 103 and 104 through the valves 106 and 107, and returns to the sea from the water outlet through the valves 108 and 109. It is like that. On the other hand, the steam exchanges heat with seawater in the condensers 103 and 104 to become liquid, and is returned to a heat source such as a boiler or a nuclear reactor as cooling water by the low-pressure condensate pump 110. The generator 111 is driven using the high-pressure turbine 100 and the low-pressure turbines 101 and 102 as prime movers.

  In such a power generation system, the heat exchanger used as the condenser 103, 104 is provided with a multifunctional layer made of carbon-doped titanium oxide or titanium alloy oxide on at least a part of the inner surface of the conduit through which the refrigerant flows. Or at least a part of the surface of the substrate made of titanium, titanium alloy, titanium alloy oxide or titanium oxide at least on the surface side, and a plurality of protrusions made of titanium oxide or titanium alloy oxide. A multi-functional layer in which the portion is carbon-doped is provided at least on the inner surface of the conduit through which the refrigerant flows.

More specifically, FIG. 17 is an enlarged view showing the condenser 103 in the portion A of FIG. 16, but as shown in the figure, the seawater flowing from the intake port is the condenser that functions as a condenser. It reaches the narrow tube 103a in the water bottle 103 and exchanges heat with steam while flowing through each thin tube 103a. In the condenser 103 (the condenser 104 has the same configuration), the multi-layer is provided at least on the inner periphery of the narrow tube 103a. In addition, a light source (not shown) is provided inside each narrow tube 103a. This light source is for causing the multifunctional layer to exhibit a photocatalytic function, and may be visible light or ultraviolet light. For example, a high fiber that has excellent flexibility and can be freely inserted into the narrow tube 103a is used. Is preferred. That is, the light source is preferably of a type that is inserted into the narrow tube 103a when necessary. Here, the multi-functional layer and the light source can of course be provided not only in the narrow tube 103a but also in a water intake tube that takes in seawater or a water discharge tube that discharges seawater.・ Effects.

  As a first method of providing the multi-functional layer as described above, the structure serving as the thin tube 103a is made of a metal member having a surface portion forming layer of titanium, titanium alloy, titanium alloy oxide or titanium oxide on the surface, or titanium, Consists of a member made of titanium alloy, titanium alloy oxide or titanium oxide, and as described as the first multifunctional material, heat treatment is performed at a high temperature using a combustion flame of gas mainly composed of hydrocarbon. The method of forming a pipe line with such a member can be mentioned.

  As a result, the inner surface of the thin tube 103a is doped with carbon in a Ti—C bond state, and has excellent durability (high hardness, scratch resistance, abrasion resistance, chemical resistance, heat resistance) and visible light. A multifunctional layer composed of a carbon-doped titanium oxide layer that functions as a responsive photocatalyst can be formed.

  In addition, as a second method, the structure is a metal member having a surface portion forming layer of titanium, titanium alloy, titanium alloy oxide or titanium oxide on the surface, or titanium, titanium alloy, titanium alloy oxide or oxidation. As described above as the second multifunctional material composed of a member made of titanium, the surface is heat-treated with, for example, an unsaturated hydrocarbon, particularly an acetylene combustion flame, and titanium oxide or titanium is formed inside the surface layer. Form a layer in which fine columns made of alloy oxide stand, and then apply thermal stress, shear stress, tensile stress, for example, and cut the layer in which the fine columns stand along the surface layer Then, a layer in which fine columns made of the titanium oxide or titanium alloy oxide are forested is usually exposed on the surface of the substrate, and most of the surface of the substrate, and a pipe line is formed by such a member. method It can gel. As a result, the multifunctional layer of the second multifunctional material, that is, the photocatalytic activity is high, functions as a visible light responsive photocatalyst, VOC can be easily adsorbed, the hardness is high, the peel resistance, and the wear resistance. A multifunctional layer having excellent properties, chemical resistance and heat resistance can be easily provided.

  Here, the metal member having the surface forming layer of titanium, titanium alloy, titanium alloy oxide or titanium oxide on the surface used in the first method and the second method is, for example, iron, iron alloy, stainless steel, etc. A film made of titanium, titanium alloy, titanium alloy oxide or titanium oxide is formed on the surface of the core material by sputtering, vapor deposition, thermal spraying or the like, or a commercially available titanium oxide sol is formed by spray coating, spin coating or dipping Can be mentioned.

  In addition, since the heat processing method in the 1st method and the 2nd method was demonstrated in detail by the manufacturing method of the 1st multifunctional material or the 2nd multifunctional material, description here is abbreviate | omitted.

  Furthermore, as a third method, a multifunctional layer containing carbon-doped titanium oxide powder is provided on the surface of the structure by a technique such as coating. In this case, although it is inferior in durability as compared with the cases of the first and second methods described above, it is very easy to provide a multifunctional layer that has a high photocatalytic activity and functions as a visible light responsive photocatalyst. There is an advantage that you can.

  In the condenser 103 having the thin tube 103a having the multi-functional layer described above, particularly when the first multi-functional member is applied by the first method or the third method, the first multi-functional material is , With excellent durability (high hardness, scratch resistance, abrasion resistance, chemical resistance, heat resistance) and excellent peeling resistance of the multi-functional layer and functions as a visible light responsive photocatalyst. At the same time, there is an effect that it is extremely excellent as a highly hygienic state. That is, it is not damaged by foreign matter in seawater, has excellent durability, and even when a highly corrosive refrigerant such as salt is used, it also has corrosion resistance against this refrigerant, and is further irradiated with visible light or preferably ultraviolet light. As a result, the organic matter decomposition function of the photocatalyst prevents adhesion of scales and the like, and the high-efficiency heat exchange can be continued for a long time.

  In addition, when the second multifunctional material is applied in the second method or the third method, the durability is somewhat inferior to that described above, but the photocatalytic activity is high, and it functions as a visible light responsive photocatalyst. In addition, VOC can be adsorbed easily, has high hardness, excellent peeling resistance, abrasion resistance, chemical resistance, and heat resistance, and also has excellent peeling resistance for multi-functional layers. Can be disassembled.

  Further, when the narrow tube 103a itself is composed of a member made of titanium, titanium alloy, titanium alloy oxide or titanium oxide by the first method or the second method, the thin tube 103a is oxidized by titanium, titanium alloy or titanium alloy. It is composed of a member having a multifunctional layer on the surface of a substrate made of a product or titanium oxide, that is, a titanium-based laminated member having a multifunctional layer on the surface, and is lightweight and highly rigid, and the entire structure is a living body. The effect of being excellent in adaptability is achieved.

  In addition, although the said embodiment demonstrated the case where the heat exchanger was the condenser 103,104, of course, it is not necessary to restrict to this. For heat exchangers that cool intermediate water (rain water and other intermediate water, sewage water), bioreactor heat exchangers, hot spring heat exchangers, etc. used in toilets in buildings and public facilities When used, a remarkable antifouling function, deodorizing function, cleaning function, etc. can be exhibited.

  Further, the multi-functional layer need not be provided only on the inner periphery of the pipe. By applying it to the easily contaminated part such as the surface of the casing, the remarkable photocatalytic function as described above can be exhibited. Further, the present invention can be similarly applied to a fan for taking in gas such as air, and the same operation and effect can be obtained.

FIG. 1 is a view showing the results of the film hardness test of Test Example 1. FIG. FIG. 2 is a diagram showing the results of XPS analysis in Test Example 5. FIG. 3 is a graph showing the wavelength response of the photocurrent density in Test Example 6. FIG. 4 is a diagram showing test results of light energy conversion efficiency in Test Example 7. FIG. 5 is a diagram showing the results of the deodorization test of Test Example 8. FIG. 6 is a photograph showing the results of the antifouling test of Test Example 9. FIG. 7 is a diagram showing the results of Test Example 11. FIG. 8 is a photograph showing the light transmission state of the carbon-doped titanium oxide layers obtained in Examples 11 and 12. FIG. 9 is a photograph showing the surface state of the carbon-doped titanium oxide layer obtained in Example 12. FIG. 10 is a photomicrograph showing the state of the multifunctional material obtained in Example 13. FIG. 11 is a photomicrograph showing the state of the surface on the thin film side of the small piece member 3 in which a large number of continuous narrow protrusions made of white titanium oxide on the thin film and fine columns standing on the protrusions are exposed. is there. FIG. 12 shows a number of continuous narrow-width protrusions made of white titanium oxide on a thin film and a number of continuous narrow-width protrusions of a small piece member 3 in which fine columns standing on the protrusions are exposed. It is a microscope picture which shows the state of the surface of the side where the fine pillar standing on the protrusion part is exposed. FIG. 13 is a photomicrograph showing the state of the layer 2 in which fine columns made of white titanium oxide stand. FIG. 14 is a graph showing the results of Test Example 15 (antifouling test). FIG. 15 is a graph showing the results of Test Example 16 (crystal structure and bonding state). FIG. 16 is an explanatory diagram conceptually showing a power plant having a heat exchanger according to an embodiment of the present invention. FIG. 17 is an enlarged view of the portion A in FIG. 16 extracted and enlarged.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 High pressure turbine 101,102 Low pressure turbine 103,104 Condenser 103a Narrow pipe 105 Circulating water pump 106,107,108,109 Valve 110 Low pressure condensate pump 111 Generator

Claims (10)

  A heat exchanger characterized in that a multifunctional layer made of carbon-doped titanium oxide or titanium alloy oxide is provided on at least a part of the inner surface of a conduit through which refrigerant flows.   2. The multi-functional layer according to claim 1, wherein the multi-functional layer is integrally formed on the surface of the substrate and the carbon is doped in a Ti-C bond state, and at least the surface layer of the substrate is made of titanium or a titanium alloy. A heat exchanger characterized by being a titanium alloy oxide or titanium oxide.   In Claim 2, the said base | substrate consists of a surface part formation layer and core material which consist of titanium, titanium alloy, titanium alloy oxide, or titanium oxide, and this core material is other than titanium, titanium alloy, titanium oxide, and titanium alloy oxide. A heat exchanger made of a material.   4. The heat exchanger according to claim 2, wherein the multi-functional layer has a Vickers hardness of 300 or more.   4. The heat exchanger according to claim 2, wherein the multifunctional layer has a Vickers hardness of 1000 or more.   At least part of the surface of the base body made of titanium, titanium alloy, titanium alloy oxide or titanium oxide has at least a part of the protrusions made of titanium oxide or titanium alloy oxide, and the protrusions are carbon-doped. A heat exchanger characterized in that a multifunctional layer is provided at least on the inner surface of a conduit through which a refrigerant flows.   7. The heat exchanger according to claim 6, wherein the multifunctional layer has a structure in which fine columns are erected and the inside of the fine is carbon-doped.   The heat exchanger according to claim 6 or 7, wherein doped carbon is contained in a Ti-C bond state.   9. The substrate according to claim 6, wherein the base body includes a surface portion forming layer made of titanium, titanium alloy, titanium alloy oxide, or titanium oxide and a core material, and the core material is titanium, titanium alloy, titanium oxide, and titanium. A heat exchanger made of a material other than an alloy oxide. The heat exchanger according to any one of claims 1 to 9, further comprising a light source that irradiates visible light or ultraviolet light to the multifunctional layer inside the conduit.

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