JP2005307277A - Method for surface-treating metallic material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for making the surface of a metal such as aluminum and titanium or an alloy material thereof electroconductive. <P>SOLUTION: A surface treatment method comprises the steps of: dispersing indium-oxide-based, antimony-oxide-based or zinc-oxide-based electroconductive fine particles in water or an other solvent; making the dispersion into mist by applying an ultrasonic wave thereto; introducing the mist into a high-temperature furnace of 200°C or higher; heating the fine particles to 150 to 600°C; contacting the high-temperature fine particles with the alloy material of aluminum or titanium, of which the surface is made non-electroconductive, for 0.5 second or longer; and at the same time, applying a voltage of 1 to 100 KV between the fine particles and the surface of the alloy to form an electroconductive coating on the material surface. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a surface treatment method for forming a conductive transparent film on a metal material having an oxide surface at normal pressure.

Aluminum alloys are used in large quantities in a wide range of fields such as structural materials and building materials because of their light weight, good thermal conductivity, corrosion resistance, and excellent plastic workability. However, since the oxide layer is formed on the surface for imparting corrosion resistance, there is almost no surface conductivity. In many cases, it is good that there is no electrical conductivity on the surface, but on the other hand, electrical conductivity is often required.

As a method of imparting conductivity to the surface of a non-conductive metal material by conventional surface treatment, it is known to apply a conductive paint, but if this is applied to an aluminum material, it becomes difficult to recover and reuse the material. There is. In addition, since organic substances are almost used as binders for these paints, there is a disadvantage that heat resistance is low, there is no metallic luster, and conductivity is not sufficient. For example, as an exterior material for mobile products, it is used for electromagnetic shielding etc. Cannot be used. In addition, a method of forming a conductive material such as ITO into a thin film by a vacuum vapor deposition method or an ion plating method on a nonconductive material such as glass is well known. This method has the disadvantage that it is necessary to carry out under vacuum and the apparatus is very expensive.

Titanium alloys are rigid and widely used as thin material molding, lightweight, and high corrosion resistance materials. The purpose of forming an oxide film on this surface by anodic oxidation is to use the color of brown to brown for decoration, so that it can be used for interior decoration of buildings, exterior parts of mobile products, small items, and highly corrosive chemicals. Used in containers. However, when this film is touched with a hand, a fingerprint remains and cannot be used in this state, and usually a transparent inorganic or organic coating is applied on the surface. For this reason, the electrical conductivity cannot be satisfactorily taken, and it is not suitable for an electromagnetic wave shielding effect and a voltage drop countermeasure.

On the other hand, Patent Document 1 proposes a method in which metal oxide fine particles are atomized at normal pressure, heated and sprayed onto the surface of a substrate such as plastic to form a crystal film. According to this method, it is difficult to form a uniform thin film on the surface of the substrate, and in particular, there is a defect that a conductive film cannot be formed on the entire surface of a commercialized material having a three-dimensional surface. In addition, it is difficult to maintain uniformity by changing the flow velocity from the injection port.
JP 2001-335922 A.

An object of the present invention is to provide a surface treatment method for imparting these performances to an aluminum or titanium material which has been difficult to impart corrosion resistance and conductivity to the surface simultaneously by anodization in the prior art.

In the present invention, indium oxide-based, antimony oxide-based, zinc oxide-based and / or tin oxide-based conductive fine particles are dispersed in water or other solvent, and ultrasonic waves are applied thereto to form a mist. Aluminum or titanium having a non-conductive film on the surface thereof, or an alloy material thereof is introduced into a conduit or a high temperature furnace heated to 200 ° C. or higher, and the fine particles are set to a temperature of 150 to 600 ° C. The contact is performed at least once at normal pressure, and the time for one time is 0.5 seconds to 30 minutes. In this case, a surface treatment method for forming a conductive film on the surface of the material is characterized by applying a voltage of 1 to 100 KV between the fine particles and the material to be treated.

The conductive fine particles used in the present invention include tin, zinc, palladium, indium, antimony, cerium, titanium, vanadium, chromium, manganese, zirconium, molybdenum and / or indium oxide, antimony oxide, zinc oxide and / or tin oxide. Or what doped iodine or its compound is used, and especially ITO, ATO, etc. which doped indium oxide or antimony oxide with tin are used preferably. From the viewpoint of supply of raw material resources, tin oxide, zinc oxide, or fine particles doped with antimony or titanium are also preferably used.

The size of the conductive fine particles is such that the average diameter is 10 in order to quickly raise the temperature in a heating conduit or a high temperature furnace, and to quickly grow crystals on the surface of an alloy material such as aluminum or titanium to form a uniform transparent film. Ultrafine particles of ˜500 nm are preferred. These fine particles are dispersed in water or another solvent, and an ultrasonic wave having a frequency of 25 kHz to 2 MHz is applied thereto to atomize the solvent together with the fine particles. The supply amount of the raw material fine particles can be adjusted by adjusting the output of the ultrasonic transmitter, or can be adjusted by adjusting the amount of fine particles dispersed in the solvent.

The atomized fine particle dispersion is guided to a high-temperature furnace, and the furnace used here may be of any type as long as it can be heated to 200 ° C. or higher. Moreover, since this furnace is used under atmospheric pressure, no special strict sealing means is required. The fine particles are heated to about 150 to 600 ° C. in a conduit leading to the high temperature furnace or in the furnace, and are brought into contact with the material to be processed. The contact time is at least one contact at normal pressure when the material to be treated is in the high-temperature furnace, and one time is preferably 0.5 seconds to 30 minutes, and at normal pressure when outside the high-temperature furnace. It is preferable that the contact is performed once or more, and the time for one time is 0.5 seconds to 30 minutes. When contacting, a voltage of 1 to 100 KV, preferably 50 to 80 KV is applied between the fine particles and the material to be treated. By applying a voltage, a suction relationship is generated between the fine particles and the material to be processed, and the adhesion rate of the fine particles is greatly improved. In addition, fine particles can be attached to the entire surface of the material to be processed having a three-dimensional structure.

As a contact condition when the material to be treated is outside the high temperature furnace, it is preferable that the speed of the fine particles coming out of the furnace is 6 to 1800 cm / min. The surface temperature of the material to be treated at this time is preferably set to room temperature to about 200 ° C. If the temperature is higher than that due to the gas injected from the high temperature furnace, the moving speed of the alloy material may be changed. The temperature can be adjusted by cooling. When the material to be processed is in a high-temperature furnace, the material can be rotated in the furnace, or a plate-shaped material can be moved by providing a slit in the furnace wall so that the material can pass through the furnace.

As the aluminum or titanium alloy used in the present invention, any of wrought material and cast material is used. However, it is a wrought material such as a rolled plate, a round bar, and an extruded material, and has been commercialized or semi-finished. Is preferred. Such products or semi-finished products include projectors, DVDs, personal computers, scanners, printers, mice in the field of office work, digital cameras, mobile phones, MDs, CD devices, video cameras, headphones, radios, etc. in the mobile product field. In the product field, there are components such as components, minicomponents, refrigerators, coolers, humidifiers, fixed telephones, etc., and products molded into accessory devices or cases.

The metal material used for the treatment of the present invention is preferably one that has been subjected to an anodizing treatment in order to impart corrosion resistance and decorative properties to the surface. By anodic oxidation, a film mainly composed of an oxide of a material metal, and in some cases, an oxide and a hydroxide is formed on the surface of the material, and these are non-conductive films.

A known method is used for the anodizing treatment. For example, sulfuric acid, phosphoric acid, an aromatic or aliphatic organic acid having one or more carboxyl group or sulfone group, or these organic acid and sulfuric acid are used as an electrolytic solution. Alternatively, phosphoric acid or a mixed acid with both is used. Anodization is preferably performed in an electrolyte solution having a concentration of 0.5 to 10 mol / L at a current density of 0.6 to 5 A / dec square meter and a voltage of 10 to 80V. The anodizing treatment in the electrolytic solution adjusted in this way is particularly preferably performed at a bath temperature of -5 to 30 ° C.

The aluminum material of the present invention can be dyed and colored to produce a product with color variation. These can be made into products with high decorativeness and aesthetics by performing electrolytic coloring or dyeing treatment after anodizing.
The thickness of the conductive material film formed on the surface of the aluminum or titanium material by the method of the present invention is as thin as about 10 to 1000 nm, and the surface of the aluminum or titanium material to be processed has irregularities or minute cavities. Can form a thin conductive film up to their inner surface. The aluminum or titanium material obtained by such treatment is used after being formed into a casing or the like of various electric parts by bending, drawing or pressing when they are plate-like.

The surface of the metal material obtained by the method of the present invention is conductive, and can be used as a material or product having excellent characteristics for electromagnetic wave shielding and voltage drop countermeasures.

Next, the present invention will be specifically described with reference to examples. In the examples, “%” means “% by weight” unless otherwise specified.

After degreasing, two aluminum JIS-A1050P materials were first etched and neutralized, and the workpiece was anodized with 1.6 mol / L sulfuric acid, bath temperature 21 ° C., current density 1 A / dec square meter, voltage 13 Anodized at 5 V for 30 minutes.
For one of the two samples, ITO fine particles with an average diameter of 50 nm are dispersed in water at a rate of 15%, atomized using a 100 KHz ultrasonic transmitter, and the temperature is reduced using air introduced from the outside. It led to a 400 degreeC high temperature furnace. Of the mist, the fine particles collide with the furnace wall and immediately reach about 300 ° C. The high-temperature fine particles were sprayed 5 times at a rate of 12 cm / min for 3 minutes on the anodized aluminum surface fixed with air at normal pressure. The temperature of the aluminum material was cooled to 90 ° C. or lower. During this treatment, a voltage of 70 KV was applied between the fine particles and the aluminum surface. By this treatment, an ITO film of about 60 nm was formed on the aluminum surface, and the resistance value was 2Ω / □.
In addition, when the same treatment was performed without applying a voltage to another sample subjected to the same anodizing treatment, the resistance value was not uniform, but the average value was about 100Ω / □. In addition, the resistance value of the anodized aluminum was 6 MΩ / □.

After degreasing the titanium plate, it was etched with a 15% hydrofluoric acid solution, neutralized with ultrasonic water washing, and then the workpiece was anodized electrolytic solution of phosphoric acid 1.2 mol / liter + sulfuric acid 0.5 mol / liter. Then, after anodizing at a bath temperature of 35 ° C., a current density of 1.5 A / dec square meter, and a final voltage of 65 V for 20 minutes, ITO fine particles were sprayed in the same manner as in Example 1. By this treatment, an ITO film of about 50 nm was formed on the surface, and the resistance value was 5Ω / □. The resistance value of the workpiece subjected to only the anodizing treatment was about 2 KΩ / □.

The aluminum material of the present invention can be applied as a material in various fields where it is advantageous to have a small surface resistance value for mobile, personal computer, motorcycle, industrial equipment such as electrical and electronic devices.

Claims (4)

Indium oxide-based, antimony oxide-based, zinc oxide-based and / or tin oxide-based conductive fine particles are dispersed in water or other solvent, and ultrasonic waves are applied thereto to form a mist. It is led to a conduit or a high-temperature furnace heated to a temperature of not less than ℃, and the fine particles are brought to a temperature of 150 to 600 ° C., and the high-temperature fine particles are brought to normal pressure with aluminum, titanium or an alloy material thereof having a nonconductive film on the surface. The surface of the material is characterized by applying a voltage of 1 to 100 KV between the fine particles and the material to be treated. A surface treatment method for forming a conductive film. Conductive fine particles are indium oxide, antimony oxide, zinc oxide and / or tin oxide, tin, zinc, palladium, indium, antimony, cerium, titanium, vanadium, chromium, manganese, zirconium, molybdenum and / or iodine or compounds thereof The surface treatment method according to claim 1, wherein the surface treatment method is performed. The contact between the high-temperature fine particles and the material to be treated is performed at least once at normal pressure in the high-temperature furnace or outside the high-temperature furnace while moving or rotating the material to be treated, and the time for one time is 0.5 seconds to 30 minutes. The surface treatment method according to claim 1 or 2. The surface treatment method according to any one of claims 1 to 3, wherein an aluminum or titanium or alloy material thereof has an anti-corrosion and non-conductive oxide film formed on the surface by anodizing treatment.