JPS6366917B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a method for surface treatment of titanium or a titanium alloy.

[Conventional technology]

Traditionally, titanium or titanium alloys, like aluminum or aluminum alloys, are chemically very active and react easily with various chemicals, and therefore, like stainless steel, they are very easy to passivate. Usually, an extremely thin and highly protective oxide film is formed on the surface, and it is known to have excellent corrosion resistance and chemical resistance against various strongly oxidizing acids, alkalis, and other chemicals.

Further, titanium or a titanium alloy has high specific strength (ratio of strength to density), and has appropriate toughness, heat resistance, thermal stability, and workability. Therefore, it has come to occupy a major position as a material for chemical plants and aerospace equipment.

However, titanium or titanium alloys have poor wear resistance, heat radiation properties, electrical conductivity, etc., which limits their use.

In other words, when titanium or titanium alloys are used, for example, in components mounted on artificial satellites that fly in space, mainly taking advantage of their excellent heat resistance and high specific strength (ratio of strength to density), Thermal radiation properties were required to keep the temperature at an appropriate level), and good electrical conductivity was required when used as radio wave circuit components. In order to satisfy these requirements, a method is known in which the surface of a substrate made of titanium or a titanium alloy is coated with gold.

Examples of such methods include (a) a method of gold plating by electrolysis, (b) a method of dry plating such as vapor deposition or sputtering, and (c) a method of forming an alloy layer using a laser.

[Problem that the invention seeks to solve]

The conventional surface treatment method for titanium or titanium alloy as described above has the following problems.

That is, according to method (a) above, electroless nickel plating and gold plating are performed through steps such as vapor degreasing, blasting, etching, and activation, but the base plate made of titanium or titanium alloy is When the surface of the material comes into contact with air or water during the above processing steps, a thin oxide film is formed and the material becomes passive.
The adhesion of the plating film becomes insufficient. In order to improve this adhesion, the temperature after electroless nickel plating is
The surface of the base material made of titanium or titanium alloy is formed by heat treatment at 450°C or higher, but a relatively high temperature of 450°C or higher is required. It is difficult to activate electroless nickel plating that is alloyed with the material surface, resulting in poor yield after gold plating and unstable quality.

In the method (a) above, copper or gold with good conductivity is coated on the surface of the substrate made of titanium or titanium alloy using equipment such as vapor deposition or sputtering. It is not possible to obtain a stable adhesion and it cannot be put to practical use.

In the method (c) above, a film is formed on the surface of a base material made of titanium or a titanium alloy by plating, vapor deposition, sputtering, etc., and then the surface temperature is heated to above the melting point with a laser to melt the surface layer and form an alloy layer. However, the melting width varies depending on the laser output or moving speed, but the melting width is 0.1~
It is only about 0.3mm, so it cannot be used practically for machining large parts.

There was a problem.

This invention was made to solve the above-mentioned problems, and its purpose is to provide excellent electrical conductivity to any part of the surface of a base material and excellent thermal radiation properties by a relatively simple method. The object of the present invention is to provide a method for applying a treatment layer having a treatment layer.

[Means for solving problems]

As a result of extensive research, the surface treatment method for titanium or titanium alloy according to the present invention has been developed by depositing a thick layer of aluminum on the surface of a base material made of titanium or titanium alloy by ion plating method, and then applying aluminum to the surface by a conventional method. It has been found that the above object can be achieved by coating copper and gold plating through treatment, and the present invention has been completed.

That is, the surface treatment method for titanium or titanium alloy of the present invention involves mechanically finishing the surface of a base material made of titanium or titanium alloy to a desired surface roughness, and then applying a thick layer of aluminum using an ion plating device. After that, pretreatment such as degreasing, pickling, zinc substitution, and copper strike treatment for aluminum is performed, and then copper plating is performed, and further gold plating is performed.

In the following, the invention will be explained in more detail.

In the surface treatment method of the present invention, first, the surface of a base material made of titanium or a titanium alloy is finished to a desired surface roughness by a mechanical method. Such mechanical methods include, for example, dry honing equipment,
There are liquid honing equipment and sandblasting equipment, but the most suitable is dry honing equipment.

In such a treatment, for example, 300 to 400 meshes of glass beads are sprayed onto any part of the surface of the substrate at an air pressure of 2 kg/cm ² to 5 kg/cm ² . When spraying onto the surface of the base material, it is preferable to spray evenly onto the required areas. In order to remove the glass beads left by such treatment, 2 kg/
Blow dry air at an air pressure of cm ² to 5 Kg/cm ² to remove as much glass beads as possible. After that, place it in a glass container filled with pure water, perform ultrasonic cleaning at room temperature for about 20 minutes, then thoroughly wash it under running pure water, and then use alcohol in the pure water and perform ultrasonic cleaning at room temperature for about 20 minutes. Do this for 20 minutes.

After this treatment, nitrogen gas is sprayed at a pressure of 2 kg/cm ² to 5 kg/cm ² so that no spots remain on the surface of the substrate made of titanium or titanium alloy, and the substrate is dried at a temperature of 70 to 90° C. for 20 minutes.

In the surface treatment method of the present invention, aluminum is then coated using an ion plating device to facilitate plating on the surface of a substrate made of titanium or a titanium alloy.

Prior to such treatment, after removing dust adhering to the surface of the base material made of titanium or titanium alloy and performing the necessary treatment to maintain a clean state,
It is desirable to remove moisture adhering to the surface by placing it in a device and heating it before forming an aluminum film by ion plating. Next, the vacuum chamber was evacuated to 10 ^-4 TORR, filled with inert gas, and a negative voltage of several 100 V was applied to the surface of the titanium or titanium alloy substrate to be ion-plated. This causes a glow discharge to occur. The glow discharge cleans the surface of the base material made of titanium or titanium alloy, and the aluminum is partially ionized in the next discharge and is attracted to the negatively charged surface of the base material made of titanium or titanium alloy, generating a large amount of energy. Since the aluminum film is vapor-deposited by holding it in place, an aluminum film with good adhesion can be obtained. In this case, since plating is performed next, the film thickness is preferably 20 to 30 microns.

In the surface treatment of the present invention, aluminum is then pretreated by a conventional method to deposit copper or gold plating to a desired thickness.

Such treatment involves pre-treatment of aluminum, such as degreasing, pickling, zinc substitution, and copper strike, followed by copper plating to obtain good electrical conductivity, and then gold plating.

In this treatment, the specific resistance value of the copper plating film was 1.72×10 ^-6 Ω-cm, and the specific resistance value of the gold plating film was 1.72×10 -6 Ω−cm.
2.2×10 ^-6 Ω-cm, so when applied to radio circuit components, the thickness of the copper plating should be increased according to the following relationship according to the frequency used, and the thickness of the gold plating should be adjusted to prevent corrosion of the copper plating. Since it is applied to obtain prevention and heat radiation properties, it is better to make it as thin as possible.

Furthermore, by applying a copper plating or gold plating bath that does not contain a brightening agent, the effect of good electrical conductivity is increased.

[Effect]

In the present invention, since aluminum is attached to the surface of the base material made of titanium or a titanium alloy by the ion plating method, the subsequent plating process is considerably facilitated.

Further, in this invention, aluminum is pretreated by a conventional method, and then copper plating is performed and then gold plating is performed, so that excellent electrical conductivity and heat radiation characteristics can be obtained.

〔Example〕

The present invention will be described in more detail below with reference to Examples.

Example A substrate made of pure titanium having a diameter of 20 mm and a thickness of 10 mm was treated according to the following steps.

(1) Triclean degreasing Immersed at a temperature of 80 to 90°C for 90 seconds.

(2) Dry honing #300 mesh glass beads with air pressure 3
Sprayed at Kg/ ^cm2 . Thereafter, glass beads adhering to the surface were removed by blowing dry air at an air pressure of 3 kg/cm ² .

(3) Immerse in pure water and perform ultrasonic cleaning at room temperature for 20 minutes (4) Rinse with running pure water at room temperature for time as appropriate (5) Immerse in alcohol and perform ultrasonic cleaning at room temperature for time
Spray nitrogen gas for 20 minutes (6).

(7) Drying Temperature: 70 to 90℃ Time: 20 minutes (9) Place the substrate in an ion plating device and preheat it to a temperature of 300℃, then heat the vacuum chamber to 10 ^-4 TORR
After evacuating and filling with argon gas, apply 150V to the base material.
A negative voltage of 25 μm was applied to deposit 25 microns of aluminum.

(10) Alkaline cleaning Temperature 50-70℃ Time 20 seconds (11) Running water washing Room temperature Time 20-30 seconds (12) Nitric acid immersion Room temperature Time 10-20 seconds (13) Running water washing Room temperature Time 20-30 seconds (14) Zinc Replacement Room temperature Time 40-60 seconds (15) Rinse with running water Room temperature Time 20-30 seconds (16) Dilute sulfuric acid immersion Room temperature Time 10-20 seconds (17) Rinse room temperature Time 20-30 seconds (18) Zinc replacement Room temperature Time 40- 60 seconds (19) Washing under running water at room temperature Time 20-30 seconds (20) Copper strike plating Temperature 20-35℃ Current density 3A/dm ² hours 5 minutes (21) Washing under running water Room temperature Time 20-30 seconds (22) Copper plating Temperature 50-70℃ Current density 2A/d
m ² hours 15 minutes (23) Washing under running water Room temperature Time 20-30 seconds (24) Gold strike plating Room temperature Voltage 5V Time 5-15 seconds (25) Washing under running water Room temperature Time 20-30 seconds (26) Gold plating Temperature 60 ~80℃ Current density 0.5/d
m ² hours 6 minutes (27) Washing with running water Room temperature Time 20-30 seconds (28) Pure water washing Room temperature Time 60-90 seconds (29) Pure warm washing Temperature 80-100℃ Time 60-90 seconds (30) Drying Temperature 40- The adhesion strength of the product obtained by processing at 60℃ for 30 to 60 minutes or more is sufficient to withstand the usage conditions, and Gier Dunkle
The infrared emissivity measured by DB100 was 0.05%.

〔Effect of the invention〕

As is clear from the above description, according to the surface treatment method of the present invention, surface treatment of a substrate made of titanium or titanium alloy, which was considered difficult with conventional wet plating methods, can be performed using both dry plating method and wet plating method. By combining it with the above, it became easier, opening up a way of application that had been restricted until now. Furthermore, in addition to the excellent specific strength of titanium or titanium alloys, it has good electrical conductivity and heat radiation properties, and we are confident that it will occupy an important position as a material for aerospace equipment, which is expected to see high growth in the future. .

Claims (1)

[Claims] 1 The surface of a base material made of titanium or titanium alloy is finished to the required surface roughness by a mechanical method, and then aluminum is coated with 20% by dry plating.
A method for surface treatment of titanium or titanium alloy, characterized in that a thickness of ~30 μm is deposited, and then aluminum is pretreated by a conventional method, copper plating is performed, and further gold plating is performed.