JPH01127681A - Black titanium material having superior adhesion - Google Patents

Abstract

PURPOSE:To improve the adhesion of a black oxide coating film by forming the film on the surface of a Ti material so that the film contains crystalline Ti2O or crystalline TiO2. CONSTITUTION:A Ti material is immersed in >=10wt.% aq. sulfuric acid soln. at >=50 deg.C for 30-60min, pulled up and washed. In is then immersed in 0.1-10wt.% aq. hydrofluoric acid soln. at <=35 deg.C for 1-100sec, pulled up, washed and heated at 200-450 deg.C for 30-60min to form a black coating film contg. crystalline Ti2O and/or crystalline TiO2 and having high adhesive strength on the surface of the Ti material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to colored titanium materials, and particularly to improving the adhesion of black oxide films.

[Conventional technology]

In recent years, colored titanium materials have been used not only as building materials in areas with severe corrosive environments, but also as interior materials or accessories that emphasize design and aesthetics.

It is also attracting attention as a decorative item such as a tie pin.

In particular, among colored titanium materials, black titanium materials are expected to have a very high potential need as accent materials.

Conventionally, such black titanium materials have been produced by depositing copper as copper oxide on the surface of the titanium material, or by immersing the titanium material in an aqueous hydrofluoric acid solution to form a black film on the surface of the titanium material. However, the former has the problem that the corrosion resistance characteristic of titanium materials is impaired because a black film made of a different metal is applied to the surface of the titanium material, and the latter has the problem of a low degree of blackening. There is.

Therefore, the applicant of the present application has developed a black titanium material that can solve the above-mentioned conventional problems of poor corrosion resistance and low degree of blackening, by immersing it in a sulfuric acid aqueous solution at a predetermined concentration and temperature, and washing it with water. An application has already been filed for a titanium material on which a black film is formed on the surface by immersing it in an aqueous solution of hydrofluoric acid at a predetermined concentration and temperature (Japanese Patent Application No. 1982-10).
(See No. 4416).

[Problem that the invention seeks to solve]

The black titanium material according to the above application has the above corrosion resistance.

Although the problem of low degree of blackening can be solved, the adhesion of the black film is not sufficient, and depending on the processing conditions, for example, during bending or cleaning, the black film may peel off. There is room for improvement.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a black titanium material in which the adhesion of the black film is significantly improved.

[Means for solving problems]

The present inventors conducted various experimental studies to discover the reason why the black film of the black titanium material related to the above application has poor adhesion, and as a result, they found that the crystal structure of the oxide that makes up the black film significantly improves the adhesion. We obtained the knowledge that it fluctuates. That is,
It has been found that when the oxide film is in an amorphous form, the adhesion is poor.

Therefore, the present invention provides a black titanium material having a black oxide film formed on its surface, wherein the oxide film is crystalline 1iT.
i*0. Crystal WTiot<7) It is characterized by being made of a titanium oxide containing one or more types.

Hereinafter, the black titanium material according to the present invention will be explained in detail.

The crystal structure of the oxide film of the black titanium material according to the present invention is as follows:
Crystalline Ti, 0. Or crystalline TiO2, for example, an amorphous oxide such as the oxide film according to the above application. In this case, the adhesion is poor. The crystal structure of the anatase form, etc. required by the present invention may be obtained by converting the amorphous oxide obtained through the sulfuric acid treatment and hydrofluoric acid treatment into the anatase form, etc. It may also be an oxide such as anatase directly produced by the above acid treatment.

Here, one example of a method for obtaining an oxide film having the above-mentioned crystal structure according to the present invention will be explained.

■ First, in the first step, the titanium material is heated to a sulfuric acid concentration of 10W.
t% or more and a solution temperature of 50℃ or more in a sulfuric acid aqueous solution of 30~
Soak for about 60 minutes, then rinse with water.

The reason why the sulfuric acid concentration is set to 10 wt% or more is that if it is less than this, the reaction with titanium is slow and it is difficult to form a black film. Although there is no upper limit to this concentration, it is preferably 30 to 50-t% in consideration of the ease of handling sulfuric acid and economic efficiency.

The solution temperature was set at 50°C or higher because sulfuric acid and titanium do not react if it is lower than this, but if the temperature is 90°C or higher, the generation of sulfuric acid mist becomes significant.
C. is preferable. Furthermore, if the immersion time is too short, the degree of blackening will be low. On the other hand, if the immersion time is too long, the degree of blackening will be saturated, so 30 to 60 minutes is preferable in consideration of productivity.

(2) Next, in the second step, the above-mentioned immersion material is further immersed in a hydrofluoric acid aqueous solution having a hydrofluoric acid concentration of 0.1 to 10-t% and a solution temperature of 35° C. or less for about 1 to 1000 seconds.

Here, the hydrofluoric acid concentration was set to 0.1 to 10 wt% because 0.1
If it is less than 1 wt%, the reaction rate will be slow, the treatment will take a long time, and productivity will be low. On the other hand, if it exceeds 10 wt%, the black film produced will dissolve and the degree of blackening will decrease. .

Furthermore, when the solution temperature exceeds 35°C, the black film reacts violently with hydrofluoric acid and becomes grayish white. There is no need to specify a lower limit, but if the temperature is too low, the treatment will take a long time, so a temperature of 5 to 20°C is preferable.

Furthermore, the reason why the immersion time was 1 to 1000 seconds was that if the immersion time was less than 1 second, the reaction would cause the above-mentioned apparent flaws;
This is because when the time is longer than 1 second, the black film is dissolved in hydrofluoric acid and the degree of blackening decreases, and this decrease in the degree of blackening.

Considering economic efficiency, the time is preferably 20 to 100 seconds.

■Finally, the above 1. 200 pieces of titanium material after the second process
Heat treatment is performed at a temperature of about ~450°C.

Here, the heating temperature was set at 200 to 450°C.
At temperatures below 450 °C, the oxide structure remains amorphous and does not change to the TizO, anatase, or rutile forms required by the present invention, while at temperatures above 450 °C, the black film becomes bluish. This is because the degree of blackening decreases.

The heating time does not need to be particularly specified, but heating for too long will not only saturate the effect, but also reduce productivity, so a period of about 30 to 60 minutes is recommended. Further, the heating atmosphere may be in the air, in a vacuum, or in an inert gas atmosphere such as nitrogen, and does not need to be particularly specified.

[Effect]

According to the black titanium material according to the present invention, since the black film is made of a titanium oxide containing one or more of crystalline TizO and crystalline tTiOt, the adhesion of the black film can be improved. . Although the details of why the adhesion is improved by forming the black film with the oxide structure of the present invention are unknown, when heat treatment is performed, oxygen diffuses from the oxide film to titanium. This is presumed to be due to an increase in the bonding strength between the oxide film and titanium.

〔Example〕

Examples carried out to confirm the effects of the present invention will be described below.

First, pure titanium cold-rolled material (300j! x300 wXo
, 6t) was immersed in a 35 wt % aqueous sulfuric acid solution at 80° C. for 60 minutes, washed with water, and further immersed in a 5 wt % aqueous hydrofluoric acid solution at 15° C. for 60 seconds to prepare a comparative test piece.

Next, a test piece made of the same material and size as in the above comparative example was subjected to the same two-step immersion treatment, and then immersed in the atmosphere at 300°C.
, 350°C, 400°C and in a nitrogen atmosphere.
Example test piece 1 was heated to a temperature of 50°C for 30 minutes each.
~4 was produced.

The black films formed on the comparative example and example test pieces were subjected to X-ray analysis measurements to investigate the crystal structure of the oxides constituting the films. Furthermore, each test piece was placed in an aqueous solution and subjected to ultrasonic cleaning for 30 minutes to investigate the peeling resistance, that is, adhesion, of the black film of each test piece.

The preparation conditions and test results for the above test piece are shown in Table 1. As is clear from this table, the oxide constituting the black film of the comparative example was in an amorphous form, and the presence of TiH2 was also observed. The brightness was slightly high at 16.8, and the black film of this comparative example was peeled off by ultrasonic cleaning, indicating that the adhesion was not sufficient.

On the other hand, in Examples 1 to 3, the crystal structure of the oxide changes from an amorphous structure to an anatase structure as the heating temperature increases, and then to an anatase structure, a rutile structure, and then a rutile structure. There is no peeling due to ultrasonic cleaning, and the adhesion is improved. Also,
The brightness also decreased as the heating temperature increased.
It can be seen that the degree of blackening has improved. In addition, Example 4
Now, since it was heated in a nitrogen atmosphere, the crystal structure is
It has a structure in which TizO + rutile and anatase forms coexist, and the adhesion is similarly good, and the brightness is even lower than in the case of heating in the air (Example 2).

In addition, in the above example, an example was shown in which the oxide of the black film was converted from an amorphous structure to an anatase form etc. by heating, but the oxide constituting the black film of the present invention does not necessarily have to be converted from an amorphous structure. Of course, it may be an oxide such as anatase directly produced in the oxide production step.

〔Effect of the invention〕

As described above, according to the black titanium material according to the present invention, the oxide film constituting the black film is TizO, and Table 1 shows a titanium oxide containing one or more of TiOz, such as rutile and anatase. This has the effect of improving the adhesion of the black film.

Patent applicant: Kobe Steel, Ltd.

Claims (1)

[Claims] (1) A black titanium material in which a black oxide film is formed on the surface of a titanium material (hereinafter including titanium alloy material), wherein the oxide film is crystalline Ti_2O, crystalline TiO_2
A black titanium material with excellent adhesion, characterized in that it is made of a titanium oxide containing one or more of the following.