JPH08246130A - Titanium-plated stainless steel sheet - Google Patents

Abstract

PURPOSE: To produce a titanium-plated steel sheet excellent in weatherability in the worked part by forming a titanium oxide film having specified film thickness via a titanium-plated film having specified film thickness on the surface of a stainless steel sheet. CONSTITUTION: On the surface of a stainless steel sheet, a titanium-plated film having 0.5 to 10μm film thickness is formed by ion plating or the like. On this film, an oxide titanium film constituted of TiO2 is formed by 0.1 to 5μm film thickness by a vacuum deposition method. The oxide titanium film formed via the titanium-plated film is excellent in adhesion, and the barrier effect of the titanium plated film and the cathode anticorrosive capacity of the oxide titanium film can be shown to the maximum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a titanium-plated stainless steel sheet which is excellent in weather resistance of a processed part when it is processed by cutting or bending.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for materials having excellent weather resistance for use in building materials. The stainless steel sheet is a material suitable for this application because it has a passivation film showing excellent weather resistance on its surface. However, in an environment where sea salt particles and sulfurous acid gas are scattered, such as in coastal areas and industrial areas, the passive film of stainless steel sheets is destroyed, so it easily rusts and has insufficient weather resistance. There is.

As a method for solving the above-mentioned problems, a method of adding elements such as Mo and Nb to steel, and a method of plating titanium surface having excellent weather resistance against chlorine ions and sulfur dioxide on the surface of a stainless steel sheet. There is. In particular, a number of titanium film forming methods have been studied because titanium film formation has become easier with the development of physical vapor deposition methods such as vacuum vapor deposition and ion plating.

However, since titanium does not have a sacrificial anticorrosion ability with respect to a stainless steel plate, corrosion progresses like a pitting corrosion starting from an exposed portion of the substrate such as a pinhole which is inevitable in a film obtained by physical vapor deposition. On the contrary, there is a drawback that perforation corrosion occurs in the stainless steel sheet in a short period of time.

To solve this problem, JP-A-63-2
Japanese Unexamined Patent Publication No. 10297 discloses a titanium-plated steel sheet in which a pinhole is sealed by sequentially forming a film of metallic chromium and chromium hydrate oxide on the titanium-plated steel sheet. Japanese Patent Laid-Open No. 63-235464 discloses that a steel plate is plated with titanium and then at 3 to 50 at 500 to 800 ° C.
A titanium alloy-plated steel sheet is disclosed in which pinholes are eliminated by subjecting a base steel sheet and a titanium plating layer to alloying by performing heat treatment for seconds.

In addition, a titanium oxide film is formed on a stainless steel substrate, and the titanium oxide film may cathodically protect the stainless steel substrate by photoelectromotive force generated by a photoelectrochemical reaction that occurs during light irradiation. A utilized stainless steel material having excellent weather resistance is disclosed in JP-A-6-10153.

[0007]

When used for building materials, it is often subjected to forming work such as cutting work and bending work by roll forming. It is also necessary to consider weather resistance. However, the technique disclosed in the above publication does not consider the weather resistance of the processed portion at all. Therefore, the present inventors investigated the weather resistance of the steel sheet disclosed in the above publication.

JP-A-63-210297 and JP-A-63-2
The titanium-plated steel sheet disclosed in Japanese Patent No. 35464 has some improvement in weather resistance when used as a flat plate without processing, but when subjected to forming processing, the end surface,
Regarding the exposed portion of the substrate such as the bent portion, the effect of improving the weather resistance was not recognized, and the weather resistance of the processed portion was poor.

Further, the stainless steel plate with a titanium oxide film disclosed in Japanese Patent Laid-Open No. 6-10153 is
Since the composition change at the titanium oxide film interface is abrupt, good film adhesion cannot be obtained, and when processing such as bending is performed, the film peeling tends to occur to the extent that cathodic protection is not achieved at the processed part, and the processed part It was found that sufficient weather resistance could not be obtained with.

That is, since the stainless steel sheet according to the technique disclosed in the above-mentioned publication has poor weather resistance in the processed portion, there is a problem that its use in building materials such as molding is restricted. is there.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a titanium-plated stainless steel sheet having excellent weather resistance in the processed portion.

The structure of the present invention for achieving the above object is a stainless steel plate having a titanium oxide film having a thickness of 0.1 to 5 μm formed on the surface of a stainless steel plate through a titanium plating film having a thickness of 0.5 to 10 μm. is there.

[0013]

The present invention will be described below.

The titanium-plated stainless steel sheet of the present invention is
This is based on the finding that the adhesion of the titanium oxide film is significantly improved by forming the titanium oxide film on the titanium plating film. The major feature is that the barrier effect of the titanium plating film and the cathodic protection of the titanium oxide film can be maximized.

Although the reason why the titanium oxide film exhibits excellent adhesion when it is formed on the titanium plating film is not always clear, a natural oxide film of titanium oxide is formed on the outermost surface layer of the titanium plating film. As a result, a sharp change in the interface composition with the titanium oxide film that is formed after this is mitigated and it becomes a kind of gradient composition, so that a good film is obtained even after processing such as bending and the like It is thought that adhesion may be obtained.

Next, the reasons for limiting the film of the present invention will be described. Titanium film layer: Indispensable for exerting excellent weather resistance especially on the flat surface due to the barrier effect, and the film thickness is 0.5-10 μm.
Must be m. If the film thickness is less than 0.5 μm, many pinholes will be present, and the barrier effect of titanium will not be fully exerted.If the film thickness exceeds 10 μm, productivity and economic efficiency will be compromised despite improved weather resistance. This is because it is significantly reduced.

By forming a titanium oxide film on this film, it becomes possible for the titanium oxide film to exhibit excellent adhesion. As a result, as described above, the barrier effect of the titanium film and the cathodic protection ability of the titanium oxide film can be maximized.

Titanium oxide film: It is extremely important for exhibiting excellent weather resistance by cathodically protecting the pinhole part of the lower titanium plating film and the exposed part of the substrate by processing. The film thickness must be 0.1-5 μm. This is because if the film thickness is less than 0.1 μm, the weather resistance becomes insufficient, and if it exceeds 5 μm, the adhesion of the titanium oxide film decreases. Further, when the film thickness is 0.8 μm or more, the cathodic protection performance is further improved, and as a result, the weather resistance,
In particular, the weather resistance at the edges is further improved. Therefore, when more excellent weather resistance is required, the film thickness is preferably 0.8 μm or more.

The reason why the titanium oxide film can exhibit excellent weather resistance is as follows. When the titanium oxide film is irradiated with light, the following photoelectrochemical reactions occur even if water containing corrosion factors such as chloride ions and sulfate ions is present on the surface, and the stainless steel plate or titanium film on the substrate Cathodic protection.

2H ₂ O → O ₂ + 4H ⁺ + 4e-This anodic reaction does not cause consumption of the coating such as a galvanized steel sheet, and therefore, cathodic protection lasts semipermanently under light irradiation. Therefore, the titanium oxide film can protect these parts from corrosion for a long time even if there are pinholes in the underlying titanium plating film and exposed parts of the substrate due to processing, and can exhibit excellent weather resistance. .

There is no particular limitation on the stainless steel plate as the substrate. Various stainless steel plates can be appropriately used according to the purpose of use. It is more preferable that the immersion potential difference between titanium and titanium is small, and as such a steel plate, for example, an austenitic stainless steel such as SUS304 is exemplified.

The effect of the present invention is not impaired even when a light-transmitting film is further formed on the titanium-plated steel sheet of the present invention.

Next, a method for manufacturing the titanium-plated steel sheet of the present invention will be described. The stainless steel plate serving as the base material is not particularly limited, and various stainless steel plates can be used.

There is no particular limitation on the method of forming titanium on the surface of the stainless steel plate. Any of physical vapor deposition such as ion plating and vacuum vapor deposition, or chemical vapor deposition may be used.

The method for forming the titanium oxide film is not particularly limited as long as it is a physical vapor deposition method. Either ion plating or vacuum deposition may be used, but the titanium oxide film has low electrical conductivity, so if the film thickness is too thick, it becomes difficult for the current to flow due to ion plating, and abnormal discharge occurs and the film becomes uneven. Therefore, the vacuum deposition method is more preferable. The titanium oxide obtained by these methods is TiO _2, which is preferable because TiO _{2 of} high purity which cannot be realized by the sol-gel method or the chemical vapor deposition method can be obtained.

[0026]

【Example】

(Example) Using a SUS304 stainless steel plate having a plate thickness of 0.1 to 1.5 mm as a substrate, a titanium film was formed by ion plating or vacuum deposition, and then a titanium oxide film was formed by vacuum deposition. Test materials within the range (No. 1 to 20) were created. The film was formed under the following conditions.

Titanium film formation by ion plating: After preheating a stainless steel plate at 100 to 300 ° C,
Pretreatment with Ar ion bombardment was performed in vacuum, and then the pure steel was heated and evaporated by electron beam at an atmospheric pressure of 1 × 10 ^-5 Torr or less while keeping the steel plate heated to 100 to 350 ℃, and the evaporated titanium particles Ionize the steel plate-100
The film was formed by applying a negative voltage of ~ -500V.

Titanium film formation by vacuum vapor deposition method: A stainless steel plate is preheated to 100 to 300 ° C. and then Ar is placed in vacuum.
Pretreatment with ion bombardment was performed, and then the steel plate was
While still heating at 0 to 350 ° C., pure titanium was heated and evaporated by an electron beam at an atmospheric pressure of 1 × 10 ⁻⁵ Torr or less to form a film.

Titanium oxide film formation by vacuum vapor deposition: TiO ₂ was heated and evaporated by an electron beam at an atmospheric pressure of oxygen partial pressure of 2 × 10 ^-4 Torr to form a film.

A coating adhesion test and a weather resistance test were conducted on the prepared test materials. The film adhesion test is 180
Bending was carried out at 0 ° for 0 t, and the peeling condition of the surface film at the bent portion was observed and evaluated by a scanning electron microscope at an acceleration voltage of 10 to 25 kV. In the evaluation, those having no peeling or cracking on the coating were evaluated as “◯”, and those having peeling or cracking on the coating were evaluated as “x”.

In the weather resistance test, a test material of the as-cut end face punched out into a circle of 45 mmφ and a test material bent at 0 ° of 180 ° were subjected to an exposure test for 12 months at Miyako Island in Okinawa Prefecture, and visually observed for flat surface. The ratio of the red rust generation area of the bent portion and the end portion (end surface) was evaluated. Evaluation is “◎”, 10% if there is no rust
Those having a rusting area of less than 10% were evaluated as “◯”, those having a rusting area of 10% or more and less than 60% were evaluated as “Δ”, and those having a rusting area of 60% or more were evaluated as “x”.

Table 1 shows the manufacturing conditions and test results of the test materials. Both have excellent weather resistance. In addition, No. 5 to 20 having a titanium oxide film thickness of 0.8 μm or more have better edge weather resistance.

[0033]

[Table 1]

(Comparative Example 1) Test materials (Nos. 21 to 23) were prepared in which the film thickness of the titanium film or titanium oxide film was out of the film thickness range of the present invention under the same substrate and the same film forming conditions as in the example. Then
The same investigation as in the example was conducted. The manufacturing conditions and test results of the test materials are shown in Table 1 which is the same as the examples. Both have poor weather resistance.

(Comparative Example 2) Using the same substrate as in Example,
Test material with only titanium film (No.31, 32), Test material with only titanium oxide film (No.33, 34), Test material with titanium film formed at 750 ° C for 23 seconds ( N
o.35), after forming the titanium film, metallic chromium is 30 mg / m ² ,
A test material (No. 36) treated with chromic acid having a hydrated chromium oxide of 36 mg / m ² was prepared. The conditions for forming the titanium film and titanium oxide film were the same as those in the example. With respect to these test materials, the same investigation as in the example was conducted. Table 2 shows the manufacturing conditions and test results of the test materials. Both have poor weather resistance.

[0036]

[Table 2]

[0037]

EFFECTS OF THE INVENTION The titanium-plated stainless steel sheet of the present invention has excellent weather resistance in the processed part, and therefore can exhibit excellent weather resistance even when processed in applications such as building materials.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshiharu Sugimoto 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (1)

[Claims] 1. A film thickness of 0.5 to 10 μm on the surface of a stainless steel plate.
A titanium-plated stainless steel sheet characterized in that a titanium oxide film having a thickness of 0.1 to 5 μm is formed through the titanium plating film of.