JP2673147B2 - Method for producing titanium metal composite material on which crystalline metal titanate thin film is formed - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is a metal titanate thin film that is homogeneous and has good crystallinity on metallic titanium having a fine shape or a complicated surface shape such as powder, fiber, and whiskers. The present invention relates to a method for producing a titanium metal composite material having a structure.

BACKGROUND ART Metal titanate metal salt compounds such as barium titanate and lead titanate are widely used as sintered bodies for devices utilizing dielectric properties, semiconductivity, and piezoelectric properties. Furthermore, by thinning these substances, the application range is expanded, and it is considered that the metal-ceramic composite material in which metallic titanium is coated with these substances improves the wear resistance of metallic titanium. The possibility of modification and new applications such as composite material of metal titanium powder with thin film and plastic are also expected.

(Prior Art) Proposals have been made for particulate and fibrous fine dielectrics and methods for producing the same. For example, Japanese Patent Publication No. 62-7160 is an application example of a fibrous dielectric. This is a metal titanate salt formed into a fibrous form by reacting an appropriate titanium compound fiber with an aqueous solution containing a divalent metal ion.

On the other hand, as a technique for forming a metal titanate thin film on metallic titanium, a method that has been tried in the past can be applied. For example, it is disclosed in a vacuum deposition method such as electron beam or sputtering, a CVD (chemical vapor deposition method), a so-called sol-gel method by a hydrolysis / polymerization reaction of a metal organic or inorganic compound in a solution, or JP-A-61-30678. For example, the chemical conversion treatment method in a strong alkaline aqueous solution.

(Problems to be Solved by the Invention) However, when a conventional derivative consisting of, for example, a metal titanate alone is compounded with plastic, there is a problem that a desired relative permittivity can be obtained but dielectric loss is large. there were.

Further, with respect to the technique of forming a metal titanate thin film on metallic titanium, it is practically difficult to apply the conventional manufacturing method as it is. That is, in the vacuum deposition method, the film composition is likely to shift when a binary compound such as a metal titanate represented by AO.TiO ₂ (where A is the group A element) is formed. Since the above is used as a raw material, unnecessary elements such as chlorine may be mixed in, and in any case, a problem may occur in electrical characteristics. Further, these methods are difficult to apply to finely-shaped substances such as powder due to the principle of film formation. Also in the sol-gel method, raw materials such as metal alkoxide are expensive, and like the previous two methods, the crystallinity of the formed thin film is insufficient, which determines the dielectric and piezoelectric electrical properties. There was a problem that became a problem. In order to ensure these crystallizations, it was necessary to crystallize the amorphous film immediately after film formation by heat treatment. Further, in the chemical conversion treatment method, the titanium metal salt thin film formed on the surface of titanium metal may be insufficiently crystallized, which causes a problem such as peeling of the thin film.

(Means for Solving the Problems) In order to solve the above problems, a manufacturing method of forming a crystalline metal titanate metal salt thin film on the surface of titanium metal is titanium metal, a predetermined amount of water, and a concentration of 0.1. The reaction vessel is filled with one or more group A element compounds consisting of Ca, Sr, Ba, etc., alkaline earth metals such as Ca, Sr, and Ba, and Pb in an amount of mol% or more, and water at a temperature of 100 to 500 ° C. The reaction is carried out under thermal conditions, whereby a titanium metal composite material is obtained in which a perovskite-type metal titanate thin film represented by ATiO ₃ (where A is the group A element) is formed on the surface of titanium metal.

The compounds such as Sr and Ba do not have to be water-soluble at room temperature and atmospheric pressure, and any compound that dissolves under hydrothermal conditions may be used. Further, when using a raw material other than a water-soluble hydroxide, it is desirable to add a strong alkali, and even a compound that does not normally dissolve may be dissolved under high alkaline conditions, and it is possible to broaden the selection range of applicable raw material compounds. it can.

Further, since the present invention is a reaction in an aqueous solution under high pressure,
There is no occurrence of shadows (parts where a thin film is not formed) due to the directionality of film formation and the undulations of the surface shape, unlike vacuum evaporation.
Further, it can be applied to a fine shape such as powder, and there is an advantage that the shape of the metallic titanium substrate is not limited as long as it is a size that can be contained in the reaction vessel. Then, a thin film having good crystallinity can be manufactured without heat treatment after film formation.

As the element of the group A of ATiO ₃ , Ca, Sr, Ba and Pb are suitable when only one kind is reacted to form a film. For example, when only Mg is used, a thin film having a perovskite structure is not formed. , Can be applied by mixing with any of the above four types. By mixing two or more kinds of Group A elements in this way, it is possible to diversify the obtained electrical characteristics.

The film formation temperature may be 100 ° C. or higher, but preferably 200
The temperature is higher than or equal to 0 ° C., and the higher temperature can shorten the time for obtaining the desired film thickness. However, above 500 ° C, it becomes difficult to select the material and structure of the reaction vessel, and economically 500
C or lower is desirable. Taking barium titanate as an example, 2
The time required to form a film with a thickness of μm is 25 at 100 ° C.
At 250 ° C, it is 2 hours, and at 500 ° C, it is shorter than 1 hour. At this time, the influence of the concentration of the barium aqueous solution is small, but about 1 mol% is appropriate, and if it is 0.1 mol% or less, the film formation time tends to be long, but on the contrary, it does not require an extremely high concentration. . The film thickness of the metal titanate thin film obtained in the present invention is limited to about 10 μm, and if it exceeds the limit, the film pressure does not increase because peeling starts from the surface. Further, the obtained film had good crystallinity in any composition, and it was not necessary to crystallize the film in an amorphous state immediately after film formation by heat treatment as in the conventional sol-gel method.

(Example) Example 1 A metal titanium plate having a minor axis of 15 mm, a major axis of 20 mm, and a thickness of 1 mm and 1 mol
90 cc of an aqueous solution of barium hydroxide of 90% was charged into a reaction vessel having an internal volume of 150 ml, and a film was formed at 250 ° C. for 2 hours. Next, the titanium plate was taken out from the container naturally cooled to room temperature, washed with water, and dried at 85 ° C. for 24 hours.

As shown in FIG. 1, X-ray diffraction (Cu anticathode, 40KV-30mA) of the main surface of the titanium plate shows a diffraction pattern of barium titanate and metallic titanium, and as shown in FIG. When observing the surface with a microscope (SEM), spherical particles with a diameter of about 0.2 μm, which are considered to be barium titanate, are deposited and cover the entire surface. Similarly, from the observation of the cross section, the film thickness is about 2 μm. It was

Moreover, as shown in FIG. 3, silver electrodes 3 (11 mm × 16 mm) were formed on both main surfaces of the titanium plate 1 by a vacuum deposition method, and LCR
It was 670 when the relative dielectric constant (ε) of the barium titanate thin film 2 was calculated from the capacitance (C) value measured with a meter, the film thickness (t) and the electrode area (S). The concrete value is C = 261nF,
t = 2 μm and S = 176 mm ² . The relative permittivity (ε) is given by the following equation.

ε = 2Ct / ε ₀ S Here, ε ₀ has a dielectric constant of 8.854 × 10 ⁻¹² in vacuum.

Example 2 A titanium metal plate having a short diameter of 15 mm, a long diameter of 20 mm, and a thickness of 1 mm, barium hydroxide 17.16 g, strontium hydroxide 4.82 g, and pure water 6
0 cc was filled in a reaction container having an internal volume of 150 ml, and a film was formed at 200 ° C. for 5 hours. Next, the titanium plate was taken out from the container naturally cooled to room temperature, washed with water, and dried at 85 ° C. for 24 hours.

Measurement by X-ray diffraction on the main surface of this titanium plate showed a pattern of a substance having a perovskite structure similar to barium titanate and titanium metal. Observation of the surface with an electron microscope revealed that spherical particles with a diameter of approximately 0.2 μm, which are considered to be metal titanate salts of barium and strontium, were deposited and covered the entire surface. It was about 2 μm. In addition, Sr, Ba, and Ti were detected in the elemental analysis of the main surface by fluorescent X-ray. Next, Example 1
If a silver electrode is made on this titanium plate by the same method as above and the relative permittivity of the thin film is calculated from the capacitance value (C = 748nF) etc.
It was 920.

Example 3 5.0 g and 0.5 mol of powdery metallic titanium having an average particle size of about 30 μm
90 cc of a barium hydroxide aqueous solution of 90% was charged into the same reaction vessel as in Example 1 and film formation was performed at 250 ° C. for 2 hours. Next, the contents were taken out from the container which was naturally cooled to room temperature, filtration-washing was repeated until the pH of the washing water reached 7, and finally the filtration product was dried at 85 ° C for 24 hours.

Measurement of this titanium powder by X-ray diffraction showed a pattern of barium titanate and metallic titanium. Observation of the surface with an electron microscope revealed that spherical particles having a diameter of about 0.2 μm, which are considered to be barium titanate, were deposited and covered the individual titanium powders.

Example 4 A titanium metal plate having a minor axis of 15 mm, a major axis of 20 mm, and a thickness of 1 mm, 18.7 g of barium chloride, 7.0 g of potassium hydroxide, and 90 cc of pure water were charged in the same container as in Example 1, and film formation was carried out at 200 ° C. for 5 hours. I went. Next, the titanium plate was taken out from the container naturally cooled to room temperature, washed with water, and dried at 85 ° C. for 24 hours.

Measurement by X-ray diffraction on the main surface of this titanium plate showed a pattern of barium titanate and titanium metal. Observation of the surface with an electron microscope revealed that spherical particles with a diameter of about 0.2 μm, which are considered to be barium titanate, were deposited and covered the entire surface. Similarly, from observation of the cross section, the film thickness was 1.5 μm. It was Moreover, Ba, Ti, and a trace amount of K were detected in the elemental analysis by the fluorescent X-ray on the main surface. Next, in the same manner as in Example 1, a silver electrode was formed on this titanium plate, and the relative dielectric constant of the thin film was calculated from the capacitance value (C) and the like, and it was 730. Instead of potassium hydroxide (KOH), sodium hydroxide (NaOH), lithium hydroxide (LiO
H) may be added.

(Effect of the Invention) The titanium metal composite material on which the crystalline metal titanate thin film is formed by the production method according to the present invention has better crystallinity of the metal titanate thin film formed on the surface of titanium metal than conventional products. , This crystallinity showed excellent relative permittivity and excellent dielectric loss. That is, the electrode-formed titanium plate (product of the present invention) manufactured in Example 1 and a metal titanium plate having the same dimensions (minor diameter 15 mm, major diameter 20 mm, thickness 1 mm) have the same thickness on the surface ( 2μm) barium titanate thin film was formed by sputtering method, and the crystallinity of the barium titanate thin film was confirmed by X-ray diffraction for the conventional product in which silver electrodes were formed on both main surfaces of this metal titanium plate by vacuum deposition method. did. Fig. 4 shows (00
It is a figure which shows the X-ray-diffraction pattern of (2) plane and (200) (020) plane. In the figure, A is a thin film according to the first embodiment, and B is a thin film according to the conventional sputtering method. Although peaks on each surface of A can be confirmed, B of the peak is unclear and shows a broad pattern, and it is clear that the crystallinity is inferior. Further, when the relative permittivity and the dielectric loss (tan δ) of A and B are compared, the results are shown in Table 1. It can be seen that in both characteristics, the product A of the present invention is remarkably excellent.

Next, a comparative example of the test results will be shown for a titanium metal composite material in which a metal titanate salt thin film is formed on fine particles of titanium metal. Table 2 shows a comparison of the test data of the conventional example and the product of the present invention regarding the relative permittivity and the dielectric loss. In carrying out this test, a practical test cannot be carried out only with a titanium metal composite material on which a metal titanate thin film has been formed, so this was carried out for a composite material in which an epoxy resin was mixed at a ratio of 50 wt%. External dimensions of composite materials are vertical
50mm, width 50mm, thickness 1mm.

As described above, according to the manufacturing method of the present invention, as is clear from the measurement by X-ray diffraction shown in FIG. 1, the crystallization of the metal titanate metal salt thin film formed on the surface of metallic titanium can be reliably performed. It is possible to obtain a metal titanium composite material having desired additional electrical characteristics based on the formation of a metal titanate thin film. Therefore, the manufacturing process for crystallizing a film in an amorphous state immediately after film formation by heat treatment, which is required in the conventional manufacturing method, is no longer required. Further, according to these manufacturing methods, a metal titanate thin film can be formed on titanium metal having a fine particle shape, a fiber shape, or a complicated structure and various shapes.

Further, when the present invention is applied to metal titanium for whiskers, it has an advantage of improving mechanical strength (tensile strength, bending strength, etc.) in addition to the above advantages when compounded with plastic or the like.

[Brief description of the drawings]

FIG. 1 is a graph showing X-ray diffraction measurement data of an example of the present invention, FIG. 2 is an electron micrograph of an example of the present invention, and FIG. 3 is a schematic diagram showing a relative dielectric constant measurement model. FIG. 4 is a graph showing a comparative example of the X-ray diffraction measurement data of the product of the present invention and the conventional product.

Continuation of front page Jury President Judge Shunji Ogishima Judge Judge Mitsuo Karato Judge Yumi Ikoshi (56) References JP 61-30678 (JP, A) JP 63-144115 (JP, A) JP SHO 50 -40480 (JP, B2)

Claims (2)

(57) [Claims] 1. Metal titanium, a predetermined amount of water, and a concentration of 0.1 m
The amount of ol% or more of alkaline earth metal such as Ca, Sr, Ba, etc., and one or more group A element compounds of Pb are filled and sealed in a reaction vessel, and water at a temperature of 100 to 500 ° C. After reacting under thermal conditions, ATiO ₃ (but A
Is a method for producing a titanium metal composite material on which a perovskite-type metal titanate thin film represented by the above-mentioned group A element) is formed. 2. A titanium metal composite material having a metal titanate thin film according to claim 1, wherein a strong alkali such as KOH, NaOH or LiOH is added to the hydrothermal reaction system in an amount of 1 mol% or more. Manufacturing method.