JPWO2017159324A1 - Conductive material and manufacturing method thereof - Google Patents

Abstract

It is a conductive material having a titanium film having an average film thickness of 1 μm or more and 300 μm or less on the surface of a substrate whose surface is conductive at least.

Description

  The present disclosure relates to a conductive material and a manufacturing method thereof. This application is based on Japanese Patent Application No. 2006-055432 which is a Japanese patent application filed on March 18, 2016 and Japanese Patent Application No. 2006-128561 which is a Japanese patent application filed on June 29, 2016. Insist. All the descriptions described in the Japanese patent application are incorporated herein by reference.

  Titanium is a metal having characteristics excellent in corrosion resistance, heat resistance and specific strength. However, titanium is expensive to produce and is difficult to smelt and process, which hinders widespread use. Currently, as one of the methods using the characteristics such as high corrosion resistance and high strength of titanium and titanium compounds, a dry film forming method using CVD (Chemical Vapor Deposition), PVD (Physical Vapor Deposition), etc. has been partially industrialized. However, there is a problem that a film cannot be formed on a substrate having a complicated shape. As a titanium film forming method that can solve this problem, a method of electrodepositing titanium in a molten salt can be considered.

Various types of molten salt baths capable of electrodepositing titanium have been known and are being studied. For example, Non-Patent Document 1 describes a method of forming a titanium film on the surface of Ni or Fe using a molten salt bath in which K ₂ TiF ₆ is added to LiF—NaF—KF. Non-Patent Document 2 describes a method of forming a titanium film on the surface of Au or Ni using a molten salt bath in which TiCl ₃ is added to LiCl—KCl. Non-Patent Document 3 describes a method of forming a titanium film on the surface of SUS304 using a molten salt bath in which K ₂ TiF ₆ is added to LiCl—NaCl—KCl. JP-A-2015-193899 (Patent Document 1) forms an alloy film of Fe and Ti on the surface of Fe wire using a molten salt bath in which K ₂ TiF ₆ or TiO ₂ is added to KF-KCl. It is described.

In addition, a refining method for depositing high-purity metallic titanium on a substrate using a molten salt bath is also known. For example, Japanese Patent Application Laid-Open No. 08-225980 (Patent Document 2) describes a method of depositing high-purity titanium on the surface of Ni using a molten salt bath in which TiCl ₄ is added to a NaCl bath. Japanese Patent Application Laid-Open No. 09-071890 (Patent Document 3) describes a method of depositing high-purity titanium on the surface of a titanium rod using a NaCl or Na-KCl bath.

JP2015-193899A Japanese Patent Application Laid-Open No. 08-225980 JP 09-071890 A

A. ROBIN et.al., “ELECTROLYTIC COATING OF TlTANIUM ONTO IRON AND NICKEL ELECTRODES IN THE MOLTEN LiF + NaF + KF EUTECTIC” Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 1987, vol230, pp.125-141 Hiroshi Takamura et al., “Smooth electrodeposition of titanium from LiCl-KCl-TiCl3 molten salt”, Journal of the Japan Institute of Metals, 1996, Vol. 60, No. 4, pp.388-397 Tsuji Daiha et al., “Characteristics of Titanium Thin Films Deposited by Molten Salt Pulse Current Method”, Journal of the Japan Institute of Metals, 1994, Vol. 58, No. 6, pp.660-667 Jianxun Song et.al., “The Influence of Fluoride Anion on the Equilibrium between Titanium Ions and Electrodeposition of Titanium in Molten Fluoride-Chloride Salt” Materials Transactions, 2014, vol.55, No.8, pp.1299-1303 Yang Song et.al., “The Cathodic Behavior of Ti (III) Ion in a NaCl-2CsCl Melt” Metallurgical and Materials Transactions B, 2016, vol.47B, February, pp.804-810

  The conductive material of the present disclosure is a conductive material having a titanium film having an average film thickness of 1 μm or more and 300 μm or less on the surface of a substrate having a conductive surface at least.

A method for producing a conductive material according to the present disclosure is a method for producing the above-described conductive material, wherein a molten salt bath forming step of preparing a molten salt bath containing KF, KCl, and K ₂ TiF ₆ and a molten salt bath are provided. A dissolution process comprising: dissolving a Ti; and an electrolytic process of depositing Ti on the surface of the cathode by performing molten salt electrolysis using a cathode and an anode provided in a molten salt bath in which Ti is dissolved. In the molten salt bath, Ti ⁴⁺ in the molten salt bath is supplied with an amount of Ti exceeding the minimum amount necessary to become Ti ³⁺ by the leveling reaction represented by the following formula (1). As a method for producing a conductive material using a base material having at least a conductive surface.
Formula (1)
3Ti ⁴⁺ + Ti metal → 4Ti ³⁺

FIG. 1 is a schematic cross-sectional view showing an example of the conductive material of the embodiment. FIG. 2 is a conceptual diagram for explaining a method of measuring the average film thickness of the titanium film. 3 shows the conductive material No. 1 in the example. 5 is a photograph of the surface of the titanium film of No. 5 observed with a scanning electron microscope (SEM). 4 shows the conductive material No. 1 in the example. It is the photograph of the secondary electron image which observed the cross section of 5 with the scanning electron microscope (SEM). FIG. 5 shows the conductive material No. in Example. 5 is a photograph of a reflected electron image obtained by observing the cross section of No. 5 with a scanning electron microscope (SEM).

[Problems to be solved by the present disclosure]
The method described in Non-Patent Document 1 has a problem that the washability after plating is poor because LiF and NaF contained in the molten salt bath hardly dissolve in water. In addition, the molten salt bath described in Non-Patent Document 2 and Non-Patent Document 3 is excellent in water washability, and can deposit titanium at a lower temperature than the molten salt bath described in Non-Patent Document 1, A smooth titanium film could not be obtained. As described in Non-Patent Document 4 and Non-Patent Document 5, it is effective to use a bath containing F ions for the production of a smooth titanium film. It is considered that a smooth titanium film could not be obtained in a bath that does not contain F ions or does not contain enough F ions as in Non-Patent Document 3.

  Further, as a result of the study by the present inventors, the method described in Patent Document 1 can electrodeposit an alloy film of Fe and Ti, but cannot deposit a metal titanium film. That is, the alloy film of Fe and Ti is stable in the molten salt bath, whereas metal Ti is not sufficient in that it is dissolved into the molten salt bath by the leveling reaction. Moreover, the method of patent document 2 and patent document 3 is a method of refining titanium, and the titanium to electrodeposit is dendritic. That is, the method described in Patent Document 2 and Patent Document 3 cannot obtain a smooth titanium film.

  Then, this indication aims at providing the electroconductive material which has the thin titanium film on the surface with few dispersion | variation in film thickness in view of the said problem.

[Effects of the present disclosure]
According to the present disclosure, it is possible to provide a conductive material having a thin titanium film on the surface with little variation in film thickness.

[Description of Embodiment]
First, embodiments of the present disclosure will be listed and described.

  [1] The conductive material of the present disclosure has a titanium film having an average film thickness of 1 μm or more and 300 μm or less on at least the surface of a substrate having a conductive surface.

  According to the conductive material, it is possible to provide a conductive material having a thin titanium film on the surface with little variation in film thickness.

  [2] When the thickness of the titanium film is measured at any five locations on the surface of the conductive material, each of the maximum thickness and the minimum thickness of the titanium film measured at any five locations is measured. Is preferably within ± 50% of the average film thickness. Thus, a conductive material having a smooth titanium film with little variation in film thickness can be provided.

  [3] In the conductive material, the titanium film has a titanium layer and a titanium alloy layer containing an alloy of titanium and a metal contained in the base material, and the titanium alloy layer includes a titanium layer and a base material. It is preferably located between. In this case, since the stress generated between the titanium film and the base material is relaxed, the titanium film is difficult to peel off.

[4] A method for producing a conductive material according to the present disclosure is a method for producing the conductive material, the molten salt bath forming step of preparing a molten salt bath containing KF, KCl, and K ₂ TiF ₆ , A surface of the cathode by supplying Ti into the salt bath and dissolving the Ti in the molten salt bath, and performing molten salt electrolysis using the cathode and anode provided in the molten salt bath in which Ti is dissolved In the dissolution step, Ti ⁴⁺ in the molten salt bath is the minimum amount necessary to become Ti ³⁺ by the leveling reaction represented by the following formula (1). In the electrolysis step, a substrate having at least a conductive surface is used as the cathode.
Formula (1)
3Ti ⁴⁺ + Ti metal → 4Ti ³⁺

  According to the method for producing a conductive material, a conductive material having a thin titanium film on the surface with little variation in film thickness can be produced.

  [5] In the method for producing the conductive material, the mixing ratio of KF and KCl is preferably 10:90 to 90:10 in terms of molar ratio. Thereby, the said electroconductive material can be manufactured with a molten salt bath lower temperature than KF independent molten salt.

[6] In the method for producing the conductive material, the content ratio of K ₂ TiF ₆ in the molten salt bath is preferably 0.1 mol% or more. Thereby, the said electroconductive material can be manufactured stably.

  [7] In the method for producing the conductive material, Ti supplied in the melting step is preferably sponge titanium. Thereby, the equalization reaction of Ti can be easily advanced in the melting step. Sponge titanium refers to a porous titanium metal having a porosity of 1% or more. The porosity of sponge titanium is calculated by 100− (volume calculated from mass) / (apparent volume) × 100.

  [8] In the above method for producing a conductive material, the anode is preferably made of Ti. Thereby, the titanium film can be stably and continuously deposited on the surface of the cathode.

[Details of the embodiment]
Embodiments of the present disclosure are described in more detail below. In addition, this embodiment is not limited to these, It is shown by the claim, and it is intended that all the changes within the meaning and range equivalent to a claim are included.

<Conductive material>
FIG. 1 is a schematic cross-sectional view showing an example of the conductive material of the embodiment. As shown in FIG. 1, the conductive material 10 is a conductive material having a titanium film 12 having an average film thickness of 1 μm or more and 300 μm or less on the surface of a substrate 11 having a conductive surface at least.

(Base material)
The base material 11 should just be what the surface has electroconductivity at least. For example, a metal having a use for forming the titanium film 12 on the surface, a conductive sintered body, or the like can be given. Specifically, nickel, iron, SUS304, molybdenum, tungsten, copper, carbon, or the like can be preferably used.

  Moreover, the shape of the base material 11 is not specifically limited. For example, it may have a flat plate shape, a rod shape, a cylindrical shape, or a complicated three-dimensional shape. According to the conductive material manufacturing method described later, the titanium film 12 can be easily formed on the surface of the base material 11 even if the base material 11 has a complicated three-dimensional shape.

(Titanium film)
The titanium film 12 is located on the surface of the base material 11. Specifically, the titanium film 12 covers the surface of the base material 11. The titanium film 12 may cover the entire surface of the base material 11 or may cover a part thereof. The titanium film 12 has an average film thickness of 1 μm or more and 300 μm or less. The average film thickness of the titanium film 12 shall be measured as follows.

  FIG. 2 is a conceptual diagram for explaining a method of measuring the average film thickness of the titanium film. As shown in FIG. 2, first, the conductive material 10 is arbitrarily divided into areas, and five locations (area 1 to area 5) are selected as measurement locations. And the cross section of the titanium film 12 in each area is observed with a scanning electron microscope (SEM). The magnification of the SEM is set so that the whole thickness direction of the titanium film 12 can be confirmed and the thickness direction can be seen as large as possible within one field of view. Then, change the field of view and observe three places in each area.

  As an example, FIG. 2 shows a conceptual diagram when three visual fields (fields 1 to 3) are observed in area 1. FIG. In each field of view, the maximum thickness dmax where the thickness of the titanium film 12 is maximum and the minimum thickness dmin where the thickness is minimum are measured. The thickness of the titanium film 12 refers to the length of the titanium film 12 extending in the vertical direction from the substrate 11. Thereby, in area 1, the maximum thickness dmax of the three visual fields and the minimum thickness dmin of the three visual fields are determined. For area 2 to area 5, as in area 1, the maximum thickness dmax and the minimum thickness dmin in the three visual fields are measured. The average value of all 15 maximum thicknesses dmax and 15 minimum thicknesses dmin measured as described above is referred to as an average film thickness of the titanium film.

  When the average film thickness of the titanium film 12 is 1 μm or more, the corrosion resistance and the heat resistance are sufficiently exhibited. In addition, since the average film thickness of the titanium film 12 is 300 μm or less, the conductive material 10 having the titanium film 12 can be provided at a low cost without excessively forming the titanium film 12 on the surface of the substrate 11. Can do. From these viewpoints, the average film thickness of the titanium film 12 is more preferably 5 μm or more and 200 μm or less, and further preferably 15 μm or more and 100 μm or less.

  The titanium film 12 is preferably a smooth film with little variation in film thickness. Since the titanium film 12 is a smooth film with little variation in film thickness, there is no portion where the film thickness of the titanium film 12 is extremely thin, so that the corrosion resistance and heat resistance of the conductive material 10 are more reliable. It becomes.

  Here, when the thickness of the titanium film 12 is measured at any five locations on the surface of the conductive material 10, the thickness of the titanium film 12 is a smooth film with little variation in film thickness. Each (all) of the maximum thickness dmax and the minimum thickness dmin of the titanium film 12 is within ± 50% of the average film thickness. That is, all of the 15 maximum thicknesses dmax and the 15 minimum thicknesses dmin measured by the above-described method for measuring the average film thickness of the titanium film 12 are within ± 50% of the average film thickness. That means.

  Returning to FIG. 1, the titanium film 12 includes a titanium layer 12 a and a titanium alloy layer 12 b, and the titanium alloy layer 12 b is preferably located between the titanium layer 12 a and the substrate 11. More specifically, it is preferable that the titanium film 12 has a configuration in which a titanium alloy layer 12b and a titanium layer 12a are stacked in this order from the substrate 11 side.

  Here, the titanium layer 12a is a layer made of only titanium (however, inevitable impurities may be included). The titanium alloy layer 12b is an alloy of metal and titanium contained in the substrate 11 (however, it may contain inevitable impurities). The metal contained in the substrate 11 means a metal that exhibits conductivity at least on the surface of the metal.

  As will be described later, the conductive material 10 is manufactured by plating titanium on the surface of the substrate 11. Titanium plating is performed in a molten salt bath at a high temperature of about 650 ° C. Therefore, if the conductive material 10 is rapidly cooled after plating, a large stress is generated due to the difference in thermal expansion coefficient between the titanium and the substrate 11. In the case where the titanium film 12 has a configuration including the titanium layer 12a on the front surface side and the titanium alloy layer 12b on the substrate 11 side, the stress is relieved by the titanium alloy layer 12b. Thereby, peeling of the titanium film 12 from the base material 11 can be suppressed.

  The thickness of the titanium alloy layer 12b is not particularly limited, and is preferably 0.1 μm or more and 20 μm or less, for example. When the thickness of the titanium alloy layer 12b is 0.1 μm or more, the titanium film 12 can be made more difficult to peel. Moreover, when the thickness of the titanium alloy layer 12b is 20 μm or less, it is possible to prevent the function of pure titanium from being exhibited (that is, the function due to the titanium layer 12a). From these viewpoints, the thickness of the titanium alloy layer 12b is more preferably 0.5 μm or more and 15 μm or less, and further preferably 1 μm or more and 10 μm or less.

For example, when the base material 11 is made of nickel, the titanium alloy layer 12b is preferably three layers. More specifically, a composite layer 2bc of TiNi ₃ and Ni, a composite layer 2bb of TiNi and TiNi ₃ and a composite layer 2ba of Ti ₂ Ni and TiNi are laminated on the surface of the substrate 11 made of Ni in this order. The titanium alloy layer 12b and the titanium layer 12a are preferably formed in this order. In this case, the buffering function for relaxing the stress generated between the titanium film 12 and the substrate 11 is enhanced.

  In addition, the titanium film 12 including the titanium alloy layer 12b can be formed on the substrate side by forming the titanium film 12 on the substrate 11 made of iron, SUS304, copper, carbon, or the like by plating. .

<Method for producing conductive material>
The conductive material manufacturing method of the present embodiment includes a molten salt bath forming step of preparing a molten salt bath containing KF, KCl and K ₂ TiF ₆ , a dissolving step of dissolving Ti in the molten salt bath, And an electrolysis step of depositing Ti on the surface of the cathode by performing molten salt electrolysis using a cathode and an anode provided in a molten salt bath. Each step will be described in detail below.

-Molten salt bath formation process-
The molten salt bath forming step is a step of preparing a molten salt bath containing KF, KCl, and K ₂ TiF ₆ .

KF-KCl eutectic molten salt has a melting point lower than that of KF or a molten salt of KCl alone, and is easily soluble in water. can do. Further, when Ti is electroplated using a molten salt bath in which K ₂ TiF ₆ is added to a KF—KCl eutectic molten salt, a smooth titanium film can be electrodeposited on the substrate surface.

  The mixing ratio of KF and KCl is preferably 10:90 to 90:10 in molar ratio. When the content ratio of KF in KF-KCl is 10 mol% or more, a smooth titanium film can be electrodeposited on the surface of the substrate. Further, when the content ratio of KF in KF-KCl is 90 mol% or less, the melting point can be lowered as compared with the molten salt of KF alone. From these viewpoints, the mixing ratio of KF and KCl is more preferably a molar ratio of 20:80 to 80:20, and still more preferably 40:60 to 60:40.

By adding K ₂ TiF ₆ to the KF—KCl eutectic molten salt, a molten salt bath capable of electrodepositing a titanium film on the surface of the substrate can be obtained. The timing of adding K ₂ TiF ₆ is not particularly limited, and KF, KCl and K ₂ TiF ₆ may be mixed and heated to form a molten salt bath, or KF-KCl eutectic molten salt may be mixed with KF. ₂ TiF ₆ may be added to form a molten salt bath.

The content ratio of K ₂ TiF ₆ in the molten salt bath is preferably 0.1 mol% or more. When the content ratio of K ₂ TiF ₆ is 0.1 mol% or more, a molten salt bath capable of efficiently depositing Ti on the surface of the substrate can be obtained.

-Dissolution process-
The melting step is a step of supplying Ti into the molten salt bath prepared by the molten salt bath forming step and dissolving Ti in the molten salt bath. The amount of Ti to be supplied may be an amount exceeding the minimum amount necessary for Ti ⁴⁺ in the molten salt bath to become Ti ³⁺ by the leveling reaction represented by the following formula (1).
Formula (1)
3Ti ⁴⁺ + Ti metal → 4Ti ³⁺

  By sufficiently dissolving Ti in advance in the molten salt bath, it is possible to prevent Ti that is electrodeposited in the subsequent electrolytic step from being dissolved in the molten salt bath. For this reason, according to the manufacturing method of the electroconductive material which concerns on this embodiment, the thin titanium film with few dispersion | variation in film thickness can be formed on the surface of a base material.

  The amount of Ti supplied to the molten salt bath is more preferably at least twice as much as the above-mentioned minimum amount, and more preferably at least three times. Further, for example, it is preferable to supply Ti so that Ti is in a state of being precipitated without being completely dissolved in the molten salt bath.

  The shape of Ti to be supplied is not particularly limited, but it is preferable to use sponge titanium or titanium powder as fine as possible. The higher the porosity of titanium sponge, the greater the specific surface area, so that it becomes easier to dissolve in the molten salt bath. For this reason, it is more preferable to use sponge titanium having a porosity of 20% or more, and it is further preferable to use sponge titanium having a porosity of 40% or more. The upper limit of the porosity is not particularly limited, but is considered to be about 85% from the viewpoints of ease of handling, ease of manufacture, and the like.

-Electrolytic process-
The electrolysis step is a step of performing molten salt electrolysis using a cathode and an anode provided in a molten salt bath in which Ti is dissolved. By performing molten salt electrolysis on the molten salt bath in which Ti is dissolved, Ti is electrodeposited, and a thin titanium film can be formed on the surface of the cathode with little variation in film thickness.

(Cathode)
Since a titanium film is formed on the surface of the cathode as described above, a conductive material base material for manufacturing purposes may be used as the cathode. The base material only needs to have a conductive surface at least, and may be a base material in the conductive material according to the above-described embodiment. By using a material alloyed with titanium as a base material, a titanium alloy layer can be generated on the base material side of the titanium film. In addition, when a high-purity titanium film that does not have a titanium alloy layer (that is, a titanium film composed of only a titanium layer) is formed, a material that does not alloy with Ti in the molten salt bath is used as the base material (cathode). Can be used.

(anode)
The anode is not particularly limited as long as it is a conductive material. For example, glassy carbon, titanium, or the like can be used. From the viewpoint of stably and continuously producing a titanium film, it is preferable to use an anode made of Ti.

(Other conditions)
The atmosphere in which the molten salt electrolysis is performed may be a non-oxidizing atmosphere that does not form a compound with titanium. For example, molten salt electrolysis may be carried out in a glove box filled with an inert gas such as argon gas or circulated.

Current density for performing molten salt electrolysis, but are not particularly limited, for example, may be set to 10 mA / cm ² or more 500mA / cm ² or less. By setting the current density to 10 mA / cm ² or more, a titanium film can be stably formed on the surface of the cathode. Moreover, by setting the current density to 500 mA / cm ² or less, the diffusion of titanium ions in the molten salt bath is not rate-limiting, and the formed titanium film can be prevented from being blackened. From these viewpoints, the current density, more preferably, to 50 mA / cm ² or more 250 mA / cm ² or less, and more preferably be 100 mA / cm ² or more 200 mA / cm ² or less.

  In the electrolysis step, the temperature of the molten salt bath is preferably 650 ° C. or higher and 850 ° C. or lower. By setting the temperature of the molten salt bath to 650 ° C. or higher, the molten salt bath can be kept in a liquid state and molten salt electrolysis can be performed stably. Moreover, it can suppress that the component of a molten salt bath evaporates and a molten salt bath becomes unstable by making the temperature of a molten salt bath into 850 degrees C or less. From these viewpoints, the temperature of the molten salt bath is more preferably 650 ° C. or more and 750 ° C. or less, and further preferably 650 ° C. or more and 700 ° C. or less.

  The time for performing the molten salt electrolysis is not particularly limited, and may be a time during which the target titanium film is sufficiently formed.

  Hereinafter, although this embodiment is described in detail based on an Example, these Examples are illustrations, Comprising: The electroconductive material of this indication, and its manufacturing method are not limited to these.

Example 1
-Molten salt bath formation process-
KCl, KF and K ₂ TiF ₆ were mixed and heated to 650 ° C. so that the mixing ratio of KCl and KF was 55:45 in terms of molar ratio, and the concentration of K ₂ TiF ₆ was 0.1 mol%, and the molten salt A bath was made.

-Dissolution process-
13 mg of sponge titanium was added to 1 g of molten salt bath in the molten salt bath prepared in the molten salt bath forming step, and dissolved sufficiently. As the sponge titanium, one having a porosity of 50% was used. In the molten salt bath, sponge titanium that could not be completely dissolved was precipitated.

-Electrolytic process-
Molten salt electrolysis was performed in a glove box with an Ar flow atmosphere. A 0.5 cm × 2.5 cm × 0.1 mmt Ni plate was used as the cathode, and a Ti rod was used as the anode. In addition, a Pt line was used as the pseudo reference electrode. Then, molten salt electrolysis was performed by applying a voltage to the cathode and the anode so that the current density was 25 mA / cm ² . The potential of the pseudo reference electrode was calibrated with the potential of metal K electrochemically deposited on the Pt line (K ⁺ / K potential). As a result, titanium was electrodeposited on the surface of the Ni plate of the cathode, and a conductive material having a titanium film could be obtained.

-Washing-
The electroconductive material was washed with water after the electrolysis process. The salt adhering to the surface of the conductive material was excellent in solubility in water and could be easily removed. Conductive material No. 1 having a titanium film by the above process. 1 was obtained.

(Example 2)
The conductive material No. 1 was the same as Example 1 except that the current density was set to 100 mA / cm ² . 2 was produced.

(Example 3)
The conductive material No. 1 was the same as Example 1 except that the concentration of K ₂ TiF ₆ was 2.0 mol%. 3 was produced.

(Example 4)
The conductive material No. 1 was the same as Example 3 except that the current density was 100 mA / cm ² . 4 was produced.

(Example 5)
The conductive material No. 1 was the same as in Example 3 except that the current density was 150 mA / cm ² . 5 was produced.

(Example 6)
Except for the current density of 200 mA / cm ² , the conductive material no. 6 was produced.

(Comparative Example 1)
The conductive material No. 1 was the same as in Example 1 except that the melting step was not performed and the current density was 150 mA / cm ² . 7 was produced.

(Comparative Example 2)
In the same manner as in Comparative Example 1 except that the concentration of K ₂ TiF ₆ was 2.0 mol% and the current density was 100 mA / cm ² , the conductive material No. 8 was produced.

(Comparative Example 3)
The conductive material No. 1 was the same as Comparative Example 2 except that the current density was 150 mA / cm ² . 9 was produced.

(Comparative Example 4)
The conductive material No. 1 was the same as Comparative Example 2 except that the current density was 200 mA / cm ² . 10 was produced.

(Comparative Example 5)
The conductive material No. 1 was the same as Comparative Example 1 except that the concentration of K ₂ TiF ₆ was 5.0 mol%. 11 was produced.

-Evaluation-
Conductive material No. 1-No. 11 was evaluated as follows.

<Appearance of titanium film>
Conductive material No. 1-No. The appearance of the film formed on the surface of the 11 substrate was visually observed, and the presence or absence of titanium in the film was examined by XRD (X-Ray Diffraction). The results are shown in Table 1 below.

  As shown in Table 1, the conductive material No. 1-No. No. 6 was confirmed to be a silver-white titanium film on the surface of the Ni plate as the substrate. On the other hand, the conductive material No. 7-No. No. 11 had a black film formed on the surface of the Ni plate, and titanium could not be detected by XRD.

<Average film thickness of titanium film>
According to the above-mentioned method, the obtained conductive material No. The maximum thickness dmax and the minimum thickness dmin of one titanium film were measured. The results are shown in Table 2 below.

  From the results in Table 2, the conductive material No. The average film thickness of the titanium film 1 was 29 μm, and it was confirmed that the maximum thickness dmax and the minimum thickness dmin were all within ± 50% of the average film thickness. Similarly, the conductive material No. 2-No. 6 was also measured, and the average film thickness and film thickness distribution were calculated. The results are shown in Table 3 below. The film thickness distribution refers to the percentage of the average film thickness within the 15 maximum thicknesses dmax and 15 minimum thicknesses dmin.

<SEM / EDX photo>
Conductive material No. FIGS. 3 and 4 show photographs of secondary electron images obtained by observing the surface and cross section of No. 5 with a Schottky field emission scanning electron microscope (SEM) “manufactured by JEOL Ltd .: JSM-7600F”, respectively. In addition, the conductive material No. FIG. 5 shows a photograph of a reflected electron image obtained by observing the cross section of No. 5 with a scanning electron microscope (SEM). The cross-section processing was performed by embedding a conductive material in a resin, and by mechanical polishing and a cross section polisher.

  In addition, the conductive material No. The composition analysis was performed by performing EDX analysis (Energy Dispersive X-ray spectroscopy) about 5. The EDX analysis was performed by using an energy dispersive X-ray analyzer (EDX: X-max80 premium manufactured by OXFORD) to set the acceleration voltage to 10 kV and performing point analysis at the center in the thickness direction of each alloy layer.

  As shown in FIGS. 3 and 4, it was confirmed that the surface of the titanium film 2 was smooth. Further, a titanium alloy layer 2b was confirmed on the substrate side of the titanium film 2, that is, between the titanium layer 2a and the Ni substrate 1. Peeling of the titanium film 2 from the Ni base material 1 was not confirmed.

As shown in FIG. 5, the titanium alloy layer 2b has a three-layer structure. From the side close to the Ni base 1, the TiNi ₃ and Ni composite layer 2bc, the TiNi and TiNi ₃ composite layer 2bb, and Ti ₂ Ni The TiNi composite layer 2ba was formed in this order. Further, the total thickness of the titanium alloy layer 2b is about 3 μm, the composite layer 2bc of TiNi ₃ and Ni is the thickest, the composite layer 2bb of TiNi and TiNi ₃ is the next thickest, and the composite layer of Ti ₂ Ni and TiNi 2ba was the thinnest.

10 conductive material, 11 base material, 12 titanium film, 12a titanium layer, 12b titanium alloy layer, 1 Ni base material, 2 titanium film, 2a titanium layer, 2b titanium alloy layer, 2ba Ti ₂ Ni and TiNi composite layer, 2bb TiNi and TiNi ₃ composite layer, 2bc TiNi ₃ and Ni composite layer).

Claims (8)

  A conductive material having a titanium film having an average film thickness of 1 μm or more and 300 μm or less on at least the surface of a substrate having a conductive surface. When the thickness of the titanium film is measured at any five locations on the surface of the conductive material,
2. The conductive material according to claim 1, wherein each of the maximum thickness and the minimum thickness of the titanium film measured at the five arbitrary positions is within ± 50% of the average film thickness. The titanium film has a titanium layer and a titanium alloy layer containing an alloy of a metal and titanium contained in the base material,
The conductive material according to claim 1, wherein the titanium alloy layer is located between the titanium layer and the base material. It is a manufacturing method of the electroconductive material of any one of Claims 1-3, Comprising:
A molten salt bath forming step of preparing a molten salt bath containing KF, KCl and K ₂ TiF ₆ ;
A dissolving step of supplying Ti into the molten salt bath and dissolving the Ti in the molten salt bath;
An electrolytic step of depositing Ti on the surface of the cathode by performing molten salt electrolysis using a cathode and an anode provided in the molten salt bath in which the Ti is dissolved;
Including
In the melting step, Ti ⁴⁺ in the molten salt bath is supplied with an amount of Ti that exceeds the minimum amount necessary to become Ti ³⁺ by the leveling reaction represented by the following formula (1).
In the electrolysis step, a method for producing a conductive material, wherein a substrate having at least a surface of conductivity is used as the cathode.
Formula (1)
3Ti ⁴⁺ + Ti metal → 4Ti ³⁺   The method for producing a conductive material according to claim 4, wherein a mixing ratio of the KF and the KCl is 10:90 to 90:10 in terms of molar ratio. The method for producing a conductive material according to claim 4 or 5, wherein a content ratio of K ₂ TiF ₆ in the molten salt bath is 0.1 mol% or more.   The manufacturing method of the electroconductive material of any one of Claims 4-6 whose said Ti supplied in the said melt | dissolution process is sponge titanium.   The method for producing a conductive material according to claim 4, wherein the anode is made of Ti.