JP3247517B2 - Plating method of titanium material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for plating a titanium material, such as nickel or copper, on a surface of a titanium material made of titanium metal or a titanium alloy.

[0002]

2. Description of the Related Art Titanium is widely used for various mechanical parts, ornaments such as watches and glasses, insoluble electrodes for water electrolysis and electroplating, or electrode support bases, because of its light weight, high strength and excellent corrosion resistance. However, due to reasons such as insufficient hardness, inability to solder, low corrosion resistance in the presence of fluoride ions, and the formation of an insulative passive film under anodic polarization, current cannot be applied. , N for some applications
i, Cu, Sn, Co, Pb, Pt, Au, Pd, Ir
It is necessary to apply such a plating film.

[0003]

[Problems to be Solved] However, a chemically stable oxide film exists on the surface of the titanium material, and even if the oxide film is removed, it is easily oxidized again in the air or water and becomes inactive. For this reason, it is difficult to form the plating uniformly with good adhesion. In particular, when the plating process is performed by electroless plating, it is difficult to deposit a desired plating itself as a problem before securing the adhesion of the plating film. For this reason, various plating pretreatment methods have been disclosed.

For example, Japanese Patent Application Laid-Open No. 3-150391 discloses that a titanium material is immersed in an aqueous solution of 0.2 to 1.0% by volume of hydrogen fluoride to form a titanium hydride on a surface to be plated of the titanium material. There is disclosed a plating method for a titanium material, which comprises forming a film having a main composition of, followed by plating. However, in this method, since the aqueous solution of hydrogen fluoride has a low concentration of 0.2 to 1.0% by volume, it is difficult to remove the oxide film on the surface of the titanium material. Therefore, an oxide film remains between the plating film and the titanium material, and the adhesion of the plating film is weak.

Japanese Patent Application Laid-Open No. 63-72894 discloses an electrodeposition coating method which comprises pickling in a pickling bath containing fluoride or hydrogen fluoride when the titanium material is electrodeposited. The titanium material is pickled and activated in the absence of nitric acid in a pickling bath as an acid mixture having a pH <4, and the residence time in the pickling bath is selected so that visible hydrogen evolution occurs in a short time. Then, the titanium material is washed in water for a short time, and thereafter, the titanium material is coated in an electrodeposition bath. As the above pickling bath, 0.5 to 5
%, And it is preferable to use a high concentration of fluoride or hydrofluoric acid, and to perform a heat treatment at 250 ° C. or more after coating.

However, in this method, since a water washing process is always performed before plating, the surface of the titanium material is reoxidized in the process to form an oxide film. In such a surface state, if a plating film is forcibly deposited by applying an electric current from the outside, even if the plating film is deposited, an oxide film exists between the plating film and the titanium material. Power is low. On the other hand, when electroless plating is performed in such a state, plating does not deposit at all, or a portion where no plating is deposited (scale).
Occurs. Even if a baking treatment at 250 ° C. or more is performed after plating, the adhesion of the plating film is not improved as long as the oxide film remains.

Japanese Patent Application Laid-Open No. 60-46390 discloses that
Activate the titanium alloy by immersing it in a concentrated acid, then dilute the same acid several times, then dilute a different acid several times, then immerse the same concentrated acid, then A plating pretreatment method is disclosed in which acid dip acid immersion is performed a plurality of times, and then immersion in a dilute plating solution containing no metal ions is performed a plurality of times.

However, in this method, the titanium alloy is always immersed in a dilute plating bath containing no metal ions immediately before plating, so that an oxide film is formed on the surface of the titanium alloy as in the case of water washing. Activate. For this reason, when electroless plating is applied to this titanium alloy, plating does not precipitate at all, or some unprecipitated portions are likely to occur. Even if the plating film is deposited, the adhesion of the plating film is low due to the presence of the oxide film. For example, 25% after plating
Even if heat treatment is performed at 0 ° C. or higher, the adhesion of the plating film does not improve as long as the oxide film remains.

Further, it is conceivable to perform a plating treatment without rinsing the titanium material in a concentrated acid by immersing it in a concentrated acid prior to plating. In this case, however, unnecessary components are mixed in the plating bath.
It has the disadvantage that the quality of the plating film is reduced and the life of the plating bath is shortened. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a method for plating a titanium material, which can form a plating film having excellent adhesion on the surface of the titanium material.

[0010]

[Means for Solving the Problems]

According to the present invention, a titanium material comprising titanium metal or a titanium alloy is converted into a fluoride ion and a transition metal ion,
A pretreatment step of activating the surface of the titanium material by contacting it with an acid solution containing at least one metal ion of zinc ions or tin ions and precipitating the metal; and bringing the titanium material into contact with water or a rinsing liquid A washing step, a step of immersing the titanium material in a plating bath containing a plating raw material, performing a plating process on the surface of the titanium material on which the activated and deposited metal is deposited, and removing the titanium material from the plating bath; A method of plating a titanium material comprising a heating step of heating the titanium material, wherein the acid solution contains 0.5 mol / mol of fluoride ions.
The rinsing liquid is a plating method for a titanium material, wherein the rinsing liquid contains not less than 0.01 mol / liter.

[0012] The most to be that the target in the present invention, the titanium material composed of titanium or titanium alloy, the anterior Kki treatment of 0.5 mol / l fluoride ions and transition metal ions, zinc ion, stannous ion That is, it is brought into contact with an acid solution containing at least one metal ion.

First, a pretreatment step and a cleaning step of the present invention will be described. In these steps, the titanium material is brought into contact with an acid solution containing not less than 0.5 mol / l of fluoride ions and then with a rinsing liquid or water containing not less than 0.01 mol / l of fluoride ions. .
In the above acid solution, if the amount of fluoride ions is less than 0.5 mol / liter, the removal of the oxide film on the surface of the titanium material is insufficient. Therefore, the deposition of the plating film becomes uneven, and the adhesion of the plating film becomes small. Examples of the fluoride ion source include hydrofluoric acid.

The upper limit of the fluoride ion is not particularly limited.
However, if the concentration exceeds 5 mol / liter, the use of only hydrofluoric acid is not preferable because the etching rate becomes too high and the surface of the titanium material becomes rough. Even if the fluoride ion concentration exceeds 5 mol / liter, the acid solution containing alkali metal ions and ammonium ions described below can reduce the etching rate, but it takes time to remove the oxide film, Not economic.

The acid solution may contain a mineral acid such as sulfuric acid, hydrochloric acid or phosphoric acid, or an organic acid such as acetic acid or formic acid, in addition to the fluoride ion. Also, as the above acid solution,
For example, by dissolving an acidic fluoride salt such as acidic ammonium fluoride, acidic sodium fluoride, acidic potassium fluoride, and acidic cesium fluoride, in addition to hydrofluoric acid, an alkali metal ion or an ammonium ion It is preferable to include As a result, the effect of suppressing excessive etching of the surface of the titanium material and forming a composite fluoride film that prevents reoxidation of the titanium surface can be obtained.

Further, in addition to fluoride ions, a metal ion such as zinc ion, tin ion, nickel ion, cobalt ion, palladium ion, or platinum ion and a complexing agent may be added to the acid solution. When pretreatment is performed using this acid solution, the oxide film on the surface of the titanium material is removed, and instead, a zinc film or tin film or a catalytic metal nucleus of nickel, cobalt, palladium, or platinum is formed.

Then, by immersing this titanium material in a plating bath, for example, in an electroless nickel plating bath, when zinc ions are contained, according to formulas (1) and (2), when tin ions are contained, According to (3) and (4), plating nuclei are formed on the surface of the titanium material. In the case of nickel, cobalt, palladium, and platinum, the metal itself becomes the core of electroless plating during deposition. Therefore, the electroless plating proceeds autocatalytically thereafter, and a plated film having a uniform thickness can be formed.

Zn → Zn ²⁺ + 2e (1) Ni ²⁺ + 2e → Ni (2) Sn → Sn ²⁺ + 2e (3) Ni ²⁺ + 2e → Ni ... (4)

The contact time between the titanium material and the acid solution in the pretreatment step is preferably several tens seconds to several minutes.
For example, with an acid solution having a low pH and a high bath temperature containing a high concentration of fluoride ions, sufficient activation can be achieved within several tens of seconds. However, if not, a long activation time of 5 minutes or more may be required. Whether this condition is appropriate or not can be determined by measuring the potential change of the titanium material in the acid solution. In this case, the potential gradually changes from base to noble, so that the predetermined noble potential is determined. Activation may be performed up to the point where the number of times has reached.

When an acid fluoride solution containing an alkali metal ion is used as the acid solution, Na ₂ TiF ₆ ,
A hardly soluble composite fluoride film such as K ₂ TiF ₆ or Cs ₂ TiF ₆ is formed on the surface of the titanium material. The composite fluoride film protects the surface of the titanium material and prevents an oxide film from being formed. When the titanium material covered with the composite fluoride film is put into a plating bath, the composite fluoride film, which has prevented reoxidation, gradually dissolves, and a plating reaction starts, resulting in a uniform film thickness. A plating film having high adhesion can be formed. Therefore, generation of undeposited portions of plating or reduction in adhesion due to washing with water is less likely to occur than in a pretreatment consisting of simple hydrofluoric acid alone.

It is not preferable to directly put the titanium material having been subjected to such a pretreatment into the plating bath because a dissolved substance contained in the acid solution is mixed and the plating bath is contaminated. In particular, in the present invention, since a relatively high concentration of fluoride ions is contained, contamination of the plating bath may not be negligible.

When the pretreated titanium material is immersed in water, contamination of the plating bath in the plating step can be prevented. However, the surface of the activated titanium material comes into contact with water and is oxidized again, so that the deposition of plating becomes non-uniform and the adhesion of the plating film decreases. This phenomenon is remarkable when a zinc or tin film or a catalytic metal nucleus such as nickel is not formed on the surface of the activated titanium material. Therefore, it is preferable to use a method of activating with a rinse solution containing a fluoride ion, which will be described later, instead of water.
New

The above-mentioned rinsing liquid contains fluoride ions at a concentration of 0.0
It is necessary to contain 1 mol / liter or more. Considering the relationship between the fluoride ion concentration in the acid solution and the amount of fluoride ion adhering to the titanium material, in some cases,
It is preferable to perform the rinsing not only once but also a plurality of times while gradually decreasing the fluoride ion concentration in the rinsing liquid . This can further reduce the incorporation of substances such as fluoride ions in the acid solution into the plating bath.

Next, describing the present onset Ming pretreatment and washing steps. In the pretreatment step, the titanium material is brought into contact with an acid solution containing 0.5 mol / L or more of fluoride ions and at least one metal ion of transition metal ions, zinc ions or tin ions, and then water or a rinsing solution. Contact.

In the above acid solution, as described above , fluoride ions must be 0.5 mol / liter or more. Metal ions such as transition metal ions contained in the acid solution precipitate on the surface of the activated titanium material, and prevent reoxidation in the subsequent washing or rinsing treatment. In addition, it is possible to reduce unnecessary components brought into the washing or rinsing solution or the plating bath. Transition metal ions include nickel ions and the like. Metal ions are
It is preferably at least one selected from the group consisting of zinc ions, tin ions and nickel ions. The concentration of the metal ion is preferably 0.5 to 0.005 mol / l.

As described above, a complexing agent may be added to the acid solution. When pretreatment is performed using this acid solution,
As described above , a plating film having a uniform thickness can be formed. The kind of acid in the pretreatment step, the contact time between the titanium material and the acid solution, and the like can be the same as described above . Thereafter, the titanium material is brought into contact with water or a rinsing liquid to prevent the introduction of unnecessary components into the plating bath.

[0027] Next, a description will be given because Kki process. The plating process in the plating step may be, for example, either electroless plating or electroplating. In particular, in the case of electroless plating, the plating state is easily affected by the oxidation state of the titanium surface. It is. The plating method of the present invention is based on Ni, Ni-P, Cu, Co, Pb, Pt, A
u or other metal plating or alloy plating, and Ni-Si
It can also be applied to composite plating of C, Ni-P-SiC, etc., and can be performed under normal plating conditions (bath temperature, pH, current density, time).

When plating a low melting point metal such as Sn or Pb-Sn or an alloy thereof, if the heat treatment after plating is not more than 250 ° C., for example, in the case of Sn plating, once it becomes inappropriate. A thin strike plating of a metal such as Ni is performed, followed by a heat treatment, and thereafter, a plating treatment is performed by an ordinary method. As a result, a plating film having good adhesion can be obtained. The above-mentioned strike plating is a pretreatment for forming a desired plating with good adhesion, and means forming a thin layer having a thickness of several μm or less. Electroplating such as a wood strike Ni bath may be mentioned, but in the present invention, electroless Ni-P plating may be formed thin.

In the plating step, in addition to fluoride ions having a concentration of 0.5 mol / l or more, nickel, cobalt, palladium, platinum or the like having a high catalytic activity is used as a pretreatment bath for electroless plating. An appropriate amount of metal ions is contained. In this case, citric acid, malic acid, ethylenediamine, EDTA and the like may be contained as appropriate as a complexing agent for preventing excessive precipitation of these metal ions. Thus, when the pretreatment is performed with the acid solution, the oxide film on the titanium alloy surface is removed. In addition, since a catalytic metal nucleus for smoothly starting the electroless plating reaction can be formed on the titanium surface, it is easy to form a uniform electroless plated film without inconvenience and unevenness of the plated film.

In the case of performing the electroplating method, the plating process is generally performed at a temperature generally lower than that of the above-mentioned electroless plating method, and it takes some time until the composite fluoride film dissolves in the plating bath. . For this reason, it is preferable to apply the current several tens seconds to several minutes after the immersion, instead of applying the current immediately after immersion in the plating bath, in order to improve the adhesion of the plating film. To set these conditions, the potential may be measured after measuring the potential of the titanium material in the plating bath and showing a certain noble value or more.

Regarding the contamination of the plating bath, it is inevitable that the acid solution is mixed into the plating bath even when the titanium material is rinsed. However,
The problem is small because a small amount of fluoride ion may be added to the plating bath from the beginning as a brightener for plating.
When a bath containing a large amount of fluoride ions (for example, a borofluoride bath) is used as the plating bath, mixing of fluoride ions does not pose a problem.

The effect of alkali metal ions and ammonium ions as other components in the plating bath is small, but the incorporation of a large amount of complexing agents and nickel ions, tin ions, zinc ions, etc. is a factor of the plating film. Care must be taken because it may affect the physical properties, plating rate, and stability of the plating bath.

The plating bath temperature may be a temperature used in a usual manner. However, when a complex fluoride film is formed in the pretreatment step, the complex fluoride film dissolves in the plating bath as the bath temperature increases. It will be easier. Therefore, a relatively high plating bath temperature is preferable in terms of shortening the plating time and improving the adhesion.

The plating time is not particularly limited, and the plating reaction is performed until a plating film having a desired thickness is formed. The formation of a multi-layered plating film does not differ from the ordinary method at all, and it is possible to form a multi-layered plating film of, for example, Cu—Ni—Cr on the surface of a titanium material.

Next, the heat treatment will be described. The temperature of the heat treatment in the heating step is 200 to 300 ° C. or 40 ° C.
The range of 0-500 degreeC is preferable. By heating at 200 ° C. or higher, the stored hydrogen is dehydrogenated, and the adhesion is improved. On the other hand, when the heating is performed at a temperature lower than 200 ° C., the occluded hydrogen remains at the interface between the plating film and the titanium material. For this reason, the adhesion of the plating film has been poor.

However, when the temperature exceeds 300.degree.
In the temperature range below, diffusion of elements between the plating film and the titanium material cannot occur sufficiently, so that oxidation at the interface gradually progresses and the difference in thermal expansion between the titanium alloy and the plating film becomes large. In addition, the adhesion of the plating film is reduced.
Therefore, heating temperatures above 300 ° C. and below 400 ° C. are unsuitable.

On the other hand, at a temperature of 400 ° C. or more, diffusion of elements between the plating film and the titanium material starts, and an intermetallic bond is formed. Therefore, the adhesion of the plating film is improved. From the results of X-ray diffraction and EPMA analysis,
Under the heat treatment conditions according to the present invention, even if an intermetallic compound layer composed of titanium and a plating metal element is not formed at the interface between the plating film and the titanium material, the adhesion of the plating film is significantly improved by the heat treatment. It has been found.

However, heat treatment at a temperature exceeding 500 ° C. requires heating in a vacuum or in an inert gas atmosphere, and depending on the type of plating material, oxidation of the plating film proceeds, so that a heating device is expensive. It must be avoided because it is uneconomical and the mechanical properties of the titanium material deteriorate. In particular, β among titanium materials
It is common to use a phase-titanium alloy in a state where a part of α phase is precipitated by appropriate work hardening and aging treatment. Heating after plating at a temperature exceeding 500 ° C reduces mechanical strength. It is not realistic to lower.

Next, the heating time at 200 to 300 ° C. is sufficient for several tens to several hours. On the other hand, 400-50
At a temperature of 0 ° C., a few minutes is sufficient. This is because the diffusion rate of the element between the plating film and the titanium material increases as the temperature increases.

As a heating method, at a temperature of 200 to 300 ° C., for example, heating in the atmosphere is performed. On the other hand, 400-50
At 0 ° C., oxidation of the titanium material and oxidation of the plating film itself other than the noble metal also pose problems. Therefore, it is preferable to heat in an inert gas furnace or a vacuum furnace. When a Ni—P alloy plating film is formed, the deposition of Ni ₃ P proceeds at about 300 ° C., and accordingly, the adhesion of the plating film rapidly changes. For this reason, it is preferable to limit the temperature to 200 to 300 ° C. and a temperature at which Ni ₃ P does not precipitate much, for example, to 240 to 280 ° C.

As the titanium material used in the present invention,
Any of α single phase (hexagonal) titanium metal or titanium alloy, β single phase (body centered cubic) titanium metal or titanium alloy, α + β2 phase mixed titanium metal or titanium alloy, or titanium intermetallic compound good.

Pure titanium is an example of the α-single-phase titanium metal, and β-C alloy (Ti-3A) is a β-single-phase titanium alloy.
1-8V-6Cr-4Mo-4Zr), and Ti-6Al-4V as an α + β2 phase mixed titanium alloy. Further, as an intermetallic compound of titanium, there is TiAl or the like. Generally, as the above-mentioned β-C alloy, it is preferable to use a material in which α-phase titanium metal or titanium alloy is finely precipitated by an appropriate aging treatment to improve hardness and tensile strength.

Since the β single-phase titanium alloy and the TiAl intermetallic compound are harder to activate than the α-phase titanium alloy, it is difficult to activate the β-phase titanium alloy and the TiAl intermetallic compound using an acid solution containing only simple hydrofluoric acid ions. Therefore, it is preferable to activate with an acid solution to which a transition metal ion such as nickel or an alkali metal is added. Further, it is preferable that the β-phase single-phase titanium alloy which is hardly activated is once heated and subjected to aging treatment to partially precipitate the α-phase titanium metal or titanium alloy. Thus, in the pretreatment step, sufficient activation can be achieved with an acid solution consisting of simple hydrofluoric acid alone.

[0044]

[Action and effect]

[0045] In this onset Ming, before plating process titanium material, and a fluoride ion 0.5 mol / l or more, transition metal ions, and metal ions of one or more zinc ions or tin ions The titanium material is brought into contact with the acid solution contained. Therefore, the titanium film is activated by removing the oxide film covering the surface by the etching action of the acid solution. At the same time, metal ions such as transition metal ions precipitate on the surface of the titanium material, and the deposited metal protects the surface of the titanium material. Therefore, it is possible to prevent the titanium material from being reoxidized in the subsequent washing or rinsing process. By the above operation, the present invention can form a plating film having a uniform film thickness and excellent adhesion on the surface of the activated titanium material.

Further, in forming a plating film having good adhesion on the surface of the titanium material, the pretreatment step and the heating step exhibit a synergistic effect. Although the reason is not clear, if the fluoride ion is less than 0.5 mol / l in the pretreatment step, the adhesion of the plating film is low even if the plating treatment and the heat treatment are performed appropriately thereafter. . From this, the improvement of the adhesion by the heat treatment is based on the premise that the oxide film on the titanium material surface has been completely removed.
This is probably because, for the first time, dehydrogenation or diffusion of the element between the plating film and the titanium material can be achieved.

The pretreatment step has the advantage that it can be easily applied to a complicated structure because it does not require an external current supply, and is particularly suitable for performing electroless plating in the plating step. In addition, taking advantage of the excellent properties of titanium materials, Ni-P and Ni-SiC having excellent wear resistance on the surface.
Etc. can be formed with good adhesion.

Accordingly, the weight and durability of automobile parts such as intake and exhaust valves, springs, and retainers in automobiles can be greatly improved. According to the present invention,
A method of plating a titanium material, which can form a plating film having excellent adhesion, can be provided.

[0049]

EXAMPLES Reference Example 1 A method for plating a titanium material according to the present invention will be described. First, a plurality of titanium alloy plates of Ti-6Al-4V material (size: 2 cm × 5 cm, thickness: 1 mm) were prepared and 2 mm × 2
The remainder was coated with an insulating resin mask except for the pattern of mm □. Next, after degreasing in an alkaline degreasing bath, the oxide film on the surface was removed with an etching solution of nitric acid or hydrofluoric acid and washed with water.

Next, the relationship between the concentration of hydrofluoric acid in the acid solution and the adhesion of the plating film was measured as follows.
First, as a pretreatment process, hydrofluoric acid 0.02-1.
Various acid solutions of 0 mol / liter were prepared. Next, the titanium alloy plate was immersed in various acid solutions at 40 ° C. for 2 minutes.

Next, the titanium alloy plate was immersed in a 0.02 mol / liter hydrofluoric acid solution for several seconds to perform a rinsing treatment. Next, as a plating process, Ni-10
In a plating bath containing a P plating raw material, electroless plating is performed at 95 ° C. for 1 hour, and the surface of the titanium alloy plate is
A plating film having a thickness of 20 μm was deposited. Thereafter, as a heating step, the titanium alloy plate was heated at 250 ° C. for 2 hours.

Next, the relationship between the concentration of fluoride ions in the pretreatment step, the deposition state of the plating film, and the adhesion was examined. First, the deposition state of the plating film was measured when the fluoride ion concentration in the acid solution and the immersion time were changed, and the results are shown in FIG. As shown in the figure, if the surface of the titanium material is activated at a hydrofluoric acid concentration of 0.5 mol / L or more, a plating film having a uniform thickness is formed without any scum (undeposited portion of the plating film). You can see that

Next, the Cu wire covered with the Sn plating film was soldered to the surface of the plating film of the titanium alloy plate, and the Cu wire was pulled by a peeling adhesion tester with the titanium alloy plate fixed. Then, the adhesion of the plating film was examined.

FIG. 2 shows the peel adhesion strength of the plating film. In the figure, the black circles indicate that the plating film did not break and the solder broke. Open circles indicate that the plating film broke and the solder did not. From the figure,
When the pretreatment was performed with an acid solution containing 0.5 mol / liter or more of fluoride ions, the solder was broken (black circles), indicating that the plating film had high adhesion.

Next, in a vacuum at 500 ° C., 2
The β-C alloy material, which has been subjected to a heat treatment for a long time and partially forms an α phase, is subjected to a pretreatment step, similarly to the Ti-6Al-4V material.
A plating step and a heating step were performed to form a plating film. Then, the adhesion of the plating film was examined.

The β-C alloy material is obtained by dividing a wire having a diameter of 6 mm into a half length of 50 mm. The adhesion of the plating film was measured using a peel adhesion tester with a Sn plating Cu wire and a solder in the same manner as described above. FIG. 3 shows the result. In FIG. 2, the meanings of the black and white circles are shown in FIG.
Is the same as As shown in the figure, by performing pretreatment with an acid solution containing 0.5 mol / L or more of hydrofluoric acid,
It can be seen that high adhesion is obtained.

Next, using a pure titanium plate and adjusting the hydrofluoric acid concentration to 0.05 mol / l and 1.0 mol / l, the pretreatment step, the washing step, the plating step, and the A heating step was performed to form a plating film.
The pure titanium plate is an α-single-phase titanium metal containing 99.9% of Ti, and has a size of 5 cm × 2 cm and a thickness of 1 mm. The adhesion of the plating film was measured by the above method.

As a result, when the hydrofluoric acid concentration is 0.05 mol / liter, the adhesion of the plating film is 1.0 to 1.0.
It was 1.9 kgf / 2 mm □, and in the case of 1.0 mol / liter, it was 7.0 to 9.5 kgf / 2 mm □.
From the results of the above measurements, after contacting the titanium material with an acid solution having a hydrofluoric acid concentration of 0.5 mol / L or more,
By performing the washing process, plating process and heating process,
It can be seen that a uniform and well-adhesive plating film can be formed.

Reference Example 2 In this example, the relationship between the heating temperature and the adhesion of the plating film was investigated. Explain how to create materials for the survey. First, the same Ti-6Al-4 as in Reference Example 1 was used.
A V material was prepared, and as a pretreatment process, the Ti-6Al-4V material was added to 1 mol / L of hydrofluoric acid at 40%.
C. for 2 minutes. Next, it was rinsed with a 0.02 mol / L hydrofluoric acid solution, immersed in a plating bath containing Ni-P (12% P) plating material at 95 ° C. for 1 hour, and taken out. As a result, a plating film having a thickness of about 8 μm was formed on the surface of the Ti-6Al-4V material. The plating film had no scale and had a uniform thickness.

Next, the Ti-6Al-4V material was added to 150
Heated at a constant temperature in the range of ５００500 ° C. for 2 hours. Then, the peel adhesion strength was examined in the same manner as in Reference Example 1. The heating at 150 to 300 ° C. was performed in an air atmosphere. The heating at 350 ° C. to 500 ° C. was performed in an argon atmosphere. The results are shown in FIG. In the figure,
The black and white circles have the same meaning as in FIGS.

As shown in FIG.
It can be seen that the adhesion is significantly improved at 500 ° C. X-ray diffraction and EPMA analysis of the heat-treated product at 500 ° C. showed no formation of an alloy layer of Ti ₂ Ni, TiNi ₂ or the like. This means that even if there is element diffusion, it is a very thin layer at the interface between Ti and Ni.

Next, the same material (Ti-6Al-
4V material) was activated in the same manner as above, and then, as a plating step, electroless plating was performed using a Ni-5P or Ni-10P plating raw material to form plated films having a thickness of 8 μm and 20 μm, respectively. Then, as a heating step,
C. or 450.degree. C. for 2 hours each. Thus, Samples 1 to 6 and C1 and C2 shown in Table 1 were obtained.

Then, the Cu film was formed on the plating film surface of each sample.
The wire was soldered and the peel adhesion strength was examined in the same manner as above. The results are shown in Table 1. As comparative examples, values when no heat treatment is performed after the plating treatment and when heat treatment is performed at 350 ° C. are also shown.

As a result of the measurement, the heated samples 1 to 6 had higher adhesion than the unheated samples C1 and C2. When the heating temperature was 250 ° C. or 450 ° C. (Samples 1, 2, 4, and 5), the adhesion was improved 5 to 6 times as compared with the case where the heating temperature was 350 ° C. (Samples 3 and 6). In samples 2, 4, and 5, the solder was broken, and the plating film was still in close contact with the surface of the Ti-6Al-4V material. on the other hand,
Samples 1, C1 and C2 were plated film and Ti-6Al-4V
Peeling occurred at the boundary with the material. From this, 200-3
It can be seen that by performing the heat treatment at a constant temperature in the range of 00 ° C. or 400 to 500 ° C., a plating film having excellent adhesion is formed.

[0065]

[Table 1]

Reference Example 3 In this example, the type of plating bath used in the plating step was examined. First, the same Ti-6Al-4V as in Reference Example 1 was used.
Materials and the following three types of electric Ni plating baths (Watts bath, total sulfuric acid bath, and sulfamic acid bath) were prepared. The pH of each of these electric Ni plating baths was 4.0 and 60 ° C.

[0067] Watts bath NiSO ₄ · 6H ₂ O 240g / l NiCl ₂ · 6H ₂ O 45g / l H ₃ BO ₃ 30g / l total sulfuric acid bath NiSO ₄ · 6H ₂ O 300g / l H ₃ BO ₃ 40g / l sulfamic Acid bath Nickel sulfamate 450 g / liter H ₃ BO ₃ 30 g / liter

Next, as a pretreatment step, a 1 mol / l aqueous solution of hydrofluoric acid or an aqueous solution obtained by adding 0.5 mol / l of hydrofluoric acid to 1 mol / l of potassium fluoride was added to the above solution. Ti-6Al-4V material at 40 ° C x 2
The substrate was immersed for 1 mm and washed with a rinse solution consisting of a 0.01 mol / liter hydrofluoric acid aqueous solution.

Next, as a plating step, the above Ti-6A
Electroplating was applied to the 1-4V material. Electroplating was performed in the above-mentioned various plating baths when electricity was supplied directly and when electricity was supplied after 5 minutes. The energizing condition is 2 A / dm ²
X 25 minutes. The obtained plating film has a thickness of about 10
μm, and both were formed to have a uniform thickness in appearance.

Next, as a heating step, the Ti-6Al-4V material covered with the plating film was subjected to a heat treatment at 250 ° C. × 2 hours. Thereafter, the Cu wire used in Reference Example 1 was soldered to the surface of the plating film, and the adhesion was measured.
The adhesion was measured using a peel adhesion tester in the same manner as in Reference Example 1. Table 2 shows the results. As a result of the above measurement,
In each of the plating baths, when a current was applied 5 minutes after the immersion, a plating film having better adhesion was obtained than when the current was applied immediately after the immersion.

[0071]

[Table 2]

Further, the Ti-6Al-4V material was subjected to 40 ° C. × 1 mol / liter hydrofluoric acid in the pretreatment step.
Soaked for 2 minutes. Next, plating was performed using a sulfamic acid bath in the same manner as described above. The energization conditions were the same as above, and the energization was performed 5 minutes after immersion in the plating bath. Thereafter, in a heating step, heat treatment was performed at 450 ° C. and 500 ° C. for 2 hours each.

The adhesion of the formed plating film was 8.2 kgf / 2 mm □ at a heating temperature of 450 ° C.
At 0 ° C., the solder rupture occurred at 8.0 kgf / 2 mm square. When this result is compared with the above measurement results (Table 2), it is more than 450 ° C.
It can be seen that the time is higher for the adhesion strength.

Reference Example 4 In this example, in the plating step, the relationship between the current supply start time after immersion in the plating bath and the adhesion of the plating film was examined. The sample used for the measurement will be described.
First, as a pretreatment, the same manner as in Reference Example 1 Ti-6Al-
The 4V material was mixed with 1 mol / l of potassium fluoride and 0.1 mol / l.
40 in an acid solution containing 5 mol / l hydrofluoric acid
C. x 2 minutes. Then, as a cleaning process, 0.0
Rinsing treatment was performed with a 1 mol / liter hydrofluoric acid aqueous solution.

Next, as a plating step, the above Ti-6Al-4 was placed in a plating bath containing a plating material of copper pyrophosphate.
The V material was immersed, subjected to electrolytic plating, and taken out. At this time, the energization start time was changed variously. The plating bath contains 80 g / liter copper pyrophosphate and 350 g
Per liter of potassium pyrophosphate. The setting conditions of the electrolytic plating were as follows: P ratio: P ₂ O ₇ / Cu = 7: 5, 60
C., pH 8.5, 5 A / dm ₂ × 10 minutes.

Next, as a heating step, a heat treatment was performed at 250 ° C. × 2 hours. As a result, a matte plating film was formed. Then, the reference example 1
The Cu wire used in the above was soldered, and the adhesion was examined in the same manner as in Reference Example 1. As a result, Ti-6Al
Immediately after activating the surface of the -4V material, the adhesion of the plating film is 0.9 kg when immediately immersed in the plating bath and energized.
f / 2 mm □. On the other hand, when electricity was supplied after immersion for 5 minutes, the value was 3.3 kgf / 2 mm □.

Further, the Ti-6Al-4V material is pre-treated, washed with a rinsing solution consisting of a 0.01 mol / l aqueous solution of hydrofluoric acid, then immediately immersed in a plating bath, immersed for 5 minutes and then energized. Or turned on immediately. As the plating bath, acidic Pt plating (Cat No. # 250) manufactured by Engelhardt Japan was used. Thereafter, a heat treatment was performed. The conditions of the pretreatment step, the energizing condition, and the heating step are the same as described above.

The Pt plating film thus formed has
No blisters were observed. When the adhesion of the Pt plating film was measured by the same method as in Reference Example 1,
5.0kgf / 2mm □ when energized after immersion for 5 minutes
However, when current was applied immediately after immersion, 2.5
kgf / 2 mm □. From the above two experiments, T
It can be seen that the adhesion of the plating film is improved when the current is applied about 5 minutes after the immersion, rather than immediately after the i-6Al-4V material is immersed in the plating bath.

REFERENCE EXAMPLE 5 In this example, the plating scale area ratio and the adhesion of the plating film were measured with the passivation (reoxidation) of the titanium material surface after the pretreatment. A method for preparing a sample to be used for measurement will be described. First, in the pretreatment step, Ti-
The 6Al-4V material was immersed in an acid solution containing 1 mol / l hydrofluoric acid at 40 ° C. for 2 minutes.

Thereafter, the substrate was washed with a rinsing solution consisting of a 0.02 mol / liter aqueous solution of hydrofluoric acid. Further, for comparison, water washing was performed under various conditions shown in FIGS. Washing was performed by immersing the pretreated Ti-6Al-4V material in water. Next, in the plating process,
In a plating bath containing a Ni-10P plating material, the above T
An i-6Al-4V material was immersed and subjected to electroless plating. Thereafter, in a heating step, heat treatment was performed at 250 ° C. for 2 hours.

FIG. 5 shows the relationship between the washing time and the adhesion of the plating film. The adhesion of the plating film was measured by the same method as in Reference Example 1. FIG. 6 shows the relationship between the washing time and the area of the slime generated on the plating film. In FIG. 6, the meaning of the white circles is the same as in FIG. 2 in the embodiment.

When the substrate was washed with a rinsing solution composed of a 0.02 mol / liter aqueous solution of hydrofluoric acid, there was no decrease in adhesion, and all solder breakage occurred. There was no invisibility. On the other hand, as a comparison, when the rinsing was not performed and the rinsing was performed, as shown in FIGS. 5 and 6, as the rinsing time became longer, the squeeze area increased and the adhesion decreased.

Reference Example 6 In this example, the relationship between the heating conditions and the adhesion of the plating film was investigated. A method for preparing a sample to be used for the survey will be described. First, as in Reference Example 1, Ti-6Al-
A 4V material was prepared and immersed in an acid solution containing 1 mol / l hydrofluoric acid at 40 ° C. for 2 minutes as a pretreatment step. Next, a rinsing treatment was performed using 0.02 mol / liter of hydrofluoric acid.

Next, Ni-10P electroless plating is performed as a plating step, and 150, 250,
Heat treatment was performed at 300 and 450 ° C. for several minutes to 4 hours. Then, for the obtained sample, the adhesion of the plating film was measured in the same manner as in Reference Example 1. FIG. 7 shows the result.

As shown in the figure, in the case of heating at 300 ° C., heating for about 30 minutes is desirable. X-ray diffraction of the plating film at this time showed that a small amount of Ni3P was deposited. When the heating was performed for one hour or more, a large amount of Ni3P was precipitated. On the other hand, in the case of 250 ° C., even if heating for 4 hours
No precipitation of i3 P was observed. At 450 ° C heating,
Adhesion was improved in a shorter time than at 250 ° C. heating. still,
When heated at 150 ° C., the adhesion was almost as low as in the case of the unheated treatment.

Reference Example 7 In this example, the adhesion of a two-layer plating film composed of a copper plating film and a Ni-10P plating film was measured. A method for preparing a sample to be used for measurement will be described. First, a Ti-6Al-4V material similar to that in Reference Example 1 was prepared and immersed in an acid solution containing 1 mol / l hydrofluoric acid at 40 ° C. for 2 minutes as a pretreatment step.
The surface of the 6Al-4V material was activated. Then, 0.
The substrate was washed with a rinsing solution consisting of a 01 mol / liter aqueous hydrofluoric acid solution. Next, in the plating step, a copper plating film having a thickness of about 2 μm was formed in the following electroless copper plating bath.

Thereafter, electroless Ni-1 for preventing copper erosion.
0P plating was performed to form a Ni-10P plated film having a thickness of 2 μm. Then, as a heating step, 450 ° C. × 2H
r heat treatment was performed. Then, the peel adhesion strength of the plating film of the obtained sample was measured in the same manner as in Reference Example 1, and it was 4.0 kgf / 2 mm □.

On the other hand, as a comparative example, 0.1
40 ° C × in acid solution containing mol / l hydrofluoric acid
It was immersed for 2 minutes and rinsed as described above. Next, the plating process was performed in the same manner as in Reference Example 1, and as the heating process,
A heat treatment was performed at 150 ° C. × 2 hours and at 350 ° C. × 2 hours to form a plating film.

The above-mentioned electroless copper plating bath contains copper sulfate 0.04
Mol / l, EDTA 0.06 mol / l,
It consists of α, α, dipyridyl 15 mg / l, potassium ferrolianide 15 mg / l (pH 12.8), and formalin 6 ml / l.

Reference is made to the adhesion of the plating film in the comparative example.
Was measured in the same manner as considered Example 1, at a heating temperature of 0.99 ° C. was 0.5 kgf / 2 mm □. Also,
At a heating temperature of 350 ° C., it was 1.5 kgf / 2 mm □. Both comparative examples had lower adhesion than the case of heating at 450 ° C. described above.

Reference Example 8 In this example, an acid solution containing a fluoride other than hydrofluoric acid (HF) and potassium fluoride (KF) was examined. A method for preparing a sample to be examined will be described. First, the same Ti-6Al-4V material as in Reference Example 1 was prepared.
As a pretreatment step, the film is immersed in an acid solution containing 0.5 mol / l of acidic ammonium fluoride or cesium fluoride at 40 ° C. for 2 minutes, and then rinsed with a 0.01 mol / l aqueous solution of hydrofluoric acid Washed with liquid.

Next, as a plating step, electroless plating was performed in a plating bath containing a Ni-10P plating raw material to form a Ni-10P plated film having a thickness of 20 μm.
Next, as a heating step, heat treatment was performed at 250 ° C. or 450 ° C. for 2 hours. Then, the peel adhesion of the plated film of the obtained sample was examined in the same manner as in Reference Example 1.

As a result, in each case, the plating film was 8
-12 kgf / 2 mm □ (solder breakage), indicating strong adhesion. As a comparative example, in the pretreatment step, pretreatment was performed with an acid solution containing 0.1 mol / liter of acidic ammonium fluoride or acidic cesium fluoride, washed with a rinse solution in the same manner as described above, After the plating step was performed in the same manner as described above, heat treatment was performed at 250 ° C. for 2 hours. The plating film of the sample thus obtained was 3.0 kgf / 2 mm square (ammonium acid fluoride) and 1.6 kgf / 2 mm square (cesium acid fluoride).
In each case, the adhesion was small.

Example1  In this example, the unaged β single-phase β
Measurement of adhesion of plating film when using -C alloy
did. First, as an acid solution containing metal ions,
Bath was prepared. NiSO_Four ・ 6H_TwoO 0.1 mol / L Sodium citrate 0.025 mol / L Cesium acid fluoride 0.25 mol / L ZnSO_Four・ 6H_TwoO 0.2 mol / L Sodium citrate 0.026 mol / L Ammonium acid fluoride 0.25 mol / L

As a titanium material, an unaged β single phase β-
C alloy was used. Then, as a pretreatment step, the above β-
The C alloy was treated with the acid solution in each of the above baths at room temperature for 30 seconds and thoroughly washed with water. Next, as a plating process, Ni
-10P electroless plating, Ni-1 of 20μm thickness
A 0P plating film was formed. Then, as a heating process,
250 ° C x 2 hours or 350 ° C when treated by bath
The heat treatment was performed for 2 hours. When the treatment was performed in a bath, heat treatment was performed at 250 ° C. × 2 hours. Then, for the obtained sample, the adhesion of the plating film was measured in the same manner as in Reference Example 1.

As a result, when the pretreatment was performed in a bath, the adhesion was 8.5 to 9.6 kgf / 2 mm □ when the heating temperature in the heating step was 250 ° C., and the adhesion was 5.5 when the heating temperature in the heating step was 350 ° C. It was 0 kgf / 2 mm □. When the pretreatment was performed in a bath and the heating temperature in the heating step was 250 ° C., the adhesion was 7.7 to 10.6 kgf / 2 mm □. When the pretreatment and the heat treatment were performed, the solder breakage occurred.

On the other hand, for comparison, a pretreatment using a bath and a plating step were performed in the same manner as described above, and a comparative sample obtained when no heat treatment was performed after plating was prepared. The adhesion of the plating film of the sample is 0.5 kgf / 2 m
m □ was low. From this fact, even when an unaged β single-phase β-C alloy is used as the titanium material, the Ti-
It can be seen that, similarly to the 6Al-4V material, a plating film having excellent adhesion is formed.

Example2  In this example, a TiAl intermetallic compound was used as the titanium material.
The adhesion of the plating film when using the product was measured.
First, it consists of TiAl (atomic ratio 1: 1) intermetallic compound
Example as a pretreatment process for an engine valve for automobiles
1In the bath,referencePreprocessing is performed under the same conditions as in Example 8.
Then, in the plating process, in the plating bath shown below
Immersed in titanium and electroless Ni-9P plated
Then, a Ni-9P plating film having a thickness of 20 μm was formed.

The plating bath was composed of nickel sulfate 0.1 mol / l, sodium hypophosphite 0.2 mol / l, malic acid 0.2 mol / l, sodium acetate 0.05 mol / l, and lead (acetic acid). 0.2 ppm, pH 5.0, temperature 90 ° C. Next, a heat treatment was performed at 250 ° C. for 2 hours as a heating step. Then, the adhesion of the plating film was measured for the obtained sample in the same manner as in Reference Example 1.

As a result, in each of the samples, 7 to
A plating film having a large adhesion force of 9 kgf / 2 mm □ (solder breakage) was formed. Further, a hard Cr plating film was further formed on the plating surface to a thickness of 3 μm by an electroplating method using an ordinary Sargent bath. However, no blistering or peeling occurred in the plating step, and the surface was in a good condition. Tables 3 and 4 show the measurement conditions of Reference Examples 1 to 8 and Examples 1 and 2 .

[0101]

[Table 3]

[0102]

[Table 4]

[Brief description of the drawings]

FIG. 1 shows that in Reference Example 1, the hydrofluoric acid concentration was Ni-
The graph which shows the influence which 10P electroless plating gives to the deposition situation.

FIG. 2 is a graph showing the relationship between the hydrofluoric acid concentration of the Ti-6Al-4V material and the peel adhesion strength in Reference Example 1.

In Figure 3 Reference Example 1, beta-C alloy (500 ° C. × 2
7 is a graph showing the relationship between the concentration of hydrofluoric acid in (Hr vacuum treatment) and peel adhesion strength.

FIG. 4 is a cross-sectional view of a Ti-6Al-4V material in Reference Example 2.
4 is a graph showing a relationship between a heating temperature and an adhesion strength of a plating film.

FIG. 5 shows a comparison example of Reference Example 5 with Ti-6A.
The graph which shows the relationship between the washing | cleaning time and peel adhesion strength of 1-4V material.

FIG. 6 shows a comparison example of Reference Example 5 with Ti-6A.
The graph which shows the relationship between the washing | cleaning time and plating plating area of 1-4V material.

FIG. 7 is a graph showing the relationship between heating time and adhesion strength when a Ti-6Al-4V material is used in Reference Example 6.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takehiro Nito 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Shin Shin Fukada 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation ( 56) References JP-A-5-51758 (JP, A) JP-A-63-72894 (JP, A) JP-A-4-136183 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 18/00-18/54 C25D 5/38

Claims (2)

(57) [Claims] 1. A surface of a titanium material made of titanium metal or titanium alloy is activated by contacting the material with an acid solution containing fluoride ions and at least one metal ion of transition metal ions, zinc ions or tin ions. A pre-treatment step of causing the metal to precipitate, a washing step of bringing the titanium material into contact with water or a rinsing liquid, and immersing the titanium material in a plating bath containing a plating raw material to activate and deposit the metal. A plating process for applying a plating treatment to the surface of the titanium material thus obtained and removing the titanium material from the plating bath; and a heating process for heating the titanium material. Contains at least 0.5 mol / l of fluoride ions, and the above-mentioned rinsing liquid contains 0.01 mol / l of fluoride ions. Plating a titanium material characterized in that it comprises above. 2. The method according to claim 1, wherein the metal ion is
A method of plating a titanium material, wherein the method is at least one selected from the group consisting of zinc ions, tin ions and nickel ions.