JPH06346300A - Pretreatment method for plating titanium material and plating method for titanium material - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a method for treating a titanium material before the plating treatment of the titanium material, which has excellent adhesion of the plating film to the titanium material when various kinds of plating are applied to the surface of the titanium material, and a method for treating the titanium material. It is an object of the present invention to provide a titanium material plating treatment method in which a pretreatment is performed and then a plating treatment is performed. [Structure] A method is a method in which a titanium material is immersed in an electrolytic aqueous solution containing at least fluorine, and an alternating voltage is applied between the titanium material and the counter electrode material to corrode the surface. The optimum AC voltage is 0.1 to 20 V and the frequency is 3 Hz to 3 kHz. Further, the optimum fluorine concentration is 0.05 to 5 wt% and the optimum concentration of the organic additive is 0.1 to 30 wt%. Further, after performing corrosion with an electrolytic aqueous solution having the above concentration, plating treatment is immediately performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pretreatment method for plating the surface of a titanium material with excellent adhesion of the plating film to the titanium material, and a plating method therefor.

[0002]

2. Description of the Related Art Titanium has been widely used for applications such as aerospace materials and seawater desalination plant materials because of its light weight and excellent corrosion resistance. In recent years, application to so-called new uses such as mechanical parts such as automobile parts and electronic material parts such as magnetic disk substrates has become active.
However, in these new applications, higher levels of wear resistance and hardness are required, and therefore it is essential to form a high hardness plating layer on the surface of a titanium material that is a relatively soft material.

However, titanium is known as a difficult-to-plate material together with aluminum and molybdenum, and it has been impossible to form a reliable plated layer having good adhesion (for example, HJWiesner, AES.Symp.Plat). .Difficul
t-to-Plate Metals 1 (1980) p.1).

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pretreatment method having high adhesion of a plating film to a titanium material. Here, the titanium material is a pure titanium material, various titanium alloys and titanium alloys with various surface states (rolled material, pickling material, shot material,
Surface-hardening material, abrasive material, etc.). In addition, the plating film here means a film formed by electroless plating and a film formed by electroplating. Further, the types of plating include Ni plating, Cu plating, palladium plating, and alloy plating of these metals.

By the way, when the above-mentioned plating film is formed without performing any pretreatment on the titanium material, the plating composition and the plating method (the above-mentioned electroless plating or electrolytic plating), and the material of the titanium material. Peeling of the plating film easily occurs regardless of

This is because a chemically stable and dense oxide film is formed on the titanium surface, and this oxide film hinders the adhesion between the plating film and the titanium surface. From this fact, in order to improve the adhesion of the plating film, it is effective to perform a corrosive treatment by pickling to remove this oxide film before the plating process, and to form a plating layer on the exposed activated surface. Is.

Conventionally, various pickling methods (corrosion solutions) have been proposed (for example, HJ Wiesner, AES.Symp.Plat.Diff.
icult-to-Plate Metals 1 (1980) p.1), there is no report that a method for forming a stable plating layer on an industrial scale has been established. The reason is that dross-like oxides remain on the titanium material surface in the conventional pickling treatment, and furthermore, the hydrophilicity of the surface after pickling is insufficient, and the plating treatment after pickling is performed. This is because an oxide film due to the atmosphere is formed on the surface again while performing the step.

Although it has been reported that titanium hydride is effective for improving the plating adhesion, a means for uniformly forming the titanium hydride on the titanium material surface has not been established (for example, S .Ruben, USPatent 4,127,709
(1978), JPWinfree, USPatent 3,647,647 (1972)).
The present invention has been made in view of such circumstances, and provides a pretreatment method of a titanium material before plating of the titanium material and a pretreatment method thereof before forming a plating film having sufficient adhesion on the surface of the titanium material. The purpose is to provide the used plating method.

[0009]

Means for Solving the Problems In order to solve the above problems, the inventors of the present invention have made earnest studies on a method for improving the adhesion of a plating film of a titanium material. As a result, an electrolytic aqueous solution containing at least fluorine, Furthermore, when the electrolytic solution is applied in an aqueous solution containing an organic additive and an alternating voltage of a specific frequency is applied between a titanium material to be plated and a counter electrode material to perform electrolytic processing, a corrosion reaction and an oxidation reaction occur. It is newly found that the atmospheric oxide film layer is uniformly removed, and a hydrophilic and homogeneous titanium hydride is formed on the titanium surface, and plating with sufficient adhesion can be performed. I found it possible. Specifically, it is as follows.

(1) The invention of claim 1 is a pretreatment method for plating a titanium material, which comprises the following steps. (A)
A step of preparing a titanium material to be plated and a counter electrode material; (b) a step of immersing the titanium material and the counter electrode material so that at least fluorine is separated from an aqueous electrolytic solution; and (c) with respect to the titanium material, A step of applying an alternating voltage between the counter electrode material.

(2) The invention of claim 2 is the pretreatment method for plating a titanium material according to claim 1, wherein the AC voltage is 0.1 V to 20 V. (3) In the invention of claim 3, the frequency of the alternating voltage is 3 Hz.
The pretreatment method for plating titanium material according to claim 1, wherein the pretreatment method is ˜3 kHz. (4) In the invention of claim 4, the electrolytic solution is an organic additive other than fluorine such as a hydroxy compound, a carbonyl compound, a carboxylic acid, an alkyl chain compound, an acetylene hydrocarbon compound, a heterocyclic aromatic compound and a derivative thereof. The pretreatment method for plating a titanium material according to claim 1, which is an electrolytic aqueous solution containing one or two of the above.

(5) The titanium material according to claim 1, wherein the electrolytic solution has a fluorine concentration of 0.05 wt% to 5 wt% and an organic additive concentration of 0.1 wt% to 30 wt%. This is a pretreatment method for plating. (6) The invention of claim 6 is a pretreatment method for plating a titanium material, which comprises the following steps. (A) a step of performing the pretreatment method according to any one of claims 1 to 5, and (b) a step of immediately performing a plating treatment on the treated titanium material.

[0013]

The shape of the titanium material to be electrolyzed is not particularly limited, and may be a plate, a rod, or a somewhat complicated shape. The counter electrode material may be a conductive material that does not dissolve much in the electrolytic solution. Since the applied voltage is an alternating current, a titanium material that is subjected to electrolytic treatment may be used. In this case, two titanium materials can be treated simultaneously by one treatment. The electrolytic solution needs to be an electrolytic aqueous solution containing at least fluorine.
This is because fluorine can corrode the oxide film formed on the surface of the titanium material. Other components of the electrolytic solution may include lactic acid, acids such as sodium that do not oxidize titanium materials, alkalis, and the like.

Normally, a DC voltage is used in the electrolytic treatment, but in the present invention, the titanium material is not anodized,
An important feature is that an AC voltage is used to generate hydride on the surface (claim 1).

The AC voltage applied is preferably 0.1V to 20V. If it is lower than 0.1 V, the oxide may be insufficiently removed, and if it exceeds 20 V, surface adhesion may cause insufficient plating adhesion (claim 2).

Next, the frequency of the AC voltage is 3 Hz or more and 3 k.
It is desirable to be within Hz. If the frequency is less than 3 Hz, the oxide may be insufficiently removed, resulting in 3 kHz.
When z is exceeded, surface oxidation becomes excessive as compared with corrosion, and therefore the adhesiveness becomes insufficient. From the above, the optimum range of the frequency of the alternating voltage is 3 Hz or more and 3 kHz or less (claim 3).

Next, when the electrolytic solution contains one or two of a hydroxy compound, a carbonyl compound, a carboxylic acid, an alkyl chain compound, an acetylene hydrocarbon compound, a heterocyclic aromatic compound and a derivative thereof as an organic additive, It is desirable because it controls the viscosity of the electrolytic solution to increase the homogeneity of the above reaction and also has its own corrosive action (claim 4).

As a result of various studies on the optimum range of the electrolytic solution, it has been found that optimum corrosion is carried out in the following fluorine and organic additive concentration ranges. It is desirable that the optimum fluorine concentration is 0.05 wt% or more and 5 wt% or less. If the concentration is less than 0.05 wt%, the oxide may be insufficiently removed, and the concentration may be 5 wt%.
If it exceeds, corrosion will be excessive and the adhesion of the plating will be insufficient. From the above, the optimum range of fluorine concentration is 0.0
It is set to 5 wt% to 5 wt%.

The concentration of the organic additive is 0.1 wt% or more 30
It is preferably within the wt%. This concentration is 0.1
This is because it was found that if it is less than wt%, the oxide may be insufficiently removed, and if it exceeds 30 wt%, the corrosion becomes excessive and the adhesion of the plating is insufficient. . Therefore, the optimum concentration of the organic additive is 0.1 wt% to 30 wt
% Is optimal (claim 5).

When the titanium material pretreated by the pretreatment method of the present invention is plated, electroless plating or electrolytic plating may be used. In addition, there are various types of plating such as Ni, Cu, Ni-P, and Ni-Cu-P. When the pretreated titanium material is plated, it is important to perform it immediately after the pretreatment. This is to prevent the surface of the titanium material from being oxidized by the atmosphere (claim 6).

[0021]

EXAMPLES Examples of the present invention will be described below. Example 1 CP-2 type pure titanium cold rolled sheet (50 × 50 × 0.85 m
m) 0.1% by weight of fluorine and 5% by weight of organic additive
In the corrosive liquid containing (a mixed aqueous solution of sodium fluoride and lactic acid), the substrate is one electrode, the other electrode is a pure titanium plate, the distance between the electrodes is 3 cm, and the frequency is 50 Hz without stirring the electrolytic solution. An electrolytic voltage of 0.05 V to 25 V was applied for 20 seconds to perform electrolytic corrosion. After that, electroless Ni
-12 wt% P plating was applied. The plating solution has the following composition.

Nickel sulfate: 30 g / liter, sodium hypophosphite: 20 g / liter, lactic acid: 30 g / liter, propionic acid: 5 g / liter, lead: 2 mg / liter PH4.5, solution temperature 90 ° C. in the above plating solution I went for 90 minutes.

Electrolytic Ni-12 wt% P plating was performed using a plating solution having the following composition. Nickel sulfate: 240 g / liter, nickel chloride: 4
5 g / liter, boric acid: 30 g / liter, phosphorous acid 3
5 g / liter, PH2 Titanium material is used as one pole in the above liquid, nickel plate is used for the other pole, the distance between the poles is 10 cm, and 1.5 A / dm2
Plating was performed for 10 seconds at the current of.

The adhesion of the plating film was evaluated for the samples subjected to the above plating treatment. Adhesion is JIS H860
The cross-cut test according to 2 was performed. However, in this example, the peeling test was conducted at arbitrary 5 points (5 points) instead of evaluating the adhesion by only the 1 point peeling test within the sample (5 × 5 cm).

The reason for this is that the plating pretreatment method of the present invention is intended to perform a uniform plating treatment. Therefore, it is necessary to investigate the variation in the adhesion of the plating depending on the location. Is to be evaluated. When peeling was not observed at all 5 points, ○ When peeling was observed at 1 to 4 points out of 5, Δ when peeling was observed at all 5 points
And

Further, the adhesion was evaluated by a bending test according to JIS H8504. ○ When peeling was not observed, △ when not peeled but cracks occurred, △,
When peeled off, it was marked with x. Table 1 shows the pretreatment conditions in this case,
The voltage and the adhesion after plating are shown. From Table 1, when the AC voltage is less than 0.1 V and exceeds 20 V, plating peeling occurs at all 5 points in both electroless and electrolytic plating.
Also, peeling occurs in the bending test. AC voltage is 0.1V
It was confirmed that in the range of 20 V or less, uniform plating can be performed without variation in adhesion, and this range of AC voltage is favorable.

For comparison, the method proposed by S. Ruben was also evaluated, and the results are shown in Table 1. The method degreased titanium material in xylene, was immersed in an aqueous solution of NH ₄ F · HF and NH ₄ F, further, dipped in H ₂ SO ₄ containing H ₂ PO ₄ 1%,
Subsequently, this is a method in which lead is used as an anode for electrolysis, Ni is finally plated, and then lead is plated. It was clear that the method of the invention is superior to this method.

[0028]

[Table 1]

Example 2 Similar to Example 1, CP-2 type pure titanium cold rolled sheet (50 ×
50 × 0.85 mm) in a corrosive liquid (mixed aqueous solution of sodium fluoride and lactic acid) containing 0.1 wt% of fluorine and 5 wt% of organic additive, the substrate being one electrode, and the other electrode being a pure titanium plate Was used, the distance between the electrodes was set to 3 cm, and the electrolytic corrosion was performed by applying an AC voltage of 4 V having a frequency of 1 Hz to 3.5 kHz for 20 seconds without stirring the electrolytic solution. Thereafter, the same electroless and electrolytic Ni-12 wt% as in Example 1 was used.
P plating was applied.

Table 2 shows the pretreatment conditions in this case, the frequency and the adhesion after plating. The evaluation was performed in the same manner as in Example 1. From Table 2, when the frequency is lower than 3 Hz and higher than 3 kHz, peeling of plating occurs at all 5 points in both electroless plating and electrolytic plating. Also, peeling occurs in the bending test. It has been confirmed that when the frequency is in the range of 3 Hz or more and 3 kHz or less, uniform plating can be performed without variation in adhesion, and the frequency is in this range.

[0031]

[Table 2]

Example 3 As in Example 1, CP-2 type pure titanium cold rolled sheet (50 ×
50 × 0.85 mm) 0.03 wt% to 7 wt% fluorine
%, And 5 wt% of an organic additive in a corrosive liquid (mixed solution of sodium fluoride and lactic acid), the substrate is one electrode, the other electrode is a pure titanium plate, and the distance between the electrodes is 3 cm. The electrolytic corrosion was performed by applying an AC voltage of 4 V with a frequency of 50 Hz for 20 seconds without stirring. After that, the same electroless and electrolytic Ni-12 wt% P plating as in Example 1 was applied. Table 3 shows the pretreatment conditions in this case, the fluorine concentration and the adhesion after plating. The evaluation was performed in the same manner as in Example 1. From Table 3, when the fluorine concentration is less than 0.05 wt% and exceeds 5 wt%, peeling of plating occurs at all 5 points in both electroless and electrolytic plating. Also, peeling occurs in the bending test. Fluorine concentration is 0.05wt%
It was confirmed that if the content is in the range of 5 wt% or less, the adhesiveness does not vary and uniform plating can be performed, and the concentration of fluorine is in this range.

[0033]

[Table 3]

Example 4 A CP-2 type pure titanium cold-rolled sheet (thickness 0.85 mm) was punched into a magnetic disk substrate shape having a diameter of 2.5 inches, which was given a predetermined inner and outer peripheral end face processing to form a titanium magnetic material. It was used as a disk substrate. This substrate was placed in one pole and the other pole in a corrosive liquid containing 0.1 wt% of fluorine and 0.05 wt% to 35 wt% of organic additive (mixed aqueous solution of sodium fluoride and organic additive). Is a pure titanium plate, the distance between the electrodes is 3 cm, and the frequency is 5 without stirring the electrolytic solution.
An AC voltage of 4 Hz of 0 Hz was applied for 20 seconds to carry out electrolytic corrosion. Thereafter, the same electroless and electrolytic Ni-1 as in Example 1 was used.
2 wt% P plating was applied. The organic additives are the following organic compounds. Isobutyl alcohol is an example of a hydroxy compound, coumarin is an example of a carbonyl compound, lactic acid is an example of a carboxylic acid, allyl aldehyde is an example of an alkyl chain compound, 1,4-butynediol is an example of an acetylene hydrocarbon compound, and heterocyclic aroma. Pyrimidine was used as an example of the group compound.

Table 4 shows the pretreatment conditions in this case, various organic additives, the concentration and the adhesion after plating. Evaluation is Example 1
The same method was used. However, the results of the cross-cut peeling test were good within the scope of claim 5, and were omitted.
From Table 4, when the concentration of various organic additives is less than 0.1 wt% and exceeds 30 wt%, stripping of plating occurs in both electroless and electrolytic plating. If the concentration of various organic additives is in the range of 0.1 wt% or more and 30 wt% or less, uniform plating can be performed without peeling of the plating, and the concentration of organic additives is good in this range. Similar effects can be obtained with additives. Even when the pretreatment is performed with an aqueous solution mixed with various organic additives, the effect is not changed as long as the concentration is within the above range.

[0036]

[Table 4]

[0037]

According to the present invention, it is possible to perform plating with good adhesion to a titanium material. The present invention can obtain the same effects with pure titanium materials, various titanium alloys, and titanium alloys with various surface states (rolled materials, pickling materials, shot materials, surface effect treatment materials, abrasive materials, etc.).

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hiroyoshi Suenaga Inventor, Marunouchi 1-2-2, Chiyoda-ku, Tokyo Japan Steel Pipe Co., Ltd. (72) Inventor, Masaki Omura 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Date Inside the Steel Pipe Co., Ltd. (72) Inventor, Hitoshi Nagashima, 1-2 Marunouchi, Chiyoda-ku, Tokyo Japan Inside Steel Pipe Co., Ltd. (72) Iwa Ida, 1-2, Marunouchi, Chiyoda-ku, Tokyo Japan Steel Pipe Within the corporation

Claims (6)

[Claims] 1. A pretreatment method for plating a titanium material, which comprises the following steps. (A) a step of preparing a titanium material and a counter electrode material to be plated, and (b) a step of separating the titanium material and the counter electrode material from each other in an electrolyte aqueous solution containing at least fluorine to immerse them, and (c)
A step of applying an alternating voltage between the titanium material and a counter electrode material. 2. The pretreatment method for plating a titanium material according to claim 1, wherein the AC voltage is 0.1 V to 20 V. 3. The frequency of the alternating voltage is 3 Hz to 3 kHz.
The pretreatment method for plating titanium material according to claim 1, wherein z is z. 4. In addition to fluorine as the aqueous solution of the electrolytic solution, a hydroxy compound, a carbonyl compound, a carboxylic acid, an alkyl chain compound, an acetylene hydrocarbon compound, a heterocyclic aromatic compound and a derivative thereof as an organic additive. Alternatively, the pretreatment method for plating a titanium material according to claim 1, which is an electrolytic aqueous solution containing two or more kinds. 5. The fluorine concentration of the electrolytic solution is 0.05 wt.
% To 5 wt% and the concentration of organic additive is 0.1 wt% to
The pretreatment method for plating titanium material according to claim 1, which is 30 wt%. 6. A pretreatment method for plating titanium material, comprising the steps of: (A) a step of performing the pretreatment method according to any one of claims 1 to 5, and (b) a titanium material subjected to the treatment,
The process of performing the plating process immediately.