JPH0734255A - Pretreatment method for plating titanium material and plating method - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a titanium material pretreatment method and a titanium material plating method, which have excellent adhesion of the plated film to the titanium material when the titanium material surface is plated. [Structure] A titanium material and a cathode material, which are materials to be plated having a predetermined surface roughness defined by Sm, Rv and Rp, are prepared, and they are separated from each other to a predetermined concentration of fluorine, chlorine, bromine and iodine. This is a pretreatment method in which at least one kind or two or more kinds of them are immersed in an electrolytic aqueous solution having a predetermined concentration and a predetermined DC voltage is applied to perform anodization. Further, it is a plating method in which the titanium material is plated after the pretreatment.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Titanium has been widely used for aerospace materials, seawater desalination plant materials and the like because it is lightweight and has excellent corrosion resistance. In recent years, application to so-called new applications such as mechanical parts such as automobile parts and electronic parts such as hard disk substrates has become active. However, higher levels of abrasion resistance and hardness are required for these new applications. For example, in applications where abrasion resistance is required, such as bolts / nuts, valve retainers, and sleeves of hydraulic tools, it is necessary to form a high hardness plating layer on the surface of titanium material, which is a relatively soft material. Indispensable. However, titanium is known as a difficult plating material along with aluminum and molybdenum (for example, H.
J. Wiesner, AES.Symp.Plat.Difficult-to-Plate Metals
1 (1980) P.1), it has been considered impossible to form a plated layer with good adhesion.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pretreatment method having high adhesion of a plating film to a titanium material. Here, the titanium material includes pure titanium material, various titanium alloys, and titanium alloys with various surface states (rolled material, pickling material, shot material, surface hardening treatment material, abrasive material, etc.).
The term "plated film" as used herein means an electroless film and a film formed by electroplating. Further, the electroless plating includes Ni plating, Cu plating, palladium plating and alloy plating of these metals.

The electroplating is Ni plating, C
u plating, Cr plating, and plating of various alloys of these metals. By the way, when the above-mentioned plating film is formed without applying any pretreatment to the titanium material, the component composition of the plating material and the plating method (the above-mentioned electroless plating,
Or electroplating), and the plating film is easily peeled off regardless of the titanium material.

This is because a chemically stable and dense oxide film is formed on the as-polished 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 necessary to perform a corrosive treatment by pickling to remove the oxide film before the plating process to form a plating layer on the exposed activated surface. It is valid.

Conventionally, pickling methods using various corrosive solutions have been proposed (for example, HJ Wiesner, AES.Sym.
p.Plat. Difficult-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 for this is that dross-like oxides remain on the titanium material surface in the conventional acid treatment, and the hydrophilicity of the surface after pickling is insufficient, and plating treatment is performed after pickling. This is because an oxide film due to the atmosphere is formed again on the surface of the titanium material in the meantime. The present invention has been made in view of the above circumstances, and is a pretreatment method for plating a titanium material for forming a film having sufficient adhesion on the surface of the titanium material, and a subsequent plating treatment after the pretreatment method. The purpose is to provide a method of doing.

[0007]

In order to solve the above problems, the inventors of the present invention have conducted various studies on methods for improving the adhesion of the plating film of titanium material, and as a result, the material to be plated has a predetermined surface condition ( Sm and Rv, Rp specified range), this titanium material is immersed in an electrolytic aqueous solution in which fluorine and at least one or more halogen elements of chlorine, bromine and iodine coexist before plating. Then, a predetermined direct current voltage was applied to perform pretreatment, and then a known electroless or electrolytic plating method was found to enable formation of a metal film on a titanium material having excellent adhesion. The specific means will be described below. (1) The invention of claim 1 is a pretreatment method for plating a titanium material, which comprises the following steps. (A) The average interval (Sm) of surface irregularities is 13 μm or less,
A step of preparing a titanium material as a material to be plated and a cathode material which are processed to have a surface roughness of 0.1 to 1 μm in average line height (Rv) and average line depth (Rp), respectively; The titanium material and the cathode material are separated from each other, and a predetermined concentration of fluorine (F) and one or more selected from chlorine (Cl), bromine (Br) and iodine (I) are halogens having a predetermined concentration. A step of immersing in an electrolytic aqueous solution containing an element,
(C) A pretreatment step of a titanium material for plating, in which the titanium material is used as an anode and the cathode material is used as a cathode, and a predetermined DC voltage is applied to perform the treatment. (2) The invention of claim 2 provides the titanium material for plating according to claim 1, wherein the predetermined concentration of fluorine (F) and the predetermined concentration of halogen elements (Cl, Br, I) are in the following ranges: This is a pretreatment method.

F: more than 0.2 wt% and less than 11 wt% Cl + Br + I; more than 0.1 wt% and less than 16 wt% (3) In the invention of claim 3, the predetermined DC voltage is 0.3V.
It is the pretreatment method of the titanium material for plating by the anodizing method of Claim 1 or Claim 2 which is more than or equal to 20 volt and less. (4) The invention of claim 4 is a method for plating a titanium material, which comprises the following steps. (A) A step of performing the pretreatment method for the material according to any one of claims 1 to 3, and (b) a step of plating the titanium material subjected to the pretreatment method.

[0009]

In the present invention, the titanium plating material, which is a material to be plated, is processed to have a predetermined surface roughness, subjected to a predetermined pretreatment, and then subjected to a plating treatment to form a metal plating film on a titanium material having excellent adhesion. Can be provided. Surface Properties of Plated Material The inventors of the present invention conducted various studies on the surface roughness and the adhesion of the plated layer of a titanium material whose surface was polished using an abrasive having a grain size of # 800 to 3000, and found that the average of the plated materials was When the spacing (Sm) exceeds 13 μm, or the average line height (Rv) and average line depth (Rp) are less than 0.1 μm, or the substrate surface is close to a mirror surface state and adhesion cannot be secured, and When Rv and Rp are more than 1 μm, it was clarified that the deep irregularities on the surface serve as the starting points of cracks and the peeling of the plating film due to plating is likely to occur, and there is an appropriate range for the surface roughness of the material to be plated. I found a thing.

Here, Sm is measured as follows. Two peak count levels (upper and lower count levels) parallel to the center line of the surface roughness curve and having a width of 70% of the maximum height are provided, and the lower peak count level and roughness are provided. When the upper count level and the point where the roughness curve intersects at least once between two points where the curves intersect, the number of the peaks is counted, and the average value of the intervals between these peaks existing in the reference length 250 μm is calculated. It is Sm.

The details of the method for measuring the average line height (Rv) and the average line depth (Rp) are given in "Measurement of Surface Roughness" (November 1991) by Kosaka Laboratory. In order to further improve the adhesion of the plating film formed on the titanium material,
In addition to specifying the surface roughness of the plated material described above,
The pretreatment method before plating is extremely important. In the present invention, it was found that it is possible to improve the adhesion of the plating film by performing pretreatment using an electrolytic aqueous solution containing fluorine and one or more of the above halogen elements as a pretreatment method (claim) 1). Component composition of the electrolytic aqueous solution As a result of examining various components of the electrolytic aqueous solution, fluorine was more than 0.2 wt% and less than 11 wt%, and the halogen element concentration was Cl + Br + I. Over 0.1 wt%, 1
It has been found that it is optimal to be less than 6 wt% (claim 2). As a result of various studies on the applied voltage and the applied voltage , the adhesion of the plating film is insufficient at 0.3 Volt or less. For the upper limit of the applied voltage, set the voltage to 20 Vol.
When it is t or more, a large amount of hydrogen gas is generated at the cathode, and the current efficiency is reduced. Further, when such a high voltage is applied, the surface of the plating film may be roughened to cause plating damage. Therefore, the desirable upper limit voltage is 20 Volt (claim 3). The cathode material and the inter-electrode distance cathode material may be any metal that is insoluble in the electrolytic aqueous solution, and for example, pure titanium, titanium alloy, Ni or the like can be used. If the distance between the electrodes is too small, a short circuit occurs, while if it is too large, the applied voltage must be increased.
About 10 cm is good.

By plating the titanium material using the above-mentioned pretreatment method by a conventionally known plating method (electroless plating and electroplating), it is possible to form a plating film having excellent adhesion. (Claim 4).

[0013]

EXAMPLES Various examples of the present invention will be described below. The pretreatment of the present invention is performed at room temperature, and detailed plating conditions such as the plating method and the composition of the plating bath will be described in Examples. As a method for evaluating the adhesion of the generated plating film, the barrel polishing test method and the bending test method described in JIS H8504 were adopted. This test method, especially considering the application as sliding parts,
This is because there is a correlation with the adhesion of the plating film on the sliding portion, and it was judged that the evaluation by the above-mentioned two types of tests was appropriate. Example 1 CP-2 type pure titanium cold rolled sheet (50 × 50 × 0.85 m
m) was plated on a titanium material whose surface was polished with an abrasive having a grain size of # 800 to 3000, and the relationship between the surface roughness of the plated material on which the plating film was formed and the adhesion of the plating film was investigated.

The pretreatment of plating is 0.4 wt% bromine water + 5
Using a wt% NaF + 1 vol% HF aqueous solution, the material to be plated was immersed in the electrolytic solution for 15 seconds and then electrolyzed for 50 seconds. At this time, the material to be plated was an anode and the cathode was a pure titanium plate, and the distance between the electrodes was 5 cm. After that, the electrolytic solution was thoroughly washed with water and then plated with NiP.

The NiP plating uses an electrolytic plating method, and the composition of the plating solution and the plating conditions are as follows.

Plating Electrolyte Composition Nickel Sulfate (Hexahydrate) (NiSO ₄ .6H ₂ O) 240 g / l Nickel Chloride (Hexahydrate) (NiCl ₂ .6H ₂ O) 45 g / l Boric Acid (H ₃ BO ₃ ) 30 g / l phosphorous acid (H ₃ PO ₃ ) 35 g / l pH; 2 plating conditions cathode; plated material, anode; nickel plate, distance between electrodes; 10
cm 2 Current density; DC 1.5 A / dm ² Electrolyte temperature; 55 ° C. Table 1 shows the surface roughness of the material to be plated and the evaluation results for each sample. When the surface roughness Rv and Rp are 0.05 or less, the plating film peels off from the front surface in the adhesion test, and this condition is not suitable. When the surface roughness Rv and Rp are in the range of 0.1 to 0.5, partial peeling is observed when the thickness of the plating film is relatively large (exceeds 15 μm), but generally good adhesion is obtained. Has been obtained.
Further, when the surface roughness Rv and Rp are 1.1 or more, the entire surface is peeled off in the adhesion test regardless of the average spacing Sm of the irregularities.

From the results shown in Table 1, as the surface roughness of the material to be plated, when Rv and Rp are in the range of 0.1 to 1 μm and the average interval Sm of the irregularities is a value of 13 μm or less, the plating film is formed. It has been revealed that sufficient adhesion can be obtained.

[0018]

[Table 1] Example 2 CP-2 type pure titanium cold rolled sheet (50 × 50 × 0.85 m
For the titanium material whose surface is m) polished with an abrasive having a particle size of # 800 to 3000, the pretreatment is performed by changing the liquid composition of the plating pretreatment liquid, and then NiP plating is performed, and the liquid composition of the pretreatment liquid is changed. The effect on the adhesion of the plating film was investigated.

However, the surface roughness of the material to be plated is R
Both v and Rp were 0.1 to 1 μm, and Sm was 13 μm or less. The composition of the plating solution and the plating conditions are the same as in Example 1. However, the thickness of the plating film was set to about 5 μm, which had good adhesion in Example 1. Table 2 shows the composition of the pretreatment liquid and the evaluation results. ○ in the table indicates
No peeling, Δ mark indicates partial peeling, and X mark indicates that the entire surface peeled.

From the results of Table 2, as the range of the liquid composition of the pretreatment liquid, the fluorine concentration is more than 0.2 wt% and less than 11 wt%, and the total halogen element concentration is more than 0.1 wt% and less than 16 wt%. By this, a plating film having excellent adhesion can be formed on the titanium material.

[0021]

[Table 2] Example 3 CP-2 type pure titanium cold rolled sheet (50 × 50 × 0.85 m
m), the surface of which is polished using an abrasive having a particle size of # 800 to 3000, and a titanium material having a surface roughness Rv and Rp of 0.1 to 1 μm and an Sm of 13 μm or less, 0.4 wt. % Bromine + 5 wt% NaF + 1 vol% H
The material to be plated was immersed in the electrolytic solution for 15 seconds using the F aqueous solution, and then electrolysis was performed for 50 seconds.

A sample is used as an anode and a pure titanium plate is used as a cathode.
The distance between the electrodes was 5 cm. Then electroless and electrolytic NiP
Plating was performed and the adhesion of the plating film at that time was examined. The plating solution composition and plating conditions are as follows.

Electroless NiP plating solution composition Nickel sulfate (hexahydrate) (NiSO ₄ .6H ₂ O) 30 g / l Sodium hypophosphite (monohydrate) (NaH ₂ PO ₂ .H ₂ O) 20 g / L Lactic acid (CH ₃ CH (OH) COOH) 30 g / l Propionic acid (CH ₃ CH ₂ COOH) 5 g / l Lead 2 mg / l pH; 4.5 Electroless plating conditions Liquid temperature; 90 ° C. Treatment time; 90 minutes electrolytic NiP plating composition nickel sulfate _{(hexahydrate) (NiSO 4 · 6H 2 O} ) 240g / l nickel chloride _{(hexahydrate) (NiCl 2 · 6H 2 O} ) 45g / l boric acid (H ₃ BO ₃₎ 30 g / l phosphorous acid (H ₃ PO ₃ ) 35 g / l pH; 2 Electrolytic plating conditions Cathode; Plated material, anode; Nickel plate, distance between electrodes; 10
cm Current density; DC 1.5 A / dm ² , electrolysis time; 5 minutes Electrolyte temperature; 55 ° C. Table 3 shows the influence on the adhesion of the plating film when the DC voltage applied during this electrolysis is changed. Show.

From the results shown in Table 3, it can be seen that the DC voltage applied during the pretreatment is 0.3 volt or more and 20 Volt or less, the plating film exhibits sufficient adhesion.

[0025]

[Table 3]

[0026]

As shown in the above embodiments, the titanium material is subjected to the pretreatment method according to the present invention and then plated, whereby a plated film having excellent adhesion can be obtained. It is possible to expand the usage of the material.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuichi Hirata 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Masanori Omura 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Inside the Steel Pipe Co., Ltd. (72) Iwa Ida, Marunouchi 1-2-2, Chiyoda-ku, Tokyo Japan Steel Pipe Within (72) Inventor, Hitoshi Nagashima 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Within the corporation

Claims (4)

[Claims] 1. A pretreatment method for plating a titanium material, which comprises the following steps. (A) The average interval (Sm) of surface irregularities is 13 μm or less,
A step of preparing a titanium material as a material to be plated and a cathode material which are processed to have a surface roughness of 0.1 to 1 μm in average line height (Rv) and average line depth (Rp), respectively; The titanium material and the cathode material are separated from each other, and a predetermined concentration of fluorine (F) and one or more selected from chlorine (Cl), bromine (Br) and iodine (I) are halogens having a predetermined concentration. A step of immersing in an electrolytic aqueous solution containing an element,
(C) A pretreatment step of a titanium material for plating, in which the titanium material is used as an anode and the cathode material is used as a cathode, and a predetermined DC voltage is applied to perform the treatment. 2. The pretreatment method for a titanium material for plating according to claim 1, wherein the predetermined concentration of fluorine (F) and the predetermined concentration of halogen element (Cl, Br, I) are in the following ranges. F: more than 0.2 wt% and less than 11 wt% Cl + Br + I; more than 0.1 wt% and less than 16 wt%. 3. The pretreatment method of a titanium material for plating according to the anodizing method of claim 1, wherein the predetermined DC voltage is 0.3 Volt or more and 20 Volt or less. 4. A titanium material plating method comprising the steps of: (a) performing a titanium material pretreatment method according to any one of claims 1 to 3; and (b) performing the pretreatment method. Process of plating titanium material.