JPH0352543B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a copper-based metal member having a phosphate-based chemical conversion coating such as zinc phosphate. It relates to metal members, and is expected to have great effects when used in copper electric wires, etc. [Prior Art] Conventional iron-based materials have been known to have their surfaces subjected to chemical conversion treatment such as zinc phosphate or zinc chromate. Chemically treated iron-based materials are used in various fields due to their excellent performance. On the other hand, in the case of copper-based metal members, since copper itself is a chemically stable metal, it has conventionally been difficult to perform the above-mentioned chemical conversion treatment applied to iron-based materials. Other methods include copper-based metal parts with a cuprous oxide film obtained by treatment in an aqueous solution of potassium chlorate or potassium perchlorate at 80 to 90°C for 5 to 10 minutes, or sodium hydroxide and persulfuric acid. Copper-based metal members having a cupric oxide-based film obtained by processing in an aqueous solution containing potassium at 100° C. or higher for 3 to 10 minutes are known. When a phosphate film was required, the entire copper metal was galvanized and then phosphated. [Problems to be solved by the invention] A conventional copper-based metal member having a copper oxide-based film has the following problems:
Because the coating has poor reactivity compared to chemical conversion coatings applied to iron-based materials, the desired performance could not be obtained even after coating. Furthermore, the chemical conversion treatment method is troublesome and is currently used only in extremely limited fields. In addition, although phosphate films are highly reactive and desirable, in order to form them on copper-based base metals, zinc plating, etc. must be applied in advance, which poses problems in terms of work efficiency and cost. Ta. In view of the above-mentioned problems, the inventors of the present invention conducted extensive research and discovered a method for forming a phosphate-based chemical conversion film on the surface of a copper-based base metal. That is, an object of the present invention is to provide a copper-based metal member having a chemical conversion film based on the above discovery. [Means for Solving the Problems] The copper-based metal member of the present invention comprises a copper-based base metal, and a chemical conversion coating formed on at least a portion of the surface of the copper-based base metal, comprising a phosphate and a copper halide. It is characterized by consisting of: Copper or a copper alloy is used as the copper-based base metal in the present invention. There are no particular restrictions on its shape; it can be plate-shaped,
Almost any shape can be used, from simple shapes such as rods or lines to complex shapes such as molded bodies. The chemical conversion film referred to in the present invention is composed of at least one phosphate selected from zinc phosphate, manganese phosphate, iron phosphate, and calcium phosphate, and at least one copper halide selected from copper chloride, copper bromide, and copper iodide. be done. Note that the copper halide is preferably cuprous halide, which has a small solubility product. The above chemical conversion film is produced by contacting the above copper base metal with a chemical conversion treatment bath containing phosphate ions, metal ions, halogen ions, etc. by a dipping method, a spray method, etc.
It is formed by reacting with copper at room temperature (°C). This chemical conversion film may be crystalline or amorphous. Further, the thickness of the film can be changed depending on the required performance, but it is preferably 2μ to 30μ because the performance is well balanced. The chemical conversion film may be formed on the entire surface of the copper base metal, or may be formed only on a portion of the surface. For example, it may be formed only on the inner surface of a copper tube, or it may be formed only on a groove or hole of a copper base metal having a groove or hole.
Note that FIG. 1 shows a schematic diagram of the copper-based metal member of the present invention. This indicates that the chemical conversion film 2 is directly formed on the surface of the copper base metal 1. The most distinctive feature of the copper-based metal member of the present invention is that it has the above-mentioned chemical conversion coating. The composition of the treatment bath for forming the chemical conversion film and the film forming mechanism will be explained below. The chemical conversion bath contains phosphate ions, metal ions,
Contains halogen ions and oxidizing agents. The metal ions contained in this chemical conversion treatment bath include zinc, manganese,
Metal ions, such as iron and calcium, which exist as stable dihydrogen phosphate compounds in aqueous solutions and whose solubility is significantly reduced by the dehydrogenation reaction shown in the following formula (1) can be used. xM( _H2PO4 )y→Mx( _PO4 )y+2yH ⁺ ...(1) As the halogen ion, _copper salts of the halogen with sufficiently small solubility products can be used, including chlorine, bromine, and iodine can be used.
Fluorine is difficult to use because its electronegativity is larger than that of oxygen, and its behavior in aqueous solutions is clearly different from that of other halogens, which have smaller electronegativity than oxygen. As an oxidizing agent, hydrogen peroxide, nitrite ion, which promotes the dissolution of copper in an acidic solution and itself performs a reduction reaction, as shown in formula (4) or formula (5).
Dichromate ion etc. can be used. When the copper base metal comes into contact with the above chemical conversion treatment bath, a chemical conversion film is formed on the surface of the copper base metal, and the process will be explained step by step. On the surface of the copper base metal that comes into contact with the above chemical conversion treatment bath, an anode reaction (oxidation reaction of metal solubility)
and a cathode reaction are occurring at the same time. First, the dissolution reaction of copper occurs, and the anode reaction of the following formulas (2) and (3) and the cathode reaction by the oxidizing agent of the following formulas (4) and (5) occur, and the following formulas (4) and (5) occur. The electrode potential of is expressed by equation (2) and (3)
It is thought that copper dissolves in the chemical conversion treatment bath because the electrode potential is higher than that of the formula. Cu→Cu ⁺ +e ...(2) Cu ⁺ →Cu ²⁺ +e ...(3) H ₂ O ₂ +2H ⁺ +2e→2H ₂ O ...(4) NO ₂ ^- +2H ⁺ +e→H ₂ O+NO↑ ... …(5) In other words, the oxidizing agent in the acidic solution of the chemical conversion treatment bath
Since the reactions in equations (4) and (5) consume electrons e, the reactions in equations (2) and (3) proceed, and copper dissolves. Next, regarding the film forming reaction, taking as an example the case where zinc is used as the metal ion and chlorine is used as the halogen ion, the anodic reaction of formula (6) occurs very close to the surface of the copper base metal, and The cathodic reaction of equation (7) occurs, and colloidal particles of zinc phosphate and cuprous chloride, which have a small solubility product, are generated, which coagulate on the surface of the copper base metal to form a film.

[Table] 3Zn ₂ ⁺ +2H ₂ PO ₄ ^- →Zn ₃ (PO ₄ ) ₂ ↓＋4H ⁺ ...(6) Cu ₂ ⁺ +Cl ^- +e→CuCl↓ ...(7) Next, the analysis results of the chemical conversion film actually formed Based on this, the structure of this chemical conversion coating will be explained. Four types of chemical conversion coatings, A, B, C, and D, were used in the analysis. Table 1 shows the composition of the chemical conversion treatment bath.
In this case, zinc ions are used as metal ions, chlorine ions are used as halogen ions, and 35% hydrogen peroxide is used as an oxidizing agent. Chemical conversion film A
and B use a copper plate as the copper-based base metal;
The copper plate was immersed in a beaker containing a treatment bath having the composition shown above, treated at 25°C for 3 minutes, washed with water, and then dried. FIGS. 2 and 3 show electron micrographs (magnification x 1500, photographing angle 45 degrees) of the chemical conversion coating A and the chemical conversion coating B. From the photograph, it is observed that the surface is covered with fine crystals, and the size of each crystal is about 1/1 of that of the crystals of conventional zinc phosphate chemical conversion coatings formed on iron surfaces.
It is 3 to 1/5 and quite dense. For chemical conversion coatings C and D, the ring-shaped copper parts used in Example 2, which will be described later, were used as the copper-based base metal,
This was formed using the same actual continuous chemical conversion treatment apparatus as in Example 2. FIGS. 4 and 5 show electron micrographs (magnification x 1500, photographing angle 45 degrees) of the chemical conversion coating C and the chemical conversion coating D. Figures 4 and 5
In the figure, as in Figures 2 and 3, nothing that can be clearly identified as a crystal can be seen.

[Table] X-ray diffraction charts of chemical conversion coating C and chemical conversion coating D are shown in FIGS. 6 and 7. Chemical conversion coating C in Figure 7 contains peak 1 of crystals of zinc phosphate tetrahydrate [Zn ₃ (PO ₄ ) ₂ 4H ₂ O], peak 2 of crystals of cuprous chloride [CuCl], and peak 3 of copper. can be seen. However, in the chart diagram of chemical conversion coating D in Figure 6, zinc phosphate 4
No peak of aqueous salt crystals can be seen. Table 2 shows the results of qualitative analysis of chemical conversion coating C and chemical conversion coating D using fluorescent X-rays. In addition, the measuring device

[Table] Unit Weight%
System 3080E manufactured by Rigaku Denki was used. From this result, it is clear that chemical conversion coating C and chemical conversion coating D have almost the same composition, and are considered to be composed of zinc phosphate and cuprous chloride. In other words, from these analysis results, chemical conversion coating C is considered to be in an amorphous rather than crystalline form since zinc phosphate does not have a peak in the X-ray diffraction chart, and chemical conversion coating D is considered to be amorphous rather than crystalline. It is thought that the situation is Next, quantitative analysis of the film constituents was performed. The analysis method is based on JIS-K-0102. Zinc ions are analyzed using atomic absorption spectrometry according to standard 53.2, copper is analyzed using atomic absorption spectrometry according to standard 52.2, and phosphate ions are analyzed using molybdenum blue absorption spectrophotometry according to standard 46.1. , chloride ions were measured by silver nitrate titration method corresponding to Standard 35.1, and the results are shown in Table 3. In other words, chemical conversion coating C contains 19% by weight of zinc ions and copper.
33% by weight, 8% by weight of phosphate ions, 19% by weight of chloride ions, and 21% by weight of other substances, and this proportion was the same no matter where in the film it was taken. Furthermore, chemical conversion coating D was composed of 27% by weight of zinc ions, 18% by weight of copper, 9% by weight of phosphate ions, 6% by weight of chloride ions, and 40% by weight of other substances, and these proportions were the same no matter where the coating was taken. . From the above three types of analysis results, it is clear that the chemical conversion film formed on the copper-based metal member of the present invention is composed of uniform crystalline or amorphous zinc phosphate and cuprous chloride. [Example] The copper-based metal member of the present invention will be explained in more detail with reference to Examples below. Example 1 A copper plate was selected as the copper-based base metal, and 15 chloride ions were added.
g/L, phosphate ion 40g/L, zinc ion 25g/L
The sample was immersed in a treatment solution containing 20 g/L of hydrogen peroxide and 35% hydrogen peroxide solution, treated at 25° C. for 3 minutes, washed with water, and dried to form a chemical conversion film. The thickness of this film was 5 μm, and the AC breakdown voltage was about 200 V according to the JIS-C-2110 short-time dielectric breakdown test method for solid insulating materials. The copper-based metal member having the chemical conversion film of the present invention is further coated with an epoxy resin-based insulating paint (product name: Eporakku-100 rust red, manufactured by Tokyo Paint Co., Ltd.) to a dry film thickness of 15 μm, assuming application to electric wires. It was applied and allowed to air dry. The copper-based metal member of Example 1 having the obtained insulating coating was subjected to the JIS-C-2110 dielectric breakdown test for solid electrical insulation materials, and the AC dielectric breakdown voltage was measured using the short-time breakdown test method. Ta. The results are shown in FIG. Conventional Example 1 As Conventional Example 1, the same epoxy resin insulating paint as in Example 1 was applied to the same copper plate as that used in Example 1 so that the dry film thickness was 15 μm, and the coating was air-dried. Then, the AC breakdown voltage was measured in the same manner as in Example 1, and the results are shown in FIG. From FIG. 8, the AC breakdown voltage of the copper-based metal member of Example 1 according to the present invention is 1200 to 1600 V, and that of the conventional example 1.
significantly larger than the 400-700V of That is, when the copper-based metal member of the present invention is applied to copper electric wires, etc.,
It has far superior performance in terms of electrical insulation than conventional products. Example 2 A ring-shaped copper part for an automobile starter with an outer diameter of 40 mm, an inner diameter of 30 mm, and a height of 20.5 mm, whose vertical cross-sectional view is shown in Fig. 9, was used as the copper-based base metal, and was used in an actual continuous chemical conversion treatment equipment. Degreasing, cleaning, acid etching, and cleaning were performed as pretreatment. Next, chlorine ion 63g/
In a treatment bath consisting of 67 g/L of phosphate ions, 80 g/L of zinc ions, and 20 g/L of 35% hydrogen peroxide.
Chemical conversion treatment was performed at 20 to 30℃ for 3 minutes to form the aforementioned chemical conversion film C.
was formed. Furthermore, using a treatment bath mainly containing sodium stearate (Bondaryube 235 manufactured by Nippon Parkerizing Co., Ltd.) in a metal bath,
A metal soap treatment was performed at ℃ for 3 minutes. Approximately 30,000 pieces of the copper-based metal member of Example 2 which had been subjected to the metal stamping treatment were subjected to cold forging press processing to produce a copper part whose vertical cross-sectional view is shown in FIG. The load applied to the press machine during this press process was measured, and the results are shown in FIG. Conventional Example 2 As Conventional Example 2, a copper part shown in Fig. 9 having the same shape as Example 2 was used, and first hot-dip galvanized.
Form a plating layer of 30μ, followed by zinc ion 5
g/L, phosphate ion 20g/L, nitrate ion 10g/L
L, fluorine ion 1g/L, nickel ion 0.5
A zinc phosphate chemical conversion film was formed by treatment at 80° C. for 1 minute in a conventional chemical conversion treatment bath containing g/L and drying with hot air at 80 to 90° C. for 2 minutes. The chemically treated copper parts of Conventional Example 2 were subjected to a metal sieving process under the same conditions as in Example 2, and pressed in the same manner to produce about 30,000 parts as shown in FIG. The load applied to the press machine during this press process was measured, and the results are shown in FIG. The arrows shown in FIG. 11 indicate the width of variation in the load applied to the press machine during approximately 30,000 press operations. It is clear from FIG. 11 that the copper-based metal member of Example 2, in which the copper-based metal member of the present invention was subjected to metal soap treatment, had a load of 71 to 74 tons, and was zinc-plated, then treated with zinc phosphate, and then subjected to metal soap treatment. Compared to the 70 to 72 tons of the copper-based metal member of Conventional Example 2, which was subjected to this process, the load applied to the press machine increases only slightly, and is sufficiently durable for practical use. That is, by using the copper-based metal member of the present invention in cold forging press processing, the galvanizing process that had to be performed in the past can be omitted, and the load on the press machine is the same as in the past. It is warm and has excellent lubricity. [Effects of the Invention] The copper-based metal member of the present invention has excellent rust prevention performance and insulation performance, and also has excellent performance as a coating base material. Therefore, great effects can be obtained by applying the copper-based metal member of the present invention to copper electric wires, for example. In other words, if the copper-based metal member of the present invention is used, the adhesion of the organic film formed from the synthetic resin applied to the wire to ensure the insulation of the wire will be improved. Significant improvement compared to without. Therefore, it has the effect of preventing damage to the coating when winding a copper wire coil to which the copper-based metal member of the present invention is applied. Furthermore, since the copper-based metal member of the present invention itself has insulating properties, electric wires using the copper-based metal member of the present invention have greater insulation performance than conventional ones in which an organic film is directly formed on the copper wire. improves. The copper-based metal member of the present invention has excellent lubricity during press processing, particularly during cold forging press processing. Furthermore, it is possible to omit the galvanizing process that was conventionally required before the phosphate chemical conversion treatment, which has the great effect of significantly shortening the process. In addition to the above, the copper-based metal member of the present invention has great potential for use in many industrial fields, similar to members having iron-based chemical conversion coatings.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a copper-based metal member of the present invention, and FIGS. 2, 3, 4, and 5 are electron micrographs of chemical conversion coatings possessed by the copper-based metal member of the present invention. , FIGS. 6 and 7 are X-ray diffraction charts of the chemical conversion coatings of the copper-based metal members of the present invention, and FIG. 8 is a line showing the dielectric breakdown voltage of the copper-based metal members of Example 1 and Conventional Example 1. Figures 9 and 9 are longitudinal cross-sectional views of the ring-shaped copper parts used in Example 2 and Conventional Example 2, and Figure 10
The figure is a longitudinal cross-sectional view of the ring-shaped copper parts after being pressed in Example 2 and Conventional Example 2, and Figure 11 is the machine used to press the copper parts processed in Example 2 and Conventional Example 2. It is a diagram showing a load.

Claims (1)

[Scope of Claims] 1. A copper-based base metal; a phosphate formed on at least a portion of the surface of the copper-based base metal; and a phosphate selected from cuprous chloride, cuprous bromide, and cuprous iodide. A copper-based metal member having a chemical conversion film comprising: a chemical conversion film comprising a copper halide containing copper halide; 2. A copper-based metal member having a chemical conversion coating according to claim 1, wherein the metal constituting the phosphate is selected from zinc, manganese, iron, and calcium.