JPH01246398A - Production of composite dispersive particles and composite plating method - Google Patents

Abstract

PURPOSE:To obtain composite dispersive particles hardly causing aggregation and precipitation in a plating bath by electrolyzing an acidic electrolyte soln. contg. Al2O3, SiO2 or ZrO2 and specified metal ions. CONSTITUTION:An acidic electrolyte soln. contg. one or more kinds of oxides selected among Al2O3, SiO2 and ZrO2 and ions of one or more kinds of metals selected among Ti, Mo, Cr, V, Mn and W is prepd. and 0.05-1.0wt.% condensed phosphate is further added to the soln. as required. The soln. is electrolyzed to absorb the metal ions on the oxides and to form composite dispersive particles. When a small amt. of the particles is added to a Zn or Zn alloy plating bath and electroplating is carried out, a plating film having improved corrosion resistance is obtd.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to so-called composite plating in which fine particles of metal oxide are eutectoided in a plating film, and in particular, to prevent coagulation and precipitation in a plating bath. The present invention relates to a method for producing composite dispersed particles with a small amount of carbon dioxide, and a composite plating method using the composite dispersed particles.

(Prior art) For example, one method of increasing the corrosion resistance of galvanized steel sheets is to plate them with an alloy of zinc and other elements. Typical examples include Zn-Fe, Zn-Ni, Zn-Go, etc. Z
This is n-based alloy plating.

On the other hand, instead of plating such an alloy, there is a method of so-called composite plating in which fine particles of a metal oxide different from the matrix metal are eutectoided into the plating film. Many patents related to this composite plating have been filed. For example, JP-A No. 61-47919 discloses a composite eutectoid of alumina in a zinc plating film, and JP-A No. 54-159342 discloses a similar method. 56-49999 discloses an electrogalvanized steel sheet in which one or more of silica, titanium oxide, and zirconium oxide are compositely eutectoided, and SiO□ is compositely eutectoided in Japanese Patent Publication No. 56-49999.

It is true that corrosion resistance can be improved by applying the above composite plating method to zinc plating or zinc-based alloy plating, but conventional composite plating has the following problems.

In composite plating, in order to sufficiently improve corrosion resistance, it is important to incorporate dispersed particles uniformly and in large quantities into the plating film. However, in the conventional composite plating method, the dispersed particles aggregate and precipitate in the plating bath, making it impossible to incorporate them uniformly and in large quantities, which limits the improvement in corrosion resistance.

Furthermore, it is not possible to manufacture products with stable quality over a long period of time.

Various patents have been proposed to solve the above-mentioned problems in composite plating.

For example, Japanese Patent Application Laid-Open No. 49-21332 describes a method of electrodepositing aluminum on a conductive substrate by electrophoresis using an aqueous solution containing a cationic or nonionic surfactant. The publication describes insoluble particles that have been treated with cation adsorption, such as NH4
``The method of ion adsorption treatment and electrodeposition is ■ 61-1
No. 27900 discloses that plating metal and A l *Os,
When simultaneously electrodepositing SiO□, there is a method of electrodepositing using a positively charged alumina colloid or aluminum ion and a metal cation with a charge of two or more adsorbed on the surface of a negatively charged silica colloid. , respectively, are disclosed.

However, in method (2), there is a risk that unnecessary or harmful organic compounds may be mixed into the plating metal matrix and impair the plating quality. In the method (2), the ion adsorption treatment alone does not have a sufficient effect on increasing the amount of electrodeposition, and in the method (2), positive charges are lost due to the reduction reaction, and those that are not incorporated into the film cause precipitation. Furthermore, substances incorporated into the film may also change the properties of the original metal matrix.

(Problems to be Solved by the Invention) An object of the present invention is to provide dispersed particles of a metal oxide that are less likely to aggregate and cause precipitation in a plating bath, and to plate these dispersed particles uniformly and in large quantities. It is an object of the present invention to provide a composite plating method that can be incorporated into a film to stably produce products of excellent quality over a long period of time.

(Means for Solving the Problems) As mentioned above, the biggest problem in composite plating is that the dispersed particles agglomerate in the plating bath and cannot be stably maintained.

Aggregation can be reduced by giving each particle the same polarity and making them electrically repel. A
ffi, 0. Dispersed particles of metal oxides such as , SiO2, and Zr(h) are weakly positively or negatively charged in the plating bath, depending on the pu, and it is difficult to eutectoid them on the plating surface that will become the cathode. Therefore, for electrodeposition, it is necessary to charge each dispersed particle more strongly and positively.

JP-A-54-15934i and JP-A No. 59-3189 mentioned above
No. 5 and No. 61-127900, Special Publication No. 62-67
The composite plating method disclosed in No. 60 and the like is based on this idea.

The present inventors also considered a method of adsorbing cations on dispersed particles, but monovalent metal ions did not result in a sufficient increase in the amount of electrodeposition, and divalent or higher valent metal ions lost charge due to reduction reaction. It becomes unstable and precipitation occurs. Therefore,
The present inventors attempted a method of manufacturing dispersed particles and performing composite plating using the following method.

Ajl! Metal ions are adsorbed onto the dispersed particles of gos, Sing and/or ZrOz, and electrolyzed with an acidic electrolyte solution different from the plating bath to convert the metal ions into oxides, which form on the surface of the dispersed particles. Composite dispersed particles adsorbed on the substrate were produced, and the composite dispersed particles were included in a plating bath for electroplating. As a result, the following was found.

By selecting a metal ion to be adsorbed that becomes an oxide through electrolysis and has a positive charge, composite dispersed particles with little agglomeration in the plating bath can be obtained. The reason why aggregation does not occur is that the composite oxide that has adsorbed a positively charged oxide is positively charged and is stable because it does not lose its charge due to a reduction reaction.

Here, the gist of the present invention is as follows (i) and (ii)
It is in.

(i)Aj! one or more oxides selected from the group consisting of gos, Sing and Zr01, Ti ions, Mo
1. A method for producing composite dispersed particles, which comprises electrolyzing an acidic electrolyte solution containing one or more metal ions selected from the group consisting of ions, Cr ions, ■ ions, Mn ions, and W ions.

(ii) Ti ions and gates on the surface of one or more oxides selected from the group consisting of Al zOs, Sing, and ZrO2. Electroplating using a plating bath containing composite dispersed particles adsorbing oxides generated from one or more metal ions selected from the group consisting of ions, Cr ions, ■ ions, in ions, and W ions. A composite plating method characterized by:

In the first invention of the present application, in a preferred embodiment, the acidic electrolyte solution containing the above oxide and metal ions further contains 0.05 to 0.05%
1.0 wt% of condensed phosphate is added and electrolyzed to produce composite dispersed particles.

Further, in a preferred embodiment of the second invention, electroplating is performed by further adding 0.05 to 0 L, 0 wt% of condensed phosphate to the plating bath containing the composite dispersed particles, and the plating metal and the composite dispersed particles are combined. It is electrodeposition.

When producing composite dispersed particles, adding a condensed phosphate to the acidic electrolyte can prevent the produced oxides from agglomerating themselves.

Moreover, if it is added to the plating bath for composite plating, a large surface active effect can be obtained, so that the composite dispersed particles can be stably maintained for a long period of time. As a result, it is possible to electrodeposit uniformly and in a large amount, and it is also possible to stably apply high-quality plating over a long period of time.

(Function) Hereinafter, the method for producing composite dispersed particles and the composite plating method of the present invention will be explained in detail.

First, the method for producing composite dispersed particles of the present invention will be described.

AX, O,, 5t (h and one or more oxides selected from the group consisting of ZrO2, Ti ions, gate ions,
When an acidic electrolyte solution containing one or more metal ions selected from the group consisting of Cr ions, ■ ions, Mn ions, and W ions is electrolyzed, the metal ions first reach the surface of the oxide in an ionic state in the bath. It is adsorbed and oxidized by electrolysis to become an oxide.

If the metal ion is Ti, set it to TtO□, if the same <Mo, set it to Moot, if it is Cr, set it to CrO3, and if it is ■, set it to VtO.

In the case of Mn, it is MnO□, and in the case of W, it is 60. becomes an oxide. As a result, composite dispersed particles are formed in which oxides generated from metal ions are adsorbed on A2□0, 5i(h and/or ZrO□ particles).

In the present invention, the reason why the metal ions used in the production of the composite dispersed particles are limited to those mentioned above is that these metal ions become oxides by electrolysis, and in the oxide state Aj! gos, 5ift and/or Zr0
This is because it is positively charged more strongly than 1. Composite dispersed particles adsorbing such positively charged particles have a strong electrostatic charge (they do not easily lose charge even in the reduction reaction that occurs in the plating bath, making them stable).

In addition, the reason why composite dispersed particles are manufactured from an acidic electrolyte solution is that metal ions do not exist stably in neutral or alkaline solutions, and become oxides and precipitate when used alone.
! , zOs, Sing and/or Zr01. This does not happen with acidic electrolyte solutions.

If composite dispersion particles are produced by further adding O,OS to 1.0 wt% of condensed phosphate to the acidic electrolyte solution, the above-mentioned effect can be obtained, but if it is less than 0.05 wt%, the effect is small. If the amount exceeds 1.0 wt%, the effect will be saturated, and the addition will be meaningless and economically disadvantageous.

Condensed phosphates include NaaPtOt, Na5PsO+o,
It is preferable to use condensed phosphates having the chemical formulas Na4P40+s and Na6PiO+w, and condensed phosphates having such chemical formulas can provide more of the above effects.

In the present invention, the metal ions can be added to the acidic electrolytic bath in the following form.

That is, when the metal ion is Ti, Tit(Son)s
, TiCff1s, in the case of Mo, NaJoO,
For Cr, use CrC12s, for ■, use VCl3, for Mn, use MnCl z, MnC
It can be added as 13 and in the case of W as WCL, WCZ. It is desirable to add one or more of these metal ions in an amount of approximately 0.1 to 30 g/l; there is no significant difference in the effects due to the differences in these metal ions.

Next, a composite plating method using these composite dispersed particles will be explained.

Composite plating can be carried out either by removing the composite dispersed particles obtained by electrolysis with an acidic electrolyte solution from the bath by filtration or the like and adding them to the plating bath, or by adding them to the plating bath without taking out the composite dispersed particles from the acidic electrolyte solution. Either add the acidic electrolyte solution containing the dispersed particles to the plating bath, or after generating the composite dispersed particles with the acidic electrolyte solution, add the metal ions to be plated to this bath and adjust the plating conditions. It can be done by plating or by any of the following methods.

A plating film with improved corrosion resistance can be obtained by adding a small amount of composite dispersed particles to the plating bath, but if the amount added is small, the effect will be small, and if it is too large, the amount incorporated into the plating film will be too large. As a result, workability is impaired. The preferred amount is 0.1-30g/j! It is.

When carrying out this composite plating, it is also preferable to add the same amount of condensed phosphate as described above.

If the content of the condensed phosphate is less than 0.05 wt%, the effect will be small, and if it exceeds 1.0 wt%, the effect will be saturated, making the addition pointless and economically disadvantageous.

If an appropriate amount of condensed phosphate is used, for example, in a zinc and zinc-based alloy plating bath, the condensed phosphate will stably exist in the bath without forming poorly soluble salts with zinc, and will have a large surfactant effect. Therefore, the composite dispersed particles can be stably maintained in a dispersed state for a long period of time in the plating bath.

f, KiB, In the composite plating method of the present invention, the plating bath for eutectoid electrodeposition of the 71 dispersed particles and the plating metal is generally a zinc plating bath or a Zn-Fe, Zn
This is a zinc-based alloy plating bath such as Ni, Zn-Co, Zn-Mr+, etc.

The present invention will be further explained below with reference to Examples.

(Example 1) A Na, SO, solution was used as the acidic electrolyte solution, and A
IJs and Ti ions were added in the form of Tit (SOJi) to produce composite dispersed particles in which positively charged Ti0f was adsorbed on the surfaces of Af, O, and under the conditions shown in (1) below.

(1) Composite dispersed particle production conditions NatSOa: loog/ 1 pH: 1.0-3.0 Bath temperature: 50-60°C'clfL density: 60-100A/da"Aj!go
s: 20g/I Tit(Son)z: 3. Og/1 Electrode used: Pt Next, the acidic electrolyte solution containing the composite dispersed particles was added to the plating bath, and electroplating was performed under the composite plating conditions shown in (2) below until the Ni content in the film was 11 .5-12
．． Evaluation sample coated with Zn-Ni alloy plating with 5wt% and coating weight of 20g/m (10hm width x 1oos+
*Length) were produced continuously.

Note that the production of composite dispersed particles and composite plating were performed by stirring with a stirrer in a 12-beaker.

(2) Composite plating conditions ZnSO4/7HtO: 140g/j! N15Oa
・6HxO: 260g/j! pH: 1.0-3.
0 Bath temperature: 50~60℃ Current density: 60~100A/c1m'' Composite dispersed grains: A2□0: Ti for 10g/l
1t:1, deposited at a ratio of OOg/f.

The obtained evaluation samples were investigated for deterioration over time in workability and corrosion resistance. The results are shown in Table 1. For those in which condensed phosphate was added during the production of composite dispersed particles and/or composite plating, the type and amount thereof are also shown in the same table.

In Table 1, evaluation 1 is an evaluation sample plated immediately after preparing the plating bath, evaluation 2 is an evaluation sample plated after continuous energization of the equivalent of 5 evaluation samples, and evaluation 3 is the same <1
The evaluation sample was plated after continuous energization for 00 sheets, and the rating 4 means the characteristics for the evaluation sample plated after 200 sheets were energized.

Corrosion resistance was evaluated by conducting a salt spray test using 5% salt water and determining the number of days until red rust appeared.

Processability was tested by taking a 90mmφ disc blank from the evaluation sample, deep drawing it into a cylindrical shape of 50mm+φ and 28ra depth, and peeling off the plating film on the side wall surface with adhesive tape. The amount of peeling was visually inspected and evaluated on a five-point scale. Rating: 5: No peeling at all.
4: The tape area to which the peeling piece is attached is less than 10% of the total area of the tape, 3: Same <10% or more and less than 30%, 2: Same <30% or more, above and less than 50%, 1 ：same＜
Ranked as 50% or more.

As is clear from Table 1, Nαl of Inventive Example 11 is different from Comparative Example Nα12, which is plated by adding A2□0° and Ti01, which corresponds to conventional composite plating, to the plating bath. In comparison, it shows high workability and corrosion resistance.
Moreover, among the examples of the present invention, those in which condensed phosphate was added during the production of composite dispersed particles and/or composite plating according to Inhibitions 2 to 11 exhibited sufficient effects.

In Comparative Examples k13 to Nα15, condensed phosphate was added during the production of composite dispersed particles during composite plating, but if the amount added was less than the amount specified in the present invention, condensed phosphate was added. It can be seen that there is no effect, and on the other hand, even if the amount is too high, the effect is saturated.

(Example 2) Using HxSO4 solution as the acidic electrolyte, one or more oxides and metal ions shown in Table 2 were added to it to produce composite dispersed particles under the conditions shown in the same table, The composite dispersed particles were added to a plating bath having the bath composition shown in Table 3, and composite plating was performed under the conditions shown in Table 3, with a coating weight of 20 g/
An evaluation sample of "m" was prepared.

The corrosion resistance and workability of the obtained evaluation samples were evaluated in Example 1.
was evaluated using the same method. Note that zinc plating has good workability (the evaluation score was 5, and no difference was observed due to the composite plating film, so only the corrosion resistance was evaluated.

Similarly, Table 3 shows the evaluation results of corrosion resistance and workability, and the type and amount of condensed phosphates added during production of composite dispersed particles and/or composite plating.

As is clear from Table 3, the inventive examples with Nα16 to 24 have Al t(h
Also, compared to Comparative Example NCL12, which was plated by adding TiOx alone to the plating bath, it showed higher workability and corrosion resistance, and even the alloy matrix of Nα5 to Nα9 showed better workability. , indicating uniform electrodeposition of the composite dispersed particles.

The comparative example of Nα25 is a condition in which condensed phosphate is simply added to the conventional bath of No. 26, but although the corrosion resistance increases slightly at the initial stage, the effect is insufficient. It can be seen that the effect can be obtained only by addition.

(Effects of the Invention) As explained above, since the composite dispersed particles obtained by the method of the present invention have a strong positive charge, they are less likely to aggregate or precipitate in the plating bath. Since composite dispersion particles are used, which have the following advantages, they can be electrodeposited uniformly and in large quantities into the plating film, and products with excellent corrosion resistance and workability can be stably produced over a long period of time.

Claims (4)

[Claims] (1) One or more oxides selected from the group consisting of Al_2O_3, SiO_2, and ZrO_2 and one or more oxides selected from the group consisting of Ti ions, Mo ions, Cr ions, V ions, Mn ions, and W ions. A method for producing composite dispersed particles, comprising electrolyzing an acidic electrolyte solution containing metal ions. (2) Claim 1, characterized in that 0.05 to 1.0 wt% of condensed phosphate is further added to the acidic electrolyte solution containing the oxide and metal ions for electrolysis. A method for producing composite dispersed particles. (3) One or more oxides selected from the group consisting of Ti ions, Mo ions, Cr ions, V ions, Mn ions, and W ions on the surface of one or more oxides selected from the group consisting of Al_2O_3, SiO_2, and ZrO_2. A composite plating method characterized by electroplating using a plating bath containing composite dispersed particles adsorbing oxides generated from the above metal ions. (4) Add 0.0% to the plating bath containing the above composite dispersed particles.
4. The composite plating method according to claim 3, wherein electroplating is carried out by adding 5 to 1.0 wt% of condensed phosphate.