JPS5914557B2 - Metsuki method - Google Patents

Description

[Detailed description of the invention] <Explanation of the gist> The present invention uses a metal that is extremely strong and easily forms a chemically stable passive oxide film, such as titanium, zirconium, hafnium, niobium, or tartar alone. , and with respect to the base metal of a metal consisting of each other or an alloy of those metals and other metals,
In addition, this invention relates to a plating method that enables strong plating adhesion.In particular, the invention involves removing a thick oxide film through preliminary treatment to form a thin oxide film, and then removing the thin oxide film in an acidic plating solution. This invention relates to a plating method that obtains a completely strong plated product by simultaneously applying a precipitated film and a plating substance.

<Prior art> As is well known, titanium, zirconium,
・Funium, niobium, or tantalum elemental metal, and
10 The base metals, such as alloys of these metals with each other or alloys of these metals with other metals, rapidly form an extremely strong and chemically stable passive oxide film.

Therefore, when plating the base metal, it is necessary to perform a pretreatment process in which the dynamic oxide film is firstly peeled off and removed by an appropriate mechanical means, and then removed by chemical dissolution secondarily. In addition, it is necessary to avoid the rapid formation of a passive oxide film. Conventionally, the method of depositing and coating the plated material has been basically adopted, and various improvement techniques have been proposed for the above-mentioned pretreatment or the combination of the pretreatment and plating treatment. There is.

25 <Problems with the prior art> Apparently, the plating method that involves the above-mentioned pre-treatment involves the step of completely peeling off the passive oxide film in the first and second steps and the subsequent plating process. However, although it is not theoretically possible to carry out the process, and even though complete experimental data have been disclosed, large amounts of Alternatively, when plating large products, time lags between processes are unavoidable, so
Complete plating is difficult to achieve, and a passive oxide film is inevitably formed due to unstable factors in the transition process from the pretreatment process to the plating process, with considerable variations. Therefore, even if plating is formed, there is a drawback that the plating may fall off due to poor adhesion.

These disadvantages also vary depending on the type of base metal; for example, with stable base metals such as niobium and tantalum, which tend to form passive oxide films, it is difficult to obtain a reliably strong plated product. Not yet. OBJECT OF THE INVENTION The purpose of the present invention is to solve the problems of the above-mentioned prior art method of plating a chemically stable base metal that facilitates the formation of a passive oxide film during multi-stage processing.
In addition to the basic proposal of removing the substantial passive oxide film of the basic metal in the plating bath in the prior art, the present invention does not only carry out the basic proposal of removing the substantial passive oxide film of the basic metal in the plating bath, but also removes the thick passive oxide film mechanically in advance, and then removes the thin passive oxide film. The base metal with a passive oxide film is immersed in a plating solution as a cathode, and the thin passive oxide film is destroyed and removed by fluorine ions from the fluoride added to the plating solution. By depositing the desired plating substance on the base metal surface, it is possible to completely maintain the absence of a passive oxide film on the surface of the base metal and to adhere a strong plating. The purpose of this invention is to provide an excellent plating method that is beneficial to the field of industrial product utilization in industry.

In order to solve the above-mentioned problems, the structure of the present invention, which is based on the above-mentioned object and the gist of the above-mentioned claims, is to solve the above-mentioned problems by providing a structure that is strong against a base metal, such as a titanium metal plate, as a metal to be plated. In addition, mechanical peeling and removal operations such as cutting and polishing are first performed on the stably formed passive oxide film, and after the thick oxide film is removed, alkali degreasing, etc. is performed secondarily. The target plating metal, gold, silver, copper, platinum group metal, or
These base metals are immersed as a cathode in a plating bath in which a fluorine compound that releases fluorine ions such as hydrogen fluoride is added to the acidic plating solution used to deposit them, and an anode is set as appropriate. When the bath type (concentration), temperature, current density, and fluorine ion specified amount of fluorine compound added are optimized based on experimental data and electricity is applied, the fluorine ions ionized from the fluorine compound are ionized on the base metal surface. When immersed in the plating bath, which promotes the dissolution reaction and generates hydrogen, the attached thin passive oxide film is chemically destroyed and removed as described above, and at the same time, it is removed from the acidic plating bath. In this case, the desired plating substance precipitates and coats the exposed area from which the passive oxide film of the base metal has been removed, and these actions are carried out simultaneously and repeatedly.The conditions in this case are optimal conditions. For example, if the amount of fluoride ions is too large, the chemical dissolution effect on the surface of the base metal becomes too strong, and as a result, hydrogen generation becomes too severe. Since there is a risk that chemical immersion of the target plating material may occur, resulting in a significant decrease in adhesive strength, it is important to carry out the process exactly as specified based on experimental data as described above. Technical measures have been taken to make it possible to obtain a product with a strong plating film coated on the base metal in a state where there is no passive oxide film.

Example Next, examples of the present invention are as follows.

(Example 1) A pure Ta plate was used as the base metal, and most of the passive oxide film was first removed by mechanical polishing, that is, to a thin film, and then alkaline degreasing was performed. After a second chemical pretreatment and after some time, Table 1
The sample was immersed as a cathode in a sulfuric acid acidic copper plating bath having the composition shown below, and plating was carried out under the following conditions.

As a result of the above-mentioned example, a shiny Cu plating layer of about 4 microns was obtained on the metal surface of the Ta plate substrate, and even when the plating layer was subjected to a subsequent bending test, no peeling phenomenon occurred at all, and the adhesion was poor. It was extremely good.

(Example 2) A pure Ti plate was used as the base metal. As in the above example, the thick part of the passive oxide film formed by mechanical polishing was first mechanically forcibly peeled off, and then the second layer was removed. Next, it was chemically pretreated to form a thin passive oxide film, and then immersed as a cathode in a hydrochloric-acidic platinum plating bath with the composition shown in Table 2, and plated under the following conditions. I went to

As a result, a semi-glossy Pt plating layer of approximately 3 microns was obtained on the metal surface of the pure Ti plate substrate, and the plating layer was exposed to air for 80°C.
When a heating test was conducted at 0° C. for 10 minutes, no peeling phenomenon was observed, demonstrating that the plating adhesion was very good.

(Example 3) Zrl and Zr-2.5wt%Nb alloy plates were used as base alloys, and thick portions of the passive oxide films coated with them were forcibly peeled off by appropriate primary mechanical polishing means as in the previous example. After that, a second chemical degreasing treatment is performed, and the Cu is cathodic immersed in a sulfuric acid-based Cu plating bath, which is the first plating bath having the composition shown in Table 3, with a thin passive oxide film. After plating, the sample was transferred to a second plating bath having the composition shown in Table 4, which is a sulfuric acid-based Cu plating bath containing no fluorine ions, and cathode immersion was performed to perform the same Cu plating.

The plating conditions are as follows.

First plating bath> As a result, a Cu plating layer of about 100 microns was coated on both base metal surfaces, and the desired plating layer was obtained.

Then, thin plating was performed in the first plating bath, and then,
Even when the film was plated thickly in a normal second plating bath, no peeling phenomenon was observed in the subsequent bending test.

In addition, as shown in the above-mentioned example, the optimum plating conditions are determined by repeated experimental data.

Further, the method of repeatedly and simultaneously performing the passive oxide film removal and plating coating of a thin film according to the present invention is used for thin plating coating as shown in the third embodiment described above, and then the plating is made thicker than the usual plating method. is just a design problem.
Effects of the Invention> As described above, according to the present invention, the invention is generally strong and.

For titanium, other metals, and alloys that tend to form a chemically stable passive oxide film, a thick passive oxide film is removed in advance, that is, a thin passive oxide film is formed, and then fluorine ions are added. Since the plating process is carried out in an acidic plating bath containing a fluorine compound that releases Since the thin passive oxide film can be destroyed by fluorine ions in the plating bath and the precipitated plating material can be coated at the same time, the base metal surface can be reliably plated in the plating bath. ,
The effect of obtaining a strong and stable adhesive-plated product is achieved. In addition, although formally it is a continuous two-stage process that includes a pre-processing process for peeling off and removing a thick passive oxide film, it is actually a one-stage process, so the processing steps are shortened and the cost is reduced accordingly. There are advantages.

Claims (1)

[Claims] 1 After removing the oxide film by preliminary treatment on the base metal of the metal that easily forms a passive oxide film, Cu,
In a plating method of electroplating any of Pt,
A fluoride-added acidic Cu plating solution and a fluoride-added acidic Pt plating bath that release fluorine ions using the base metal as a cathode, which has a thick oxide film removed by preliminary treatment to form a thin oxide film. A plating method characterized by electroplating by immersion in one of the plating baths.