JPS5914100B2 - Electroless nickel plating method for high nickel chromium alloys - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention applies to high nickel, chromium alloys such as high grade stainless steel, carpenter, bath alloy, Inconel 600
The present invention relates to a method for applying electroless nickel plating with excellent adhesion to surfaces such as the like.

Generally, direct nickel plating on high nickel chromium alloys is not practical due to poor adhesion when using normal electroplating methods. Therefore, as shown in the process of pretreatment (degreasing, pickling) → nickel strike plating → electrolytic nickel plating, which is performed to improve adhesion, nickel strike plating is a necessary condition, and the pretreatment 10 Degreasing and surface activation by pickling are important points for improving plating adhesion. By the way, when it is necessary to apply electroless nickel plating with good adhesion to a high nickel or chromium alloy, for example, the hardness of Ni-P15 alloy obtained by electroless nickel plating may be required.

Although the method of the present invention meets the needs of this case,
Conventionally, it has been difficult to apply nickel plating with good adhesion using direct electroless plating, regardless of the previous process. For example, even if you remove 20% of the solvent as a pre-treatment, pickle with nitric-hydrofluoric acid, and then perform strong activation, and immediately perform electroless plating, it is not possible to obtain nickel plating with good adhesion. . This is thought to be due to the fact that the surface to be treated is inactivated prior to the reduction and precipitation of nickel in the electroless plating solution25. Therefore, as a pre-process of electroless nickel plating, nickel strike plating is required as in the electroplating process described above, and by performing appropriate pre-activation on the surface to be treated with high nickel and chromium, nickel strike plating with good adhesion can be achieved. Plating 30 is possible. However, in the case of electrolytic nickel plating, good results can be obtained using normal methods, but when finishing with electroless nickel plating, the adhesion between the nickel strike surface and the electroless nickel plated surface is poor, resulting in a peeling phenomenon. cause. 35 As a result of various tests and studies in order to improve this adhesion, the present inventors further acid-treated and activated the strike nickel surface with a strong acid such as nitric-hydrofluoric acid solution, and after washing with water, it was immediately removed. It has been discovered that by applying electrolytic nickel plating, nearly perfect adhesion can be obtained.

Furthermore, instead of activation by acid treatment, the same effect can be obtained by using the material as an anode in a nickel plating solution and electrolytically dissolving it at a relatively low current density. Adhesion is 180 for the plating finish sample.
The paper was folded in half at the same angle as the paper, and the criterion was that there should be no peeling cracks at the folded part. In a series of plating processes, further acid treatment and activation of the nickel surface precipitated by strike plating has not been demonstrated in practice or introduced in literature, etc., and this is a feature of the present invention. This is a new treatment, and the mechanism of its adhesion improvement effect has not yet been clarified.However, due to the elution of the strike nickel surface caused by the acid treatment, it is possible to partially reveal the base alloy on a microscopic level. It is thought that the potential relationship of the metals present on the surface has a favorable effect on the deposition of electroless nickel plating and the adhesion. As described above, the method of the present invention is an electroless nickel plating method for high nickel and chromium alloys, which is characterized by a series of pretreatment steps (strike nickel plating for degreasing and acid turbidity → acid treatment activation → electroless nickel plating). Nickel strike plating baths are typically Nict224O9/T, HctlOO
~125111't.

In the method of the present invention, the acids used in the activation treatment performed immediately before electroless nickel plating include Hct, H
F, and a mixture of HNO3 and HCt or HF.

Its concentration is usually less than 20%. In the method of the present invention, the anodic electrolysis elution treatment for activating the nickel strike plating layer is carried out in a nickel plating solution under conditions that allow elution to occur without causing anodic oxidation.

The electroless nickel plating solution used in the method of the invention is typically NlCt23Of! /t1 Sodium hypophosphite 309/t1 Sodium acetate 109/t Contains PH5
However, there are commercially available products containing various additives.

The bath is usually heated to 90-100°C. Next, examples of the present invention will be shown.

Example-1 Inconel 600 (composition, Ni: 76.0%, Cr: 1
6.0%, Fe: 7.0%) plate material (thickness 1TfL0,
Preliminary degreasing by triclene vapor degreasing, washing with water, Na
sPO4459/T,. Na2CO3ll9/T. Na
2.8A/D in 7'C electrolyte containing OH239/t
After electrolytic degreasing for 2 minutes at a current density of m2 (cathode) and washing with water,
55 to a nitric fluoric acid mixture containing 5% HNO3l and HF37O.
After soaking at °C for 2 minutes to activate the acid treatment, the NiC
t224Of! /T. Strike plating was performed for 2 minutes at a current density of 10 A/Dm2O at room temperature in a strike plating solution containing HCtlOOcc/t, and after washing with water, the above acid treatment was activated again (HNO3l 5%, HF 3%, 55°C).
was carried out for 30 seconds, and immediately after washing with water, electroless nickel plating was applied.

Electroless Nickel Metsuki is Kanizen's "Blue Schema No. 1"
It was immersed for 10 minutes at 9'C.

A 4μ thick nickel plating layer was formed by this electroless nickel plating. The plating adhesion of the sample finished with electroless nickel plating according to this example was examined by a 180-meter double-folding test, and the results showed that there were no peeling cracks and that the sample had sufficient adhesion.

On the other hand, the sample obtained under the same conditions as above but omitting the acid treatment activation after nickel strike plating had 180%
The bending test caused peeling of the entire bent part, and the strike nickel surface and electroless plating surface peeled off easily.
Adhesion could not be obtained.

Example-2 Hastelloy G (composition, Fe:
19.570,. Cr: 22%, MO: 6.5%, Cu
:270,. A plate material of 1 thickness (Nb: 2%, Ni: balance) was heated under the same conditions, and the activation treatment immediately before electroless nickel plating was performed by anodic electrolytic elution treatment, and electroless nickel plating was performed. A plating layer with a thickness of 4 μm was obtained.

Anodic electrolytic elution treatment includes NlCt, 24O and AlHCll.
Using an electrolyte containing OOCC/t, at room temperature, 0.5A/
Electricity was applied for 3 minutes at a current density of Dm2.

Claims (1)

[Claims] 1. An application to a high nickel chromium alloy characterized by applying nickel strike plating as a pre-process of electroless nickel plating, and subsequently performing activation treatment on the nickel strike plated surface. Electrolytic nickel plating method. 2. The electroless nickel plating method according to claim 1, wherein the activation treatment is treatment with a strong acid. 3. The electroless nickel plating method according to claim 2, wherein the strong acid is hydrochloric acid, hydrofluoric acid, or a mixture of nitric acid and hydrochloric acid or hydrofluoric acid. 4. The electroless nickel plating method according to claim 1, wherein the activation treatment is an anodic electrolytic elution treatment.