JP2001073174A - Pretreating method to plating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new pretreating method to plating capable of easily and effectively executing the removal of an oxidized film and surface roughening treatment requiring much time and cost among plating pretreatments. SOLUTION: The object 1 to be plated prior to a plating treatment is dipped into water, in the water, a high pressure water stream is jetted to the optional plating face in the object 1 to be plated to generate erosion, so that an oxidized film 2 on the surface is removed, and simultaneously, the surface is roughened into a spongy shape. In this way, the plating pretreating stages are simplified to improve the treating efficiency, and moreover, the adhesion of the plating film 4 for a base material 3 by anchor effect remarkably is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plating pretreatment method required for performing electroplating, electroless plating, or the like on a metal member or the like.

[0002]

2. Description of the Related Art In general, the surfaces of metal members such as cylinder blocks, piston rings, and bearing metals that constitute an engine are plated or sprayed for the purpose of improving mechanical properties and corrosion resistance, preventing rust or preventing scuffing, and the like. Or surface treatment such as heat treatment or vapor deposition.

[0003] Among these conventional surface treatment methods, the one most frequently used is a plating treatment by electroplating or electroless plating (chemical plating). This plating treatment is generally performed by degreasing or oxidizing an object to be plated. It is performed after a series of plating pretreatment steps such as film removal.

For example, when Ni-P electroplating is performed on a predetermined plating surface of an aluminum metal member,
As shown in FIG. 10, first, the non-plated portion of the metal member is masked, and then the exposed plated portion is alkali-degreased to remove unnecessary deposits such as oil and dirt. After that, the oxide film on the surface of the metal member is removed by mixed acid etching. Next, the metal member from which the oxide film has been removed is washed again with water, and then the surface of the metal member is roughened by nitric acid etching. That is, the surface of the metal member is roughened to increase the surface area of the metal member and improve the adhesion of the plating film. After that, after such a plating pretreatment step, a zinc substitution treatment for further improvement of adhesion and uniform film formation is performed,
After washing with water again, Ni-P electroplating is performed to apply plating to the surface of the metal member.

[0005]

However, in such a conventional plating pretreatment method, since many steps such as washing with water, mixed acid etching, washing with water, and nitric acid etching are required after alkali degreasing, the treatment efficiency is low. There are drawbacks.

[0006] In addition, in the removal of the oxide film and the surface roughening treatment, it is necessary to use a large amount of several chemicals,
There is an inconvenience that preparation, maintenance, and management of each chemical solution require a great deal of trouble. In addition, a large amount of harmful chemical waste liquid is generated, and a great deal of cost is required for the treatment of the waste liquid.

Accordingly, the present invention has been devised in order to effectively solve such a problem, and an object thereof is to remove an oxide film, which requires a great deal of labor and cost, among plating pretreatments. An object of the present invention is to provide a novel plating pretreatment method capable of easily and effectively performing a surface treatment.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method of immersing an object to be plated before plating in water, and applying a high-pressure water stream to an arbitrary plating surface of the object in the water. Is sprayed to remove the oxide film on the surface and at the same time roughen the surface into a sponge shape.

That is, an object to be plated before plating is immersed in water, and a high-pressure water stream is sprayed on any plating surface of the object to be plated in the water, whereby the surface of the object to be plated is eroded by the water pressure. At the same time as the oxide film is mechanically destroyed and removed, the surface of the object to be plated after the oxide film is further removed is eroded and eroded into pit holes, and roughened into a sponge shape.

As a result, a series of steps such as water washing → mixed acid etching → water washing → nitric acid etching in the pre-plating process can be performed simultaneously in one step, so that the labor required for the processing is greatly reduced and the processing efficiency is reduced. Is greatly improved.

Further, the roughened surface in the form of a sponge increases the contact area between the plating film formed thereon and the base material, and further improves the adhesion of the plating film due to the anchor effect.

Furthermore, since no chemicals are used, there is no need for preparation, maintenance and management of chemicals, and equipment for the treatment of waste liquids is also unnecessary, so that processing costs and labor can be greatly reduced. Becomes possible.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a plating method including a plating pretreatment method according to the present invention.

As shown in the drawing, first, when plating is performed only on an arbitrary portion of the object to be plated, a portion not to be plated,
That is, after the non-plated portion is masked, the exposed portion is alkali-degreased to remove unnecessary oils and dusts and other deposits, and is cleaned. For example, if the object to be plated is an aluminum linerless cylinder block, and only the portion is to be plated to reinforce the bore surface, the portion excluding the bore surface is masked before the plating. The bore surface is cleaned with an alkaline detergent or the like.

Next, the object to be plated which has undergone such a masking step and an alkaline degreasing step is immersed in a water tank filled with water, and as shown in FIG. Is sprayed with a high-pressure water stream having a pressure of, for example, several thousand kgf / cm ² . Then, as shown in FIG. 2 (2), erosion occurs on the surface of the object 1 due to the impact of the high-pressure water flow, and the oxide film 2 covering the surface of the object 1 is mechanically broken by the action. The base material 3 is removed and exposed, and the surface of the base material 3 is further eroded.
It is eroded to form a large number of pit-shaped holes and roughened. For example, when the object 1 is a cylinder block, a piston ring, a piston, a bearing metal, or the like, which is a metal part made of an aluminum alloy requiring high plating adhesion, a nozzle for jetting a high-pressure water flow is provided on the plating surface. About 200 degrees from the nozzle
When high-pressure water is jetted at a pressure of 0 kgf / cm ² and sprayed at right angles to the plating surface, the strong aluminum oxide film formed on the plating surface is forcibly destroyed and removed, and the base material is directly exposed to water. At the same time, the surface of the base material is roughened into a sponge shape, and the surface area of the plating surface is dramatically increased.

As a result, the removal of the oxide film, the surface roughening treatment, and the water washing step are simultaneously performed, so that a series of these pre-plating treatments, which require a great deal of time and effort, are greatly reduced. Processing efficiency is greatly improved.

Further, since no chemicals such as mixed acid or nitric acid are used as in the conventional method, the washing step and the preparation, maintenance and management of the chemical solution are not required, and the equipment required for the waste liquid treatment is also unnecessary. Therefore, processing cost and labor can be significantly reduced.

Further, the removal of the oxide film by the high-pressure water flow and the surface roughening treatment of the present invention are performed in water, and the treated surface does not come into contact with air. Can be effectively prevented.

Then, after passing through such a pre-plating process, a zinc substitution process for improving adhesion and forming a uniform film is performed in the same manner as in the conventional plating process. When a plating layer is formed on the surface of the plating material by electroplating or electroless plating, as shown in FIG. 2 (3), the plating layer 4 comes into contact with the base material 3 over a wide area, and at the same time, the plating layer 4 Since the coating is formed so as to penetrate into the inside, further excellent adhesion is exerted by further adding an anchor effect.

The object to be plated applicable to the method of the present invention is not particularly limited as long as an oxide film or the like is formed on the surface thereof and the surface is eroded by erosion. Instead, for example, the present invention can be applied to a metal material such as cast iron and steel, or a resin or an inorganic material, in addition to the above-described aluminum alloy. Also, the water pressure of the high-pressure water flow is not particularly limited as long as the erosion action occurs, but when the object to be plated is an aluminum alloy, cast iron, or the like, 1000 to 200.
About 0 kgf / cm ² is preferable. That is, if the pressure is below this range, it is difficult to obtain a sufficient erosion effect because the water pressure is too low, and if it exceeds this range, the erosion effect is too high and the base material itself may be greatly damaged.

Further, the roughness of the object to be plated is not particularly limited since it varies depending on the material and shape of the object to be plated or the required adhesion as described later. However, when the object to be plated is a cylinder block, a piston ring, a piston, a bearing metal, or the like that requires high plating adhesion, at least R
It is necessary to have a roughness of 20 μm or more. The adjustment of the roughness can be easily performed by adjusting the water pressure, the spraying time, the spraying distance and the like as appropriate.

Further, as a device for generating a high-pressure water flow, it is not particularly necessary to newly develop it for the present invention, and a high-pressure water generation device which has been conventionally used for cutting or processing metal can be applied as it is. it can.

In the case of an object to be plated which needs to be plated over the entire surface, it is needless to say that the masking step which is the first step in FIG. 1 can be omitted. If it is in a clean state where it is not adhered, it is also possible to omit even the alkali degreasing step and immediately carry out the oxide film removal and surface roughening treatment by the high-pressure water flow according to the present invention.

[0025]

Next, specific examples of the present invention will be described.

(Example 1) A plate-shaped AC was used as a sample.
A 2B material (sample 1), an AC8A material (sample 2) and a pin-shaped AC2B material (sample 3) are prepared, and high-pressure water is sprayed on each sample in water (hereinafter referred to as a water jet). After performing a roughening treatment with a target of a surface roughness Rz of 20 μm, an appearance inspection was performed on each sample, and the shape of the cross section of the processed surface was examined.

Here, as shown in Table 1, three nozzles having a nozzle diameter of 0.3 mm were used,
000 kgf / cm ² , discharge flow rate 4.2 L / min, nozzle distance 25 mm, nozzle rotation speed 1000 rpm.

Example 2 A pin-shaped MMC material (sample 4) was used as a sample, and as a roughening condition, as shown in Table 1, a discharge pressure of 1500 kgf / cm ² and a discharge flow rate of 3.7 L / m.
A similar inspection was performed after performing a surface roughening treatment under the same conditions as in Example 1 except that “in” was set.

[0029]

[Table 1]

As a result, first, according to the appearance inspection, Sample 1
In Example 2, the surface was uniformly roughened, but in Sample 2, pit-shaped holes were observed, and the roughened state was uneven. Sample 3 also had an uneven portion in the roughened state. From this result, it was found that even when the water jet treatment was performed under the same conditions, the material and shape were different, which affected the progress of the surface roughening. On the other hand, sample 4 which differs not only in material but also in water jet treatment conditions
It was found that when the water pressure was about 1500 kgf / cm ² , the surface was not sufficiently roughened.

Next, the shape of the cross section of the treated surface was examined with a microscope (× 20).
As a result of comparative observation using 0), it was confirmed that the surface state of Sample 1 and Sample 3 was intricate sponge-like as shown in FIGS. 3 and 5 as compared with other samples. This proved that the surface of the sample was sufficiently eroded by the water jet, and that the sample was roughened into a sponge shape. On the other hand, samples 2 and 4 shown in FIGS. 4 and 6, respectively, and glass bead blasts and shot blasts (FIGS. 7 to 9) used as comparisons of water jets shown in Example 3 described later are shown. Although the surface irregularities can be confirmed as described above, it was confirmed that the surface was not in a sponge-like roughened state.

Example 3 Each sample as shown in Table 2 below was subjected to a surface roughening treatment using a water jet, a surface roughening treatment using glass bead blasting, and a surface roughening treatment using shot blasting. Then, the surface roughness was measured by a surface roughness meter.

[0033]

[Table 2]

As a result, as can be seen from Table 2, under the same test conditions, the AC2B material (Rz 38, 8 μm) is more roughened than the AC8A material (Rz 20.6 μm). In the bead blast treatment, no significant difference was observed between the two. Further, even with the same AC2B material, a large difference was observed in the surface roughness in the processed surface shape. On the other hand, M
Almost no change was observed in the surface roughness of the MC material.

From the comparison of the roughness results, it was confirmed that the surface roughening effect of the water jet according to the present invention was slightly inferior to shot blast, but exceeded that of glass bead blast.

[0036]

In summary, according to the present invention, the following excellent effects can be exhibited.

Since the removal of the oxide film and the surface roughening treatment on the surface of the object to be plated can be performed almost simultaneously, the labor and time required for the plating pretreatment can be greatly reduced.
Processing efficiency is greatly improved.

Since the surface is roughened into a sponge shape, the contact area between the plating film and the base material is increased, and the adhesion of the plating film to the base material is further improved by the anchor effect.

Since the removal of the oxide film and the surface roughening treatment are performed in water, reoxidation after the surface roughening can be effectively prevented.

Since it is not necessary to use several kinds of chemicals in a large amount as in the conventional method, preparation, maintenance,
Significant labor and cost required for management can be saved.

Further, since almost no harmful chemical waste liquid is generated, it is possible to omit the cost required for the treatment of the waste liquid, and it is possible to suppress an increase in the product price.

[Brief description of the drawings]

FIG. 1 is a process chart showing one embodiment of a plating pretreatment method according to the present invention.

FIGS. 2A and 2B are conceptual diagrams showing a state in which an oxide film is removed and a surface is roughened by spraying a high-pressure water stream on an object to be plated. (3) is a conceptual diagram showing a state in which a plating film has been applied to the surface of the object to be plated after the state of (2).

FIG. 3 is a photomicrograph showing a cross-sectional shape of a roughened surface of Sample 1 (a flat plate of AC2B material).

FIG. 4 is a photomicrograph showing a cross-sectional shape of a roughened surface of Sample 2 (a flat plate of AC8A material).

FIG. 5 is a microscope photograph showing a cross-sectional shape of a roughened surface of sample 3 (AC2B material pin).

FIG. 6 is a micrograph showing the cross-sectional shape of a roughened surface of sample 4 (MMC material pin).

FIG. 7 is a micrograph showing the cross-sectional shape of the AC2B material after glass bead blasting.

FIG. 8 is a photomicrograph showing a cross-sectional shape of an AC8A material after glass bead blasting.

FIG. 9 is a photomicrograph showing a cross-sectional shape of the MMC material after shot blasting.

FIG. 10 is a process chart showing an example of a conventional plating method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plating object 2 Oxide film 3 Base material 4 Plating film

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Takayuki Wakie 3-25-1, Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture F-term in the Kawasaki Plant of Isuzu Motor Co., Ltd. 4K024 AA05 BA06 BB04 BC10 DA04 FA05 GA01 4K053 PA10 PA11 QA01 RA07 SA09 TA09 TA12 TA18 XA22

Claims (8)

[Claims] 1. An object to be plated before plating is immersed in water, and a high-pressure water stream is jetted in the water to an arbitrary plating surface of the object to destroy and remove an oxide film on the surface. A plating pretreatment method, wherein the surface is roughened into a sponge shape. 2. Before immersing the object to be plated in water,
The plating pretreatment method according to claim 1, wherein the surface of the object to be plated is alkali-degreased. 3. Before immersing the object to be plated in water,
3. The pre-plating method according to claim 1, wherein the non-plated portion of the plating object is masked. 4. The plating pretreatment method according to claim 1, wherein a water pressure of the high-pressure water flow is 1,000 to 2,000 kgf / cm ² on the surface of the object to be plated. 5. The surface roughness of the object to be plated is Rz 20 μm.
The plating pretreatment method according to any one of claims 1 to 4, wherein: 6. The plating pretreatment method according to claim 1, wherein the object to be plated is a metal part. 7. The pre-plating method according to claim 6, wherein said metal component is made of an aluminum alloy. 8. The plating pretreatment method according to claim 6, wherein the metal component is any one of a cylinder block, a piston ring, a piston, and a bearing metal.