JPH02298295A - Formation of nickel-aluminium composite plating layer - Google Patents

Abstract

PURPOSE:To easily form an Ni-Al composite plating layer maintaining high hardness even at high temp. over a long period of time by carrying out electroplating with an Ni plating bath contg. dispersed Al particles. CONSTITUTION:Al particles of pure Al, an Al alloy, etc., are dispersed in a known Ni plating bath and electroplating is carried out with the resulting bath. The dissolution of the Al particles is preferably inhibited by electroless plating with an Ni or Cu alloy or other method. The particle size of the Al particles is about 0.1-100mum, preferably about 1-30mum and the proper amt. of the particles added is about 5-500g per 100g metallic Ni. The electroplating is preferably carried out while stirring the bath. An Ni-Al composite plating layer having satisfactory adhesion and high hardness at high temp. is formed on the cathode. When the plating layer is heated at 200-800 deg.C to form an Ni-Al alloy by a reaction between the Ni and Al particles, the hardness of the plating layer at ordinary temp. and high temp. can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for forming a nickel-aluminum composite plating layer on a substrate, which has high hardness even at high temperatures.

In addition, in this specification, unless it is particularly necessary,
Aluminum and aluminum alloys will be collectively referred to simply as "aluminum".

Further, "nickel-aluminum composite plating" refers to a state in which aluminum particles are dispersed in nickel in a plating layer to a state in which nickel and aluminum completely form an alloy. Therefore, “
"Nickel-aluminum composite plating" includes, for example, a case where the surface portion of the initial aluminum particles forms an alloy with nickel, and the remaining portion exists as particles.

Conventional technology and its problems Conventionally, as surface coatings for parts that require high hardness,
Chrome plating has been mainly used. Components that require such high hardness include wear-resistant parts such as bearings, shafts, and rolling rolls for machines and parts; molds for plastics, metals, glass, and the like. In recent years, as industrial machinery has become more efficient and faster, mechanical parts such as bearings and shafts are increasingly exposed to high temperatures.

However, although the hardness of conventionally used chrome plating is very high near room temperature, it gradually decreases as the operating temperature rises, especially at temperatures above 4,00°C.
becomes extremely low. This is because the high hardness of chromium plating, which is caused mainly by distortions and fine crystal grains in the plating film, decreases due to the release of distortions due to rising temperatures and coarsening of crystal grains due to recrystallization. It is thought to be from

Furthermore, heat-treated products of nickel-based alloy plating, such as nickel-phosphorus alloy plating and nickel-tungsten alloy plating, are also used as surface coating films for parts that require high hardness. All of these alloys are precipitation hardening alloys, and high hardness is achieved by fine precipitates produced by heat treatment. However, in a coating made of a precipitation hardening alloy, if the operating temperature is higher than the temperature of the heat treatment performed to generate precipitates, the precipitates become coarse and the hardness decreases significantly. Then, even if the temperature is lowered again, the coarsened precipitates will not become finely dispersed as before, so it is impossible to obtain high hardness again with the same coating.

Therefore, it has also been proposed to use other types of alloy plating in place of single metal plating films such as chromium and precipitation hardening alloy plating films. For example, alloys with an L12W structure such as nickel-aluminum alloys do not change their structure or structure at all even at high temperatures, and therefore exhibit high strength and hardness. If it can be formed, it can be a film that exhibits high hardness even at high temperatures and can be used continuously for a long time.

At present, nickel-aluminum alloy films on substrates are mainly formed by thermal spraying.

However, nickel-aluminum alloy films formed by thermal spraying have many pores, insufficient adhesion to the substrate, and oxides of aluminum and nickel produced during thermal spraying are mixed into the alloy film. Therefore, there are problems such as the alloy film becoming brittle. These problems can be solved by forming an alloy film by plasma spraying under reduced pressure, but in this case, the atmosphere must be reduced in pressure, which requires large equipment and increases costs. There are drawbacks.

Attempts have been made to form a nickel-aluminum alloy film by electroplating, but since it is not possible to electrochemically deposit aluminum from an aqueous solution, it is not possible to form a nickel-aluminum alloy film on a substrate. cannot be formed as .

Means for Solving the Problems As a result of repeated research in view of the above-mentioned problems of the prior art, the inventor of the present invention has discovered that aluminum particles are dispersed in a known nickel plating bath and the substrate is electrically coated with aluminum particles. It has been found that when plating is performed, it is possible to form a nickel-aluminum composite plating layer that exhibits excellent hardness even at high temperatures.

Furthermore, the inventors have also discovered that properties such as hardness and strength of the plating layer can be further improved by heat-treating the nickel-aluminum composite plating layer formed in this manner at a specific temperature.

That is, the present invention provides the following method: ■ Electroplating is performed using a nickel plating bath in which aluminum particles are dispersed. A nickel-aluminum composite plating layer is formed on a base material. How to form.

■On a substrate characterized by forming a nickel-aluminum composite electroplating layer on the substrate using a nickel plating bath in which aluminum particles are dispersed, and then heating the plating layer at 200 to 800°C. A method of forming a nickel-aluminum composite plating layer on.

(2) A method for forming a nickel-aluminum composite plating on a substrate, which is characterized by electroplating using a nickel plating bath in which dissolution-inhibited aluminum particles are dispersed.

■ After forming a nickel-aluminum composite electroplated layer on the substrate using a nickel plating bath in which aluminum particles subjected to dissolution suppression treatment are dispersed, the plating layer is heated at 200 to 800°C. A method of forming a nickel-aluminum composite plating layer on a characteristic base material.

As the nickel plating bath used in the present invention, any known nickel plating bath can be used as is, except for the aluminum particles dispersed therein. Such a nickel plating bath is not particularly limited, and all known nickel plating baths such as Watt nickel plating bath, nickel sulfamate plating bath, chloride bath, and sulfate bath can be used.

The aluminum particles to be dispersed in the nickel plating bath are not particularly limited, and include not only pure aluminum but also various alloys such as aluminum-silicon alloy, aluminum-magnesium alloy, aluminum-iron alloy, and aluminum-zinc-silicon alloy. Can be mentioned. The particle size can be in the range of about 0.1 to 100 μm, and in consideration of ease of handling, smoothness of the surface of the nickel-aluminum composite plating layer to be formed, etc.
More preferably, the thickness is about 30 μm.

In addition, the concentration of metallic nickel in the nickel plating bath is 13g.
/Q, if the pH of the nickel plating bath is 3 or less, or if the bath temperature exceeds 70°C, aluminum particles will dissolve in the plating bath, resulting in poor adhesion of the plating film to the substrate and electrodeposition. Cracking or peeling may occur due to increased stress. Therefore, in the present invention, it is preferable to perform surface treatment to suppress dissolution of the aluminum particles, if necessary. A method for performing such surface treatment is to form an electroless plating layer of nickel (nickel, nickel alloy, nickel-boron, etc.), copper, copper alloy, etc. on the surface of the aluminum particles; Examples include a method of boiling in water to form a hydroxide film; and a method of coating aluminum particles with a silane coupling agent. All of these methods can be carried out by known means. For example, when forming an electroless copper plating layer or an electroless copper alloy plating layer on the surface of the aluminum particles, a known electroless plating method using a reducing agent such as formaldehyde or dimethylamine borane can be used. Distilled water is usually used when aluminum particles are boiled in water, but triethanolamine, monoethanolamine, etc. may be added to the water if necessary. As the silane coupling agent for coating the aluminum particles, known ones such as γ-aminopropyltriethoxysilane, vinyltriethoxysilane, ethyltriethoxysilane, and γ-mercaptopropyltrimethoxysilane can be used as they are. Electroless plating layer that covers the surface of aluminum particles, hydroxide,
The thickness of the silane coupling agent is not particularly limited, but it is sufficient as long as it can substantially suppress the dissolution of aluminum into the nickel plating bath, and it is preferable not to make it too thick. do not have.

In the method of the present invention, the materials used as the base material, that is, the cathode, include all materials that are subject to normal nickel plating, and specifically include various metal materials such as iron and steel, ceramic materials, and plastics. Examples include base materials. It is preferable that these materials be pretreated by a conventional method prior to plating. However, when performing the heat treatment described below after plating or when using plated products at high temperatures, materials that decompose or melt at the heating or use temperature, such as low-melting point metals such as tin, zinc, and lead, and plastics must be used. etc., use is restricted.

As the anode material, all materials used in normal nickel plating methods can be used without limitation.

During the plating operation according to the present invention, it is preferable to stir the plating bath in order to uniformly disperse the added aluminum particles in the plating bath. For stirring, stirrer stirring,
This can be carried out by known means such as air agitation, circulation agitation of the liquid using a pump, and agitation using a plate pump.

The amount of aluminum particles added in the nickel plating bath is
Although it varies depending on the composition of the desired nickel-aluminum composite plating, it is usually appropriate to set the amount to about 5 to 500 g per 100 g of nickel (as metal). The ratio of nickel (as metal) and aluminum particles used in the plating bath approximately corresponds to the composition of the nickel-aluminum composite plating to be formed.

The plating conditions were a bath temperature of about 20 to 70°C, and a cathode current density of 0.
．． 5 to about IOA/drf, and pH to about 1 to 6. In order to further improve the smoothness of the nickel-aluminum composite plating film surface, the cathode current density should be 2 to 4 A/drr.
It is more preferable to set it to about f. Further, when using aluminum particles without surface treatment, it is preferable to set the pH of the plating bath to about 3 to 4 and the bath temperature to about 40 to 60° C. in order to suppress dissolution of the particles.

The nickel-aluminum plating layer thus formed on the base material has a form in which aluminum particles are dispersed in nickel as a matrix. Even in this state,
Adhesion to the base material is good, and the hardness at room temperature and high temperature is superior to that of a nickel plating layer. 80 products with this nickel aluminum plating layer
When used in a heated state up to 0°C, a reaction occurs between nickel and aluminum particles to form a nickel-aluminum alloy, which gradually improves the hardness at room and high temperatures.

In the present invention, the nickel-aluminum plating layer formed on the base material is alloyed in advance by actively heating the nickel-aluminum plating layer,
Hardness at room temperature and high temperature can be further improved. The heat treatment is performed at a temperature of 200 to 800°C. It goes without saying that the higher the heating temperature, the shorter the treatment time, and the lower the heating temperature, the longer the treatment time. Although the heating temperature varies depending on the dimensions of the product to be heated, the material of the base material, etc., it is more preferably about 400 to 700°C in consideration of uniform heating and appropriate processing time. In the present invention, it is not necessary that all the aluminum particles dispersed in nickel be alloyed with nickel through heat treatment. That is, the surface portion of the aluminum particles may form an alloy with nickel, and the internal portion may exist in the form of particles with a smaller diameter than the initial size.

Effects of the Invention The nickel-aluminum composite plating film according to the present invention has high hardness even at high temperatures, both when aluminum exists as particles in nickel and when nickel and aluminum form an alloy. Demonstrates performance over a long period of time. Therefore, such a nickel-aluminum composite plating film is useful as a film for mechanical parts such as bearings and shafts that are exposed to high temperatures, surfaces that come in contact with molten metal or glass of molds, and the like.

In addition, when carrying out the method of the present invention, ordinary nickel plating equipment can be used as is, so
It's advantageous. For example, existing equipment for bright nickel plating is usually equipped with an air agitation device, so
The aluminum particles can be easily dispersed by stirring.

EXAMPLES Examples and comparative examples are shown below to further clarify the features of the present invention.

Example 1 A nickel-boron plating layer with a thickness of about 0.1 μm was formed on aluminum particles having an average particle size of 4 μm by electroless plating.

Next, nickel sulfate 240g/L nickel chloride 45g
20 g/l of the above surface-treated aluminum particles were added to a Watt nickel plating bath having a composition of 30 g/l and 30 g/l of boric acid, and while stirring with a plate bomber, a nickel plate was used as an anode, and stainless steel pretreated by a conventional method was used as a cathode. Plating was carried out for 24 hours using a steel plate.

Plating conditions were cathode current 4A/dtrl', pH 4.0.
, the bath temperature was 50°C.

In this way, a nickel-aluminum composite plating film of about 1000 μm was formed on the stainless steel plate.

Appearance of the formed plating film and the completion of the plating process (24
aluminum concentration in the plating bath (measured by atomic absorption spectrometry using a nitrous oxide-acetylene flame)
are shown in Table 1 together with the results of Examples 2 to 4 and Comparative Example 1.

Example 2 A copper plating layer having a thickness of about 0.1 μm was formed on aluminum particles similar to those used in Example 1 by electroless plating.

Using this pretreated aluminum particle, the same plating process as in Example 1 was carried out to coat a stainless steel plate with approximately 100%
A 0 μm nickel-aluminum composite plating film was formed.

Example 3 Aluminum particles similar to those used in Example 1 were pretreated by boiling in distilled water for 20 minutes.

Using this pretreated aluminum particle, the same plating process as in Example 1 was carried out to coat a stainless steel plate with approximately 100%
A 0 μm nickel-aluminum composite plating film was formed.

Example 4 Aluminum particles similar to those used in Example 1 were
It was immersed in a silane coupling agent solution consisting of 3 parts of γ-aminopropyltriethoxysilane, 3 parts of water, and 94 parts of ethanol at 30°C for 16 hours, and then dried.

Using this pretreated aluminum particle, the same plating process as in Example 1 was carried out to coat a stainless steel plate with approximately 100%
A 0 μm nickel-aluminum composite plating film was formed.

Comparative Example 1 A nickel-aluminum composite plating film of about 1000 μm was formed on a stainless steel plate in the same manner as in Example 1, except that aluminum particles similar to those used in Example 1 were not pretreated. Ta.

Table 1 Example Appearance AI concentration (ppm) 1
Smooth and uniform 8 2 Smooth and uniform 2 3 Smooth and uniform 24 4 Smooth and uniform 28 Comparative example 1 Cracking and peeling 18000 As is clear from the results shown in Table 1, Comparative example 1 using aluminum particles without pretreatment Since the nickel concentration in the plating bath is high, approximately 90% of the aluminum particles are dissolved in 24 hours.

As a result, the formed nickel-aluminum composite plating film cracks and peels off.

In contrast, in Examples 1 to 4, in which aluminum particles were pretreated by various methods, dissolution of aluminum was extremely effectively suppressed, and as a result, a smooth and uniform nickel-aluminum composite plating film was obtained. is formed.

Example 5 Aluminum particles with an average particle size of 10 μm were pretreated by boiling them in distilled water for 20 minutes.

Next, 20g/l of the above surface-treated aluminum particles were added to a nickel plating bath having the composition shown in Table 2 below, and while air was stirred, a nickel plate was used as an anode, and a mild steel plate pretreated by a conventional method was used as a cathode. Then, plating was carried out for 5 hours under the conditions shown in Table 3 below.

In this way, a nickel-aluminum composite plating film of about 100 μm was formed on the mild steel plate.

Table 4 shows the aluminum content and Vickers hardness (50 g) in the formed plating film.

Note that Table 4 also shows the results of Examples 6 to 7 and Comparative Example 2.

Example 6 A nickel-aluminum composite plating film of approximately 100 μm was formed in the same manner as in Example 5 except that an ABS resin plate was used as the cathode.

Example 7 The same procedure as in Example 5 was carried out except that aluminum particles similar to those used in Example 5 were used without pretreatment and a stainless steel plate was used as the cathode.
A 0 μm nickel-aluminum composite plating film was formed.

Comparative Example 2 Using a nickel plating bath having the composition shown in Table 2, a nickel plating film of about 100 μm was formed on a mild steel plate under the same conditions as in Example 5 without adding aluminum particles.

Table 2 Nickel sulfate 24g/l Nickel chloride 4.5g/l boric acid
3.0g/l Table 3 Bath temperature 50°C Cathode current density 2A/drrr pH 4,0 Table 4 AI content Hardness (wt%) (Hv) Example 5 2, 3 3306 2
, 3 3307 1, 3
250 Comparative Example Example 8 Thickness approximately 0. 20 g/l of aluminum-silicon alloy particles (silicon content 12% by weight) having an average particle diameter of 30 μm and having an electroless copper plating layer of 1 μm were added to a nickel plating bath having the composition shown in Table 2 above, and while stirring with air. Plating was carried out for 24 hours under the conditions shown in Table 3 using a nickel plate as an anode and a copper plate pretreated in a conventional manner as a cathode.

Thus, a nickel-aluminum composite plating film of about 500 It m (aluminum content of 2.5 m) was formed on the copper plate.
3% by weight) was formed.

Next, the Vickers hardness (load: 50 g) of the copper plate on which the composite plating film was formed was measured from room temperature to 700°C. Hardness measurement at high temperatures is performed using a high temperature hardness measuring device (“HT
-5'', manufactured by Nippon Kogaku Co., Ltd.).

In FIG. 1, the change in hardness from room temperature to 700° C. is shown as curve A.

Example 9 Aluminum-silicon alloy particles (containing 12% silicon in total) with an average particle diameter of 30 μm were mixed with 3 parts of γ-aminopropyltriethoxysilane, 3 parts of water, and 94% of ethanol.
The sample was immersed in a silane coupling agent solution consisting of 500 ml at 30° C. for 16 hours and dried.

20 g/l of these aluminum-silicon alloy particles (silicon content: 12% by weight) were added to a nickel plating bath having the composition shown in Table 2 above, and plating was carried out in the same manner as in Example 8.

In this way, a nickel-aluminum composite plating film (aluminum content: 2.2% by weight) of about 500 μm was formed on the copper plate.

Figure 1 shows a temperature of 700 m from room temperature measured in the same manner as in Example 8
Curve B shows the change in the hardness of the plated film up to °C.

Comparative Example 3 Using a nickel plating bath having the composition shown in Table 2 above,
Plating was carried out in the same manner as in Example 8 without adding aluminum particles.

In this way, a nickel plating film of about 500 μm was formed on the copper plate.

Figure 1: 70°C from room temperature measured in the same manner as in Example 8.
Curve C shows the change in hardness of the nickel plating film up to 0°C.
Shown as

As is clear from the results shown in Figure 1, in the case of a nickel plating film that does not contain aluminum particles, the peel curve C)
, the hardness gradually decreases as the temperature rises to 500℃
Therefore, the hardness is approximately 1/2 of the room temperature hardness.

On the other hand, in the case of nickel-aluminum composite plating films (curves A and B), the hardness decreases as the temperature rises in the range from room temperature to approximately 300°C, but from approximately 300°C, the hardness decreases again. increases and reaches a maximum altitude at about 650°C. In any temperature range, the nickel-aluminum composite plating film has significantly higher hardness than the nickel plating film.

Example 10 20 g of aluminum particles with an average particle size of 0.5 μm having an electroless nickel-phosphorus plating layer with a thickness of about 0.1 μm
1 was added to a nickel plating bath having the composition shown in Table 2 above, and while stirring with air, using a nickel plate as an anode and an alumina ceramic plate pretreated by a conventional method as a cathode, the conditions shown in Table 3 above were carried out. Plating was carried out for 24 hours.

In this way, a nickel-aluminum composite plating film (3.0% by weight of aluminum-containing plate) of about 500 μm was formed on the alumina ceramic plate.

Next, the nickel-aluminum composite plating film was coated with 6
Heat treatment was performed at 00°C for 1 hour.

Figure 2 shows a temperature difference of 700 m from room temperature measured in the same manner as in Example 8.
The change in hardness of the nickel-aluminum composite plating film after the heat treatment up to 0.degree. C. is shown as a curve.

Comparative Example 4 Using a nickel plating bath having the composition shown in Table 2 above,
Plating was carried out in the same manner as in Example 8 without adding aluminum particles.

Thus, a thickness of about 500 μm was deposited on the alumina ceramic plate.
A nickel plating film of m was formed.

Next, the nickel plating film was heat-treated at 600°C for 1 hour.

Figure 2 shows a temperature difference of 700 m from room temperature measured in the same manner as in Example 8.
Curve E shows the change in hardness of the nickel plating film up to .degree.

As is clear from the results shown in Figure 2, in the case of a nickel plating film that does not contain aluminum particles (curve E
), the hardness gradually decreases with increasing temperature.

On the other hand, in the case of the heat-treated nickel-aluminum composite plating film (curve D), the hardness gradually increases as the temperature rises, reaches the maximum hardness at about 650°C, and then decreases.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the relationship between temperature and hardness of a nickel-aluminum composite plating film that is not heat treated (curves A and B) and a nickel plating film that is not heat treated (curve C).

FIG. 2 is a graph showing the relationship between temperature and hardness of a heat-treated nickel-aluminum composite plating film (curve D) and a heat-treated nickel plating film (curve E).

(that's all) Figure 1 11 feet 1 戊 (°C) Figure 2 $ Norisada Shiko J Branch (’C)

Claims (4)

[Claims] (1) A method for forming a nickel-aluminum composite plating layer on a substrate, which comprises performing electroplating using a nickel plating bath in which aluminum particles are dispersed. (2) After forming a nickel-aluminum composite electroplating layer on the substrate using a nickel plating bath in which aluminum particles are dispersed, the plating layer is heated to 200 to 800°C.
A method for forming a nickel-aluminum composite plating layer on a base material, the method comprising heating the base material with a nickel-aluminum composite plating layer. (3) A method of forming a nickel-aluminum composite plating on a substrate, characterized by performing electroplating using a nickel plating bath in which aluminum particles subjected to dissolution suppression treatment are dispersed. (4) After forming a nickel-aluminum composite electroplating layer on the base material using a nickel plating bath in which aluminum particles subjected to dissolution suppression treatment are dispersed, the plating layer is heated at 200 to 800°C. A method for forming a nickel-aluminum composite plating layer on a base material, characterized in that: