JPH06272093A - Formation of metallic heat insulating layer - Google Patents

Abstract

PURPOSE:To simply and surely produce a metallic heat insulating layer having excellent heat insulating function, excellent in thermal shock resistance and free from the generation of blister or the like. CONSTITUTION:After a metal plated film 2 is formed on the surface of a metallic base body 1 to form the heat insulating layer, a composite plated film 3 having a gradient function, in which the dispersing quantity of ceramic particulates is gradually increased from the metallic plated film side and after reaches maximum, gradually decreased, is formed on the metal plated film by using a composite plating solution made by dispersing the ceramic particulates in a metal plating solution. Next, the metal plated film 4 is formed on the composite plated film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a metal heat insulating layer having excellent heat resistance and thermal shock resistance on a metal substrate such as an internal combustion engine member, a welding nozzle, a thermal spray nozzle, a heat insulating member, a cold insulating member and the like. .

[0002]

2. Description of the Related Art Internal combustion engine members, such as automobile liners, are required to be such that heat in the combustion chamber is difficult to transfer to the engine body. Further, it is desired that the heat of the high-temperature fluid flowing inside the welding and thermal spray nozzles is not easily conducted to the outside.

Conventionally, as a method of blocking such high heat and enhancing the heat insulating effect, it is known to form a ceramic layer on the surface of a metal substrate such as a liner or nozzle exposed to high heat by thermal spraying or the like. However, there is a problem that the ceramic layer is fragile, the adhesion to the metal substrate is not sufficient, and further, peeling and peeling occur during use at high temperature due to difference in thermal expansion coefficient and the like.

Therefore, there is a demand for forming a heat insulating layer which adheres well to a metal substrate as described above, is unlikely to peel or peel off, and is excellent in heat resistance and thermal shock resistance.

[0005]

Means and Actions for Solving the Problems As a result of intensive investigations in order to meet the above demands, the present inventor found that after forming a metal plating film on the surface of a metal substrate on which a heat insulating layer is to be formed, In the composite plating solution obtained by dispersing ceramic fine particles in a metal plating solution, the amount of fine particles dispersed is gradually increased from the side of the metal plating film, and further, the amount of fine particles is maximized, and then the amount of fine particles is gradually increased. By forming a composite plating film having a decreasing gradient function and then forming a metal plating film on the composite plating film, a metal heat insulating layer having excellent heat insulation properties and heat resistance, thermal shock resistance, etc. It was found that

That is, conventionally, composite plating is carried out using a composite plating solution prepared by dispersing ceramic fine particles in a metal plating solution to form a composite plating film formed by uniformly dispersing ceramic fine particles in a metal matrix. However, in this case, in order to impart a good heat insulating property to the composite plating film, it is necessary to increase the amount of ceramic fine particles dispersed in the film. However, if the dispersion amount of the ceramic fine particles is increased, the adhesion of the composite plating film to the metal substrate is lowered, and the same disadvantages as in the case of forming the ceramic sprayed layer occur.

Therefore, for the purpose of solving such a problem, the inventor of the present invention forms, on a metal substrate, a composite plating film having a gradient function in which the dispersion amount of ceramic fine particles gradually increases from the metal substrate side to the surface side. Although this plating film has good adhesion to the metal substrate (although there is room for improvement), there is a sudden heat fluctuation, especially in the area where the amount of ceramic fine particles dispersed is large. It was discovered that exposure to high temperatures and temperatures causes problems such as blister formation.

Therefore, as a result of further studies by the present inventors, as described above, a metal plating film is first formed on the metal substrate, and the amount of dispersion of the ceramic fine particles is gradually increased from this metal plating film side. Then, form the composite plating film in which the dispersion amount of the ceramic fine particles is gradually reduced, and finally form the metal plating film, that is, the dispersion amount of the ceramic fine particles is maximum in the central portion in the thickness direction and By interposing a composite plating film having a gradient function in which the amount of dispersion gradually decreases toward both sides in the depth direction, it is possible to provide excellent adhesion to a metal substrate, heat resistance, thermal shock resistance, and It has been found that a heat insulating layer having excellent properties such as corrosion resistance and chemical resistance and having an excellent heat insulating function without occurrence of blisters is formed, and thus the present invention is made. Is that Tsu.

Therefore, the present invention uses a composite plating solution in which a metal plating film is formed on the surface of a metal substrate on which a heat insulating layer is to be formed and then ceramic fine particles are dispersed in the metal plating solution. The fine particle dispersion amount gradually increases from the metal plating film side, and after the fine particle dispersion amount reaches the maximum, a composite plating film having a gradient function of gradually decreasing the fine particle dispersion amount is formed, and then on the composite plating film. Provided is a method for forming a metal heat insulating layer, which comprises forming a metal plating film on the metal.

According to the present invention, the metal plating film is exposed on the surface portion, and the dispersion amount of the ceramic particles on the surface side is small. Therefore, the thermal conductivity on the surface side is good. However, as the ceramic particles increase toward the central portion in the thickness direction of the composite plating film, and the ceramic particles become the maximum in the central portion, a good heat insulating function is exerted in this portion, and it is transmitted to the surface portion. The heat conduction can be blocked as much as possible.

Moreover, the heat insulating layer of the present invention is a metal layer whose surface portion does not contain ceramic fine particles, and since the ceramic fine particles are dispersed so as to gradually increase from the central portion to the central portion, a rapid temperature change may occur. Even when the ceramic fine particles are exposed to room temperature, the ceramic fine particles are surely prevented from peeling off and cracking, and the occurrence of blisters and the like can be prevented.

Further, since the heat insulating layer of the present invention has a gradient function in which the ceramic fine particles gradually decrease from the central portion in the thickness direction to both sides in the thickness direction, physical properties such as strength, mechanical properties and heat resistance are gradually increased. Since it changes, there is no concentration of mechanical stress or thermal stress locally,
It retains good physical properties and supports good thermal insulation.

The present invention will be described in more detail below. In the method for forming a heat insulating layer of the present invention, first, as shown in FIG. 1, a metal plating film 2 is formed on a desired surface of a metal substrate 1.

Here, the metal substrate 1 may be any member as long as it is necessary to form a heat insulating layer, for example, a liner of an automobile or other internal combustion engine member, a nozzle used for welding or thermal spraying, heat retention, A member for keeping cold is mentioned.

As the material of the metal base 1, nickel, nickel alloys such as Ni-P, Ni-B, Ni-Co and Ni-Fe, copper, copper alloys such as Cu-Zn and Cu-Zn-Sn are used. , Iron, iron alloy, etc. can be used.

As the metal plating solution for obtaining the metal plating film 2 formed on the metal substrate 1, a suitable metal plating solution such as nickel, nickel alloy, copper, copper alloy, iron, iron alloy plating is used. The plating solution may be an electroplating solution or an electroless plating solution. These may have a known bath composition, and for example, a sulfamic acid bath, a Watts bath, a high nickel sulfate bath, a high chloride bath, or the like can be used as the electrolytic nickel plating solution.

Next, in the present invention, the composite plating film 3 is formed on the metal plating film 2. The composite plating film 3 is formed by dispersing fine ceramic particles in a metal matrix. In this case, a layer 3a formed in the central portion in the thickness direction in which the amount of fine ceramic particles dispersed is largest,
The ceramic fine particles formed on both sides thereof have a gradient function of layers 3b and 3c in which the dispersed amount of the ceramic fine particles gradually decreases from the central portion toward the outside thereof.

The formation of the composite plating film 3 is performed using a composite plating solution in which ceramic fine particles are dispersed in a metal plating solution. In this case, the composition of the metal plating solution may be the same as or different from that of the metal plating solution used for forming the metal plating film 2, but it is preferable to use the plating solution of the same metal.

Examples of the ceramic fine particles include zirconia, yttria, ceria, silica, alumina, titania, mullite, and silicon carbide, and solid solution particles of these can also be used.

As a method of obtaining the composite plating film having the above-mentioned gradient function, a method of increasing or decreasing the dispersion amount of the ceramic fine particles in the metal plating solution is adopted.

That is, the dispersion amount of the ceramic fine particles in the metal plating solution is appropriately selected in the range of 0 to 1000 g / l. In this case, if the other conditions are the same, the larger the dispersion amount is, the more the eutectoid amount is. Increase. Therefore, a plating film having the above-mentioned gradient function can be formed by preparing a plurality of identical plating baths having different amounts of dispersed ceramic fine particles and sequentially plating.

The particle size of the above ceramic fine particles can be selected variously, but is 0.1 to 30 μm, more preferably 0.5 to 1.
0 μm (average particle size) is preferable. If the particle size is too small or, conversely, too large, the amount of co-deposition of particles decreases, and it may be difficult to control the amount of co-deposition, which makes it difficult to impart a sufficient gradient function.

It is also effective to control the specific surface area of the particles. In this case, the smaller the specific surface area,
The amount of eutectoid increases with the same amount of dispersion.

In the present invention, as a method of forming the plating film having the above-mentioned gradient function, a method of changing the plating conditions other than changing the dispersion amount and the specific surface area of the ceramic fine particles in the plating solution is also adopted. To be done.

That is, when the sulfamic acid bath is used as the plating bath, the eutectoid amount of the ceramic fine particles is larger than that when the sulfate bath is used, and the non-ionic activator and the anion activator are contained in the plating solution. Agent, cationic activator, etc.
Although it can be added in the range of 001 to 1 g / l, particularly 0.01 to 0.1 g / l, the amount of eutectoid increases in the order of anionic activator, nonionic activator, and cationic activator. The greater the amount, the greater the amount of eutectoid. As the activator, any of those conventionally used for plating is preferably used, but from the viewpoint of increasing the amount of eutectoid, a hydrocarbon-based surfactant and a fluoroalkyl group-based surfactant are preferable, and Sodium lauryl sulfate is preferably added in an amount of 0.5 to 1 g / l from the viewpoint of preventing pits in the plated film.

Further, a known nickel plating primary brightener such as an organic sulfimide compound and a secondary brightener such as an acetylene alcohol compound are added in an amount of 0.5 to 20.
The addition of g / l is effective in improving the flexibility and appearance of the plating film.

The pH of the plating solution can be in the usual range depending on the type of plating bath. For example, in the case of an electric nickel plating solution or the like, the pH can be 3.5 to 4.5. The amount of eutectoid tends to increase as the pH decreases.

Next, when performing electroplating,
Cathode current density is usually 0.5 to 10 A / dm²Select in the range
Although it can be determined that the lower the current density,
The amount of eutectoid increases. In addition, the stirring of the plating solution
Mechanical stirring, pump stirring, air stirring, cathode locking, etc.
Can be adopted, and mechanical stirring is particularly preferable, but stirring in this case is preferable.
The stronger the stirring, the more the amount of eutectoid. For example, mechanical agitation (Pro
In propeller agitation), the rotation speed of the propeller is 50 to 25
It can be set to a range of 00 rpm, and the
The plating solution circulation rate is 10 to 100 times / hour.
In the air agitation, the amount of air can be 0.5 to 3
0m³ / M²/ Min can be, cathode locking
In, the amplitude is 0.5 to 200 cm, the number of round trips is 0.5
~ 150 times / min, but with vigorous stirring
This increases the amount of eutectoid ceramic fine particles.

The above method of changing the cathode current density and the degree of agitation can be effectively adopted as a method of controlling the amount of eutectoid ceramic fine particles, since continuous control is possible without changing the composition of the plating solution. To be done.

The plating temperature is usually 30 to 60 ° C. from the viewpoint of obtaining a flexible plating film having a low electrodeposition stress, but the higher the plating temperature, the more the amount of eutectoid. Therefore, the eutectoid amount can be controlled by changing the plating temperature.

After forming the composite plating film 3, the metal plating film 4 is formed thereon. The metal plating film 4 is formed by using the same metal plating solution as that for forming the metal plating film 2. The coating 4 is preferably a coating of the same metal as the matrix of the composite plating coating 3.

Here, the thickness of each plating film can be appropriately selected according to its application and the like.

The amount of ceramic fine particles dispersed in the central layer 3a is preferably 20 to 40% (volume%, the same applies hereinafter), and particularly 25 to 35%. In this case, the ceramic fine particles may be evenly dispersed in the central layer 3a, and the ceramic fine particles are most abundant in the center and are unevenly dispersed so that the ceramic fine particles gradually decrease toward the inner and outer surfaces. May be.

The amount of ceramic particles dispersed in each of the inner and outer layers 3b and 3c is preferably 40% or less.
In this case, the inner and outer layers 3b and 3c are divided into, for example, two layers, and the amount of ceramic fine particles dispersed in the layer close to the central layer 3a is 10 to 4.
0%, especially 15 to 25%, and the dispersion amount of the distant layer is 10%
The following can be made 5% or less in particular. Further, ceramic fine particles may be uniformly dispersed in each of these layers 3b and 3c, and may be non-uniformly dispersed such that the ceramic fine particles gradually decrease from the central layer 3a side toward the inner and outer surfaces. . The dispersion state of the ceramic fine particles in the layers 3b and 3c may be the same or different.

In the present invention, the gradual decrease of the dispersion amount of the ceramic fine particles may be continuous in the direction from the central part to the inner and outer surfaces as described above, or may be decreased stepwise, but the metal base material may be decreased. Preferably has a substantially maintained integrity so that the tilting function is effectively exerted. Therefore, in such a case, since the metals are common, the clear boundary line as shown in FIG. 1 is not actually formed between the respective films and layers.

[0036]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to the following examples.

A car liner was pretreated by a conventional method and then plated with an electric nickel plating solution having the following composition under the following conditions to form a nickel layer having a thickness of 10 μm.

Plating solution composition and conditions NiSO ₄ .6H ₂ O 300 g / l NiCl ₂ .6H ₂ O 45 g / l H ₃ BO ₃ 40 g / l Pit inhibitor 0.5 g / l pH 4.2 Temperature 45 ° C. Cathode current Density 3A / dm ²

Next, composite plating was performed under the following conditions using a zirconia particle-dispersed electric nickel plating solution having the following composition.

Plating solution composition and conditions Nickel sulfamate 300 g / l Boric acid 30 g / l Pit inhibitor 0.5 g / l Zirconia particles (average particle size 2 μm) 0-600 g / l Temperature 40 ° C. Cathode current density 3 A / dm ²

In this plating solution composition, a plating solution containing no zirconia particles was first prepared, and then zirconia particles were gradually added (0 to 28 minutes) to reach the maximum amount, and then the plating was performed for a predetermined time. (28-11
2 minutes), and then by filtering a predetermined amount of the plating solution to gradually reduce the amount of zirconia particles dispersed in the plating solution (112 to 140 minutes), the inner middle portion (thickness 30 μm, ZrO ₂ Eutectoid amount inclined to 0-40%), central part (thickness 90 μm, ZrO ₂ eutectoid amount 40
%), The outer middle portion (thickness 30 μm, ZrO ₂ eutectoid amount 40
~ 0%).

Next, plating was performed using the electric nickel plating solution having the above composition to obtain a plating film having a thickness of 10 μm.

The thermal shock resistance of the obtained liner to the above plating film was excellent.

Nickel plating film and various ZrO
The thermal conductivity of the _two amounts of composite plating film is as follows.
Here, the thermal conductivity was measured by a laser flash method using various composite plating film samples processed into a disk shape having a size of about φ10 × 2 (mm). The measuring device is LF / TCM-FA8510B manufactured by Rigaku Co., Ltd., and the thermal diffusivity and heat capacity are measured in the range of room temperature to 800 ° C.
The thermal conductivity was measured. The results are shown in Table 1.

[0045]

[Table 1]

[0046]

EFFECTS OF THE INVENTION According to the present invention, a metal heat insulating layer having an excellent heat insulating function and a good thermal shock resistance and capable of easily producing a metal heat insulating layer free from blister and the like can be manufactured. is there.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a metal heat insulating layer obtained by the present invention.

[Explanation of symbols] 1 metal substrate 2 metal plating film 3 composite plating film 4 metal plating film

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Morito Togawa 1200 Higashitanaka, Komaki City, Aichi Prefecture Inside the Nagoya Induction Propulsion System Mfg. Co., Ltd. Industrial Co., Ltd. Central Research Laboratory (72) Inventor Masudao Okada 3-35-23 Kajimachi, Moriguchi City, Osaka Prefecture

Claims (1)

[Claims] 1. A metal plating film prepared by forming a metal plating film on the surface of a metal substrate on which a heat insulating layer is to be formed, and then using a composite plating solution in which ceramic fine particles are dispersed in the metal plating liquid. From the side, the fine particle dispersion amount is gradually increased, and further, the fine particle dispersion amount is maximized, and then a composite plating film having a gradient function of gradually decreasing the fine particle dispersion amount is formed, and then a metal plating film is formed on the composite plating film. A method for forming a metal heat insulating layer, the method comprising: forming.