JPS5815311B2 - Aluminum-based metal/dissimilar metal composite material and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a bonding strength of approximately
Aluminum-based metals and dissimilar metal composite materials with good edibility,
In particular, the present invention relates to aluminum-based metal/iron-based metal composite materials, aluminum-based metal/copper-based metal composite materials, and manufacturing methods thereof.

Conventionally, the method used to join aluminum-based metals and dissimilar metals was to immerse the dissimilar metals in molten aluminum, perform aluminizing treatment, and then cast and join the aluminum-based metal onto the aluminized surface. .

However, the composite material obtained by this method has a brittle alloy (intermetallic compound) between dissimilar metals and aluminum at the joint boundary.
, for example, Al-Fe compounds, Al-Cu compounds, etc. are formed, and these intermetallic compounds reduce the bonding strength,
This was a factor that impaired the corrosion resistance of the joint.

In addition, in the above-mentioned bonding, a thin layer of Sn is added to the surface of the dissimilar metals in order to improve wetting of the dissimilar metals by molten aluminum during aluminizing treatment or to suppress the formation of intermetallic compounds between the dissimilar metals and aluminum.
It was also known to apply plating, etc., but in these methods, because Sn etc. has a low melting point, it is washed away by molten aluminum and diffused into the aluminum, and does not remain as a Sn layer etc. Therefore, the formation of intermetallic compounds could not be effectively prevented.

The present invention provides an aluminum-based metal/dissimilar metal composite material in which there is no formation of intermetallic compounds that are brittle and have poor corrosion resistance at the joint boundary, and therefore the joint strength and corrosion resistance of the joint are significantly improved, and a method for producing the same. This is what we provide.

The aluminum-based metal/dissimilar metal composite material of the present invention is formed by bonding an aluminum-based metal and a dissimilar metal by sequentially forming a nickel layer and an aluminum-nickel alloy layer from the dissimilar metal side at the bonding interface, and This is a composite material characterized by a nickel layer that blocks aluminum-based metals and dissimilar metals.

In the composite material of the present invention, a nickel layer with a thickness of 12 μ or more, preferably 15 to 30 μ, is coated on the joint surfaces of dissimilar metals, and then the nickel coating layer is aluminized, and then the aluminized surface is coated with an aluminum layer. It can advantageously be manufactured by casting metals together.

Examples of the aluminum metal in the composite material of the present invention include pure aluminum, aluminum alloy for casting, aluminum alloy for die casting, and the like.

Further, examples of the dissimilar metal in the composite material of the present invention include various metals other than aluminum-based metals, such as iron-based metals and copper-based metals.

The composite material of the present invention is particularly preferably a composite material in which the dissimilar metal is an iron-based metal or a copper-based metal from the viewpoint of versatility of use.

Examples of iron-based metals include pure iron, carbon steel, stainless steel, cast and forged iron, and examples of copper-based metals include pure copper, brass, bronze, German silver, and copper.

A nickel layer and an aluminum-nickel alloy layer are formed sequentially from the dissimilar metal side at the bonding interface of the composite material of the present invention, but the nickel layer sufficiently blocks the aluminum metal and the dissimilar metal. In other words, the nickel layer exists in a complete layer with a thickness sufficient to prevent alloying between aluminum and dissimilar metals, and the thickness of the nickel layer is usually 10μ or more, preferably 15 to 30μ. be.

If the thickness of the nickel layer is too thin, it will not be possible to completely prevent alloying between aluminum and dissimilar metals due to diffusion, resulting in a decrease in joint strength and corrosion resistance of the joint.

However, even if the thickness of the nickel layer is increased more than necessary, the strength and corrosion resistance will not change, or rather, it will be disadvantageous due to increased cost.

Next, the above-mentioned method, which is particularly advantageous for producing the composite material of the present invention, will be explained in detail.

First, a nickel layer is coated on the surfaces of dissimilar metals to be joined.

The nickel layer can be coated by any method such as chemical plating or electroplating, but electroplating is particularly preferred.

The thickness of the nickel layer applied to the joint surfaces of dissimilar metals is 12 microns or more, preferably 15 to 30 microns.

If the thickness of the applied nickel layer is too thin, the nickel layer will not be thick enough to sufficiently isolate the aluminum-based metal and different metals in the resulting composite material.

Further, even if the nickel layer is too thick, a proportionate effect cannot be obtained, and the cost is rather high, which is economically disadvantageous.

Next, the nickel layer of a dissimilar metal covering the nickel layer is subjected to aluminizing treatment using aluminum or an aluminum alloy.

Aluminum alloys for aluminizing treatment include:
Examples include Al-5%Si alloy and Al-10%Cu alloy.

Aluminizing treatment is usually performed by applying the above-mentioned nickel plating layer to molten aluminum or aluminum alloy.
It is convenient to carry out the method by dipping for ~300 seconds.

Next, the nickel-coated and aluminized dissimilar metal is transferred to a mold, molten aluminum is poured into the mold, and the dissimilar metal and cast aluminum/minilam metal are joined by casting on the aluminized surface. .

In the thus obtained aluminum-based metal/dissimilar metal composite material, the aluminum-based metal and the dissimilar metal are bonded by forming a nickel layer and an aluminum/nickel alloy layer sequentially from the dissimilar metal side at the bonding interface. In addition, since the aluminum metal and dissimilar metals are sufficiently isolated by the nickel layer, there is no formation of fragile intermetallic compounds at the joint, resulting in not only high joint strength but also strong bond strength. It also has excellent corrosion resistance.

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Example 1 After applying nickel electroplating to a thickness of 20μ on the end face of a round bar made of JL, S5S41 steel with a diameter of 20mrn, the nickel-plated end face was immersed in pure aluminum molten metal at 750°C for 30 seconds to undergo aluminizing treatment. Did.

Next, this round bar was set in a mold, and pure aluminum molten metal at 720°C was injected to join the round bar and cast aluminum on the aluminized surface.

When the obtained joint rod was processed into a JIS Z2201 No. 4 test piece and the tensile joint strength was measured, it broke at the aluminum part.

Further, attached FIG. 1 shows a microscopic photograph of the joint portion of this joint rod.

In this photo, from the left, 5S41 steel, nickel plating layer, nickel-aluminum alloy layer (extremely thin diffusion layer), and pure aluminum material can be seen, and the thickness of the nickel plating layer is approximately 12.5 μm. Met.

As can be seen from the photo, the 5S41 steel material and the aluminum cast body are sufficiently isolated by the nickel plating layer, completely preventing the formation of brittle Fe-Al compounds.

For this reason, it exhibits the high bonding strength mentioned above.

Comparative Example 1 A round bar made of the same 5S41 steel used in Example 1 was completely nickel-plated.

Other than that, a connecting rod was manufactured in the same manner as in Example 1.

circle? CQ(z,"'Ic Eye911 ?C: 1 piece, 6.
Yu. A tensile test showed that the joint strength was 1.3k.
It was gAIt4.

Further, attached FIG. 2 shows a microscopic photograph of the joint portion of this joint rod.

The left side of this photo is 5S41 steel, the right side is pure aluminum material, and the layer interposed between the two is an Fe-A1 alloy layer.

Since this Fe-A1 alloy layer is a brittle compound, this joining rod has extremely low tensile strength as described above.

Example 2 Thickness 20μ on the end face of pure copper round bar with diameter 207nrIL
After applying nickel electroplating of
It was immersed in pure aluminum molten metal No. C for 10 seconds, and the nickel-plated surface was subjected to aluminizing treatment.

Next, this round bar was immediately set in a mold and heated to 750°C.
An aluminum alloy (JIS A1C4C aluminum alloy for casting) was injected, and the round bar and the cast aluminum alloy were joined by casting on the aluminized surface.

The bonding strength (strength before the salt spray test) and the same strength after the salt spray test of this bonding rod as in Example 1 are as shown in Table 1, and the bonding strength of this bonding rod is the same as in Example 1. It also had excellent corrosion resistance.

Comparative Example 2 A joining rod was manufactured in the same manner as in Example 2 except that the same copper rod used in Example 2 was not plated with nickel at all.

The same bonding strength as in Example 1 (strength before salt spray test) and the same strength after salt spray test are shown in Table 1, and this bonding rod has low bonding strength and corrosion resistance. It was significantly inferior to

[Brief explanation of the drawing]

FIG. 1 shows a micrograph (magnification: 1000 times) of the joint portion of the joint rod of Example 1. This photo shows 5841 steel material, nickel plating layer, Ni-A I alloy layer (thin layer), and pure aluminum material in order from the left. Further, FIG. 2 shows a micrograph (magnification: 25 times) of the joint portion of the joining rod of Comparative Example 1. This photo shows the 5S41 steel material on the left, the pure aluminum material on the right, and the Fe-A1 alloy layer in the middle.

Claims (1)

[Scope of Claims] 1. An aluminum-based metal and a dissimilar metal are joined by sequentially forming a nickel layer and an aluminum-nickel alloy layer from the dissimilar metal side at the bonding interface, and the nickel layer is an aluminum-based metal. An aluminum-based metal/dissimilar metal composite material that is made by blocking and dissimilar metals. 2. The composite material according to claim 1, wherein the nickel layer has a thickness of 10 μm or more. 3. An aluminum-based method characterized by coating the joining surfaces of dissimilar metals with a nickel layer with a thickness of 12μ or more, then aluminizing the nickel coating layer, and then casting and joining an aluminum-based metal onto the aluminized surface. Manufacturing method for metal/dissimilar metal composite materials. 4. The method according to claim 3, wherein the nickel layer is coated with a thickness of 15 to 30 microns.