JP2001026856A - Production of copper - aluminum composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve wear resistance by thermally spraying Cu or Cu alloy powder and Al or Al alloy powder in such a manner that only one part of these powder is melted. SOLUTION: The Cu alloy can contain one or more kinds selected from the group consisting of, by weight, <=40% Pb, <=30% Sn, <=0.5% P, <=15% Al, <=10% Ag, <=5% Mn, <=5% Cr, <=20% Ni and <=30% Zn by 0.5 to 50% in total. As the Al alloy, the one contg. 12 to 60% Si can be used. Then, as for the ratio between the Cu alloy and the Al alloy, the former is preferably controlled to 80 to 30 wt.%. To the Cu-Al composite material, <=3 wt.% graphite powder or <=10 wt.% Al2O3, SiO2, SiC, ZrO2, Si3N4, BN, AlN, TiN, TiC, Fe-P compds., Fe-B compds. or the like can be added as well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a copper-aluminum composite material. The technical fields to which the present invention relates are composite materials, thermal spraying techniques, aluminum alloy sliding materials and copper alloy sliding materials.

As a metal-based composite material, a metal-ceramic composite material has been mainly studied, and its production method is a method of press-molding a mixed powder of copper powder and Al ₂ O ₃ powder, followed by sintering (Japanese Patent No. 2854916) Al to ceramic carbon
There is a method of impregnating a molten alloy (Japanese Patent No. 2846635). Regarding the thermal spraying technology, see the Metallurgy Society of Japan, Vol. 33 (1994) No. 3, P268-27
5 There is a commentary entitled "Recent Advances in Thermal Spraying Technology", which describes a method for producing a metal-ceramic composite material. Similarly, Tribologists Vol 41 (199
6), No. There is a commentary on thermal spraying technology on pages 11, 19-24.

As a material belonging to the copper-aluminum composite material of the present invention, JP-A-9-122555 discloses a plain bearing in which a soft layer having a hardness similar to that of white metal is dispersed in an aluminum alloy base material. is there.
That is, in this plain bearing, the aluminum alloy soft alloy does not fuse and integrate, but exists as an independent composite component. This method of manufacturing a composite material includes a first step in which a flat plate made of an aluminum alloy material with a back metal is tested, and a second step in which a soft material of Sn, Pb or white metal is adhered to the front surface of the flat plate with a thickness of 50 to 100 μm. Forming a soft alloy layer by locally irradiating a laser beam to the flat plate on which the soft material is adhered, thereby dissolving the soft material into the aluminum alloy;
A fourth step of bending the flat plate into a semi-cylindrical shape, and machining the softened material after machining the laser-irradiated surface to expose a composite layer of an aluminum alloy and a soft alloy layer on the inner surface thereof. It comprises a fifth step.

Among copper alloys, particularly, as a sliding alloy, Cu-Pb, which has added Pb to improve adhesion resistance and seizure resistance, is widely used. On the other hand, copper alloys do not have excellent wear resistance.
It is known that sintering is performed by adding a hard material such as Fe ₂ P as proposed in No. 84.

[0005]

2. Description of the Related Art Conventionally, the following materials are known as aluminum alloy-based sliding materials which require properties such as wear resistance and seizure resistance. (A) An Al-Si based ingot alloy (arzil alloy) utilizing the wear resistance of eutectic Si or primary crystal Si. This alloy generally has a Si content of 3 to 18%, and is processed into a material shape by forging or casting. (B) An aluminum alloy in which hard particles such as Si particles and Fe particles are agglomerated in the process of processing and heat-treating a rolled aluminum alloy plate (German Patent No. 32 of the present applicant)
49133). This alloy achieves excellent seizure resistance and the like by allowing bulk Si or the like to adapt the mating shaft. (C) An aluminum alloy in which a small amount of Cr is added to an Al-Sn-based alloy to prevent coarsening of the Sn phase and improve fatigue resistance (US Pat. No. 4,153,756 of the present applicant). (D) Powder metallurgy alloy using rapidly solidified powder (for example, Japanese Patent Publication No. 2535789). In this publication,
A hot-pressed and then hot-extruded powder obtained by rapidly solidifying an aluminum alloy melt containing 30 wt% Si to provide a slide having excellent properties such as wear resistance, mechanical strength, light weight, and low coefficient of thermal expansion. Manufactures moving materials.

The technique of spraying a sliding material of a copper alloy is known from International Publication WO95 / 25224 of the present applicant, and this publication also discloses a copper-hard composite material.

When the Si content of the alloys (a) to (c) is more than 20%, casting becomes difficult, and working such as forging becomes more difficult. Therefore, the wear resistance of these alloys is limited by the amount of Si. The alloy of the above (2) can contain a large amount of Si, but it is necessary to adopt a forming method such as hot pressing or hot extrusion.
For example, application to a half metal for a main bearing of an internal combustion engine (commonly called “metal”) is practically impossible.

[0008]

Conventionally, a metal-ceramic composite material has been manufactured by a thermal spraying technique. However, a metal-metal composite material, for example, a Cu-Pb alloy and an Al-Si alloy composite material has been used. No manufacturing is done. When these two alloys are completely fused by thermal spraying,
Although a very fragile Cu-Si alloy is also produced and a practical material cannot be obtained, the present inventors have succeeded in obtaining a copper-aluminum composite material by devising thermal spraying conditions.

[0009]

That is, the present invention is characterized in that a copper or copper alloy powder and an aluminum or aluminum alloy powder are sprayed so that a part of the powder is melted and the remainder is not melted. . Hereinafter, "copper or copper alloy" is generically called "copper alloy" and "aluminum or aluminum alloy" is generically called "aluminum alloy". by the way,
When spraying a mixed powder of a copper alloy powder and an aluminum alloy powder, there is a general tendency that (a) when the average particle diameters of both powders are equal, the aluminum alloy powder is dissolved, and (b) the average particle diameter of the aluminum alloy powder. Is much larger than the copper alloy powder, the former dissolves. By utilizing such a tendency, it is possible to produce a copper-aluminum composite material in which a part of the copper alloy powder and the aluminum alloy powder is dissolved, and the remainder substantially maintains the properties of the solid powder.

In the present invention, the copper and aluminum alloys include all alloys that can be used in a sprayed state. When the tempered state of metal is roughly classified into cast state and rolling, drawing and other processing states, thermal spray alloys belong to the former tempered state,
Cast copper alloys such as bronze, lead bronze, and phosphor bronze are to be treated in the present invention. On the other hand, since the copper-brought product used in the electronic equipment is an alloy in a processed and tempered state, it can be sprayed, but cannot exhibit its original performance. Similarly, the wrought alloy is excluded, and a cast aluminum alloy such as an Al-Si based cast alloy is to be treated in the present invention.

In the present invention, the copper alloy is expressed as a percentage by weight,
Up to 40% Pb, up to 30% Sn, up to 0.5% P, up to 15% Al, up to 15% Ag, up to 5% Mn, up to 5% Cr, up to 20% Ni and One or more selected from the group consisting of 30% or less of Zn is 0.5% or more, preferably 1% or more and 50% or more in total.
The following can be contained. Lead is the most preferred element for improving the sliding characteristics under dry conditions. However, if the lead content exceeds 40%, the strength of the copper alloy is reduced, so it is necessary to set the upper limit to 40%. The preferred lead content is 1 to 30%, more preferably 2 to 15%. The additional elements other than lead mainly form a solid solution in copper to enhance its wear resistance and seizure resistance. Among them, Ag significantly enhances the sliding characteristics under the condition that the lubricating oil is small. Regarding the addition amount, Sn precipitates at 10% or more and Mn at 1% or more, and the precipitates enhance the wear resistance. Sn exceeds 30%,
P exceeds 0.5%, Al exceeds 10%, Mn is 5%
, Cr exceeds 5%, Ni exceeds 20%, Zn
Exceeds 30%, the thermal conductivity inherent in copper, good sliding properties with iron or aluminum-based mating materials, wear resistance,
Seizure resistance is lost. Therefore, it is necessary that these elements do not exceed the above upper limits. Preferred contents are Sn: 0.1 to 20%, P: 0.2 to 0.5% or less,
Ag: 0.1-8%, Mn: 0.5-4%, Cr: 0.
5 to 3%, Ni: 0.5 to 15%, Zn zinc: 5 to 25
%, More preferably Sn: 0.1 to 15%, A
g: 0.2-5%, Mn: 0.5-3%, Cr: 1-2
%, Ni: 1 to 10%, and Zn: 10 to 20%. For the above reasons, the total amount of the added elements should be in the range of 0.5 to 50%.

In the present invention, an aluminum alloy containing 12 to 60% by weight of Si can be used. If the Si content is less than 12%, the effect of improving the wear resistance and seizure resistance is small, and if it exceeds 60%, the strength is significantly reduced and the wear resistance is reduced. The preferred Si content is 15-50%. If the size of the Si particles exceeds 50 μm, the Si particles are likely to fall off. Preferred dimensions are between 1 and 40 μm. Next, the Al-Si-Sn-based alloy is a material having excellent wear resistance and seizure resistance as a wear-resistant and seizure-resistant part such as a metal or a bush in which an Al-Sn alloy is conventionally used. Sn is a component that imparts lubricity and conformability, and is uniformly dispersed in the aluminum matrix. Sn adheres preferentially to the mating shaft, and prevents Al adhered to the mating shaft and Al of the bearing from sliding with each other by the same material, thereby improving seizure resistance. Sn
If the content is less than 0.1%, the effect of improving lubricity is small, and if it exceeds 30%, the strength of the alloy is reduced. The preferred Sn content is 5 to 25%. It is thought that it exists very close to the Sn particles and prevents the Sn particles from coarsening, thereby improving the fatigue resistance. Aluminum alloys can contain the following optional elements. Cu: Cu is supersaturated in the aluminum matrix to form a solid solution to increase the strength, thereby suppressing the adhesive wear of aluminum and the wear caused by the Si particles falling off. Further, Cu is S
A part of n and a Sn-Cu intermetallic compound are generated to enhance wear resistance. However, if the Cu content exceeds 7.0%, the alloy is excessively hardened, and thus becomes unsuitable as a sliding member. The preferred Cu content is 0.5-5%. Mg: Mg combines with a part of Si to form an Mg-Si intermetallic compound and enhances wear resistance. However, if the Mg content exceeds 5.0%, a coarse Mg phase is generated, and the sliding characteristics deteriorate. Mn: Mn has a similar effect to Cu by forming a super-saturated solid solution in an aluminum matrix to increase its strength. However, when the content of Mn exceeds 1.5%, the alloy is excessively hardened and thus becomes unsuitable as a sliding member. The preferred Mn content is 0.1-1%. Ni: Ni has a similar effect to Cu by forming a solid solution in an aluminum matrix in a supersaturated manner to increase its strength. However, if the Ni content exceeds 8%, the alloy is excessively hardened, and thus becomes unsuitable as a sliding member. The preferred Ni content is 0.1-5%.

In the present invention, the weight ratio of the copper alloy to the aluminum alloy is preferably 80 to 30% for the former and the balance is the latter.

The main structure of the copper-aluminum composite material of the present invention includes (a) a structure dissolving copper or a copper alloy, (b) a structure dissolving copper or a copper alloy, (c) a structure dissolving aluminum or an aluminum alloy, and (ii) a structure dissolving aluminum or It consists of one or more combinations of aluminum alloy undissolved structures (however, excluding combinations of only (a) and (c) and combinations of only (b) and (d)). Before describing the features of the structure of the copper-aluminum composite material of the present invention, general features of the metal structure of the sprayed layer will be described. This is a structure obtained by melting and solidifying powder such as atomized powder. In one embodiment, the droplets generated by melting in the thermal spraying frame are deformed by colliding with the substrate surface, and when viewed in a layer cross section, a layered, flaky or flat portion is viewed as a small disk in a layer plane, Scales are piled up. In yet another form, when the powder such as atomized powder is pumped into the frame by gas, it retains the form of isolated particles in which each is dispersed, and a part of the particles is united, but in the form as it is. It is thought to melt. The molten droplet collides with the base material and solidifies, but if the thickness of the sprayed layer is reduced and the cooling is accelerated, one or several droplets do not coalesce with many other droplets due to fusion etc. Solidifies as independent particles. In this way, relatively small droplets are crushed, and a large number of fine layered pieces are stacked as a whole to form a sprayed layer. In other forms, the droplets coalesce into a large layer and solidify. In the present invention, “dissolution” is as described above.

In the present invention, a part of the powder does not dissolve during the thermal spraying and remains in the sprayed layer, and a mixed structure of a dissolved structure and an undissolved structure of the powder is formed. First of all, this feature
The u-Pb alloy will be described, and the Al-Si alloy will be described later. The undissolved structure of the lead bronze powder constituting this structure is such that the rapidly quenched structure of the lead bronze powder does not disappear during the spraying flame and remains in the sprayed layer. In this structure, a layer mainly composed of lead is dispersed in fine particles or is distributed in a layer at copper grain boundaries. This structure is a kind of casting structure, but it is characterized by (a) the main cooling direction is the direction from the periphery of the particles to the inside, and (b) a quenching structure rather than ordinary ingot casting or continuous casting. There is.

In the present invention, when a copper alloy and an aluminum alloy fuse, for example, when Si in an Al alloy forms a melt with Cu and solidifies, a coarse intermetallic compound is formed, and Cu—Al— Since a Pb-Si alloy is produced, a combination consisting only of (a) and (c) of the above structure is excluded. In other words, under the conditions where the copper alloy melting structure (a) and the aluminum alloy melting structure (b) are generated, the molten copper alloy and the molten aluminum alloy are almost completely fused unless the undissolved powder coexists. It is necessary to avoid a thermal spraying method in which only (c) exists. Organization (a) and
When (b) and / or (ii) are present in (c), fusion of the copper / aluminum alloy is prevented. Further, at the interface of the undissolved copper alloy of the structure (a), the interface of the aluminum alloy of (d), and the interface of the aluminum alloy and the undissolved copper alloy of the structure (b), the two alloys generate a low-melting substance and are fused. Occurs, but to a lesser extent. Therefore, in the present invention, such an interface structure is not included in the main structure, and the main structure is separated into (a), (b), (c), and (d) in the structure state of the molten powder.

From the above, the combination of the structures of the copper-aluminum composite material in the present invention is as follows. (A) + (ii) B. (A) + (b) + (ii) C.I. (B) + (c) D. (B) + (c) + (ii) (A) + (b) + (c) (A) + (b) + (c) + (ii) (A) + (c) + (ii).

The characteristics of the copper / aluminum composite material having these structures will be described with respect to examples of Cu-Pb alloy and Al-Si. In the undissolved Cu alloy powder (B, C, E, F), the fine Pb phase in the atomized powder remains in the sprayed layer and contributes to the improvement of the sliding characteristics. Dissolved Cu-Pb alloy powder (A, B,
E, F, and G) represent Pb when Cu and Pb melt and solidify.
The phase coarsens, and the Al-Si alloy powder is bonded by a reaction occurring between the molten Cu and the Al-Si alloy powder. At this time, the surface of the powder is often melted (F,
G). Dissolved Al alloy powder (C, D, E, F, G) in the thermal sprayed layer has a distinctly longer direction in one direction, such as found in the primary crystal Si of a conventional molten alloy or the Si particles of a rolled alloy. In this case, granular Si having a spherical shape, a massive shape, a polygonal shape, and other irregular shapes that are not classified into these are dispersed in any direction, not in a particle shape having a characteristic.
Further, in the case of the present invention, it is difficult to distinguish between the primary crystal Si and the eutectic Si which are obvious in the conventional ingot alloy. Also, melting A
The reaction which takes place between the l-Si alloy powder and the Cu-Pb alloy powder combines the latter powder.

Subsequently, a method of forming the composite sliding layer by thermal spraying will be specifically described. In the present invention, various thermal spraying methods described in the above-mentioned tribologist, page 20, FIG. 2 can be employed. Among them, high-speed gas flame thermal spraying (HVOF, High velocity oxyfuel) is preferably employed. it can. This method is described on page 20, right column, Nos. 4-13.
Since it has the features described in the row,
And Sn particle morphology is believed to be obtained. Since the sprayed Al is hardened by rapid solidification, it has a feature of high retention of Si particles. Therefore, as a thermal spray powder capable of suppressing abrasion due to Si particles falling off, Cu-Pb
An atomized powder such as an alloy, an Al-Si alloy, or an Al-Si-Sn alloy can be used. These atomized powders may be completely melted on the substrate and then solidified, or may be partially undissolved and deposited on the substrate so that the structure of the powder remains. The spraying conditions were: oxygen pressure 0.45 to 0.76 MPa, fuel pressure 0.45 to
0.76 MPa and a spraying distance of 50 to 250 mm are preferred. The thickness of the sprayed layer is preferably from 10 to 500 μm.

Subsequently, an average powder particle size adjusting method will be described as a method for producing the above-described various composite materials A to G. Table 1 shows an example of mixing an aluminum alloy powder similar to a copper alloy powder having a particle size showing a normal distribution around one average value, and further, coarse particles having one or both of a copper alloy and an aluminum alloy having a normal distribution particle size. Table 2 shows an example of mixing fine particles.

[0021]

[Table 1]

[0022]

[Table 2]

As the substrate on which the thermal spray layer is formed, iron, copper,
Various metal substrates such as aluminum can be used. The shape of the substrate is arbitrary, such as a plate, a disk, and a tube. If the surface of the substrate is roughened to a surface roughness of preferably Rz 10 to 60 μm by shot blasting or the like, the adhesion strength of the film increases. The hardness can be adjusted by subjecting the sprayed layer to heat treatment.

The above-mentioned copper alloys having various thermal spray structures are
10% or less, preferably 1-10% of Al ₂ O _3, Si
O ₂ , SiC, ZrO ₂ , Si ₃ N ₄ , BN, AlN, Ti
One or more compounds selected from the group consisting of N, TiV, B, C, an iron-phosphorus compound, an iron-phosphorus compound, an iron-boron compound, and an iron-nitrogen compound are added as an anti-wear component. be able to. The added amount of these components is 1
If it exceeds 0%, lubricity and conformability become poor, and as a result, seizure tends to occur.

Further, in the present invention, the bronze may contain not more than 3% by weight of graphite. Graphite is an additive that improves lubricity and prevents cracking of the swash plate sliding layer. If the graphite content exceeds 3%, the strength of the bronze decreases, which is not preferable. The preferred graphite content is
0.15 to 1.5%.

In the present invention, copper, nickel, aluminum, a copper-nickel alloy, a nickel aluminum alloy, a copper aluminum alloy, a copper tin System alloy, nickel self-fluxing alloy and cobalt self-fluxing alloy, an intermediate layer made of one or more materials selected from the group consisting of plating, sputtering,
It is preferably formed by a method such as thermal spraying. All of these materials require their surfaces to be rough, but since they are easily alloyed with bronze, they are firmly bonded to the (un) dissolved layer during thermal spraying and are bonded to the thermal spray layer and back metal. Increase strength. The preferred thickness of the intermediate layer is 5 to 100 μm. As the copper-tin alloy, a Cu-Sn-P-based alloy can be used. Since this alloy has a good molten metal flow and is hard to be oxidized, excellent performance can be obtained when the intermediate layer is formed by thermal spraying. Hereinafter, the method of the present invention will be described in more detail with reference to examples.

[0027]

EXAMPLE 1 75% by weight of Cu-10% by weight Pb-4% by weight Sn alloy atomized powder (average particle size: 60 .mu.m) and 25% by weight of aluminum alloy atomized powder (however, 40% by weight of Si was added to A2024 aluminum alloy) Atomized powder of the alloy thus obtained, and an average particle diameter of 100 μm) were mixed, and a steel grid (size 0.7
mm), and the surface is made to have a roughness of Rz4.
It was sprayed on a substrate roughened to 5 μm. HVO for thermal spraying
Using an F-type thermal spraying machine (DJ manufactured by Sulzer Metco), thermal spraying was performed under the following conditions. Oxygen pressure: 150 psi Fuel pressure: 100 psi Spray distance: 180 mm Spray thickness: 250 μm As a result, a spray layer having an average hardness Hv = 200 to 260 was formed. FIG. 1 shows the microstructure observed without etching the surface of the sprayed layer, and FIG. 2 shows the surface structure etched for 5 seconds with a graded liquid (5 g of ferric chloride, 100 cc of hydrochloric acid, 100 cc of water). FIG. 3 shows the microscopic structure observed in the above, and FIG. 4 shows the cross-sectional structure obtained by etching with the graded liquid. That is, the copper alloy powder has a lump portion that remains in the form of an atomized powder, judging from the form, and a portion that disappears and crystallizes together with the aluminum alloy melted during thermal spraying. Aluminum alloy, on the other hand, leaves little powder form. Since the aluminum alloy phase is a base for crystallizing the copper alloy phase into a net or flake, the aluminum alloy is almost completely melted,
It is determined that it reacted with the dissolved copper and crystallized as a Cu-Al compound.

[0028]

As described above, since the present invention provides a method for producing a copper-aluminum composite material by thermal spraying, a desired material is obtained by a single process of applying a mixed powder to a substrate. be able to. In addition, in this composite material, copper (alloy) and aluminum alloy are not essentially fused and are finely mixed, so that it is expected that the properties of these alloys are utilized. Further, such a composite material can be formed as a sliding layer such as a sliding member of a compressor.

[Brief description of the drawings]

FIG. 1 is a photomicrograph of the surface structure of a thermal sprayed composite material of Example 1 of the present invention observed without etching.

FIG. 2 is a micrograph obtained by etching and observing the surface structure of the thermal sprayed composite material in Example 1 of the present invention.

FIG. 3 is a photomicrograph of the cross-sectional structure of the thermal sprayed composite material of Example 1 of the present invention observed without etching.

FIG. 4 is a micrograph obtained by etching and observing a sectional structure of the thermal sprayed composite material in Example 1 of the present invention.

Claims (9)

[Claims] 1. A method for producing a copper powder, comprising: spraying copper or copper alloy powder and aluminum or aluminum alloy powder so that a part of the powder is melted and the remainder is not melted.
Manufacturing method of aluminum composite material. 2. The main structure of the copper-aluminum composite material is (a) a structure dissolving copper or copper alloy, (b) a structure not dissolving copper or alloy, (c) a structure dissolving aluminum or aluminum alloy, and (ii) aluminum or aluminum. 2. The copper alloy according to claim 1, comprising one or more combinations of the unmelted structure of the alloy (however, excluding combinations of only (a) and (c) and combinations of only (b) and (d)). Manufacturing method of aluminum composite material. 3. The method for producing a copper-aluminum composite material according to claim 1, wherein the copper alloy is a Cu—Pb alloy and the aluminum alloy is an Al—Si alloy. 4. The copper alloy contains 40% by weight or less of Pb, and the aluminum alloy contains 12 to 60% of Si.
The method for producing a copper-aluminum composite material according to claim 3, wherein the copper-aluminum composite material is contained by weight. 5. The aluminum alloy according to claim 1, wherein said aluminum alloy is at most 30% by weight of Sn, at most 7.0% by weight of Cu, at most 5.0% by weight of Mg, at most 1.5% by weight of Mn, at most 1.5% by weight. Fe, 8% by weight or less of Cr and 8.0% by weight or less of Ni
The method for producing a copper-aluminum composite material according to claim 4, comprising at least one element from the group consisting of: 6. The method according to claim 6, wherein the copper alloy contains 30% by weight or less of Sn,
0.5% by weight or less of P, 15% by weight or less of Al,
5% by weight, 5% by weight of Mn,
% Or less of Cr, 20% or less of Ni and 30% or less of Zn selected from the group consisting of 0.5 to 50% by weight. The method for producing a copper-aluminum composite material according to claim 4 or 5. 7. The method according to claim 1, further comprising spraying 30% by weight or less of graphite powder.
The method for producing a copper-aluminum composite material according to the above item. 8. Further 30% by weight of Al ₂ O _3, Si
O ₂ , SiC, ZrO ₂ , Si ₃ N ₄ , BN, AlN, Ti
N, TiC, B ₄ C, and iron-phosphorus, iron-boron,
The method for producing a copper-aluminum composite material according to any one of claims 1 to 7, wherein one or more kinds selected from the group consisting of iron-nitrogen-based iron compounds are sprayed. 9. The method for producing a copper-aluminum composite material according to claim 1, wherein thermal spraying is performed on the roughened metal substrate.