JP2002241879A - Extruded aluminum alloy material for cylinder liner and cylinder liner - Google Patents

Abstract

[PROBLEMS] To improve the wear resistance and seizure resistance of an extruded aluminum alloy material for a cylinder liner. Kind Code: A1 Abstract: 5 to 30% of Si and 3 to 2% by volume.
0% Fe-P compound - however, include P10~20 wt% and consisting essentially Fe ₃ P - containing, having a composition the balance being substantially aluminum, Si particles and Fe-P Extruded aluminum alloy material for cylinder liners having a structure in which compounds are dispersed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy extruded material for a cylinder liner and a cylinder liner using the same.

[0002]

2. Description of the Related Art Recent internal combustion engines have been developed to use aluminum alloy cylinder liners instead of conventional cast iron cylinder liners for weight reduction. However, it is not easy to make the sliding characteristics of an aluminum alloy comparable to that of cast iron. Therefore, for example, in Japanese Patent Application Laid-Open No. 2-120443, silicon carbide or Al ₂ O ₃ is added to an Al-Si alloy in order to improve wear resistance.
It has been proposed to add graphite to further improve lubricity. This publication discloses that hard machinability is improved by making hard Al ₂ O ₃ particles finer.

Further, according to Japanese Patent Application Laid-Open No. 2000-109944, it has been proposed that the wear resistance is improved by setting the average particle diameter of Si particles in an Al-Si alloy for a cylinder liner to 1 to 5 μm.

According to JP-A-6-316702,
Aluminum alloys for automotive sliding parts such as valve lifters are 0.1-5.0% Fe and 0.6-5.0%
Relative to 100 parts by weight of the aluminum alloy matrix containing Cu, 0.1 to 5.0 percent B, borides 1.0 to 15% and from 1.0 to 15% of Fe ₂ O _3, Fe ₃ C , Fe ₄ N, Fe
In a composite material in which an iron compound such as B or Fe ₂ P is dispersed, a tensile test piece is prepared by hot extrusion, and a wear test piece is prepared by vacuum hot pressing and cutting. Test result Aluminum alloy (In the example, the mating material is JIS, AC2B)
The result is that they can slide between each other.

[0005]

Conventionally, an Al-Si-based aluminum alloy cylinder liner mounted on a commercial vehicle is subjected to electrolytic polishing so that irregularities formed by protruding primary crystal Si particles from the surface are collected in an oil pool. We are utilizing it. Al-Si
Some attempts have been made to finish the surface of the cylinder liner of aluminum-based aluminum alloy by polishing.However, since the aluminum alloy liner has low hardness and is easy to plastically flow, it has a honing process that becomes an oil reservoir. It is difficult to form eyes. For this reason, the aluminum alloy liner is inferior in seizure resistance in a depleted lubrication state when the engine is started at a low temperature to a cast iron-based liner. On the other hand, in an aluminum alloy liner formed by electropolishing, if irregularities are worn by sliding with a piston ring, seizure occurs when the engine is started.

The above-mentioned Japanese Patent Application Laid-Open Nos. H2-122043 and 2
In 000-109944, the height of the unevenness is low because any of the composite or secondary phase particles is fine,
As a result, the oil pool effect may be insufficient.

[0007]

SUMMARY OF THE INVENTION In view of the above-mentioned state of the art, the present invention provides 5-30% Si and 3-2% by volume.
0% Fe-P compound, which contains 10 to 20% by mass of P and consists essentially of Fe ₃ P, with the balance being substantially aluminum, Si particles and the Fe An aluminum alloy extruded material for a cylinder liner, characterized by having a structure in which the -P compound is dispersed, and a surface of the extruded material formed by polishing the sliding surface of the extruded material with a piston, and having a polished surface having protruding irregularities. It is intended to provide a cylinder liner characterized by being substantially formed of a P compound.
Hereinafter, the present invention will be described in detail.

First, the composition of the extruded aluminum alloy material for a cylinder liner of the present invention will be described. Si (silicon) lowers the coefficient of thermal expansion of the aluminum alloy, and is mostly present as Si particles, which enhances wear resistance.
In order to sufficiently exhibit such an effect, the particle diameter of the Si particles is preferably substantially all, more preferably 2 to 10 μm. The Si content needs to be 5 to 30% by volume. When the Si content is less than 5% by volume, the above effect is insufficient. On the other hand, when the Si content is more than 30% by volume, the aggressiveness to the counterpart material increases, so that the wear of the counterpart material increases. A more preferred Si content is 15 to 25% by volume. The volume%
Is measured by an optical microscope.

The Fe-P compound containing 10 to 20% by mass of P and substantially consisting of Fe ₃ P imparts abrasion resistance and the particles form unevenness on the surface of the material, thereby exhibiting a pool. Since the Fe-P compound is brittle and easily crushed, the workability is good. Further, the hardness of the Fe-P compound is Hv 700-8.
The hardness is lower than that of Al ₂ O ₃ and Si (Hv 1200 to 1500), so the wear resistance of the alloy itself is low. However, this has an advantageous effect on workability. That is, it is not necessary to make the Fe-P compound particles fine in order to improve the processability, and since coarse particles can be used, a deep oil reservoir can be formed. As a result, a sufficient oil reservoir is formed and abrasion is reduced, so that the abrasion resistance of the Si particles is sufficient, and it is not necessary to take measures such as miniaturizing the Si particles as in the related art. An Fe-P compound having a P content of 10 to 20% by mass is substantially Fe ₃ P, and P is not separated from Fe ₃ P. On the other hand, in the case of a Fe—P compound substantially composed of Fe ₂ P and / or FeP, an Al—P compound is formed by the reaction of the following formula, and the extruded material becomes brittle: 3Fe ₂ P → 2Fe ₃ P + P 3FeP → Fe ₃ P + 2P Al + P → The particle diameter of the AlP Fe-P compound is preferably substantially all, more preferably 10 to 80 μm, more preferably 10 to 80 μm.
３０30 μm. Crushed powder, atomized powder and the like can be used as the Fe-P compound.

[0010] The balance of the above composition is substantially aluminum to achieve the properties of a lightweight cylinder liner.
However, it is permissible to add a small amount of a component that does not reinforce or impair the action of the above Si, Fe-P compound. For example, aluminum may contain at least one of Fe, Cu, Mn, Mg, Zn, Ni and Pb in a mass percentage of 10% or less. Of these, Fe, Mn, and Ni form intermetallic compounds as heavy metals to enhance the wear resistance of aluminum alloys, Cu strengthens the matrix, and Zn enhances heat resistance. Although Pb enhances lubricity, in the present invention, fluid lubrication is achieved by a sufficient oil reservoir, so that the frequency of direct contact of the aluminum alloy with the partner material is low, and the effect of Pb is negligible. Rather, Pb is expected to enhance the machinability of the aluminum alloy. Further, hard particles such as Al ₂ O ₃ are not preferable because they reduce the extrudability, and the effect of graphite is small, but there is no actual harm even if added if the content is 5/100 parts by volume or less of the Fe-P compound. . However, when hard particles are added, it is preferable to strengthen the aluminum matrix as fine particles.

The structure of the above aluminum alloy will be described with reference to FIG. FIG. 1 is a copy of main particles observed in a microstructure photograph, and the illustration of crystal grain boundaries and MgSi precipitates in a matrix is omitted. As can be seen from this figure, relatively coarse Fe-Si compound particles and relatively fine Si particles are uniformly dispersed in the aluminum alloy. The maximum roughness (Rz) of the aluminum alloy surface is
It is determined by Fe-Si compound particles. The Fe-Si particles are elongated in the extrusion direction.

The above-mentioned aluminum alloy is mixed with a raw material powder so as to have a predetermined composition, mixed well, and then mixed with each other.
Preformed at ~ 500 ° C to make a round bar blank, then heated to 400-500 ° C and then 150-180MP
It can be manufactured by extruding into a tube at the pressure of a. In order to process this into a cylinder liner, heat treatment and cutting are performed if necessary, and finally polishing is performed. The surface roughness after polishing is preferably 0.5 to 5 μm Rz. Although there is no actual harm even if electropolishing is performed, it is not necessary.

[0013]

The Fe-P compound suppresses the formation of adhesion nuclei, reduces seizure damage, and forms irregularities on the polished surface due to the difference in hardness from the aluminum matrix. The convex portions support the load, and the concave portions serve as oil pools to hold the lubricating oil. Hereinafter, the present invention will be described in more detail with reference to examples.

[0014]

EXAMPLES Test pieces were prepared by mixing Al-Si alloy powder having an average particle size of 50 μm and Fe ₃ P having an average particle size of 27 μm so as to have the composition shown in Table 1. Note that among the Al-Si alloys, No. 1, 6, and 12 were Fe, Cu, Mg
And so on. Furthermore, in Comparative Example 15, Al ₂ O ₃ was blended, and in Comparative Examples 16 and 17, Al ₂ O ₃ and graphite were blended. After mixing these blended powders in a blender, the mixture was mixed at 450 ° C. with a diameter of 250.
mm in a round bar, followed by 4 tons in a 300 ton extruder.
It was extruded at 00 ° C. into a 20 mm round bar.

A test piece having a diameter of 10 mm and a thickness of 3 mm was cut out from the extruded rod, and polished under conditions assuming the actual polishing of a cylinder liner, and the roughness was set to 2.5 μmRz.
The test material thus prepared was assembled in a double-pin-disc tester shown in FIG. 2 and subjected to a load increasing test and an oil cut test. In the figure, 1 is a test material, 2 is a thermocouple,
3 is an S45C hardened disk, 4 is a pad, 5 is an oil dropping tube, 6 is a hit adjustment steel ball, and 7 is a holder.

The test conditions are as follows. Test conditions Condition Gradual increase test Rotation speed: 1790 rpm (peripheral speed 15 m / s) Surface pressure: 2 MPa / 5 min Gradually increase Lubrication method: Pad lubrication Condition oil cut test Rotation speed: 1790 rpm (peripheral speed 15 m / s) Surface pressure: 5 MPa Lubrication method : Table 1 shows the results of a 0.5 cc test applied to the surface of the test material.

[0017]

[Table 1]

As shown in Table 1, no Fe ₃ P was added (No. 1).
0), small amount of Fe ₃ P added (No. 11), and fine Fe ₃ P added (No. 13) all have poor seizure resistance. If Fe ₃ P is coarse, molding becomes impossible (No. 12). Al ₂ O ₃ , graphite addition (Nos. 16, 17, 18) and Fe ₂ P addition (Nos. 14, 15) of the reference example, which correspond to the prior art, have poor seizure resistance in a depleted lubrication state. On the other hand, in Examples of the present invention (Nos. 1 to 9), the performance was excellent in both the load increasing test for examining the seizure resistance under a high load and the oil cut test for examining the seizure resistance in a depleted lubrication state. ing.

A wear test was performed under the following test conditions. Test condition conditions Wear test Rotation speed: 600 rpm (peripheral speed 5 m / s) Surface pressure: 10 MPa / 5 min Lubrication method: pad lubrication Counterpart material: quenching S45C The results of the test are shown in Table 2.

[0020]

[Table 2]

[0021]

As described above, it can be said that the improvement of the sliding characteristics of the conventional aluminum alloy cylinder liner has almost reached a practical level by the present invention.

[Brief description of the drawings]

FIG. 1 is a view showing a microstructure of a cross section of a cylinder liner according to the present invention.

FIG. 2 (a) is a schematic front view of a double push pin disk tester, and FIG. 2 (b) is a plan view.

[Explanation of symbols]

 1 Test material 2 Thermoelectric material

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuaki Goto 3-65 Midorigaoka, Toyota City, Aichi Prefecture Inside Daitoyo Kogyo Co., Ltd. (72) Inventor Hirofumi Michioka 1st Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F-term (reference) 3G024 AA26 AA27 GA07 GA16 HA07

Claims (4)

[Claims] 1 to 5% to 30% of Si and 3 to 3% by volume.
20% of the Fe-P compound - however, include P10~20 wt% and consisting essentially Fe ₃ P - containing, having a composition the balance being substantially aluminum, Si particles and the Fe- An aluminum alloy extruded material for a cylinder liner, which has a structure in which a P compound is dispersed. 2. Fe, Cu, Mn, M of not more than 10% by mass percentage.
2. The extruded aluminum alloy material for a cylinder liner according to claim 1, further comprising at least one of g, Zn, Ni and Pb. 3. The cylinder according to claim 1, wherein substantially all of the Fe-P compound has a particle size of 10 to 80 μm, and substantially all of the Si particles have a particle size of 2 to 10 μm. Extruded aluminum alloy for liner. 4. The aluminum alloy extruded material for a cylinder liner according to any one of claims 1 to 3, wherein the sliding surface with the piston is polished, and the polished surface has a roughness of 0.5 to 0.5.
A cylinder liner characterized by 5 μmRz.