JP3426475B2 - Aluminum alloy composite material for brake discs with excellent wear resistance - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy composite material having excellent wear resistance, more specifically, an aluminum alloy suitable for a member to which a high load frictional force is applied, particularly for a motorcycle, a four-wheel vehicle, and a brake disc for a railroad vehicle. Regarding composite materials.

[0002]

Brake discs for two-wheeled vehicles, four-wheeled vehicles, and railway vehicles are usually made of a steel material such as stainless steel or chrome steel, but from the viewpoint of improving the running performance of the vehicle body and improving fuel economy, The weight reduction of the vehicle body is required, and the use of aluminum alloy material instead of steel material is also considered for the brake disc in order to reduce the weight.

When a normal aluminum alloy material is used as a brake disc material, there is a problem that the disc material is significantly worn and excessively scratched. In order to improve this difficulty, a brake disc material has been proposed in which hard particles such as alumina (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), and silicon carbide (SiC) are dispersed in an aluminum alloy matrix. However, since the above aluminum alloy brake disc material is provided as a casting material in which hard particles are added to the molten aluminum alloy, , There is a problem in the uniform dispersion of hard particles in the aluminum alloy matrix, and because the wettability between the hard particles and the aluminum alloy melt is not always good, it is often the case that sufficient properties such as wear resistance cannot be obtained. Also, since only large hard particles can be added, the machinability is poor, and the damage to the brake pad material, which is the mating material of the disc material, becomes large. There is also a problem.

A composite material for a brake disc in which 5 to 30% of hard particles having an average particle size of 1 μm or more and less than 5 μm are dispersed in a matrix of a powder compact obtained by powder metallurgy (Japanese Patent Application No. 8-295376). , Al-2 to 10% Si to N
Average particle size of 1 to 15 μm in the matrix of the aluminum alloy powder compact containing 1% or more of i, Cu, Zn, Mn, Ti, Zr, and Cr added in a total of 2% or less.
3 to 15% of at least one of SiC and AlN particles of m
Dispersed aluminum alloy composites for brake discs have also been proposed (Japanese Patent Application No. 7-352106 ). However, even in the case of these brake disc materials, when the brake pad is pressed under a high load in which the pressing pressure exceeds 3 MPa, the aluminum alloy on the disc surface undergoes shear deformation and shear fracture in a minute region due to frictional force, and the wear amount increases. Has been experienced to cause problems.

During braking, the temperature of the disk material rises sharply due to frictional heat, and especially when the load is high, the disk material temperature rises significantly, causing the disk material to burn,
Since severe scratches occur on the disc material, it is important that the brake disc material has strength and wear resistance.In addition to this, the friction coefficient is large, and in forming the brake disc, Since it involves forging and cutting, excellent forgeability and machinability are also required.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in order to solve the conventional problems in aluminum alloys for brake discs and to obtain an aluminum alloy composite material satisfying the above-mentioned characteristics required for brake disc materials. Based on the above-mentioned aluminum alloy composite material with the aluminum alloy powder compact proposed as a matrix, based on the results of experiments and studies on the relationship between the dispersion conditions of hard particles and the properties of the composite material. The purpose is to have excellent strength and wear resistance, and in particular to have wear resistance to withstand high load braking.
An object of the present invention is to provide an aluminum alloy composite material having a high friction coefficient, excellent forgeability and machinability and excellent in wear resistance.

[0007]

A brake disc having excellent wear resistance according to claim 1 for achieving the above object.
Aluminum alloy composite material for use is Si: 5-15%, C
u: 0.5 to 3%, Fe: 0.5% or less, and further
Zr: 0.5% or less, V: 0.5% or less, Ni: 0.
5% or less, Mn: 1% or less, Mo: 0.5% or less, C
r: 0.5% or less, Ti: 0.5% or less, Zn: 0.5
% Or less, and the balance Al and
S in the aluminum alloy matrix consisting of impurities
_{iC, Al 2 O 3, AlN} , Si 3 N 4, made of one or more hard particles selected from among SiO ₂ dispersed suddenly
Powder metallurgy or spray forming using cold solidified powder
In the composite material produced by the casting method, the content of the hard particles in the composite material is 7 to 20% for the hard particles having an average particle diameter of 1 to 5 μm, and 0 for the hard particles having an average particle diameter of 7 to 25 μm. 0.5 to 5%, and the total content is 7.5 to 22%.

A brake having excellent wear resistance according to claim 2.
Aluminum alloy composite materials for disks, you to claim 1
And the aluminum alloy further contains Mg: 0.05.
It is characterized by containing ~ 0.5% .

SiC particles, Al ₂ O ₃ particles, AlN particles, Si ₃ N ₄ particles and SiO ₂ particles are used as a brake disc material by dispersing one or more of these hard particles in an aluminum alloy matrix. Wear resistance when rubbing against the brake pad,
Although the seizure resistance is improved and the friction coefficient is increased, in the present invention, fine hard particles having an average particle size of 1 to 5 μm are used in an amount of 7 to 2
It is characterized in that 0.5% to 5% of relatively coarse hard particles having an average particle size of 7 to 25 μm are contained at 0%, and the total content of these hard particles is set to 7.5 to 22%.

When only hard particles having an average particle size of 1 to 5 μm are dispersed, the wear resistance during high-load braking is insufficient. By dispersing a certain amount of hard particles having an average particle size of 7 to 25 μm together with fine hard particles having an average particle size of 1 to 5 μm, the shear deformation of the aluminum alloy in the minute area of the disk surface is suppressed, and the high load is exerted. Wear resistance is improved. Hard particles having an average particle size of 1 to 5 μm are preferably contained in the range of 7 to 20%.
If the average particle size is less than 1 μm, agglomeration is likely to occur and it is difficult to manufacture a composite material, and if it exceeds 5 μm, the machinability deteriorates, and seizure easily occurs when the brake disc is applied to the brake pad at high pressure. If the content is less than 7%, sufficient wear resistance and seizure resistance cannot be obtained, and if it exceeds 20%, forgeability and machinability deteriorate. The more preferable content of the hard particles having an average particle diameter of 1 to 5 μm is 8 to 15%.

Hard particles having an average particle size of 7 to 25 μm are 0.5
It is preferable to disperse in the range of 5%. Average particle size is 7
If it is less than μm, the effect of improving the wear resistance under high load is not sufficient, and if it exceeds 25 μm, the machinability deteriorates. Further, if the content is less than 0.5%, the effect is small, and if it exceeds 5%, the machinability becomes poor. The total content of the hard particles having an average particle size of 1 to 5 μm and the hard particles having an average particle size of 7 to 25 μm is preferably in the range of 7.5 to 22%, and when it exceeds 22%, the machinability is deteriorated.

The preferred aluminum alloy forming the matrix in the present invention is based on an Al-Si type alloy, but the significance of the alloy components and the reasons for limitation will be explained. Si means Si particles in the matrix of the material. Disperses as to increase the wear resistance of the material. A preferred content is in the range of 5 to 15%, and if it is less than 5%, its effect is not sufficient, and if it exceeds 15%, the forgeability and machinability deteriorate, and cracking easily occurs during forging.

Cu functions as a solid solution in an aluminum alloy to improve strength and wear resistance. A preferable content range is 0.5 to 3 %, and if it is less than 0.5%, the effect is not sufficient, and if it exceeds 3 %, forgeability and machinability are deteriorated.

Mg forms a solid solution in an aluminum alloy to enhance strength and wear resistance. In particular, it exhibits a remarkable effect when coexisting with Cu. Preferred content is 0.05-0.5%
Is less than 0.05%, the effect is small,
If it exceeds 0.5%, the forgeability deteriorates.

Fe is contained in the range of 0.5% or less.
This improves strength, wear resistance and seizure resistance.

Further, Zr: 0.5% or less, V: 0.5
% Or less, Ni: 0.5% or less, Mn: 1% or less, Mo:
By containing one or more of 0.5% or less, Cr: 0.5% or less, Ti: 0.5% or less, Zn: 0.5% or less, the strength of the material is increased, and as a result, As a result, wear resistance and seizure resistance are improved.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The aluminum alloy composite material of the present invention can be manufactured by the following method. (1) Powder metallurgy method A rapidly solidified aluminum alloy powder having a predetermined composition is manufactured by an atomizing method. Then, the aluminum alloy powder and the hard particles are mixed with each other by various stirring type mixers or a crusher such as a ball mill. In order to obtain a high-strength and high-toughness composite material and to obtain a uniform mixed state with hard particles, it is desirable that the aluminum alloy powder be fine, and a powder of 100 μm or less is usually used. By filling the mixed powder into a can and heating the mixed powder to a temperature of 400 to 500 ° C., the inside of the can is evacuated or replaced with an inert gas, or a preform obtained by cold-compressing the mixed powder is not supported. 400 to 50 in active gas atmosphere or vacuum
By heating to a temperature of 0 ° C., degassing treatment for removing gas and moisture adsorbed on the surface of the aluminum alloy powder is performed.

Subsequently, the mixed powder or the preformed mixed powder filled in the can is solidified by hot pressing or extrusion to densify the mixed powder to a density of 100%. When used as a brake disc material, after solidification, it is cut into an appropriate size, forged if necessary, and finished by cutting to form a brake disc.

(2) Spray forming method This is a method of obtaining a rapidly solidified body by spraying hard particles together with the atomized molten aluminum alloy and simultaneously depositing them on the collector. Since the composite of the deposited aluminum alloy and hard particles, that is, the preform, has a relative density of 97 to 99%, the pores inside the preform are crushed by hot pressing, forging, or a combination of these to increase the density. When used as a brake disc material, finish processing is performed by cutting to form a brake disc.

[0020]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. Example 1 An aluminum alloy powder having the composition shown in Table 1 was produced by the air atomizing method. This was classified to 105 μm and mixed with the hard particles shown in Table 2 for 15 minutes using a cross rotary mixer with forced stirring blades. The obtained mixed powder was filled in a container having an outer diameter of 90 mm and a height of 200 mm, degassed by vacuum evacuation for 1 h at 480 ° C., and then sealed into cans, which were loaded in a closed mold having an inner diameter of 94 mm. Was solidified by hot pressing with a load of 500 tons at a temperature of 400 ° C., and uniaxial free forging was further performed at a temperature of 400 ° C. until the height became 1/2.

[0021]

[Table 1]

[0022]

[Table 2]

Next, Si: 7.5%, Cu: 1.3
%, Fe: 0.15%, Zn: 0.1%, aluminum alloy containing the balance Al and impurities (alloy H)
And Si: 7.5%, Cu: 1.4%, Mg: 0.3
%, Fe: 0.10%, Ti: 0.1%, aluminum alloy containing the balance Al and impurities (alloy I)
Was melted, and the molten metal was made into droplets by a nitrogen atomizing method and deposited in a semi-solidified state on the rotating disk type collector below the atomizing nozzle. At this time, at the same time, SiC particles having an average particle diameter of 5 μm and an average particle diameter of 12 μm were put on nitrogen gas for atomizing and sprayed onto a collector to deposit together with an aluminum alloy to obtain a composite material preform. The dimensions of the preform were 150 mm in diameter and 150 mm in height. Table 3 shows the content of the hard particles in the composite material.

Then, the preform was processed by uniaxial free forging at a temperature of 400 ° C. to a height of ½, and a test material No. 16 and No. 16 It was set to 17. In addition,
The content of the added hard particles was quantified by measuring the insoluble content after melting the aluminum alloy from the preform.

[0025]

[Table 3]

The resulting composite material was subjected to a tensile test at room temperature to measure the tensile performance, and a pin-disk type friction and wear tester was used to measure the wear amount and friction coefficient of the disk under the following conditions. It was measured. The results are shown in Table 4. Aluminum alloy composite material according to the invention, test N
o. All of 1 to 17 are excellent in wear resistance and have a high friction coefficient. The forgeability and machinability were also good.

Pin-disc type friction and wear test: The produced test material (aluminum alloy composite material) was used as a disc, and a sectional shape was obtained from a commercially available pad material for copper brakes (brake pad: C04A manufactured by Nippon Brake Industry Co., Ltd.). Was formed into a square pin having a size of 7 mm × 7 mm, the disc was rotated, and three pins were pressed against the side face of the rotating disc to cause friction, and the wear amount (wear depth) of the disc was measured.

The test condition is that the test load is a surface pressure of 0.5 MPa.
(Low load) and 5 MPa (High load), friction speed 5
m / s, no lubrication, test time 10 minutes. The coefficient of friction was also measured during the test.

[0029]

[Table 4]

Comparative Example 1 Aluminum alloy powder (alloy A) produced in Example 1
And aluminum alloy powder (Si: 20.5%, Cu: 1.5%, manufactured by the air atomizing method, as in Example 1.
Fe: 0.10%, Mn: 0.10%, balance Al and impurities (alloy J) were classified to 105 μm and mixed with hard particles shown in Table 5 for 15 minutes using a cross rotary mixer with forced stirring blades. Outside diameter 90
mm container, height 200 mm, and then degassed by vacuum evacuation at 480 ° C. for 1 h to seal a can, which is then loaded in a closed mold having an inner diameter of 94 mm and a load of 500 ton at a temperature of 400 ° C. Was solidified by hot pressing, and uniaxial free forging was further performed at a temperature of 400 ° C. until the height became 1/2.

[0031]

[Table 5]

Separately, an aluminum alloy having the same composition as the alloy A of Example 1 was melted and held at a temperature of about 620 ° C. in the crucible so as to be in a solid-liquid coexisting state, and the hard particles shown in Table 6 were added thereto. Stir while adding little by little until the prescribed amount is reached,
While continuing strong stirring, lower the temperature to 605 ° C, and
The casting material was manufactured by performing compo-casting for casting into a thick disk die having a height of 50 mm and a height of 50 mm. Then, the obtained cast material was forged at a temperature of 400 ° C. to a height of 40 mm, and a test material No. It was set to 26.

[0033]

[Table 6]

The obtained test material was subjected to a tensile test at room temperature to measure the tensile performance, and a pin-disk type friction / wear tester was used under the same conditions as in Example 1.
The wear amount and friction coefficient of the disc (test material) were measured. The results are shown in Table 7.

[0035]

[Table 7]

As shown in Table 7, the test material No. 18 is
Since the SiC particles have a small average particle size and the particles do not uniformly disperse in the material matrix, the strength and elongation are low and the wear amount is large. Test material No. Since No. 19 has a large average particle size of SiC particles, it has poor machinability and cannot be applied as a brake disc. Test material No. Since No. 20 has a small amount of dispersed SiC particles, it has a large amount of wear and a low coefficient of friction. Test material No. In No. 21, since SiC particles were excessively added, the forgeability was poor and large cracks occurred in the forging process. As a result of conducting a tensile test by taking a tensile test piece from a healthy portion, both strength and elongation were inferior.

Test material No. 22 is an average particle size of 7 to 25 μm
Since no hard particles are added, high load (5MP
In the wear test of a), seizure occurred about 1 minute after the start of the test. Test material No. In addition, since the hard particles 2 are excessively added, the test material No. 23 has the test material No. 23. In No. 24, the hard particles 2 are coarse, so that the machinability is poor, and therefore it cannot be applied as a brake disc material. Test material No. 25
Is Si in the aluminum alloy forming the matrix
Since the amount was large, the forgeability was poor, and cracks occurred during forging. Test material No. No. 26 has a large segregation of hard particles,
Also, many casting defects were recognized, and the strength and elongation were inferior.

[0038]

As described above, according to the present invention, an aluminum alloy composite material having excellent wear resistance is provided, and when applied as a brake disc material, the amount of wear is small, especially when a high load brake is applied, It can be suitably used as a brake disc for two-wheeled vehicles, four-wheeled vehicles, and railway vehicles without causing seizure.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI F16D 65/12 F16D 65/12 E (72) Inventor Furuya Seiichi, Osaka Prefecture Osaka City, Konohana Ward, Shimaya 5-chome 1-109 Sumitomo Metals Industrial Co., Ltd. Kansai Works Steel Works (72) Inventor Hiroshi Higashiguchi 5-1109 Shimaya, Konohana-ku, Osaka City, Osaka Sumitomo Metal Industries Co., Ltd. Kansai Works Steel Works (72) Inventor Okubo Kimasa 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industry Co., Ltd. (72) Inventor Kazuhisa Shibue 5--11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industry Co., Ltd. (56) References Special Kaihei 9-125179 (JP, A) JP 2-25538 (JP, A) JP 3-173741 (JP, A) JP 9-184037 (JP, A) JP 9-279270 ( JP, A) Special Kai 63-227735 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C22C 1/10 C22C 21 / 00-21 / 18 F16D 65/12

Claims (2)

(57) [Claims] 1. Si: 5 to 15% (weight%, hereinafter the same)
), Cu: 0.5-3%, Fe: 0.5% or less
Zr: 0.5% or less, V: 0.5% or less, N
i: 0.5% or less, Mn: 1% or less, Mo: 0.5% or less
Below, Cr: 0.5% or less, Ti: 0.5% or less, Zn:
Contains 0.5% or less of one kind or two or more kinds, and the balance Al
SiC, Al ₂ O ₃ , AlN, Si ₃ N ₄ , SiO in the matrix of the aluminum alloy consisting of
_A powder metallurgical method or a spray powder in which one or more hard particles selected from ₂ are dispersed and which uses a rapidly solidified powder.
A composite material produced by the warming method , wherein the content of the hard particles in the composite material is 7 to 20% for the hard particles having an average particle diameter of 1 to 5 μm and 0 for the hard particles having an average particle diameter of 7 to 25 μm. Brake disc with excellent wear resistance, characterized in that the total content is 0.5 to 5%, and the total content is 7.5 to 22%.
Aluminum alloy composite material for use . 2. The aluminum alloy further comprises Mg:
The wear resistance according to claim 1, which contains 0.05 to 0.5%.
Excellent aluminum alloy composite material for brake discs .