JP6312189B2 - Sliding member and manufacturing method of sliding member - Google Patents

Description

  The present invention relates to a sliding member made of an aluminum alloy-based sintered body and a manufacturing method thereof. In particular, the present invention relates to a sliding member that is excellent in wear resistance and has low wear resistance (partner aggression) of a mating member that is in sliding contact with the sliding member.

  Sintered members are used for machine parts in various fields such as automobiles, office automation equipment, and household electrical appliances. Sintered members are excellent in mechanical properties such as strength and wear resistance, and can be manufactured in a shape close to the final product shape, and thus are suitable for materials of products having a complicated three-dimensional shape. On the other hand, a sliding member made of a lighter material has been demanded, and a material using an aluminum alloy has been proposed. For example, Patent Document 1 discloses a sintered aluminum alloy in which hard particles are added to an aluminum alloy so as to achieve both strength and wear resistance. This sintered aluminum alloy is a liquid phase sintered aluminum alloy containing a predetermined amount of hard particles of alumina or mullite in an Al—Zn—Mg—Cu alloy.

JP 2009-242883 A

  However, even with the above sintered aluminum alloy, there is room for further improvement with regard to the compatibility between wear resistance and opponent attack.

  The present invention has been made in view of such circumstances, and one of its purposes is to provide a sliding member having high wear resistance and low opponent attack and a method for manufacturing the same.

  In order to improve the wear resistance of a sliding member obtained by adding hard particles to an aluminum alloy, the inventors have changed the Al—Zn—Mg—Cu alloy of Patent Document 1 to an Al—Si—Mg—Cu alloy. The sliding member replaced with was examined. At that time, it was found that if the amount of Si in the Al-Si alloy was increased with emphasis on wear resistance, the amount of precipitated Si particles dropped off and the opponent attack increased significantly. Based on this, we investigated the factors of the opponent's aggression. As a result, when the sliding member is in sliding contact with the mating material, the hard particles fall off from the metal phase of the Al-Si-Mg-Cu alloy, and the hard particles are interposed between the sliding member and the mating material. As a result, it was found that wear of both the sliding member and the counterpart material is one factor that increases the opponent's aggressiveness. Accordingly, the present inventors have completed the present invention by studying a sliding member that can easily avoid a state where the hard particles fall between the sliding member and the counterpart material even if the hard particles fall off.

  The sliding member of the present invention comprises a high Si aluminum alloy phase having a Si content of 6% by mass or more, a low Si aluminum alloy phase having a Si content of 2% by mass or less, and a nonmetallic inorganic material. And hard particles dispersed in each aluminum alloy phase.

  According to this configuration, even when the hard particles fall off from the metal phase, the hard particles dropped off in the relatively soft low-Si aluminum alloy phase are easily embedded again and held. Therefore, when the sliding member is brought into sliding contact with the mating member, it is easy to suppress the falling hard particles being moved between the two members, and the mating attack of the sliding member can be reduced. it can. In addition, a relatively hard high-Si aluminum alloy phase is provided as a metal phase, and hard particles of non-metallic inorganic material are dispersed in the metal phase, thereby suppressing the decrease in strength of the sliding member and improving the wear resistance. be able to. Therefore, the sliding member of the present invention can achieve both high wear resistance and low opponent attack.

  As one form of the sliding member of the present invention, the content of the low Si aluminum alloy phase in the metal phase of the sliding member is 10% by mass or more and 60% by mass or less.

  According to this configuration, by setting the content of the low Si aluminum alloy phase to a predetermined amount, it is possible to more effectively realize a reduction in the opponent attack property while maintaining the hardness of the sliding member.

  One form of the sliding member of the present invention is that the average particle size of the hard particles is smaller than the average particle size of the low Si aluminum alloy phase.

  According to this configuration, by using hard particles having an average particle size smaller than the average particle size of the low Si aluminum alloy phase, it is easy to hold the hard particles in the low Si aluminum alloy phase, and the hard particles fall off. However, it can be easily held in the low Si aluminum alloy phase again.

  One form of the sliding member of the present invention is that the average particle size of the hard particles is 30 μm or less.

  According to this structure, it can be set as the sliding member excellent in abrasion resistance by using a fine hard particle.

  One form of the sliding member of the present invention is that the content of hard particles in the sliding member is 0.5% by mass or more and 10% by mass or less.

  According to this configuration, by defining the content of the hard particles, a sliding member having a strength and hardness comparable to or higher than those of other sintered members can be obtained, and the other party's aggression can be moderately suppressed. Can be a moving member.

  One form of the sliding member of the present invention is that the high Si aluminum alloy phase is composed of an Al—Si—Mg—Cu alloy.

  Al-Si-Mg-Cu alloy is excellent in hardness and contributes to improving the wear resistance of the sliding member by using it as a metal phase.

  As one form of the sliding member of the present invention, the nonmetallic inorganic material may be a material having a Vickers hardness of Hv800 or more.

  By defining the hardness of the hard particles, a sliding member having high wear resistance can be obtained.

  As one form of the sliding member of the present invention, the nonmetallic inorganic material may be alumina or mullite.

  If the hard particles are alumina, it is possible to obtain a sliding member that is particularly excellent in wear resistance and has a moderately low opponent attack property. If the hard particles are mullite, a sliding member that is slightly inferior to alumina but excellent in wear resistance and sufficiently low in attacking the other party can be obtained.

As one form of the sliding member of the present invention, when a chip-on-disk type sliding test is performed under the following conditions, the sliding surface of the chip after the test is more than the surface roughness of the sliding surface of the chip before the test. A form having a smaller surface roughness is mentioned.
Tip: Tip made of the sliding member of the present invention Disc: Disc made of the same material as the tip Peripheral speed of the tip pressure contact point of the disc: 1.6 m / sec
Load and time: 30 kgf x 1 hour Lubrication: In oil Temperature: Room temperature

  According to this configuration, the surface roughness of the sliding surface is smaller after the sliding test than before the sliding test. Therefore, when the sliding member is slid with the counterpart material of the same material, initial familiarity is obtained. After that, it is easy to suppress an increase in wear for both the sliding member and the counterpart material.

The manufacturing method of the sliding member of this invention includes the following preparatory process, a formation process, and a sintering process.
Preparation step: A mixed powder containing a high-Si aluminum alloy powder having a Si content of 6% by mass or more, a high-purity aluminum powder substantially containing no Si, and hard particles of a nonmetallic inorganic material is prepared.
Molding process: This mixed powder is molded into a molded body.
Sintering step: This compact is sintered, a high Si aluminum alloy phase having a Si content of 6% by mass or more, a low Si aluminum alloy phase having a Si content of 2% by mass or less, and these alloys A sintered body containing hard particles dispersed in a phase is used.

  According to this method, the sliding member of the present invention can be obtained.

  As one form of the manufacturing method of the sliding member of this invention, sintering of a molded object is mentioned at the appearance temperature of a liquid phase.

  By liquid phase sintering, the pores contained in the sintered body can be reduced, and a higher-density sliding member can be easily formed.

  According to the sliding member of the present invention, it is possible to achieve both wear resistance and low opponent attack. Moreover, according to the manufacturing method of the sliding member of this invention, the sliding member of this invention can be obtained easily.

The chip | tip used for a sliding test is shown, (A) is a front view, (B) is a right view, (C) is explanatory drawing of the wear width w of a chip | tip. It is explanatory drawing of the test method of a sliding test. It is a graph which shows the result of a sliding test. (A) is a SEM photograph of the sliding surface before the sliding test of the sample relating to the sliding member of the present invention, and (B) is an SEM photograph of the sliding surface after the sliding test. It is a graph which shows the surface roughness of the sliding surface before and behind a sliding test.

  Embodiments of the present invention will be described below.

  The sliding member of the present invention includes a high Si aluminum alloy phase, a low Si aluminum alloy phase, and hard particles. Hereinafter, the constituent requirements of the sliding member will be described, and then the manufacturing method of the sliding member will be described.

[Sliding member]
(High Si aluminum alloy phase)
<Composition>
The high-Si aluminum alloy phase of the sliding member of the present invention is an Al—Si alloy that is composed of an aluminum alloy composed of an additive element and the balance of Al and impurities, and contains 6 mass% or more of Si. The composition of the base material can be selected as appropriate. In particular, an Al—Si—Mg—Cu-based alloy can be suitably used. Al-Si-Mg-Cu alloys are preferred because of their excellent wear resistance. The specific composition of the Al-Si-Mg-Cu alloy is 6-18% Si, 0.2-1.0% Mg, 1.2-3.0% Cu, and the balance is Al and impurities. Is mentioned. In particular, Si is preferably contained in an amount of 8 to 15%. The additive element in the base material exists as a solid solution or crystallization and precipitation in aluminum. The composition (element and content) of the base material can be measured by using, for example, SEM-EDX or an emission spectroscopic analysis method. The composition of the base material may be adjusted according to the composition of the base material powder as a raw material.

<Content>
The content of the high Si aluminum alloy phase in the metal phase of the sliding member is preferably 40% by mass or more and 90% by mass or less. By containing a high Si aluminum alloy phase that is not less than the lower limit, a sliding member having high hardness and excellent wear resistance can be obtained. Furthermore, it can be set as the sliding member which is excellent also in intensity | strength. By containing a high Si aluminum alloy phase that is less than or equal to the upper limit value, the remaining metal phase can be a low Si aluminum alloy phase, and a sliding member with low opponent attack can be obtained. This content is the content of the high Si aluminum alloy phase when the material obtained by removing the hard particles from the sliding member is the metal phase and the metal phase is 100% by mass.

<Average particle size>
The average particle size of the high Si aluminum alloy phase is preferably about 45 μm to 350 μm. By setting the average particle size within this range, the moldability, sinterability, and manufacturability are excellent. This average particle size can be regarded as substantially the same as the average particle size of the high-Si aluminum alloy powder that is the raw material powder. A more preferable average particle diameter is about 45 μm or more and 100 μm or less.

<Others>
The sliding member of the present invention is a sintered material that has not undergone an extrusion process, and the aspect ratio (ratio between the maximum diameter and the minimum diameter) of the crystal grains of the metal phase (including the low Si aluminum alloy phase described below) Is small (less than 5). That is, by examining the metal structure of the sliding member, it can be confirmed that it has been manufactured by sintering. The sliding member of the present invention is also different from the melted material. It is difficult to disperse hard particles such as non-metallic inorganic materials in the melted material.

(Low Si aluminum alloy phase)
<Composition>
The low Si aluminum alloy phase is composed of a composition comprising an additive element, aluminum and impurities in the high Si aluminum alloy phase. As will be described later, the sliding member of the present invention is manufactured by using, as a raw material powder, a high-Si aluminum alloy powder having a Si content of 6% by mass or more and a high-purity aluminum powder substantially containing no Si. Is done. When a compact including such a raw material powder is sintered, some of the additive elements of the high-Si aluminum alloy powder diffuse into the high-purity aluminum powder to produce a low-Si aluminum alloy phase. Examples of the additive element contained in the high Si aluminum alloy phase include Si, Mg, and Cu. Of these, Si hardly dissolves in high-purity aluminum powder during sintering. On the other hand, Mg and Cu are easily dissolved in high-purity aluminum powder during sintering. Therefore, although the low Si aluminum alloy phase has a low Si content, Mg and Cu may be contained to a degree close to the Mg and Cu content in the high Si aluminum alloy phase. The Si content in the low Si aluminum alloy phase is 2% by mass or less, preferably 1% by mass or less, further 0.5% by mass or less, particularly less than 0.1% by mass, and may not be substantially contained.

  This low Si aluminum alloy phase exists in a state where it can be distinguished from the high Si aluminum alloy phase even in the sliding member of the sintered body. As described above, the low Si aluminum alloy phase is generated by diffusion of the additive element of the high Si aluminum alloy powder contained in the raw material powder into the high purity aluminum powder. However, the amount of Si in the high Si aluminum alloy powder dissolved in the high purity aluminum powder is very small, and the low Si aluminum alloy phase exists independently of the high Si aluminum alloy phase. This low Si aluminum alloy phase can be confirmed by analyzing the sliding member by surface analysis using SEM-EDX.

<Content>
The content of the low Si aluminum alloy phase in the metal phase of the sliding member is preferably 10% by mass or more and 60% by mass or less. By containing a low Si aluminum alloy phase that is equal to or greater than the lower limit value, a sliding member with low opponent attack can be obtained. This is considered to be because when the sliding member is in sliding contact with the mating member, the soft low Si aluminum alloy phase can hold again the hard particles dropped from the sliding member. Furthermore, it is considered that this low Si aluminum alloy phase also has a holding function that makes it difficult for hard particles to fall off in the sliding member. By containing a low Si aluminum alloy phase below the upper limit, the remaining metal phase can be made into a high Si aluminum alloy phase, which can be a sliding member with high hardness and excellent wear resistance. A decrease in strength of the member can be suppressed. This content is also the content of the low Si aluminum alloy phase when the material obtained by removing the hard particles from the sliding member is the metal phase and the metal phase is 100% by mass.

<Average particle size>
The average particle size of the low Si aluminum alloy phase is preferably about 45 μm or more and 350 μm or less, like the high Si aluminum alloy phase. By setting the average particle size to be equal to or greater than the lower limit, the alloy component diffuses and a sliding member having high strength can be obtained. By setting the average particle size below the upper limit, it is possible to obtain a sliding member that easily holds the hard particles that have fallen off. This average particle diameter can also be regarded as substantially the same as the average particle diameter of the high-purity aluminum powder that is the raw material powder. A more preferable average particle diameter is about 45 μm or more and 100 μm or less.

<Shape>
The particle shape of the low Si aluminum alloy phase is often flat and has a large aspect ratio. This is because the low Si aluminum alloy phase is softer and more deformable than the other constituent materials in the sliding member, and is thus easily deformed by compression during molding. Specifically, the aspect ratio is often about 1 to 5.

(Hard particles)
<Composition>
In the sliding member of the present invention, hard particles are dispersed in the metal phase described above. The hard particles are made of a non-metallic inorganic material. Nonmetallic inorganic materials include ceramics, intermetallic compounds, diamond, and the like. In particular, non-metallic inorganic materials of compounds can be suitably used. More specific materials include compounds such as alumina (Al ₂ O ₃ ), mullite (a compound of alumina and silicon oxide), SiC, AlN, and BN in addition to Si alone. Among these, when alumina is used, a sliding member having good reactivity with the metal phase and excellent wear resistance can be obtained, and when mullite is used, a sliding member having low opponent attack can be obtained. These various hard particles may be of a single type, or may be mixed with a plurality of types and included in the sliding member. The composition of the hard particles in the sliding member (single element, compound element and content) can be measured by using, for example, SEM-EDX, X-ray diffraction, chemical analysis, and the like.

<Content>
The content of hard particles in the sliding member (the total content when plural kinds of hard particles are contained) is preferably 0.5% by mass or more and 10% by mass or less. When it is 0.5% by mass or more, it is easy to obtain wear resistance comparable to or higher than that of other sintered members, and furthermore, it can have practically sufficient strength and hardness. A more preferred lower limit is 1% by mass or more. The greater the hard particle content, the better the wear resistance and hardness. However, if it exceeds 10% by mass, the strength decreases and the wear and damage of the counterpart material becomes severe. A more preferable upper limit value is 5.0% by mass or less, particularly 3.0% by mass or less.

<Hardness>
The hardness of the hard particles is higher than that of Si. In particular, the Vickers hardness is preferably Hv 800 or more, more preferably Hv 1000 or more, and particularly preferably Hv 1500 or more. By using hard particles having such hardness, a sliding member having high hardness and excellent wear resistance can be obtained. For example, alumina is about Hv2600 and mullite is about Hv1150. The measuring method of Vickers hardness Hv is based on JIS Z 2244 (2003).

  The hardness of the sliding member tends to increase as the hardness of the hard particles increases or as the content of the hard particles increases.

<Particle size>
The smaller the average particle size of the hard particles, the lower the tensile strength. If the average particle size of the hard particles is too large, they will easily fall off and the opponent attack will increase. This average particle size is preferably smaller than the average particle size of the low Si aluminum alloy phase. By using such fine hard particles, it is possible to provide a sliding member with high strength and excellent wear resistance, and hold hard particles that have fallen off during sliding contact with the mating material so that they are embedded again in the low Si aluminum alloy phase. By doing so, the opponent aggression can be effectively suppressed. For example, the average particle size is preferably 30 μm or less. In particular, it is preferable that the maximum diameter of the hard particles is smaller than the average particle diameter of the low Si aluminum alloy phase. By defining the maximum diameter as described above, the dropped hard particles can be more easily retained in the low Si aluminum alloy phase. For example, the maximum diameter is preferably 30 μm or less.

  More specifically, the average particle diameter of hard particles is preferably 10 μm or less, more preferably 1 μm or more and 6 μm or less in the case of alumina particles. In particular, the maximum diameter is preferably 10 μm or less, more preferably 5 μm or more and 10 μm or less. When the alumina particles having a size satisfying the above range are contained in the specific range, there is an effect of improving the sinterability of the sliding member. In the case of mullite particles, the average particle size is preferably 20 μm or less, more preferably 1 μm or more and 15 μm or less.

  The particle size distribution of the hard particles used as the raw material is measured by, for example, a microtrack method (laser diffraction / scattering particle size analysis method). The average particle diameter and the maximum diameter of the hard particles in the sliding member are measured as follows. An arbitrary cross section of the sliding member is observed with an optical microscope (100 to 400 times), and this observation image is image-processed to measure the area of all hard particles present in the cross section. The equivalent circle diameter of each area is calculated, the equivalent circle diameter is defined as the diameter of each particle, and the maximum diameter in the cross section is defined as the maximum diameter of the cross section. The maximum diameter is obtained for n = 10 cross sections, and the average of the 10 maximum diameters is defined as the maximum diameter of the hard particles. Moreover, the average of all the particle diameters in one cross section is obtained, the average is obtained for n = 10 cross sections, and the average of the 10 diameters is further averaged to obtain the average particle diameter of the hard particles.

<Shape>
The shape of the hard particles preferably has no sharp edge, in other words, is as close to a sphere as possible. By using hard particles close to a sphere or hard particles whose corners are not square, opponent attack can be reduced as compared to the case of using elongated particles.

[Sliding characteristics of sliding members]
In the sliding member of the present invention, the surface roughness of the sliding surface tends to be smaller after the sliding test than before. Therefore, when the sliding member is slid with the counterpart material of the same material, the initial familiarity is good, it is easy to suppress the fine gap variation between them, and the sliding member and the counterpart material suppress increase in wear. easy. This surface roughness is evaluated by, for example, arithmetic average roughness Ra in JIS B0601 94. The surface roughness of the sliding surface after the test is preferably 50% or less, particularly about 30% or less, compared to the surface roughness of the sliding surface before the test. On the other hand, for example, in the case of a melted material, the surface roughness of the sliding surface tends to be rougher before the test. This is thought to be because Si of the melted material has a large average particle size, and the Si drops off to form holes, or the sliding surfaces of both the sliding member and the counterpart material are damaged by the dropped Si.

[Mechanical characteristics of sliding members]
Since the sliding member of the present invention contains hard particles finer and higher in hardness than the aluminum alloy phase, it tends to be excellent in wear resistance and high in strength. Although depending on the composition of the metal phase and the manufacturing method, the sliding member of the present invention can suppress a decrease in strength and satisfy the tensile strength of 150 MPa or more compared to the case where hard particles are added to other alloy systems. it can. The hardness can satisfy 60 or more in HRB.

[Sliding member manufacturing method]
Said sliding member is provided with the preparation process of a raw material powder, a formation process, and a sintering process, and is obtained by performing a sizing process and a heat treatment process as needed. Details of each step are as follows.

(Preparation process)
In the preparation step, raw material powder for the sliding member is prepared. In this raw material powder, high Si aluminum alloy powder containing 6 mass% or more of Si (hereinafter referred to as Al alloy powder), high purity aluminum powder containing substantially no Si (hereinafter referred to as high purity Al powder) , And a mixed powder containing hard particles. The Al alloy powder is an additive element similar to the high Si aluminum alloy phase in the sliding member (sintered body), and a powder having a composition higher than the content of each additive element in the high Si aluminum alloy phase can be used. . The specific composition of the Al alloy powder includes, by mass, 6 to 40% Si, 0.2 to 2.0% Mg and 1.2 to 8.0% Cu, with the balance being Al and impurities. A more preferable Si content is 8 to 30%, and a still more preferable Si content is 17 to 18% or 12 to 13%. The eutectic point of the Al alloy is, for example, in the case of rapidly solidified powder when the Si content is around 17 to 18%, and in the case of the smelting powder, when the Si content is around 12 to 13%. is there. Near the eutectic point, Si is most likely to precipitate in the smallest amount, so if the Si content is close to the Si content at the eutectic point (± 1%), a sliding member with lower opponent attack can be obtained. Can do. The high-purity Al powder is typically composed of aluminum having a purity of 97% or more. For example, pure aluminum having a purity of 99% by mass or more can be used. Furthermore, the Al alloy powder may contain Mg in an amount of 0.03% by mass to 2% by mass. By containing a predetermined amount of Mg, the sinterability can be enhanced. The mixing of the raw material powders is preferably performed by a mixing method in which each powder particle is not pulverized as much as possible. When the soft high-purity Al powder is contained, in addition to the retention of the falling hard particles described above, the moldability is excellent.

  The hard particles used as the raw material remain substantially intact in the sliding member. Therefore, the amount and size of the hard particles used as a raw material are adjusted so that the content and size of the hard particles in the sliding member become a desired amount and a desired size. Further, the particle diameters of the Al alloy powder and the high purity Al powder are substantially maintained in the sliding member.

(Molding process)
Molding is performed by filling the above-mentioned mixed powder into a mold and compressing it. For example, cold pressure forming such as cold mold forming can be used. The molding pressure is about ² to 10 ton / cm ² . By adjusting the shape of the cavity of the mold, it is possible to obtain a molded body having a complicated shape.

(Sintering process)
The obtained molded body may be sintered at the liquid phase appearance temperature. Typical sintering conditions include an inert atmosphere such as nitrogen or argon, temperature: 550 to 600 ° C., time: 0 (starting temperature decrease upon reaching specified temperature) to 60 minutes. By this sintering process, the Al alloy powder becomes a high-Si aluminum alloy phase containing 6 mass% or more of Si, and the high-purity Al powder diffuses part of the additive elements in the Al alloy powder and the Si content is 2 A low Si aluminum alloy phase having a mass% or less is obtained, and a sintered body containing hard particles dispersed in these alloy phases is obtained.

  When the compact is sintered in the liquid phase as described above, the pores between the raw material powders are reduced by the liquid phase, resulting in a sintered body with fewer holes and higher density than the sintered material of solid-phase sintering. . In addition, the vacancies between the raw material powders before the appearance of the liquid phase are irregular shapes with many irregularities, but the vacancies tend to be rounded after the appearance of the liquid phase. For this reason, when the cross section of the sliding member of the present invention is observed, there are many holes having a shape close to a circle.

(Sizing process)
The obtained sintered body may be appropriately sized. Sizing may be hot or cold. Cold sizing can improve dimensional accuracy, and hot sizing can improve strength.

(Heat treatment process)
After sintering or sizing, solution treatment and aging heat treatment may be appropriately performed. As heat treatment conditions, known conditions can be used. Moreover, sizing can be performed after solution treatment, and then aging can be performed to increase dimensional accuracy. This is because the sintered body after solution forming is soft and easy to size with high accuracy.

[Test example]
Samples of sliding members containing various hard particles were prepared and their sliding characteristics were examined. Each sample was produced in the process of preparation of raw material powder → molding → sintering → cold sizing → heat treatment. The manufacturing conditions for each sample are as follows. Samples No. 1 to No. 6 all satisfied tensile strength: 150 MPa or more and hardness: HRB 60 or more.

<< Sample No.1: Al-Si-Mg-Cu alloy + hard particles >>
Al-18Si-3.25Cu-0.81Mg (unit: mass%) The Al-Si-Mg-Cu alloy powder (high Si aluminum alloy powder) with the composition and high-purity aluminum powder with the composition Al-0.5Mg And alumina powder are prepared. Each of Al-Si-Mg-Cu alloy powder and high-purity aluminum powder has an average particle diameter of 50 μm, and alumina powder has an average particle diameter of 2 μm (maximum diameter 6 μm). A mixed powder is prepared by mixing the prepared Al-Si-Mg-Cu alloy powder, high-purity aluminum powder, and alumina powder. The mass ratio of Al-Si-Mg-Cu alloy powder and high-purity aluminum powder is 80:20, and this ratio is the mass of the high-Si aluminum alloy phase and low-Si aluminum alloy phase in the metal phase of the sliding member. It is a ratio. The metal powder and the alumina powder are mixed so that the alumina powder is 1.0 mass% with respect to the mixed powder. The obtained mixed powder was mold-molded at a surface pressure of 5 ton / cm ² to produce a molded body. Subsequently, this compact was subjected to liquid phase sintering in a nitrogen atmosphere under sintering conditions of 560 ± 5 ° C. × 50 minutes. The obtained sintered body is heated to 490 ° C, then water-cooled to form a solution, and then cold-sized under the condition of 6 ton / cm ² and further subjected to aging at 175 ° C x 7 hours to contain hard particles A sintered Al-Si-Mg-Cu alloy sample was prepared.

<< Sample No.2: Al-Si-Mg-Cu alloy + hard particles >>
A sample of sintered Al-Si-Mg-Cu alloy containing hard particles under the same conditions as sample No. 1 except that the content of alumina particles in the mixed powder of sample No. 1 was 3.0% by mass Produced.

<< Sample No.3: Al-Si-Mg-Cu alloy + hard particles >>
The mixed powder of sample No. 1 contains hard particles under the same conditions as sample No. 1 except that the mass ratio of Al-Si-Mg-Cu alloy powder and high-purity aluminum powder was set to 70:30 A sample of sintered Al-Si-Mg-Cu alloy was prepared.

<< Sample No. 4: Al-Si-Mg-Cu alloy + hard particles >>
The mixed powder of sample No. 1 contains hard particles under the same conditions as sample No. 1 except that the mass ratio of Al-Si-Mg-Cu alloy powder and high-purity aluminum powder was 60:40 A sample of sintered Al-Si-Mg-Cu alloy was prepared.

<< Sample No.5: Al-Si-Mg-Cu alloy + hard particles >>
The mixed powder of sample No. 1 contains hard particles under the same conditions as sample No. 1 except that the mass ratio of Al-Si-Mg-Cu alloy powder and high-purity aluminum powder is 40:60 A sample of sintered Al-Si-Mg-Cu alloy was prepared.

<< Sample No.6: Al-Si-Mg-Cu alloy + hard particles >>
The mixed powder of sample No. 1 contains hard particles under the same conditions as sample No. 1 except that the mass ratio of Al-Si-Mg-Cu alloy powder and high-purity aluminum powder was 90:10 A sample of sintered Al-Si-Mg-Cu alloy was prepared.

<Sample No. 11: F-08C2>
A commercially available sintered member (F-08C2) was prepared. The mechanical properties of Sample No. 11 are hardness: HRB75 and tensile strength: 430 MPa.

<Sample No. 12: A390>
Prepare an extruded product of A390 (Al-Si hypereutectic alloy for castings containing 17% by mass of Si) and heat treatment under the same conditions as sample No. 1 to prepare a sample of A390 alloy did. The mechanical properties of Sample No. 12 are hardness: HRB80 and tensile strength: 390 MPa.

<Sample No.13: Al-Si-Mg-Cu alloy>
A mixed powder having the same composition as Sample No. 1 was molded into a molded body under the same conditions except that it did not contain hard particles. This molded body was sintered at 560 ± 5 ° C x 50 minutes, and the subsequent cold sizing and heat treatment were performed under the same conditions as in sample No. 1 to prepare a sintered Al-Si-Mg-Cu alloy sample. Produced. The mechanical properties of Sample No. 13 are hardness: HRB75 and tensile strength: 300 MPa.

<< Sample No.14: Al-Si-Mg-Cu alloy + hard particles >>
The mixed powder of sample No. 1 contains hard particles under the same conditions as sample No. 1 except that the mass ratio of Al-Si-Mg-Cu alloy powder and high-purity aluminum powder was 20:80 A sample of sintered Al-Si-Mg-Cu alloy was prepared. The mechanical properties of this sample No. 14 are hardness: HRB57, tensile strength: 275 MPa.

<< Sample No.15: Al-Si-Mg-Cu alloy + hard particles >>
A sample of sintered Al—Si—Mg—Cu alloy containing hard particles was prepared under the same conditions as in sample No. 1 except that the mixed powder of sample No. 1 did not contain high-purity aluminum powder. The mechanical properties of Sample No. 15 are hardness: HRB78 and tensile strength: 257 MPa.

(Sliding test)
A chip having a predetermined shape made of each of the above materials is manufactured, and a chip-on-disk wear test is performed. After this test, the wear width w on the sliding surface of the chip 10 shown in FIG. The result is shown in the graph of FIG.

《Chip shape》
The chip 10 used for the sliding test was a tongue-like block shown in FIGS. 1 (A) and 1 (B). One end surface of the chip 10 is a plane on which a support for holding the chip 10 is attached in the sliding test, and a hole for inserting the support is formed. The other end surface is a sliding surface with respect to the disk, and is circular. It consists of an arcuate curved surface. The dimensions of the chip 10 are as follows.
Width (up / down distance in Fig. 1 (A)): 10mm
Thickness (left / right distance in Fig. 1 (A)): 5mm
Length (left / right distance in Fig. 1 (B)): 10mm
Bending radius of sliding surface: 5mm

<Sliding conditions>
As shown in FIG. 2, the tip 10 is pressed against a rotating disk 20 and the wear amount of the tip is measured. The sliding conditions are as follows. In this sliding test, since the co-slidability with the same material of the chip and the disk is evaluated, the wear amount of the chip and the disk is almost the same. Therefore, if the wear amount of the chip is small, it can be said that the wear amount of the disk as the counterpart material is also small.
Disc material: Same as the tip Peripheral speed of the tip pressure contact point of the disc: 1.6m / sec
Pressure welding condition: 30kgf x 1 hour Lubrication: In oil Temperature: Room temperature

(Surface roughness measurement)
For sample Nos. 2, 12, and 13, the surface roughness of the sliding surface before and after the sliding test was measured. Specifically, arithmetic average roughness Ra in JIS B0601 94 was measured. The results are shown in the graph of FIG. This graph shows the surface roughness of the sliding surface after the test as a relative value, assuming that the surface roughness of the sliding surface before the test is 100%. Note that the sliding surface before the sliding test is in the state of the chip after aging described above and is not polished. The surface roughness Ra of the sliding surface before this test is 0.35 μm or less.

(Particle size measurement)
The average grain size of high Si aluminum alloy phase and low Si aluminum alloy phase in each sample was measured. The cross section of each sample embedded in the resin is polished, and surface analysis is performed on the cross section by SEM-EDX at a magnification of 150 times. The particles of the high Si aluminum alloy phase and the low Si aluminum alloy phase were extracted from the photographed image of the sample cross section by image processing, and the average particle size of each was determined by the following procedure. The maximum diameter of each particle is defined as the major axis D _L , the maximum diameter of the surface perpendicular to the major axis D _L is defined as the minor axis D _S, and the particle size r _s of each particle is obtained by Then, the average of the particle size r _s is calculated for 10 particles, and the value is set as the average particle size r _AVE .
Individual particle size r _s = (major axis D _L × minor axis D _S ) ^1/2

(result)
<Sliding surface state>
FIG. 4A shows an SEM photograph of the sliding surface before the sliding test, and FIG. 4B shows an SEM photograph of the sliding surface after the sliding test. These photographs are all photographs of the sliding surface of Sample No. 1. In this photograph, white particles are alumina particles, and the gray portion of the background is the metal phase. Although it is difficult to understand in this photograph, surface analysis by SEM-EDX reveals that the metal phase is mottled in granular regions of high Si aluminum alloy phase and low Si aluminum alloy phase. Furthermore, in the photograph (A) of the sliding surface before the sliding test, it can be seen that the alumina particles protrude from the metal phase, whereas in the photograph (B) of the sliding surface after the sliding test, the alumina particles are It turns out that it hold | maintains so that it may dig into a metal phase.

  Further, as shown in FIG. 5, the surface roughness of Sample No. 12 (A390) obtained by extruding the melted material is significantly rougher after the sliding test than before the sliding test. This is presumably because the average particle size of Si in the sample is large. In Sample No. 13 to which no alumina particles were added, the surface roughness of the sliding surface before and after the sliding test was slightly changed, but the surface roughness after the sliding test was still slightly lower than before the sliding test. Is rough. In contrast, Sample No. 2 to which alumina particles were added shows that the surface roughness after the sliding test is much smoother than before the sliding test. Specifically, it can be seen that the surface roughness after the test is about 30% of the surface roughness before the test.

《Metal phase particle size and Si content》
The average particle diameters of the high Si aluminum alloy phase and the low Si aluminum alloy phase in each sample were values close to 50 μm, which is the average particle diameter of the high Si aluminum alloy powder and the high purity aluminum powder. Further, as a result of the above surface analysis, in the sintered Al—Si—Mg—Cu based alloy member (sliding member) of sample No. 1, the Si content of the high Si aluminum alloy phase is about 15% by mass. -Si-Mg-Cu alloy powder had a lower Si content. On the other hand, the low Si aluminum alloy phase contains an extremely small amount of Si of less than 0.1% by mass, and it is considered that Si of the Al-Si-Mg-Cu alloy powder was dissolved in high purity aluminum powder. . In addition, as for the samples No.2 to No.6, No.13, and No.14, as a result of surface analysis, the Si content of the high-Si aluminum alloy phase was Si content of the Al-Si-Mg-Cu alloy powder. Whereas the amount was lower than the amount, the low Si aluminum alloy phase contained a trace amount of Si of less than 0.1% by mass. Therefore, the high Si aluminum alloy phase is derived from the Al-Si-Mg-Cu alloy powder, but depending on the mixing ratio with the high purity aluminum powder, the Al-Si-Mg-Cu system It is considered that the additive element of the alloy powder is in solid solution. The Si content in the high Si aluminum alloy phase can be changed by adjusting the mass ratio of the Al—Si—Mg—Cu alloy powder and the high purity aluminum powder. The results are shown in Table 1.

《Abrasion amount》
The results of the sliding test are shown in Table 1 and FIG. As shown in the graphs of Table 1 and FIG. 3, in the raw material powder, Al—Si—Mg—Cu alloy powder and high-purity aluminum powder are mixed at a mass ratio of 40:60 to 90:10, and this mixed powder is mixed. In contrast, samples No. 1 to No. 6 containing alumina particles have a smaller wear width than sample No. 13 containing no alumina particles. In particular, Sample No. 2 containing 3% by mass of alumina particles shows the wear resistance closest to Sample No. 11 of a commercially available sintered member. Sample No. 14, in which the mass proportion of the Al-Si-Mg-Cu alloy powder is too small in the raw material powder, has a large wear width because the Si content of the high Si aluminum alloy phase is small. Recognize. On the other hand, in the raw material powder, sample No. 15 consisting only of Al-Si-Mg-Cu alloy powder (not including high-purity aluminum powder) has a large wear width because a low Si aluminum alloy phase is not generated. I understand that.

  Sample No. 12 (A390) of aluminum alloy containing no alumina particles had the largest wear width.

<Discussion>
The following is considered from the above results.
(1) From the photograph in FIG. 4, when hard particles are included in the metal phase of the high Si aluminum alloy phase and the low Si aluminum alloy phase, the wear resistance is improved and even if the hard particles fall off from the metal phase, Since these fallen particles are held so as to be embedded in the low Si aluminum alloy phase, it is considered that the opponent aggression can be reduced.

  (2) From the graph of FIG. 3, it has a high Si aluminum alloy phase and a low Si aluminum alloy phase, and since the high Si aluminum alloy phase contains Si in a specific range, the wear resistance tends to be improved. . Furthermore, wear resistance tends to be improved by increasing the content of hard particles.

  (3) From the graph in FIG. 5, when the high Si aluminum alloy phase and the low Si aluminum alloy phase contain hard particles, the surface roughness tends to be smaller after the sliding test than before the sliding test. It is in.

  Note that the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist of the present invention, and is not limited to the above-described configuration. For example, the composition of the high Si aluminum alloy phase and the content of hard particles can be changed as appropriate.

  The sliding member of the present invention can be suitably used as a product material in various fields in which sufficient strength is provided, wear resistance is excellent, opponent attack is low, and weight reduction is desired. The manufacturing method of the sliding member of this invention can be utilized suitably for manufacture of the sliding member of this invention, especially a complicated three-dimensional shaped sliding member.

10 chips 20 disks

Claims (6)

A high-Si aluminum alloy phase composed of an Al-Si-Mg-Cu-based alloy having a Si content of 6 mass% or more;
A low Si aluminum alloy phase having a Si content of 2% by mass or less;
A sliding member comprising hard particles dispersed in each aluminum alloy phase,
The mass ratio of the high Si aluminum alloy phase and the low Si aluminum alloy phase in the metal phase of the sliding member is 40:60 to 90:10,
The hard particles are
Made of Al ₂ O ₃ ,
The average particle size is 1 μm or more and 6 μm or less ,
The maximum diameter is 10 μm or less ,
The content occupying the sliding member Ri der 0.5 mass% to 3.0 mass%,
When a chip-on-disk type sliding test is performed under the following conditions, the surface roughness of the chip sliding surface after the test is 50% or less of the surface roughness of the chip sliding surface before the test. Moving member.
Chip: chip made of the sliding member
Disc: Disc made of the same material as the chip
Peripheral speed at the tip contact area of the disk: 1.6 m / sec
Load and time: 30 kgf x 1 hour
Lubrication: In oil
Temperature: room temperature   The sliding member according to claim 1, wherein an average particle diameter of the hard particles is smaller than an average particle diameter of the low Si aluminum alloy phase. The sliding member according to claim 1 or 2 , wherein the high Si aluminum alloy phase has a Si content of 6 to 18 mass%. When configured high Si aluminum alloy powder in Al-Si-Mg-Cu alloy the Si content is 6 wt% or more, and high-purity aluminum powder containing substantially no Si, of _Al 2 _{O 3} Preparing a mixed powder containing hard particles;
Forming the mixed powder into a molded body;
The compact is sintered, and a high Si aluminum alloy phase composed of an Al—Si—Mg—Cu based alloy having a Si content of 6% by mass or more, the Si content is 2% by mass or less. A step of forming a low Si aluminum alloy phase and a sintered body containing hard particles dispersed in the alloy phase;
In the step of preparing the mixed powder ,
The high Si aluminum alloy powder and the high purity aluminum powder are mixed at a mass ratio of 40:60 to 90:10,
Said hard particles have an average particle diameter of 1μm or more 6μm or less, under 10μm at the largest diameter, the content occupied in the mixed powder and 3.0 wt% or less than 0.5 wt%,
When a chip-on-disk type sliding test was performed on the sliding member obtained from the sintered body under the following conditions, the surface roughness of the sliding surface of the chip after the test was determined as follows. A manufacturing method of a sliding member that is 50% or less of the surface roughness of the sliding surface .
Chip: chip made of the sliding member
Disc: Disc made of the same material as the chip
Peripheral speed at the tip contact area of the disk: 1.6 m / sec
Load and time: 30 kgf x 1 hour
Lubrication: In oil
Temperature: room temperature The manufacturing method of the sliding member according to claim 4 which makes content of Si in said high Si aluminum alloy powder 17-18 mass% or 12-13 mass% in said preparatory process. The method for manufacturing a sliding member according to claim 4 or 5 , wherein the sintering of the molded body is performed under conditions of 550 to 600 ° C x 0 to 60 minutes, which is an appearance temperature of a liquid phase .