JP2006057138A - Composite material and sliding member obtained by using the composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite material in which strength reduction and the occurrence of cracks are prevented and which has improved productivity. <P>SOLUTION: The composite material is composed of a sliding face layer mainly made up of carbon and a sintered compact layer coupled to the circumference of the sliding face layer. The sliding face layer is preferably obtained by mixing 100 pts.wt. of graphite powder having a mean particle diameter of 1 to 200 μm with 5 to 80 pts.wt. of a binder, and firing the mixture. The sintered compact layer is preferably obtained by sintering the powder of metal and/or ceramics having a mean particle diameter of 1 to 200 μm. Further, the ratio in thickness between the sliding face layer and the sintered compact layer is preferably 5:95 to 70:30. The composite material is preferably used as a sliding member. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a composite material used for a sliding member, and more specifically, a composite material composed of a sliding surface layer mainly made of carbon and a sintered body layer bonded around the sliding surface layer. And a sliding member using the composite material.

Conventionally, there is a bearing having a multilayer structure disclosed in Patent Document 1 below. Patent Document 1 discloses a fuel pump bearing comprising a sliding contact layer mainly made of carbon and a support layer mainly made of carbon and metal and bonded to the sliding contact layer to support the sliding contact layer. Is disclosed.
JP 2003-286922 A

  However, since the support layer is mainly composed of carbon and metal in Patent Document 1, the strength of the bearing is lower than when the support layer is made of metal alone, and the dimensional accuracy when the support layer is post-processed is deteriorated. Further, since the support layer is bonded after the slidable contact layer is roughly formed, the interface between the slidable contact layer and the support layer can be clearly defined, and sufficient adhesive force cannot be obtained. There is a problem that cracks occur. Furthermore, the thing of patent document 1 has to press-mold twice, and there exists a problem that productivity is bad.

  Accordingly, the object of the present invention is to provide both the advantages of both carbon and / or ceramics, which are excellent in self-lubricating and corrosion resistance, but weak in strength, and strong in strength, but not self-lubricating and in corrosion resistance. The carbon layer and the metal and / or ceramic layer are not formed separately and integrated to make the best use of the carbon layer and the metal and / or ceramic layer by forming the carbon layer and the metal and / or ceramic layer simultaneously. It is to provide a composite material composed of layers and having a structure in which the interface between both layers is unclear, and improving performance and productivity as a sliding member.

  As a result of earnest research to solve the above problems, the present inventor has found that the particle diameter of graphite powder used for the sliding surface layer, the blending ratio of the binder, and the particles of metal and / or ceramic powder used for the sintered body layer It is found that the diameter can be specified, and the sliding surface layer and the sintered body layer can be formed at the same time so that the strength can be prevented from being reduced, the occurrence of cracks can be prevented, and the productivity can be improved. It is a thing.

  That is, the present invention is a composite material composed of a sliding surface layer mainly made of carbon and a sintered body layer bonded around the sliding surface layer. The composite material of the present invention is preferably obtained by mixing and baking 5 to 80 parts by weight of a binder with respect to 100 parts by weight of graphite powder having an average particle diameter of 1 to 200 μm. In the composite material of the present invention, the sintered body layer is preferably formed by sintering a metal and / or ceramic powder having an average particle diameter of 1 to 200 μm. Moreover, it is preferable that ratio of the thickness of the said sliding face layer and the said sintered compact layer is 5: 95-70: 30. Furthermore, the composite material of the present invention is preferably used as a sliding member.

With the above configuration, according to the present invention, the sliding surface layer can make use of the characteristics of carbon excellent in self-lubricity and corrosion resistance, and the strength of the composite material can be increased by the support layer made of metal and / or ceramics. A composite material capable of post-processing with dimensional accuracy can be provided. Further, by integrally forming the carbon layer and the metal and / or ceramic layer, it is possible to improve productivity at the time of forming.
Further, according to the composite material of the present invention, there is no clear interface between the carbon layer and the metal and / or ceramic layer, so that no peeling or cracking occurs. In the specification of the present invention, it is expressed as “layer”, but this is a wide concept including not only a clear interface but also an unclear interface.
Furthermore, according to the composite material of the present invention, dimensioning by press working (hereinafter referred to as sizing) can be used in a finishing process for dimensioning. In the present invention, the carbon layer is not cracked by sizing, so that a sliding member having excellent dimensional accuracy can be produced efficiently and inexpensively. Note that finishing with a drill or the like has poor dimensional accuracy, poor productivity, and high cost.

Next, the present invention will be described in more detail with reference to embodiments.
The composite material of the present invention is a composite material composed of a sliding surface layer mainly made of carbon and a sintered body layer bonded around the sliding surface layer. The sliding surface layer is obtained by mixing and baking 5 to 80 parts by weight of a binder with respect to 100 parts by weight of graphite powder having an average particle diameter of 1 to 200 μm. In the composite material of the present invention, the thickness ratio between the sliding surface layer and the sintered body layer is 5:95 to 70:30. When the thickness ratio is less than 5:95, the sliding surface layer is thin, so that the life as a sliding material is shortened, which is not practical. On the other hand, if it exceeds 70:30, the strength reinforcing effect of the support layer is reduced, which is not preferable.

  Examples of the graphite powder (carbon) used in the present invention include artificial graphite, natural graphite, and soot, but are not particularly limited. When the average particle diameter is less than 1 μm, the fluidity of the molding powder is deteriorated and the moldability is lowered. When the average particle diameter exceeds 200 μm, not only the strength is lowered, but also the sliding surface layer is easily peeled off. Therefore, the average particle diameter of the graphite powder is more preferably 10 to 100 μm.

  Examples of the binder used in the present invention include pitch, tar, and synthetic resin. As the synthetic resin, any of a thermosetting resin and a thermoplastic resin can be used. Particularly suitable synthetic resins include phenolic resins, epoxy resins, and furan resins.

The type of metal or ceramic powder used in the present invention is not particularly limited, and commercially available products can be used. The metal powder may be a metal powder of various metals or an alloy powder. As the metal powder, copper, iron, zinc, tin, brass, bronze and alloys thereof are suitable. Moreover, a copper-phosphorus alloy, iron boride, etc. can be used as an additive. As the ceramic powder, alumina, silicon carbide, silicon nitride or the like can be used, and various sintering aids may be used. The metal powder and ceramic powder may be mixed and used.
The average particle diameter of the metal or ceramic powder used in the present invention is 1 to 200 μm. When the average particle diameter is less than 1 μm, the fluidity of the molding powder is deteriorated and the moldability is lowered. If it exceeds 200 μm, the material structure becomes rough, causing a decrease in material strength and a deterioration in sliding characteristics. Therefore, the average particle diameter is more preferably 5 to 100 μm.

Next, the manufacturing process of the composite material of this invention is demonstrated. As a first step, a production step of a material used for the sliding layer of the composite material of the present invention will be described.
First, graphite powder and a binder are kneaded. The compounding ratio of the graphite powder and the binder is 5 to 80 parts by weight, preferably 10 to 50 parts by weight of the binder with respect to 100 parts by weight of the graphite powder. When the amount of the binder is less than 5 parts by weight, the sliding surface layer is easily peeled off, and the amount of wear during sliding increases. On the other hand, if the amount of the binder exceeds 80 parts by weight, the shrinkage during firing is large and cracking is likely to occur. Further, since the amount of graphite is reduced, the sliding characteristics are deteriorated. When kneading, an appropriate amount of an organic solvent such as alcohol or acetone may be added as necessary. Moreover, you may add an additive, for example, a solid lubricant, a film | membrane regulator, to graphite powder as needed. That is, a solid lubricant such as molybdenum disulfide or tungsten disulfide may be added, or a film modifier such as alumina, silica, or silicon carbide may be added. Next, the kneaded mass is pulverized and adjusted to a molding powder (hereinafter referred to as a molding powder). In addition, you may add additives, such as a mold release agent and a lubricant, to the obtained shaping | molding powder.

  Next, a molding process for producing the composite material of the present invention will be described as a second process. As shown in the schematic cross-sectional view of FIG. 1A, a mold 11 used in this molding step is a cylindrical die 5 and a cylindrical shape that is fitted into the die 5 from below and has a pressing ring at the lower end. The lower punch 2 is fitted along the cylinder inner wall of the lower punch 2 and has a cylindrical threshold member 6 having a pressing ring at the lower end, and is fitted along the cylinder inner wall of the threshold member 6 at the lower end. A cylindrical lower punch 3 having a pressing ring, a rod-like lower punch 4 fitted along the cylinder inner wall of the lower punch 3, and an upper punch 1 that can be fitted to the die 5 from above. Become.

Next, the step of forming a molded body using the mold 11 will be specifically described.
First, a metal and / or ceramic powder 9 indicated by hatching is filled in a space surrounded by the die 5, the lower punch 2, and the threshold member 6 of the mold 11 (see FIG. 1A).
Next, the lower punch 3 is moved downward until the upper end of the lower punch 3 and the upper end of the lower punch 2 are in the same position, and the molding powder 10 mainly made of carbon is cut into the cutting member 6 and the lower punches 3 and 4. The space surrounded by is filled (see FIG. 1B).
Then, the threshold member 6 is moved downward until the upper end of the threshold member 6 between the molding powder 10 and the metal and / or ceramic powder 9 is at the same position as the upper end of the lower punch 3 and the upper end of the lower punch 2. Move (see FIG. 1C). As described above, when the threshold member 6 is lowered, the molding powder 10 and the metal and / or ceramic powder 9 can be integrally molded, and the interface between the two layers does not occur.
Thereafter, the upper punch 1 is fitted into the die 5 from above and pressed downward, and the respective press rings are pressed upward while preventing the positions of one end of each of the lower punches 2 and 3 and the threshold member 6 from being displaced. Is pressed to pressure-mold the metal and / or ceramic powder 9 and the molding powder 10 (see FIG. 1D). In this way, both the metal and / or ceramic powder 9 and the molding powder 10 are firmly bonded and molded into the metal and / or ceramic layer 7 and the molding layer 8.
After molding, the upper punch 1 is removed upward from the die 5 and pushed upward so that the positions of the lower punches 2 and 3 and the squeeze member 6 are not displaced, and the lower punch 4 is moved downward from the molded body and pulled out. (See FIG. 1 (e)), a cylindrical molded body made of the metal and / or ceramics layer 7 and the molding layer 8 is taken out from the mold 11. A molded body is thus obtained.
In the molding method shown in FIG. 1, the sliding surface layer is formed inside the support layer, but the sliding surface layer may be formed outside the support layer.

Next, firing of the molded body will be described as a third step.
The firing of the molded body is preferably performed in a non-oxidizing atmosphere or a reducing atmosphere. The firing temperature is a temperature at which the metal or ceramic does not melt or decompose, and is, for example, 500 to 2000 ° C. By calcination in a non-oxidizing atmosphere or a reducing atmosphere, oxidative deterioration of the molded product is prevented. The firing temperature can be appropriately selected according to the melting point of the metal or ceramic used in the support layer. The fired molded article may be subjected to a rust prevention treatment such as applying an antioxidant.

  According to the above embodiment, the sliding surface layer can make use of the characteristics of carbon excellent in self-lubricating property and corrosion resistance, and the strength of the composite material can be increased by the support layer made of metal and / or ceramics. A composite material that can be post-processed can be provided. Further, by integrally forming the carbon layer and the metal and / or ceramic layer, it is possible to improve productivity at the time of forming. Further, in the finishing process for dimensioning the molded product obtained in the above embodiment, it is possible to use sizing that can obtain excellent dimensional accuracy. Furthermore, since cracks do not occur in the sliding surface layer due to sizing, it can be produced efficiently and inexpensively.

  In addition, the composite material of this invention can be used for a sliding member. A bearing is preferable, and a bearing used in a high-temperature atmosphere up to about 300 ° C. in a liquid or gas atmosphere is particularly preferable.

Hereinafter, the present invention will be specifically described with reference to examples.
Example 1
To 100 parts by weight of artificial graphite powder (average particle diameter 10 μm), 25 parts by weight of phenol resin was blended, and kneaded at room temperature so that the artificial graphite powder and the resin were uniformly mixed. The obtained kneaded product was pulverized to an average particle size of 40 μm to obtain a molding powder.

  After filling the mold with copper powder (average particle size 40 μm) as shown in FIG. 1 (a), the molding powder is filled into the mold as shown in FIG. 1 (b). Compression molding was performed at a normal pressure and a pressure of 300 MPa by the described molding process. The obtained molded product was fired at 800 ° C. in a reducing atmosphere.

  Sizing was performed on the fired molded article. At this time, no crack occurred in the sliding surface layer of the molded product. The obtained product had an outer diameter of 15 mm, an inner diameter of 5 mm, and a height of 10 mm, and the ratio of the thickness of the sliding surface layer to the support layer was 30:70.

(Example 2)
The same operation as in Example 1 was performed, except that iron powder (average particle diameter of 80 μm) was used as the metal powder and was fired at 1100 ° C. in a reducing atmosphere. Sizing was performed on the fired molded product, but no crack was generated in the sliding surface layer of the molded product, as in Example 1.

(Example 3)
For the metal powder, a mixed metal powder having a weight ratio of copper powder (average particle diameter of 40 μm) and iron powder (average particle diameter of 80 μm) of 50:50 was used and fired at 800 ° C. in a reducing atmosphere. The same operation as in the case was performed. Sizing was performed on the fired molded product, but no crack was generated in the sliding surface layer of the molded product, as in Example 1.

(Comparative Example 1)
After the copper powder (average particle diameter of 40 μm) is compression molded first, the molded powder used in Example 1 is filled in the inner part of the mold without removing the copper powder molded product from the mold. The same operation as in Example 1 was performed except that the compression molding was performed again. Sizing was performed on the fired molded product, but cracks occurred at the interface between the carbon layer and the metal layer.

  Thus, even if sizing was performed on the molded product obtained in the example according to the present invention, it was confirmed that no cracks occurred in the sliding surface layer of the molded product.

  The present invention can be changed in design without departing from the scope of the claims, and is not limited to the above-described embodiments and examples.

(A) is a cross-sectional schematic diagram when a metal and / or ceramic powder is filled in a mold. (B) is a schematic cross-sectional view when the molding powder is then filled. (C) is a cross-sectional schematic diagram when the cleaving member between the molding powder and the metal and / or ceramic powder is removed. (D) is a cross-sectional schematic diagram at the time of pressure molding. (E) is a cross-sectional schematic diagram at the end of molding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper punch 2, 3, 4 Lower punch 5 Dies 6 Cutting member 7 Molding powder layer 8 Metal and / or ceramic layer 9 Metal and / or ceramic powder 10 Molding powder 11 Mold

Claims (5)

  A composite material comprising a sliding surface layer mainly made of carbon and a sintered body layer bonded around the sliding surface layer.   The composite material according to claim 1, wherein the sliding surface layer is obtained by mixing and baking 5 to 80 parts by weight of a binder with respect to 100 parts by weight of graphite powder having an average particle diameter of 1 to 200 µm.   The composite material according to claim 1 or 2, wherein the sintered body layer is obtained by sintering metal and / or ceramic powder having an average particle diameter of 1 to 200 µm.   The composite material according to any one of claims 1 to 3, wherein a thickness ratio between the sliding surface layer and the sintered body layer is 5:95 to 70:30. The sliding member using the composite material in any one of Claims 1-4.

Images