JP2003328057A - Sliding material of metal-impregnate carbon and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sliding material of a metal-impregnated carbon superior in sliding characteristics and abrasion. <P>SOLUTION: The sliding material of the metal-impregnated carbon comprises a base carbon having the lattice constant Co=0.672 nm-0.685 nm, when measured by a lattice constant measuring method for graphite specified by Japan Society for the Promotion of Science, and a metal impregnated into the base carbon, which occupies 20-65 wt.% of the total and comprises, by weight ratio, 90-98 wt.% Zn and 2-10 wt.% Al. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal-impregnated carbon sliding material used for bearings and seals of various pumps and compressors, vanes of vacuum pumps, and the like. 2. Description of the Related Art Conventional metal-impregnated carbon sliding materials include, for example, artificial graphite, natural graphite, and the like, as shown in "New Carbon Industry" published by Toshinori Ishikawa and Todori Nagaoki. One or more aggregates such as graphite, carbon black, coke and the like and one or more binders such as tar pitch and coal tar are appropriately blended, and these are charged into a kneader and kneaded at a temperature of 150 to 300 ° C. Next, after cooling this kneaded material to room temperature,
Pulverized to an average particle size of 10 to 300 μm, then 50 to 20
It is molded at a pressure of 0 MPa, fired in a non-oxidizing atmosphere at 800 to 3000 ° C. or graphitized as necessary, and further impregnated with the fired or graphitized product with a metal such as lead or copper.
In particular, lead is a low-melting-point metal and is not only easy to impregnate, it also reduces the coefficient of friction, reduces wear, and improves seizure resistance. Moving material is widely used. In the case of a lead-impregnated carbon sliding material, the above-mentioned calcined product or graphitized product is immersed in a lead melting tank under the conditions of a temperature of 400 to 500 ° C. and a reduced pressure of 5 torr or less, and then is inerted with an inert gas such as nitrogen or argon gas. Pressure is applied to 0.49 to 0.98 MPa to impregnate the pores of the carbon substrate with lead. Thereafter, after being pulled up from the lead melting tank and cooled, the pressure is returned to the atmospheric pressure to complete the impregnation, thereby obtaining a lead-impregnated carbon sliding material. This lead-impregnated carbon sliding material is machined and provided as a sliding material. [0003] However, lead, which is a heavy metal, is concerned about environmental pollution, so that not only must waste be recovered from the market, but the use of lead itself has been restricted or abolished. [0004] The present invention provides a lead-free metal-impregnated carbon sliding material having sliding characteristics equivalent to those of a lead-impregnated carbon sliding material. According to the present invention, a lattice constant Co = 0.6 obtained by a method of measuring the lattice constant of graphite by the Gakushin method.
90 nm Zn on a carbon substrate of 72 nm to 0.685 nm
To 98% by weight of Al and 2 to 10% by weight of Al
A metal-impregnated carbon sliding material impregnated with 0 to 65% by weight. DETAILED DESCRIPTION OF THE INVENTION The metal-impregnated carbon bearing material according to the present invention contains 90 to 98 Zn as an impregnating metal instead of lead.
A metal having a ratio of 2 to 10% by weight of Al is used. A carbon substrate having a lattice constant smaller than Co = 0.672 nm is soft and causes a decrease in load resistance and an increase in abrasion loss. On the other hand, if the lattice constant Co is larger than 0.685 nm, a sufficient effect of reducing the friction coefficient cannot be obtained, and wear resistance, friction characteristics, conformability and the like are impaired. Further, the metal impregnation amount is preferably 20% by weight to 65% by weight, and if it is less than 20% by weight, the pores of the carbon base material cannot be filled with the metal, so that the mechanical strength is reduced and the effect of the sliding properties is reduced. Not enough, causing increased wear. If the impregnation ratio is more than 65% by weight, the lubricating effect of the carbon base material cannot be obtained, the friction coefficient increases, and the wear amount increases. As raw materials for producing the metal-impregnated carbon bearing material according to the present invention, graphite powder, oil smoke, etc. having an average particle size of about 20 μm are used as aggregates, and tar pitch, coal tar and the like are used as binders. used. The metal-impregnated carbon sliding material according to the present invention can be manufactured by heating and kneading, pulverizing, molding, and firing the above raw materials, followed by metal impregnation. Heat kneading is performed using a double-arm kneader or the like.
Each raw material is 150 ° C to 300 ° C, more preferably 180 ° C
To 270 ° C, more preferably 200 to 250 ° C. When the kneading temperature is high, the mechanical strength tends to decrease, and when it is low, the kneading time tends to increase.
The kneading time varies depending on the amount of the kneaded material, the mixing ratio of the aggregate and the binder, and therefore it is necessary to appropriately select the kneading time each time. In the pulverization, the powder obtained by heating and kneading is mixed with various pulverizers to have an average particle size of about 20 to 300 μm, more preferably 20 to 200 μm, and still more preferably 20 to 200 μm.
This is performed by pulverizing to a size of 100 μm.
However, the average particle size can be appropriately selected in consideration of the subsequent molding method and the characteristics of the carbon substrate obtained after firing or graphitization. The molding is carried out by shaping the powder obtained by the pulverization into a block shape by a method such as a die press. The molding pressure is preferably from 50 to 200 MPa, more preferably from 60 to 150 MPa, and more preferably from 80 to 130 MPa.
Pa is more preferred. If the molding pressure is low, the mechanical strength tends to decrease, and if the molding pressure is high, the dissipation of volatile components during firing is suppressed, and an internal pressure is generated in the molded product, which tends to cause cracking. The molded article obtained as described above is fired. The firing is carried out in a non-oxidizing atmosphere using an inert gas such as nitrogen or argon or in a reducing atmosphere by packing carbon powder around a molded article. The maximum temperature during firing is preferably 800 ° C to 1000 ° C, and 850 to 1000 ° C.
C. is more preferable, and 900 to 1000 C. is even more preferable. When the firing is performed at a temperature lower than 800 ° C., carbonization is insufficient and sufficient sliding characteristics cannot be obtained. When the firing is performed at a temperature of 1000 ° C. or higher, the firing furnace tends to deteriorate. The firing time is determined by the mixing ratio of the raw materials, the product shape, the capacity of the furnace, and the like, and is not particularly limited in the present invention, but is completed in as short a time as possible from the viewpoint of productivity and production cost. Good. Specifically, 5 hours to 10 hours
0 hours is preferable, 10 hours to 400 hours is more preferable, and 20 hours to 350 hours is further preferable. In order to obtain a target carbon substrate, the obtained fired product may be further graphitized at a high temperature of 1000 ° C. or higher. The maximum temperature in this case is preferably from 1200 to 3000 ° C, more preferably from 1500 to 3000 ° C,
0-3000 degreeC is more preferable. The calcined or graphitized product thus obtained is measured by a method of measuring the lattice constant of graphite by the Gakushin method. The metal impregnation is carried out by using the lattice constant Co =
A carbon substrate of 0.672 nm to 0.685 nm is placed in a metal impregnated container, degassed under reduced pressure to 5 torr or less, and then Zn
Is immersed in a molten alloy consisting of a metal having a ratio of 90 to 98% by weight and Al having a ratio of 2 to 10% by weight and
It is performed by pressurizing to 9 to 0.98 MPa.
The thus obtained metal-impregnated carbon material can be machined into a product shape such as a bearing, a seal, or a vane having a desired shape. Embodiments of the present invention will be described below. (Example 1) 45% by weight of tar pitch (trade name: PKL, manufactured by Kawasaki Steel Co., Ltd.) was mixed with 55% by weight of homemade artificial graphite powder having an average particle size of 20 μm as an aggregate, and The mixture was heated and kneaded at 250 ° C. for 5 hours using a mold kneader. Thereafter, the above-mentioned kneaded material is added to an average particle size of 25 μm.
Crushed. The size of this ground powder is 150 × 250 × 50
mm and a molding pressure of 100 MPa.
The obtained molded article is cooled to 1000 ° C.
The temperature was raised over 0 hours and then cooled. The fired product is placed in a metal impregnation vessel and 3 to
After degassing under reduced pressure to rr, Zn was 96% by weight and Al was 4% by weight.
Immersed in a molten alloy consisting of
The pressure was increased to 8 MPa. Table 1 shows the physical properties, lattice constant, impregnation rate, and wear test results of the obtained metal-impregnated carbon material.
Shown in [Table 1] (Example 2) As an aggregate, the average particle diameter was 20.
μm homemade artificial graphite powder 40% by weight, natural graphite 10% by weight (trade name: CB150, manufactured by Nippon Graphite Co., Ltd.) and tar pitch (produced by Kawasaki Steel Corporation, trade name: P
KL), and kneaded by heating at 250 ° C. for 5 hours using a double-arm kneader. Thereafter, the above kneaded material was pulverized to an average particle size of 25 μm. This pulverized powder is placed in a mold having a size of 150 × 250 × 50 mm, and a molding pressure of 10 mm.
Molded at 0 MPa. The obtained molded product was heated to 1000 ° C. over 400 hours in a reducing atmosphere and then cooled. The fired product is placed in a metal impregnation vessel and 3 to
After degassing under reduced pressure to rr, Zn was 96% by weight and Al was 4% by weight.
Immersed in a molten alloy consisting of
The pressure was increased to 8 MPa. Table 1 shows the physical properties, lattice constant, impregnation rate, and wear test results of the obtained metal-impregnated carbon material.
Shown in (Example 3) As an aggregate, the average particle diameter was 20.
7% by weight of home-made artificial graphite powder with a mean particle size of 20 μm
m of pitch coke and 40% by weight of tar pitch (PKL manufactured by Kawasaki Steel Co., Ltd.) as a binder were mixed at a temperature of 250 ° C. using a double-arm kneader.
The mixture was heated and kneaded for hours. Thereafter, the above-mentioned kneaded material is mixed with an average particle size of 2
It was pulverized to 5 μm. This crushed powder has dimensions of 150 × 250
It was placed in a mold of × 50 mm and molded at a molding pressure of 100 MPa. The obtained molded product was heated to 1000 ° C. over 400 hours in a reducing atmosphere and then cooled. As a result of measuring the open porosity of the obtained calcined product by an underwater substitution method, the calcined product was placed in a metal-impregnated container, and degassed under reduced pressure at 3 torr.
It was immersed in a molten alloy of 96 wt% Zn and 4 wt% Al and pressurized to 0.98 MPa with nitrogen gas. Table 1 shows the physical properties, lattice constant, impregnation rate, and wear test results of the obtained metal-impregnated carbon material. (Embodiment 4) The carbon substrate described in Embodiment 1 was placed in a metal-impregnated container, degassed under reduced pressure at 3 torr, and then a molten alloy of 90 wt% Zn and 10 wt% Al was obtained. 0.98MPa by immersion in nitrogen gas
Pressurized. Table 1 shows the physical properties, lattice constant, impregnation rate, and wear test results of the obtained metal-impregnated carbon material. (Example 5) The carbon substrate described in Example 1 was put into a metal-impregnated vessel, and after degassing under reduced pressure at 3 torr, a molten alloy of 98% by weight of Zn and 2% by weight of Al It was immersed in the solution and pressurized to 0.98 MPa with nitrogen gas. Physical properties of the obtained metal-impregnated carbon material,
Table 1 shows the lattice constant, the impregnation ratio, and the results of the wear test. Comparative Example 1 The carbon substrate obtained in Example 2 was further graphitized at 3000 ° C. The graphitized product was placed in a metal impregnation vessel, degassed under reduced pressure at 3 torr, immersed in a molten lead metal, and pressurized to 0.98 MPa with nitrogen gas. Table 1 shows the physical properties, lattice constant, impregnation rate, and wear test results of the obtained metal-impregnated carbon material. (Comparative Example 2) The carbon substrate obtained in Comparative Example 1 was put into a metal-impregnated container,
After degassing under reduced pressure, the alloy was immersed in a molten alloy containing 89% by weight of Zn and 11% by weight of Al and 0.98% by nitrogen gas.
Pressurized to MPa. Table 1 shows the physical properties, lattice constant, impregnation rate, and wear test results of the obtained metal-impregnated carbon material. Comparative Example 3 As an aggregate, the average particle size was 20.
3% by weight of home-made artificial graphite powder with a mean particle size of 20 μm
and 50% by weight of a pitch coke having a weight of 50 m and a pitch of 40% by weight of tar pitch (a carbon base material obtained from Kawasaki Steel Co., Ltd., quotient comparison example 1 and trade name PKL) as a binder. The mixture was heated and kneaded at 250 ° C. for 5 hours using a mold kneader. Thereafter, the above-mentioned kneaded material was added to an average particle size of 25 μm.
Crushed. The size of this ground powder is 150 × 250 × 50
mm and a molding pressure of 100 MPa.
The obtained molded article is cooled to 1000 ° C.
The temperature was raised over 0 hours and then cooled. The carbon substrate described in Example 1 was used, placed in a metal-impregnated container, and 3 torr.
r, immersed in a molten alloy containing 99% by weight of Zn and 1% by weight of Al, and 0.98% by nitrogen gas.
Pressurized to MPa. Physical properties of the obtained metal-impregnated carbon material,
Table 1 shows the lattice constant, the impregnation ratio, and the results of the wear test.
The underwater abrasion test was performed by rotating an 8 × 12 × 18 mm test piece (sliding surface 12 × 18 mm) in water with an outer diameter φ85.
It was performed by sliding on a circular disk (material: SUS304) of mm. The peripheral speed is 10 m / s, and the surface pressure is 0.98 MPa.
A 00 hour test was performed to measure the coefficient of friction and the amount of wear. As shown in Table 2, Examples 1 to 5 correspond to Comparative Example 2
Comparative Examples 1 and 3 had a smaller coefficient of friction and less wear, and the same sliding characteristics as the lead-impregnated carbon bearing of Comparative Example 1 were confirmed. According to the present invention, the metal-impregnated carbon sliding material according to the first aspect does not contain lead and has sliding characteristics equivalent to those of the lead-impregnated carbon sliding material. It is very suitable in terms of quality.

Claims (1)

Claims: 1. A lattice constant Co = 0.672 nm to 0.685 nm obtained by a method of measuring the lattice constant of graphite by the Gakushin method.
90 to 98% by weight of Zn and 2 to 2% of Al
A metal-impregnated carbon sliding material impregnated with 20 to 65% by weight of a metal at a ratio of 10% by weight.