JP2003322153A - Metal-impregnated carbon bearing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal-impregnated carbon bearing material having a sliding characteristic approximately equal to a lead-impregnated carbon bearing material, while it is free of lead. <P>SOLUTION: The metal-impregnated carbon bearing material is structured so that a carbon base material containing a solid lubricant is impregnated with an alloy composed of 20-29 wt.% Zn, 2-8 wt.% Cu, and Sn as a remainder. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal-impregnated carbon bearing material used for bearings of various pumps, compressors and the like.

[0002]

2. Description of the Related Art Conventional metal-impregnated carbon bearing materials include, for example, artificial graphite, natural graphite and carbon black, as shown in "New Carbon Industry" published by Toshinori Ishikawa and Nagaoki Dori. One or more aggregates such as coke and one or more binders such as tar pitch and coal tar are appropriately mixed, and these are put into a kneader and kneaded at a temperature of 200 to 300 ° C.

Next, after cooling the kneaded material to room temperature,
Grind to an average particle size of 20-30 μm, then 69-14
After molding at a pressure of 7 MPa, firing is performed in a reducing atmosphere at 800 to 1000 ° C., and the fired product is further impregnated with a metal such as lead or copper. In particular, lead is a low melting point metal and not only the impregnation work is easy, but also the friction coefficient is lowered, the wear amount is reduced, and the seizure resistance is further improved. The material is widely used.

The lead-impregnated carbon bearing material shown above is, for example, 0.49- The pressure is increased to 4.9 MPa to impregnate the pores of the fired product with lead. After that, it can be obtained by pulling out from the inside of lead melting, cooling, returning to the atmosphere, and completing impregnation. Then, the obtained lead-impregnated carbon bearing material is machined to be used as a bearing.

However, the bearing using the lead-impregnated carbon bearing material as described above is concerned not only with the environmental pollution by lead which is a heavy metal, but it is necessary to collect the waste product from the market and to use the lead itself. The current situation is that restrictions are being abolished or abolished.

[0006]

The present invention does not contain lead and has sliding characteristics equivalent to those of a lead-impregnated carbon bearing material.
A metal-impregnated carbon bearing material is provided.

[0007]

According to the present invention, a carbon base material mixed with a solid lubricant is used in which 20 to 29% by weight of Zn and Cu are added.
The present invention relates to a metal-impregnated carbon bearing material impregnated with an alloy containing 2 to 8% by weight and the balance Sn. The present invention also relates to the above-mentioned metal-impregnated carbon bearing material containing a solid lubricant in an amount of 2 to 3% by weight in the total composition of the carbon base material. Further, the present invention relates to the metal-impregnated carbon bearing material, wherein the carbon base material has an open porosity of 8 to 20% by volume.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The metal-impregnated carbon bearing material according to the present invention is an alloy containing 20 to 29% by weight of Zn, 2 to 8% by weight of Cu and the balance Sn as an impregnating metal in place of lead, and preferably 23 to 29% by weight of Zn. , An alloy containing 2 to 6% by weight of Cu and the balance Sn is used.
If the amount of Zn is less than 20% by weight, it becomes a hard and brittle alloy, and if it exceeds 29% by weight, the fluidity when the alloy is melted deteriorates, making it difficult to penetrate into the deep pores of the carbon base material and sufficiently impregnated. However, there is a problem that it is not possible (the impregnation rate is low). Further, if the amount of Cu is less than 2% by weight, it becomes a soft alloy, and if it exceeds 8% by weight, it becomes a hard and brittle alloy, and the wear resistance, load resistance, conformability, embedding property, etc. of the bearing material are impaired.

In the present invention, the carbon base material impregnated with the alloy has a so-called lubricating solid such as molybdenum disulfide, talc, zinc white, and graphite in order to obtain the effect of reducing the coefficient of friction that lead has. It is preferable to add 2 to 3% by weight of a lubricant to the total composition of the carbon substrate, and to add 1.5 to 2.5.
It is more preferable to add the composition in a weight percentage. If the content of the solid lubricant is less than 2% by weight, a sufficient friction coefficient reducing effect tends not to be obtained, and if it exceeds 3% by weight, the mechanical strength of the carbon base material tends to decrease.

The open porosity of the carbon substrate is 8 to 20.
It is preferably in the range of 10% by volume,
It is more preferable that the range is If the open porosity is less than 8% by volume, the molten alloy may not be able to penetrate into the pores, and a sufficient impregnation effect may not be obtained. Even if it is too large, the mechanical strength of the carbon substrate tends to be low. There is. In order to improve mechanical strength and wear resistance by impregnating with the above alloys, it is important to fill the pores of the carbon base material with the alloy, and it is sufficient that any open pores remain. There is a risk that a sufficient liquid film cannot be formed and the amount of wear increases.

In the present invention, the impregnation rate of the alloy into the carbon substrate is 30 with respect to the carbon substrate containing the solid lubricant.
The range is preferably 80 to 80% by weight, more preferably 40 to 70% by weight. If it is less than 30% by weight, open pores remain, and a sufficient liquid film cannot be formed, and the amount of wear tends to increase. If it exceeds 80% by weight, the ratio of carbon on the sliding surface is small and the friction coefficient is large. Tends to increase.

As a raw material for obtaining the carbon shaft base material in the present invention, a carbon material such as graphite powder or oil smoke having an average particle size of about 20 μm is used as an aggregate, and talc or molybdenum disulfide is used as a solid lubricant. And the like, and tar pitch, coal tar, etc. are used as a binder.

The carbon base material in the present invention can be manufactured by blending the above-mentioned raw materials and heating and kneading, pulverizing, molding and firing. The heating and kneading is performed by using a double-arm kneader or the like, and each raw material is preferably 230 to 270 ° C.
Knead at the temperature of. At this time, when the kneading temperature is high, the mechanical strength tends to decrease, and when the kneading temperature is low, the kneading time tends to be long. The kneading time varies depending on the amount of the kneaded product, the mixing ratio of the aggregate, the binder, etc., and is appropriately selected each time.

Pulverization can be carried out by using various pulverizers obtained by heating and kneading. At this time, it is preferable to grind so that the average particle diameter is about 20 to 30 μm. If the average particle size is less than 20 μm, the mechanical strength tends to decrease, and if it exceeds 30 μm, the denseness tends to be impaired.

The molding is performed by shaping the powder obtained by crushing into a block shape by a method such as a die press. The molding pressure is preferably in the range of 69 to 147 MPa. If the molding pressure is less than 69 MPa, mechanical strength tends to decrease, and if it exceeds 147 MPa, cracking tends to occur during firing.

Next, the molded product obtained above is fired.
Firing is preferably 800 to 1000 in a reducing atmosphere.
It can be performed by raising the temperature to ° C. Baking time is 300 ~
500 hours is preferred. As a method of firing in a reducing atmosphere, there is a method of filling a molded product with carbon powder or the like and firing. The open porosity of the obtained fired product can be measured by an underwater substitution method.

Next, the alloy thus obtained is impregnated into the fired product (carbon base material containing a solid lubricant) obtained as described above. The following method is preferable as the impregnation method. That is, after putting the baked product in a metal impregnated container and degassing under reduced pressure to 5 torr or less, Zn20-
An alloy melt containing 29% by weight, 2 to 8% by weight of Cu, and the balance Sn is poured into the container, and the baked product is dipped therein. Then, the pressure of 0.49 to 4.9 MPa is applied with nitrogen gas to obtain a metal-impregnated carbon bearing material. The metal-impregnated carbon bearing material thus obtained can be machined into a bearing having a desired shape.

[0018]

EXAMPLES The present invention will be described below with reference to examples. Example 1 Home-made artificial graphite powder 4 having an average particle size of 20 μm as an aggregate
Molybdenum disulfide powder 2 as a solid lubricant to 3% by weight
% By weight, tar pitch as a binder (Kawasaki Steel Co., Ltd.,
Product name PKL) 45% by weight and coal tar 10% by weight
Was mixed and heated and kneaded at a temperature of 250 ° C. for 5 hours using a double-arm kneader.

Thereafter, the above-mentioned kneaded product was treated with an average particle size of 25 μm.
crushed to m. The size of this crushed powder is 150 x 250 x
It was put in a 50 mm mold and molded under the condition of a molding pressure of 123 MPa. The obtained molded product is subjected to 1000 under reducing atmosphere.
The temperature was raised to 400C over 400 hours and then cooled. The open porosity of the obtained fired product (carbon substrate) was measured by an underwater substitution method, and as a result, it was 10% by volume.

This fired product was placed in a metal-impregnated container for 3 torr
After degassing under reduced pressure, an alloy melt consisting of 70 wt% Sn, 25 wt% Zn and 5 wt% Cu was injected and the fired product was immersed. Then, it was pressurized to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon bearing material. With respect to the obtained metal-impregnated carbon bearing material, the impregnation rate of the alloy on the carbon substrate was calculated to be 46% by weight.

Example 2 Home-made artificial graphite powder 4 having an average particle size of 20 μm as an aggregate
3% by weight, 2% by weight of talc powder as a solid lubricant, tar pitch as a binder (Kawasaki Steel Co., Ltd., trade name PK
L) 45% by weight and coal tar 10% by weight,
The mixture was heated and kneaded at a temperature of 250 ° C. for 5 hours using a double arm type kneader.

Thereafter, the above kneaded product was mixed with an average particle size of 25 μm.
crushed to m. The size of this crushed powder is 150 x 250 x
It was put in a 50 mm mold and molded under the condition of a molding pressure of 123 MPa. The obtained molded product is subjected to 1000 under reducing atmosphere.
The temperature was raised to 400C over 400 hours and then cooled. The open porosity of the obtained fired product was 10% by volume as measured by the underwater substitution method.

This fired product was placed in a metal-impregnated container for 3 torr.
After degassing under reduced pressure, an alloy melt composed of Sn 69 wt%, Zn 29 wt% and Cu 2 wt% was injected and the fired product was immersed. Then, it was pressurized to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon bearing material. With respect to the obtained metal-impregnated carbon bearing material, the impregnation rate of the alloy into the carbon substrate was calculated to be 47% by weight.

Example 3 Home-made artificial graphite powder 4 having an average particle size of 20 μm as an aggregate
Molybdenum disulfide powder 2 as a solid lubricant to 5% by weight
% By weight, tar pitch as a binder (Kawasaki Steel Co., Ltd.,
Product name PKL) 43% by weight and coal tar 10% by weight
Was mixed and heated and kneaded at a temperature of 250 ° C. for 5 hours using a double-arm kneader.

Thereafter, the above kneaded material was mixed with an average particle size of 25 μm.
crushed to m. The size of this crushed powder is 150 x 250 x
It was put in a 50 mm mold and molded under the condition of a molding pressure of 123 MPa. The obtained molded product is subjected to 1000 under reducing atmosphere.
The temperature was raised to 400C over 400 hours and then cooled. The open porosity of the obtained fired product was 13% by volume as measured by an underwater substitution method.

This baked product was placed in a metal-impregnated container for 3 torr.
After degassing under reduced pressure, an alloy melt consisting of 70 wt% Sn, 25 wt% Zn and 5 wt% Cu was injected and the fired product was immersed. Then, it was pressurized to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon bearing material. With respect to the obtained metal-impregnated carbon bearing material, the impregnation rate of the alloy into the carbon substrate was determined to be 54% by weight.

Comparative Example 1 As an aggregate, home-made artificial graphite powder 4 having an average particle size of 20 μm
5% by weight, tar pitch as a binder (Kawasaki Steel Co., Ltd.)
45 kg by weight (trade name: PKL) manufactured by K.K.

Thereafter, the above kneaded product was mixed with an average particle size of 25 μm.
crushed to m. The size of this crushed powder is 150 × 250 × 5
It was put in a 0 mm mold and molded under the condition of a molding pressure of 123 MPa. The obtained molded product is heated at 1000 ° C in a reducing atmosphere.
Up to 400 hours and then cooled. The open porosity of the obtained fired product was measured by the water displacement method, and was 10% by volume.
Met.

This baked product was placed in a metal-impregnated container for 3 torr.
After degassing under reduced pressure, a lead melt was injected and the fired product was immersed. Then, it was pressurized to 0.98 MPa with nitrogen gas to obtain a lead-impregnated carbon bearing material. With respect to the obtained lead-impregnated carbon bearing material, the impregnation rate of lead into the carbon substrate was calculated to be 70% by weight.

Comparative Example 2 The fired product obtained in Example 1 was placed in a metal-impregnated container, degassed under reduced pressure to 3 torr, and then an alloy melt consisting of Sn 63 wt%, Zn 32 wt% and Cu wt 5% was injected, The baked product was immersed. Then, it was pressurized to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon bearing material. With respect to the obtained metal-impregnated carbon bearing material, the impregnation rate of the alloy into the carbon base material was determined to be as low as 2% by weight.

Comparative Example 3 The calcined product obtained in Example 1 was placed in a metal-impregnated container and deaerated under reduced pressure to 3 torr, and then an alloy melt composed of Sn 65 wt%, Zn 25 wt% and Cu 10 wt% was injected and fired. The item was immersed. Then, it was pressurized to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon bearing material. With respect to the obtained metal-impregnated carbon bearing material, the impregnation rate of the alloy into the carbon base material was determined to be 45% by weight.

Reference Example 1 Home-made artificial graphite powder 4 having an average particle size of 20 μm as an aggregate
6% by weight of molybdenum disulfide powder as a solid lubricant 1
% By weight, tar pitch as a binder (Kawasaki Steel Co., Ltd.,
Product name PKL) 45% by weight and coal tar 10% by weight
Was mixed and heated and kneaded at a temperature of 250 ° C. for 5 hours using a double-arm kneader.

Thereafter, the above kneaded material was mixed with an average particle size of 25 μm.
crushed to m. The size of this crushed powder is 150 × 250 × 5
It was put in a 0 mm mold and molded under the condition of a molding pressure of 123 MPa. The obtained molded product is heated at 1000 ° C in a reducing atmosphere.
Up to 400 hours and then cooled. The open porosity of the obtained fired product was measured by the water displacement method, and was 10% by volume.
Met.

This baked product was placed in a metal-impregnated container for 3 torr.
After degassing under reduced pressure, an alloy melt consisting of 70 wt% Sn, 25 wt% Zn and 5 wt% Cu was injected and the fired product was immersed. Then, it was pressurized to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon bearing material. With respect to the obtained metal-impregnated carbon bearing material, the impregnation rate of the alloy into the carbon substrate was determined to be 48% by weight.

Reference Example 2 Home-made artificial graphite powder 4 having an average particle size of 20 μm as an aggregate
0 wt%, molybdenum disulfide powder 2 as a solid lubricant
Wt% and tar pitch as a binder (Kawasaki Steel
Co., Ltd., trade name PKL) 45% by weight and coal tar 1
3% by weight is blended and the temperature is set to 250 using a double-arm kneader.
The mixture was heated and kneaded at 5 ° C for 5 hours.

Thereafter, the above kneaded product was mixed with an average particle size of 25 μm.
crushed to n. The size of this crushed powder is 150 × 250 × 5
It was put in a 0 mm mold and molded under the condition of a molding pressure of 123 MPa. The obtained molded product is heated at 1000 ° C in a reducing atmosphere.
Up to 400 hours and then cooled. The open porosity of the obtained fired product was measured by an underwater substitution method, and as a result, it was 7% by volume.

This baked product was placed in a metal-impregnated container for 3 torr.
After degassing under reduced pressure, an alloy melt consisting of 70 wt% Sn, 25 wt% Zn and 5 wt% Cu was injected and the fired product was immersed. Then, it was pressurized to 0.98 MPa with nitrogen gas to obtain a metal-impregnated carbon bearing material. With respect to the obtained metal-impregnated carbon bearing material, the impregnation rate of the alloy into the carbon base material was determined to be 8% by weight.

Next, with respect to the metal-impregnated carbon bearing materials obtained in Examples 1 to 3, Comparative Examples 2 to 3 and Reference Examples 1 and 2, and the lead-impregnated carbon bearing material obtained in Comparative Example 1, physical properties and wear tests were conducted. I went. The results are shown in Table 1. The bending strength is 10 mm in thickness, 10 mm in width and 50 in length.
The rectangular parallelepiped test piece of mm was measured in accordance with JCAS (Standard of Carbon Association) -10-1968.

The hardness is measured by a Shore hardness tester, and the underwater abrasion test is performed by rotating an 8 × 12 × 18 mm test piece (sliding surface 12 × 18 mm) in water to obtain an outer diameter of 85 mm ( The friction coefficient and the amount of wear were measured by sliding it on a disc (φ) (material SUS304) and performing a test for 100 hours under the conditions of a peripheral speed of 10 m / s and a surface pressure of 0.98 MPa.

[0040]

[Table 1]

As shown in Table 1, the metal-impregnated carbon bearing materials of Examples 1 to 3 had no problem in bending strength and hardness, and those of Comparative Examples 2 to 3 and Reference Examples 1 and 2. The friction coefficient is smaller than that of carbon-impregnated carbon bearing materials,
Moreover, the amount of wear was small, and it was confirmed that these values have sliding characteristics almost equal to those of the lead-impregnated carbon bearing material of Comparative Example 1.

[0042]

Industrial Applicability The metal-impregnated carbon bearing material of the present invention does not contain lead and has substantially the same sliding characteristics as the lead-impregnated carbon bearing material, and is industrially very suitable.

Claims (3)

[Claims] 1. A carbon base material containing a solid lubricant,
20 to 29 wt% Zn, 2 to 8 wt% Cu, and the balance Sn
A metal-impregnated carbon bearing material impregnated with an alloy containing. 2. The metal-impregnated carbon bearing material according to claim 1, wherein the total carbon base composition contains a solid lubricant in an amount of 2 to 3% by weight. 3. The metal-impregnated carbon bearing material according to claim 1, wherein the carbon base material has an open porosity of 8 to 20% by volume.