JPH0543996A - Sintered sliding member and its production - Google Patents

Abstract

PURPOSE:To produce a sintered sliding member composed essentially of iron, where graphite exists dispersedly in a sintered structure and no free cementite exists and superior sliding characteristic is provided. CONSTITUTION:The member is a sintered sliding member having a composition consisting of, by weight, 3-8% graphite, 0.5-5% aluminum, and the balance iron or a sintered sliding member consisting of a duplex layer where the above sintered layer is integrally joined to a backing plate made of steel. In these sintered sliding members, graphite exists dispersedly in a sintered structure and no free cementite exists and superior sliding characteristic can be produced.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a sintered sliding member containing iron as a main component and a method for producing the same, and more specifically, the structure of the base material shows pearlite or a structure in which pearlite and part of ferrite coexist. The present invention relates to an iron-based sintered sliding member in which graphite is dispersed and present in the structure without free cementite, and a method for producing the same.

[0002]

2. Description of the Related Art Heretofore, many iron-based sintered sliding members have been proposed in which graphite is dispersed in the structure by utilizing the solid lubricating action of graphite.

[0003]

However, in a sintered sliding member whose base material is iron as a main component, iron powder and graphite powder react in the sintering process and free cementite having a high hardness is present in the structure. (Fe ₃ C) is generated, and this cementite damages the mating material when sliding with the mating material, which is a disadvantage that must be avoided as much as possible in the sliding member.

As a method for preventing the formation of free cementite, for example, a small proportion of graphite (1% by weight or less) and sintering at a low temperature (1000 ° C. or less) where free cementite cannot be produced. However, the solid lubrication action of the compounded graphite cannot be expected by the above method, and the mechanical strength as a sliding member is low by the above method, and it can be obtained by any method. The sliding member has a problem that it is difficult to put it to practical use.

Further, as another method, by using a so-called copper-clad graphite powder obtained by plating a graphite powder with copper, it is possible to obtain an iron-based sintered sliding member free from the formation of free cementite. In the method, a step of pre-plating the graphite powder with copper is required and the cost is high, it is industrially difficult to copper-plat all the graphite particles without fail, and as a result of the above, complete formation of free cementite is completed. There are problems such as being difficult to prevent.

[0006]

[Means for Solving the Problems] As a result of intensive studies in view of the above-mentioned problems, the present inventors have found that iron powder and graphite powder are blended with aluminum powder in a fixed ratio,
Exhibiting a coexisting structure of pearlite or pearlite and a part of ferrite which is a preferable structure as an iron-based sintered sliding member,
Further, they have found that not only graphite is dispersed and present in the structure, but also a sintered sliding member in which free cementite is not formed can be obtained, and the present invention has been completed.

That is, the first object of the present invention is graphite 3
~ 8% by weight, 0.5 to 5% by weight of aluminum, the balance iron, or 10 to 30% by weight of copper or copper
It is an object of the present invention to provide a sintered sliding member containing 10 to 30% by weight and 1 to 10% by weight of tin, and a method for producing the same.

A second object of the present invention is to provide a multilayer sintered sliding member in which a sintered layer having the above-described composition is integrally bonded to a steel backing metal to form a multilayer, and a method for producing the same. It is in.

Further, the sintered sliding member of the present invention can be applied as an oil-impregnated sintered sliding member by subjecting it to an oil impregnation treatment depending on its intended use and application.

In the above-mentioned component composition, graphite (Gr) is present dispersed in the tissue and has a solid lubricating action. In order to exert the solid lubricating action, a blending amount of at least 3% by weight is required. To be done. In addition, since the presence of the aluminum component described later does not cause the generation of free cementite due to the reaction between the graphite and the iron component, a large amount of 8% by weight can be blended. However, if the content exceeds 8% by weight, the mechanical strength of the sliding member is impaired, so the addition ratio is limited to 8% by weight. Therefore, the proportion of the graphite component added is preferably 3 to 8% by weight, and more preferably 4 to 6% by weight.

Aluminum (Al) forms a liquid phase during the sintering process and forms a solid solution with the iron component, and does not function to suppress the above-mentioned diffusion of graphite into the iron component, in other words, the reaction between the iron component and graphite. As a result, it prevents the formation of free cementite. When the addition ratio is less than 0.5% by weight, the function of preventing the formation of free cementite is not recognized.
If it is added in excess of wt%, the amount of liquid phase increases and the sinterability is adversely affected. Therefore, the addition ratio of the aluminum component is 0.5 to 5% by weight, preferably 1.5 to 3% by weight.

A copper (Cu) component or a copper component and a tin (Sn) component can be added in a fixed ratio to the above-mentioned graphite component and aluminum component. In the sintering process, a part of the copper component diffuses and forms a solid solution with the iron component that is the main component, and the other component forms a liquid phase that acts as a binder and densifies the sintered body to improve its strength. Further, the pearlite structure is densified and the hardness of the pearlite structure is enhanced. And, if the addition ratio of the copper component is 10% by weight or less, the above-mentioned effects are not sufficiently exhibited, and if it is added in excess of 30% by weight, the amount of the liquid phase increases, which adversely affects the sinterability. As a result, not only the scale but also the dimensional stability of the sliding member becomes defective. Therefore, the addition ratio of the copper component is 10 to 30% by weight, and preferably 15 to 25% by weight.

The tin component produces a liquid phase from a temperature of 232 ° C. during the sintering process, forms a solid solution with the above-mentioned copper component and alloys to form bronze, and plays the role of a binder as well as the above-mentioned copper component and sinters. It densifies the body and contributes to improvement in strength, toughness and mechanical strength of the sintered body. If the addition ratio of the tin component is 1% by weight or less, the above-mentioned effects are not sufficiently exhibited, and if it is added in excess of 10% by weight, the sinterability is adversely affected. Therefore, the tin component is preferably added in an amount of 1 to 10% by weight, and more preferably 3 to 8% by weight.

Next, a method for manufacturing a sintered sliding member having the above-mentioned composition will be described.

3 to 8% by weight of graphite powder and 0.5 to 5% by weight of aluminum powder are added and mixed with iron powder to form a mixed powder, or 10 to 30% by weight of copper powder or copper is further added to the mixed powder. 10 to 30% by weight of powder and 1 to 10% by weight of tin powder are added and mixed to form a mixed powder.

Next, the mixed powder is loaded into a mold having a required shape and compression-molded under a pressure of ^{2 to} 7 ton / cm ² to form a green compact composed of the mixed powder. The green compact thus obtained is sintered in a heating furnace adjusted to a neutral or reducing atmosphere at a temperature of 1050 to 1100 ° C for 30 to 60 minutes, then cooled in the furnace and taken out of the furnace, and machined. It is processed into a desired size to obtain a sintered sliding member. Here, as the neutral or reducing atmosphere, ammonia decomposition gas, nitrogen gas, endothermic gas or the like is used.

In the sintered sliding member thus obtained, the base structure exhibits a pearlite structure or a structure in which a ferrite structure partially coexists in the pearlite structure, and free cementite is not formed in the structure. In addition, graphite is dispersed in the structure, and during sliding between the sintered sliding member and the mating material,
The solid lubricating action of the graphite is sufficiently exerted. Further, this sintered sliding member can be applied as an oil-impregnated sintered sliding member by subjecting it to an oil impregnation treatment depending on its intended use and application. In this oil-impregnated sintered sliding member, the synergistic action of the solid lubricating action of graphite in the sintered body and the liquid lubricating action of the lubricating oil is exhibited.

Next, a method for producing a multi-layer sintered sliding member will be described in which a sintered body having the above-mentioned component composition is integrally bonded to a steel backing metal as a sintered layer to form a multi-layer sintered sliding member.

As the steel backing which forms this multilayer sintered sliding member, a steel plate made of general structural rolled steel (JIS G-3101), a plurality of independent protrusions on the surface or continuous protrusions on the surface And a steel pipe having a plurality of recesses formed by the protrusions and a steel pipe made of a general structural carbon steel pipe (JIS G-3444).

Hereinafter, a method of manufacturing a multilayer sintered sliding member using each of the above backing metals will be described.

[Manufacturing Method of Multi-Layer Sintered Sliding Member Using Steel Plate for Back Metal] When a steel plate is used for the back metal, it is preferable to use a powder rolling method as a manufacturing method, and this powder rolling method is used. The manufacturing method will be described. A mixed powder similar to the above-mentioned mixed powder is formed, and a 1 to 15 wt% aqueous solution of a powder binder is added to the mixed powder in an amount of 0.
1 to 5.0% by weight is added and uniformly mixed to form a raw material powder which imparts wettability to the mixed powder.

As the powder binder, hydroxypropyl cellulose (HPC), polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HE) can be used.
C), methyl cellulose (MC), gelatin, gum arabic, starch and the like can be mentioned, of which use of HPC is preferred. As a solvent for the powder binder, water or an aqueous solution of 5 to 20% by weight of a hydrophilic compound such as ethyl alcohol may be used in addition to water. The powder binder is preferably added to the above solvent in an amount of 1 to 15% by weight to form an aqueous solution. The addition ratio of the powder binder aqueous solution is preferably 0.1 to 5.0% by weight with respect to the mixed powder, and if added in excess of this amount, uncontrollable pores (pores) increase in the structure of the sintered body, resulting in the obtained sintering. It reduces the strength and wear resistance of the layer.

The raw material powder to which the above-mentioned wettability is given is then supplied to a rolling roll by a conveyor and a hopper, and the raw material powder is formed into a rolled sheet (compacted powder sheet) by the rolling roll. A horizontal rolling mill having twin rolls is used for rolling the raw material powder. The density and thickness of the rolled sheet can be adjusted by the rolling load, while the rolling load depends on the roll speed and the roll distance. Therefore, it is possible to adjust the density and thickness of the rolled sheet by changing the roll speed and the roll interval. For example, when the roll speed is 0.1 to 1.0 m / min and the roll interval is 0.4 to 1.0 mm, a rolled sheet having a density of 5.5 to 6.7 g / cm ³ and a thickness of 1.38 to 1.83 mm can be obtained. The rolled sheet thus obtained is cut into a size corresponding to the size of the steel plate as the back metal using a cutting machine or the like, and the cut rolled sheet is superposed on the steel plate.

Then, the steel sheet and the rolled sheet laminated on the steel sheet are placed in a heating furnace adjusted to a neutral or reducing atmosphere, and the steel sheet of the rolled sheet is sintered simultaneously with sintering of the rolled sheet under pressure. Diffusion / bonding to the upper side to obtain a multilayer sintered sliding member in which a sintered layer is integrally bonded on a steel plate.

In this sintering step, the pressure at the time of sintering increases the density of the sintered structure and improves the joint strength with the steel sheet. In the present invention, it is 1.0 to 4.0 kgf / cm ² , preferably
It is 1.5 to 3.0 kgf / cm ² .

The sintering temperature has a sensitive influence on the sintered structure, and it is necessary to pay particular attention to temperature control. In the present invention, it is performed in the range of 1050-1100 ° C. When a copper component or a copper component and a tin component are added to the components of the rolled sheet, a liquid phase is generated during the sintering of the rolled sheet and the sintering progresses. The density increases as a whole, but the liquid phase generated during sintering is discharged to the outside of the sintered body by simple pressure from above and below with the increase of the pressure, and the peculiarity of the liquid phase gradually decreases. To have a different organization. Therefore, the lower limit of the above temperature range is used as the sintering temperature when the copper component or the copper component and the tin component are added to the components.

The sintering time does not affect the sintered structure as sensitively as the sintering temperature, but does affect the mechanical strength of the sintered layer. In the present invention, good results are obtained when the sintering time is in the range of 30 to 60 minutes.

In the multi-layer sintered sliding member thus obtained, the iron component in the components of the rolled sheet diffuses into the steel sheet simultaneously with the sintering of the rolled sheet during pressure sintering and is integrally joined. The structure of the sintered layer has a pearlite structure similar to the structure of the above-mentioned sintered sliding member or a structure in which a part of ferrite structure coexists in the pearlite structure, and free cementite is formed in the structure. Rather, graphite is present dispersed in the tissue. This multi-layered sintered sliding member can be applied as an oil-impregnated multi-layered sintered sliding member by subjecting it to oil impregnation treatment according to its intended use and application.

When a steel sheet having a plurality of independent protrusions on the surface or a plurality of independent protrusions formed on the surface and a plurality of independent recesses formed by the protrusions is used, the steel sheet is A high-density region and a low-density region are dispersedly formed in the sintered layer integrally bonded on the top, and this has the advantage of significantly improving the load resistance as a sliding member. Further, in the multi-layered sintered sliding member subjected to the oil impregnation treatment, the oil-impregnated region having a high oil content in the low-density region and the oil-impregnation region having the low oil content in the high-density region are dispersed, The synergistic effect of the solid lubricating action of graphite and the liquid lubricating action of lubricating oil is exhibited.

[Manufacturing Method of Multi-Layer Sintered Sliding Member Using Steel Pipe for Back Metal] A mixed powder similar to the mixed powder in the above-described manufacturing method of the sintered sliding member is formed, and this mixed powder is required. In the mold, pressure molding is performed under a pressure in the range of ² to 7 ton / cm ² to form a cylindrical green compact.

The cylindrical green compact was press-fitted onto the inner surface of a steel pipe, placed in a heating furnace adjusted to a neutral or reducing atmosphere, and pressed at a temperature of 1050-1100 ° C. for 30-60 minutes. Simultaneously with the sintering of the powder, the green compact is diffusion-bonded to a steel pipe to obtain a multilayer sintered sliding member in which a sintered layer is integrally bonded to the inner surface of the steel pipe.

In this manufacturing method, when the inner diameter of the cylindrical green compact is 40 mm or more, the expansion amount (outer diameter side) of the green compact during sintering is smaller than the expansion amount of the steel pipe. So
The inner surface of the green compact is filled with ceramic powder to restrain the expansion amount of the green compact toward the inner diameter side, and this is directed to the outer diameter side, and further toward the inner diameter side of the green compact during cooling after sintering. By restraining the amount of shrinkage of the steel and directing it toward the outer diameter side, a strong joint is obtained between the steel pipe and the green compact.

The ceramic powder used in the above-mentioned method is one that does not melt within the sintering temperature range and is non-reactive in the neutral or reducing atmosphere with respect to each component of the composition of the green compact. Anything will do as long as it is. Examples thereof include Al ₂ O ₃ , SiO ₂ , ZrO ₂ and MgO, and their composite oxides.

Further, the inner diameter of the green compact is particularly large (about 70
mm) or more), the expansion amount (outer diameter side) of the green compact during sintering becomes even smaller than the expansion amount of the steel pipe, so in addition to the above effects due to the ceramic powder filling, Further, by inserting the core into the inner surface of the green compact and utilizing its expansion force, a stronger joint can be obtained between the steel pipe and the green compact. As the core, one having a large coefficient of thermal expansion and durability, for example, austenitic stainless steel (coefficient of thermal expansion of about 1.5 × 10 ⁻⁵ / ° C.) is preferable.

The multi-layered sintered sliding member thus obtained has a structure in which the iron component in the components of the green compact diffuses into the steel pipe simultaneously with the sintering of the green compact during sintering. The structure of the sintered layer is a structure in which the sintered layer has a pearlite structure or a structure in which a part of the pearlite structure coexists with the ferrite structure, and the cementite is free cementite. There is no formation of graphite, and graphite is present dispersed in the tissue. This multi-layered sintered sliding member can be applied as an oil-impregnated multi-layered sintered sliding member by subjecting it to oil impregnation treatment according to its intended use and application.

[0036]

[Operation] Generally, in an iron-based sintered sliding member containing a large amount of graphite in iron powder to exert a solid lubricating action, it is inevitable that high hardness free cementite is formed in the sintered structure. However, by containing a certain amount of aluminum powder as in the present invention, a large amount of graphite can be contained without generating free cementite in the structure. The reason is not necessarily clear, but one of them is that the solid solution limit of other elements to the iron component is constant,
During sintering of a mixed powder containing an aluminum component and a graphite component, the aluminum component preferentially forms a solid solution with the iron component to reach the solid solution limit, and prevents the solid solution of the graphite component with the iron component. Therefore, the present inventors presume.

The sintered sliding member thus obtained does not generate high hardness free cementite in the structure and contains a large amount of graphite, and the presence of free cementite in the structure when sliding with the mating material. The drawbacks that must be avoided as much as possible in the sliding member that damages the mating material due to the above are completely eliminated.

Further, in a sintered sliding member in which a copper component or a copper component and a tin component are added to the components, since these components generate a liquid phase during sintering, the sintered body can be densified. , Improve the strength of the sintered body. Further, in the multilayer sintered sliding member in which the sintered layer is integrally joined to the back metal, the load resistance of the sliding member is greatly improved.

[0039]

EXAMPLES Hereinafter, the sintered sliding member of the present invention will be described in detail based on its examples.

<Example 1> 2% by weight of aluminum powder passing through 250 mesh was mixed with reduced iron powder passing through 240 mesh for 20 minutes by a V-type mixer,
5 wt% of 48-250 mesh natural graphite powder was added and mixed again for 5 minutes with a V-type mixer to obtain a mixed powder (Fe:
93%, Al: 2%, graphite: 5%).

Then, this mixed powder was loaded into a mold,
A cylindrical green compact having an inner diameter of 18 mm, an outer diameter of 25 mm and a length of 18 mm was obtained at a molding pressure of 3 ton / cm ² . This cylindrical green compact was placed in a heating furnace in an atmosphere of ammonia decomposition gas, sintered at a temperature of 1100 ° C. for 60 minutes, and then machined to a desired size to obtain a sintered sliding member. The density of this sintered sliding member is 5.01g / cm ³
Met.

The structure of this sintered sliding member exhibited a pearlite structure, no free cementite was formed in the structure, and graphite was present in a dispersed state. Then, the sliding member was subjected to oil impregnation treatment to obtain an oil impregnated sintered sliding member having an oil content of 25% by volume.

<Example 2> 2% by weight of aluminum powder passing through 250 mesh, 20% by weight of electrolytic copper powder passing through 150 mesh, and atomized tin passing through 250 mesh based on reduced iron powder passing through 240 mesh Add 3.3% by weight of powder and mix with a V-type mixer for 20 minutes.
Add 5% by weight of 250-mesh natural graphite powder and repeat V
Mix for 5 minutes with a mold mixer to obtain mixed powder (Fe: 69.7
%, Al: 2%, Cu: 20%, Sn: 3.3%, graphite: 5%).

Then, this mixed powder was loaded into a mold,
A cylindrical green compact having an inner diameter of 18 mm, an outer diameter of 25 mm and a length of 18 mm was obtained at a molding pressure of 3 ton / cm ² . This cylindrical green compact was placed in a heating furnace in an atmosphere of ammonia decomposition gas, sintered at a temperature of 1050 ° C. for 30 minutes, and then machined to a desired size to obtain a sintered sliding member. The density of this sintered sliding member is 5.27 g / cm ³
Met.

As shown in the photomicrograph (magnification 170 times) of FIG. 1, the structure of this sintered sliding member has a pearlite structure as the base material and no free cementite is formed in the structure, and graphite A is dispersed in the structure. It was confirmed that it was doing. In addition, the code | symbol B in a figure is a copper tin alloy. Then, the sliding member was subjected to an oil impregnation treatment to obtain an oil impregnated sintered sliding member having an oil content of 23% by volume.

<Example 3> 2% by weight of aluminum powder passing through 250 mesh, 20% by weight of electrolytic copper powder passing through 150 mesh, and atomized tin passing through 250 mesh based on reduced iron powder passing through 240 mesh Add 3.3% by weight of powder and mix with a V-type mixer for 20 minutes.
Add 5% by weight of 250-mesh natural graphite powder and repeat V
Mix for 5 minutes with a mold mixer to obtain mixed powder (Fe: 69.7
%, Al: 2%, Cu: 20%, Sn: 3.3%, graphite: 5%).

5% by weight of HPC aqueous solution (HPC
100 g, 120 ml of ethyl alcohol and 1780 ml of water) were added at 0.5% based on the weight of the mixed powder and uniformly mixed for 5 minutes with a V-type mixer to obtain a wet raw material powder.

The raw material powder was applied to a horizontal rolling roll having twin rolls having a diameter of 603 mm, the roll interval was 0.1 mm, and the roll speed was 0.3 m /
It was passed under the condition of min to form a rolled sheet (compacted powder sheet) having a density of 6.25 g / cm ³ and a thickness of 1.48 mm. This width
170mm, length 600mm, width 170mm, length 600mm,
Two sheets are laminated on a steel plate of a general structural rolled steel (JIS G-3101) with a thickness of 5 mm, placed in a heating furnace in an ammonia decomposition gas atmosphere for 30 minutes at 1050 ° C, while applying a pressure of 3.0 kgf / cm ² , After the rolled sheet is sintered and simultaneously diffused and joined to the steel sheet, it is machined to the desired dimensions and a sintered sliding member consisting of multiple layers is obtained by integrally joining the sintered layers on the steel sheet. It was The density of the sintered layer of this sintered sliding member is 5.47 g / cm ³
And the joint strength between the steel plate and the sintered layer is 570 kg / cm ²
Met.

It was confirmed that the structure of the sintered layer of this multi-layer sintered sliding member had a pearlite structure, no free cementite was formed in the structure, and graphite was dispersed in the structure. .. Then, the sliding member is oil-impregnated to obtain the oil content.
A 21% by volume oil-impregnated sintered sliding member was obtained.

Example 4 A rolled sheet having a thickness of 1.48 mm was formed in the same manner as in Example 3 above. As the back metal, a plurality of independent protrusions having a rectangular planar shape are arranged on the surface in a direction orthogonal to each other, the surface of the protrusion is a flat surface, and the peripheral portion is descended from the surface of the protrusion to the surface of the back metal. Width 150 mm, length 26 formed on the sloped surface
A square steel plate (rolled steel plate SS41) with a thickness of 0 mm, a thickness to the back metal of 8 mm, and a protrusion height of 1.695 mm was used. Cut the rolled sheet into a width of 150 mm and a length of 260 mm, and cut it into 2
The sheets were stacked, placed in a heating furnace in an ammonia decomposition gas atmosphere, and subjected to a pressure of 3.0 kgf / cm ² at a temperature of 1050 ° C. for 30 minutes while simultaneously sintering the rolled sheets and performing diffusion / bonding with the steel sheets. After that, it was machined to a desired size to obtain a sintered sliding member composed of a plurality of layers in which a sintered layer was integrally bonded on a steel plate.

The sintered layer of this sintered sliding member was formed to have a thickness of 0.8 mm on the surface of the protruding portion and 2.5 mm on the surface of the steel sheet, and the density of the sintered layer on the surface of the protruding portion was 6.3 g / cm ³ , the density of the sintered layer on the surface of the steel sheet was 5.35 g / cm ³ , and the bonding strength between the steel sheet and the sintered layer was 600 kg / cm ² .

It was confirmed that the structure of the sintered layer of the multilayer sintered sliding member had a pearlite structure, no free cementite was formed in the structure, and graphite was dispersed in the structure. .. Then, the sliding member was subjected to oil impregnation treatment, and the sintered layer in the high density area on the surface of the protruding portion had 12% by volume, and the sintered layer in the low density area on the steel plate surface had 23% by volume. The moving member was obtained.

<Example 5> 2% by weight of aluminum powder passing through 250 mesh, 20% by weight of electrolytic copper powder passing through 150 mesh, and atomized tin passing through 250 mesh based on reduced iron powder passing through 240 mesh Powder 3.3
Add wt% and mix for 20 minutes with V-type mixer, then 48
5 wt% of natural graphite powder of ˜250 mesh was added and mixed again for 5 minutes with a V-type mixer to obtain a mixed powder (Fe: 69.
7%, Al: 2%, Cu: 20%, Sn: 3.3%, graphite: 5%).

This mixed powder was loaded into a mold and the molding pressure was applied.
A cylindrical green compact having an inner diameter of 18 mm, an outer diameter of 24 mm and a length of 30 mm was obtained at 3 ton / cm ² . This cylindrical green compact has an inner diameter of 24
mm, outer diameter 34 mm, length 30 mm, and press fit to the inner diameter surface of a steel pipe made of general structural carbon steel pipe (JIS G-3444), and place it in a heating furnace in an ammonia decomposition gas atmosphere. Place it, sinter it at a temperature of 1050 ° C for 30 minutes, and at the same time as sinter the cylindrical green compact, diffuse and bond it to the inner diameter surface of the steel pipe, then machine it to the desired size. A sintered sliding member composed of multiple layers was obtained. The density of the sintered layer of this sintered sliding member was 5.30 g / cm ³ , and the bonding strength between the steel pipe and the sintered layer was 550 kg / cm ² .

It was confirmed that the structure of the sintered layer of this multi-layer sintered sliding member had a pearlite structure, no free cementite was formed in the structure, and graphite was dispersed in the structure. .. Then, the sliding member is oil-impregnated to obtain the oil content.
An oil-impregnated sintered sliding member of 23% by volume was obtained.

<Example 6> 2% by weight of aluminum powder passing through 250 mesh, 20% by weight of electrolytic copper powder passing through 150 mesh, and atomized tin passing through 250 mesh based on reduced iron powder passing through 240 mesh Add 3.3% by weight of powder and mix with a V-type mixer for 20 minutes.
Add 5% by weight of 250-mesh natural graphite powder and repeat V
Mix for 5 minutes with a mold mixer to obtain mixed powder (Fe: 69.7
%, Al: 2%, Cu: 20%, Sn: 3.3%, graphite: 5%).

The mixed powder was loaded into a mold to obtain a cylindrical green compact having an inner diameter of 42.5 mm, an outer diameter of 48.5 mm and a length of 25 mm at a molding pressure of 3 ton / cm ² . Internal diameter of this cylindrical pressure body prepared separately
Two steel pipes having a size of 48.5 mm, an outer diameter of 55 mm and a length of 50 mm were press-fitted in the inner diameter surface in the axial direction.

A ceramic powder (Al ₂ O ₃ : 8) was formed on the inner diameter surface of the pressure-dividing body of a steel pipe in which a cylindrical green compact was press-fitted on the inner diameter surface.
3% by weight and a mixture of SiO ₂ : 17% by weight, 35 to 150 mesh) particles were filled, and then sintered in an ammonia decomposing gas atmosphere at a temperature of 1050 ° C. for 30 minutes to burn the cylindrical green compact. At the same time as binding, the inner surface of the steel pipe was diffused and joined, and then machined to a desired size to obtain a sintered sliding member composed of multiple layers. The density of the sintered layer of this sintered sliding member was 5.30 g / cm ³ , and the bonding strength between the steel paif and the sintered layer was 550 kg / cm ² .

It was confirmed that the structure of the sintered layer of this multilayer sintered sliding member had a pearlite structure, no free cementite was generated in the structure, and graphite was dispersed in the structure. .. Then, the sliding member is oil-impregnated to obtain the oil content.
An oil-impregnated sintered sliding member of 23% by volume was obtained.

Next, the sliding characteristics of the sintered sliding member obtained in each of the above-mentioned examples will be described with respect to the results of testing under the following test conditions.

-Test conditions for the sintered sliding members of Examples 1 and 2-Durability test Friction speed 5 m / min Load 20 kgf / cm ² stroke 200 mm Test stroke 100,000 cycles (400 mm / cycle) Sliding distance 40,000 m Mating material Carbon steel for machine structure (S45C) tester Linear reciprocating motion tester

--Test conditions for the sintered sliding members of Examples 3 and 4--Durability test Friction speed 7 m / min Load 120 kgf / cm ² stroke 80 mm Test stroke 100,000 cycles (160 mm / cycle) Sliding distance 16,000 m Mating material Carbon steel (S45C) tester for machine structure Plane reciprocating tester

-Test conditions for the sintered sliding members of Examples 5 and 6-Durability test Friction speed 40 m / min Load 10 kgf / cm ² stroke 200 mm Test stroke 100,000 cycles (400 mm / cycle) Sliding distance 40,000 m Mating material Carbon steel for machine structure (S45C) tester Linear reciprocating motion tester

In the above durability test, the friction coefficient and wear amount of each sintered sliding member were measured. The results are shown in Table 1. Comparative examples in Table 1 are Japanese Industrial Standards (JIS)
The iron-carbon-copper-based oil-containing sintered material (SMF type 4) specified in Z-2550 of No. 2 is used, and
The result of having tested on the test conditions of is shown.

[0065]

[Table 1]

From the test results shown in Table 1, the sintered sliding member of the present invention showed a slightly high coefficient of friction immediately after the start of the test, but it gradually decreased with the progress of the test and remained stable. Particularly, as can be seen from the comparison with the comparative example, the oil-impregnated sintered sliding member was significantly improved in both the friction coefficient and the wear amount.

Observation of the state of the surface of the mating material after the test revealed that a thin coating of graphite was formed on the surface of the mating material and no damage was observed.

Further, the sintered sliding member of the present invention is a sliding member composed of the sintered simple substance of Examples 1 and 2, a sliding member composed of a plurality of layers of Examples 3 to 6, and its sliding member. It is applicable to a wide range of uses of moving members.

[0069]

EFFECTS OF THE INVENTION The sintered sliding member of the present invention does not generate high hardness free cementite in its structure, and therefore, in sliding with a mating member, which is an extremely important factor in the sliding member,
This has the effect of not damaging the surface of the mating material.

Further, since the sintered sliding member of the present invention can be made into a multi-layer by integrally bonding the sintered layer to the steel backing metal, the range of application as the sliding member is greatly increased.

[Brief description of drawings]

FIG. 1 is a micrograph (magnification 170 times) showing a sintered structure of a sintered sliding member of the present invention.

FIG. 2 is a plan view showing an example of a backing metal used for a sintered sliding member composed of multiple layers of the present invention.

3 is a cross-sectional view taken along the line EE of FIG.

4 is a cross-sectional view showing a sintered sliding member composed of multiple layers using the backing metal of FIG.

[Explanation of Codes] 1 Steel plate 2 Projection 4 Sintered layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B32B 15/01 Z 7148-4F C22C 33/02 B 7619-4K 38/06

Claims (22)

[Claims] 1. Graphite 3-8% by weight, aluminum 0.5-
A sintered sliding member composed of 5% by weight and the balance iron. 2. The sintered sliding member according to claim 1, wherein copper is contained in a proportion of 10 to 30% by weight. 3. The sintered sliding member according to claim 2, wherein tin is contained in a proportion of 1 to 10% by weight. 4. Iron powder to which 3 to 8% by weight of graphite powder and 0.5 to 5% by weight of aluminum powder are added and mixed to form a mixed powder, and the mixed powder is formed into a required shape to form a green compact. After that, the method for producing a sintered sliding member is characterized in that the green compact is sintered in a heating furnace adjusted to a neutral or reducing atmosphere at a temperature of 1050 to 1100 ° C. for 30 to 60 minutes. 5. The method for producing a sintered sliding member according to claim 4, wherein copper powder is added to the mixed powder in a proportion of 10 to 30% by weight. 6. The method for producing a sintered sliding member according to claim 5, wherein tin powder is added to the mixed powder in a ratio of 1 to 10% by weight. 7. Graphite 3-8% by weight, aluminum 0.5-
A sintered sliding member formed by integrally joining a sintered layer of 5% by weight and the balance iron to a steel backing. 8. The sintered sliding member according to claim 7, wherein the sintered layer contains 10 to 30% by weight of copper. 9. The sintered sliding member according to claim 8, wherein the sintered layer contains tin in an amount of 1 to 10% by weight. 10. The sintered sliding member according to claim 7, wherein the steel backing is made of a steel plate. 11. The sintered sliding member according to claim 7, wherein the steel backing is made of a steel plate having a plurality of independent protrusions on its surface. 12. The steel backing is made of a steel plate having a continuous protrusion on the surface thereof and a plurality of independent recesses formed by the protrusion, as claimed in any one of claims 7 to 9. Sintered sliding member. 13. The sintered slide according to claim 11, wherein a low-density region and a high-density region are formed in a dispersed manner in a sintered layer integrally bonded on a backing plate made of a steel plate. Element. 14. The sintered sliding member according to claim 7, wherein the steel backing is made of a steel pipe. 15. Iron powder to which 3 to 8% by weight of graphite powder and 0.5 to 5% by weight of aluminum powder are added and mixed to form a mixed powder, and 1 to 15% by weight aqueous solution of a powder binder is added to the mixed powder. 0.1 to 5.0% by weight is added to the mixed powder and uniformly mixed to obtain a raw material powder, the raw material powder is supplied to a rolling roll to form a rolled sheet, and the rolled sheet is superposed on a backing plate made of a steel plate. , In a heating furnace adjusted to a neutral or reducing atmosphere at a temperature of 1050-1100 ° C 1.
13. The sintering according to claim 10, wherein the rolling sheet is sintered and diffusion-bonded to the backing metal at the same time under a pressure of 0 to 4.0 kgf / cm ² for 30 to 60 minutes. The method for manufacturing a sintered sliding member according to any one of claims. 16. The method for producing a sintered sliding member according to claim 15, wherein copper powder is added to the mixed powder in a proportion of 10 to 30% by weight. 17. The method for producing a sintered sliding member according to claim 16, wherein tin powder is added to the mixed powder in a ratio of 1 to 10% by weight. 18. A baking unit integrally bonded onto a backing plate made of a steel plate having a plurality of independent protrusions on the surface or a plurality of protrusions continuous with the surface and a plurality of independent recesses formed by the protrusions. 18. The method for producing a sintered sliding member according to claim 15, wherein a low-density region and a high-density region are dispersedly formed in the tie layer. 19. Iron powder to which 3 to 8% by weight of graphite powder and 0.5 to 5% by weight of aluminum powder are added and mixed to form a mixed powder, and this mixed powder is pressure-molded to form a cylindrical green compact. It is manufactured, and the green compact is pressed into the inner surface of the backing made of steel pipe, and this is sintered in a heating furnace adjusted to a neutral or reducing atmosphere at a temperature of 1050 to 1100 ° C for 30 to 60 minutes. 15. The method for producing a sintered sliding member according to claim 14, wherein the sintering of the green compact and the diffusion bonding to the steel pipe are simultaneously performed. 20. The method for producing a sintered sliding member according to claim 19, wherein copper powder is added to the mixed powder in a proportion of 10 to 30% by weight. 21. The method for producing a sintered sliding member according to claim 20, wherein tin powder is added to the mixed powder in a ratio of 1 to 10% by weight. 22. A ceramic powder is filled on the inner surface of a green compact, and the ceramic powder expands the inner diameter side during sintering and shrinks the inner diameter side during cooling after sintering. By constraining the expansion amount and the contraction amount toward the outer diameter side, a high contact pressure is generated on the inner surface of the backing metal, and this contact pressure causes diffusion of the green compact component to the inner surface of the backing metal. 22. The sintered body according to claim 19, wherein the sintered layer is integrally bonded to the inner surface of the back metal.
A method for manufacturing a sintered sliding member according to any one of 1.