KR101650174B1 - Cu-Carbon binded powder and pressed articles and slide material manufactured therewith - Google Patents

Abstract

The present invention relates to copper-carbon binding powder which prevents the segregation of mixed powder and improves other flowing type physical properties by binding particles of copper powder and graphite powder by a predetermined binder. Copper-graphite binding powder is also formed by including a plurality of copper-graphite binding particles. A copper-graphite particle is formed by including: a particle of copper powder; a particle of graphite powder for improving lubricity as a slide material after a sintering operation; and a binder of binding the particle of copper powder with the particle of graphite powder in a solid state. The binder functions as a lubricant for improving the flow ability of the copper-graphite binding powder by being positioned between the plurality of copper-graphite binding particles.

Description

Copper - carbon bond powder and green compacts and slides made therefrom. {Cu-carbon bonded powder and pressed articles and slide material manufactured therewith}

The present invention relates to a copper-carbon bond powder and a green compact produced by using the same, and more particularly, to a copper-carbon bond powder and a green compact made by using the same, wherein the copper powder and the graphite powder are bonded to each other by a predetermined binder Copper-carbon bond powder and the like which can remove the phenomenon but also improve flowability and other physical properties.

The metal powder is used for manufacturing a metal product by charging the metal powder into a die having a predetermined shape, compressing it to form a green compact, taking out it, and sintering it. However, when various materials such as graphite and metal for alloying are added to and mixed with metal as a main material, the sizes, shapes and densities of the particles are different from each other in preparing the main material. Therefore, Thereby causing a phenomenon.

Particularly, in the case of a mixed powder containing graphite, due to lack of flowability of the graphite, the mixed powder is not filled up to the corner of the mold in the process of injection into the mold for the compaction step Problems such as product weight deviation occur. This is particularly a problem when filling is performed at high speed. Specifically, it affects powder properties such as external density and flowability, and further affects product characteristics such as strength and shrinkage rate deviation.

3.65 to 4.35% by weight of nickel (Ni), 1.38 to 1.62% by weight of copper (Cu), and 0.01% by weight of copper are disclosed in Korean Patent No. 1345982 (hereinafter, referred to as a method of manufacturing a mechanical component by powder metallurgy, 0.1 to 0.9% by weight of carbon (C) and 0.4 to 1.2% by weight of a lubricant are added to an iron alloy powder composed of molybdenum (Mo) 0.4 to 0.6% by weight and unavoidable impurities and residual iron (Fe) And mixing for 30 to 40 minutes.

KR 1345982 B

Conventional technique 1 segregates in the course of mixing raw material components, transferring mixed powder after the mixing process, or introducing the mixed powder into a subsequent process, thereby reducing the product dimensions in a later sintering process, There is a possibility that a problem of large single-center deviation (weight and dimensions, etc.) occurring in mass production may occur.

In order to solve the above problems, the present invention provides a copper-graphite bonded particle, comprising copper-graphite bonded particles, wherein the copper-graphite bonded particles are composed of particles of copper powder, Graphite particles; and a binder agent for binding particles of the copper powder and particles of the graphite powder in a solid state, wherein the binder agent is disposed between the plurality of copper- Graphite bond powder characterized in that it is a lubricant having a function of improving the flowability of the copper-graphite bond powder.

Further, there is provided a green compact manufactured by using the copper-graphite bonded powder having the above-described structure.

Further, there is provided a slide member manufactured using the copper-graphite bond powder having the above-described structure.

DISCLOSURE OF THE INVENTION It is an object of the present invention to provide a method of binding (bonding) particles having different specific gravity to each other, such as copper particles, graphite particles, alloy particles, and the like, Or the effect thereof can be minimized, the flowability is improved owing to the application of the lubricant, so that when the product is formed by the subsequent compaction or sintering process, the density of the product can be made uniform, And a third effect is that the product quality can be improved by generating a small weight and dimensional deviation even in a high-speed process application for mass production.

1 is an SEM image of powders according to Example 2 (lower row) and Comparative Example 2 (upper row) of the present invention.
2 is an SEM image of powder according to Example 3 (lower row) and Comparative Example 3 (upper row) of the present invention.
3 is an SEM image of powders according to Example 4 (lower row) and Comparative Example 4 (upper row) of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" (connected, connected, coupled) with another part, it is not only the case where it is "directly connected" "Is included. Also, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises" or "having" and the like refer to the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The copper-graphite binding powder of the present invention comprises a plurality of copper-graphite binding particles.

The copper-graphite binding particles include copper powder particles, graphite powder particles for improving lubricant properties as a slide material after sintering, and a binder agent for binding the copper powder particles and the graphite powder particles.

The copper-graphite binding powder of the present invention refers to a powder comprising a plurality of copper-graphite binding particles.

The individual copper-graphite binding particles constituting the copper-graphite binding powder can be formed by binding graphite powder particles to the copper powder particles. The particle size (size) of the copper-graphite binding particles is one of the factors determining the density before sintering, density after sintering, strength and other characteristics of the product to be manufactured later using the copper-graphite binding powder, . The particle size of the copper-graphite binding particles is determined by the particle size of the copper particles and the graphite particles constituting the particles. When the particle size of the copper particles is larger than that of the graphite particles, the overall constitution of the copper- One or more graphite powder particles may be in a shape to which they are bonded, but the opposite case is not excluded. However, the main material is copper, and the graphite particles should be determined in consideration of the fact that it is a material for enhancing physical properties such as lubricity and processability that copper, which is the main material, does not have.

Hereinafter, each constituent element constituting the copper-graphite bonded particle will be described in detail.

The copper powder may be prepared by a known method so as to have a predetermined purity and particle size. There is no particular limitation on the average particle size of the copper powder particles, but it is preferably in the range of 5 to 250 micrometers. Considering that the copper-graphite bonded powder of the present invention is used for manufacturing a slide member such as a magnetic core, a bearing, a bush, etc. through a compaction step of forming a product shape through pressurization and a subsequent sintering process , And if the average particle size of the copper powder particles is too large, the size of the pores (pores) in the compaction step is not uniform. On the other hand, if the average particle size of the copper powder particles is too small as compared with the average particle size of the graphite powder particles, the segregation phenomenon due to the difference in density between the copper powder particles and the graphite powder particles may be increased.

The graphite powder may be prepared by a known method so as to have a predetermined particle size. The graphite powder particles function as a solid lubricant. Especially when the copper-graphite binding powder of the present invention is used as a slide material, it is exposed to the outside of the final product and copper, which is the main material, And performs a function of preventing wear. The average particle size of the graphite powder particles can be preferably in the range of 5 to 200 micrometers. Since graphite functions as a substance which interferes with and inhibits sintering of a product as an inorganic substance and is large in size, it is difficult to form and sinter the product. To complement the graphite powder, graphite powder having a small particle size is generally advantageous. In addition, as described above, the average particle size of the graphite powder particles should be determined according to the mixing amount with the average particle size of the copper powder particles. Also, in the production of the copper-graphite bonded powder, most of the objects to be mixed are taken up by the copper powder as the main material. When the particle size of the graphite powder is large, the number of the particles of the graphite powder becomes small, It is considered that this may be a problem because it means that the particles of the powder are likely to be localized in a specific region of the copper powder.

The granular phase of the graphite powder particles is generally flattened and is externally exposed in a manner to be partially recessed-bonded to the copper matrix produced in the sintering process to perform a predetermined function. The binding force between the graphite powder particles and the copper matrix The surface of the product may be roughened by dropping out of the slide, and the frictional resistance and the like may be lowered. Therefore, such a problem can be solved by coating the surface of the graphite powder particles with the same components as those of the matrix of copper or the like.

The binder agent has a function of binding the copper powder particles and the graphite powder particles so that the copper powder particles and the graphite powder particles have a difference in density although the graphite powder particles and other alloy powder particles are the copper powder (Segregation) relative to the particles, and prevent the phenomenon that the powder particles are bundled together (first function). In addition, the binder agent proposed in the present invention further includes a function (second function) that is located between a plurality of copper-graphite binding particles and improves (lubricates) flowability at the time of injection of the metal mold.

To explain the lubrication of the second function, there is a lubrication effect which acts between the wall of the die to which the powder is compressed and the copper-graphite powder to prevent excessive friction between the green compact and the die, And the lubricating action that ensures the flowability in the process of being loaded into the die. Particularly in the former case, it is possible to reduce the force (extraction force) for separating the green compact from the die to maintain the life of the die, and to prevent damage to the die surface and the product surface in advance.

The binder of the present invention maintains a solid state in a state where copper powder particles and graphite powder particles are bonded to each other at room temperature, and does not include those having a liquid phase at room temperature. When a liquid additive is used as a binder, the flowability is lowered, which is a problem in later compaction steps. In the case of storage for a long period of time, there is a problem that the binder is precipitated in the direction of gravity and segregation can not be avoided.

In the present invention, any kind of lubricant may be used without limitation to a specific material as long as it is used as a lubricant for powders as the binder agent. Preferably selected from the group consisting of lithium stearate (Li-C18H36O2), zinc stearate (Zn-C18H36O2), Acrawax (C38H76N2O2), kenolube paraffin, aluminum stearate, Waxes, and waxes may be used. It is, of course, not limited to these materials as described above. Lithium stearate, zinc stearate and the like are metal soaps which are metal salts other than alkali metals as salts of higher fatty acids, and generally have insolubility. These lubricants basically function to improve the flowability while being present between the metal powder particles. Furthermore, these lubricants have the advantage of burning at a preheating stage (500 to 600 degrees Celsius) of the sintering process, leaving less impact on the product. Further, these lubricants have a rust inhibiting function for preventing the deterioration of copper powder as a main material through the function of removing moisture on the metal powders.

When the lubricant is mixed with the metal composite powder in the form of powders according to a conventional method, the lubricant powder, the copper powder and the graphite powder can independently move relative to each other, and thus the problem of the above-described deterioration can be maintained. Accordingly, in the present invention, the lubricant is used as a binder agent for binding copper powder and graphite powder through a predetermined treatment process to remove segregation phenomenon. Furthermore, since the lubricants have a solid phase at room temperature, they do not cause a problem of deterioration of flowability unlike liquid phase additives.

In short, the binder of the present invention is a binder in which a part of the initial blend (powder form) is denatured into a liquid phase by a predetermined process, and is placed between the particles of the copper powder and the particles of the graphite powder and then cooled and solidified, And the remaining portion of the initial mixture remains in powder state to perform the internal lubrication function between the copper-carbon bond particles and the external lubrication between the molding die and the powder at the same time will be.

The binder of the present invention is preferably added in an amount of 0.1 part by weight to 3.0 parts by weight based on 100 parts by weight of the total of the copper-graphite bond powder. In the binder of the present invention, a part of the initial blend (powder form) is melt-denatured by a predetermined process to function as a binder, and the remainder remains in powder form to form an inner lubrication function between copper- , The initial mixing amount has an important meaning. Therefore, when the binder agent is contained in an amount of less than 0.1 part by weight based on the total weight, there arises a problem that the binder agent and the lubricant can not be simultaneously performed. Further, when the binder agent exceeds 3.0 parts by weight based on the total weight portion, there is a problem that the ratio of the void space generated in the product while the lubricant particles are burned in the sintering step (or the preheating step) There is a problem that a metal residue which may contaminate the inside of the furnace can be left over the allowable value.

The copper-graphite bonded powder of the present invention may further comprise a powder for alloying. At this time, the particles of the alloy powder can bind to the particles of the copper powder by the binder agent. Such an alloy powder may be selected from lead-tin alloys and alloys thereof for the production of tin, zinc, bismuth (Bi), and process alloys. However, other known alloys for improving the properties of copper such as rust- The alloy powder is not excluded. The actual alloying process occurs during sintering and must be able to prevent segregation of the alloy powder in the mixed (binder) powder phase, which also means that particles of the alloy powder are bonded to the copper powder particles by the binder ≪ / RTI >

If the average particle size of the alloy powder is smaller than that of the copper powder, it is possible for particles of the plurality of alloying powders to be bonded to one particle of the copper powder. The average particle size of the powder for alloying is to be determined in consideration of the alloy composition ratio to ensure the required physical properties. Further, in the production of the copper-graphite bonded powder, most of the objects to be mixed are taken up by the copper powder as the main material, and when the particle size of the alloy powder is increased, the number of particles of the powder becomes smaller, It is considered that there is a possibility that the particles of the powder may be localized in a specific region of the copper powder, which may be a problem.

In preparing the copper-graphite bonded powder of the present invention, 0.5 to 10 parts by weight of graphite powder, 0.1 to 3 parts by weight of a binder, 5 to 13 parts by weight of tin powder, and the remaining amount of copper powder are contained . When the amount of the graphite powder is less than 0.5 parts by weight, the effect of improving the lubricating action of the sintered product is insufficient. When the amount of the graphite powder is more than 10 parts by weight, the strength of the sintered product There arises a problem that the temperature is lowered. The content of the binder agent has been described above. When the tin powder is contained in an amount of less than 5 parts by weight, there is a problem in strength, corrosion resistance and abrasion resistance. When the tin powder is contained in an amount exceeding 13 parts by weight, do.

Further, the green compact can be produced by using a copper-graphite binding powder. As an example of the green compact, a toroidal or other type of pressure-sensitive core or the like may be used. These green compacts may be further formed through a sintering process after the greening process. Generally, lubricants should be taken into consideration when there is a problem in reducing the discharge pressure when the height of the manufactured product is large. In addition, the influence of reduction of the die friction of the lubricant should be grasped to determine the pressure acting on the die and the output power.

Further, the slide material can be produced by using a copper-graphite bond powder. The slide material refers to a material for producing products such as bearings, bushes and the like in which a dynamic load is repeatedly applied. Particularly, the graphite particles included in the copper-graphite binding powder of the present invention perform a friction reducing function.

EXAMPLES Hereinafter, examples of the present invention will be described together with comparative examples.

[Example 1]

≪ Preparation of copper powder &

100% purity of copper was atomized using hydration and the sprayed powder was dried at a temperature of about 120 degrees Celsius.

Under a nitrogen / Ax air atmosphere, at a temperature range of about 600 to 700 degrees Celsius, and the reduced powder passed through was crushed using a hammer mill.

Thereafter, 100 meshes were classified.

≪ Preparation of mixed powder &

Copper powder, tin powder, graphite powder, and zinc stearate powder were simultaneously charged into a double cone mixer at a rate of 88.3 wt%, 10 wt%, 1 wt%, and 0.5 wt%, respectively.

The primary blended mixed powders were put into a weightless mixer, and low speed mixing was performed while slowly raising the temperature from room temperature to 170 degrees Celsius for 30 minutes.

Thereafter, low-speed mixing was performed while maintaining the temperature at 170 DEG C for 50 minutes.

Thereafter, the mixture was cooled with low speed mixing from 170 to 65 degrees Celsius for 2 hours, and then the powder was discharged.

The discharged powders were classified into 80 mesh and 60 mesh, and then mixed in a double cone mixer for 3 minutes.

[Example 2]

Graphite powder was mixed in an amount of 3 wt%.

[Example 3]

Graphite powder was mixed in an amount of 5 wt%.

[Example 4]

Except that graphite powder was mixed in an amount of 7 wt%.

[Comparative Example 1]

≪ Preparation of copper powder &

Was prepared under the same conditions as in Example 1.

≪ Preparation of mixed powder &

Copper powder, tin powder, graphite powder, and zinc stearate as a lubricant were prepared at a mixing ratio of 88.3 wt%, 10 wt%, 1 wt%, and 0.5 wt%, respectively.

Copper powder, tin powder, zinc stearate powder and graphite powder were sequentially added to a double cone mixer to perform mixing.

[Comparative Example 2]

Except that graphite powder was mixed in an amount of 3 wt%.

[Comparative Example 3]

Except that graphite powder was mixed in an amount of 5 wt%.

[Comparative Example 4]

Except that graphite powder was mixed in an amount of 7 wt%.

The results of measurement of density (A.D.), fluidity (F.R.) and particle size characteristics of the mixed powders prepared in Examples 1 to 4 and Comparative Examples 1 to 4 are shown in Table 1 below.

division unit Comparative Example 1 Experimental Example 1 Comparative Example 2 Experimental Example 2 Comparative Example 3 Experimental Example 3 Comparative Example 4 Experimental Example 4 A.D. g / cm3 2.93 3.16 2.68 2.92 2.33 2.63 2.10 2.44 F.R Sec / 50g 43.9 28.2 53.8 39.5 - 53.4 - 66.1 +106
μm

Wt% 1.5 2.5 1.7 2.4 1.6 1.8 1.5 1.7 +75 12.4 13.2 12.2 11.8 11.0 11.5 10.7 11.2 +45 37.4 38.6 37.6 38.1 36.1 36.3 35.1 35.8 -45 48.7 45.7 48.5 47.7 51.3 50.4 52.7 51.3

From the viewpoint of the apparent density (AD Apparent Density), the values in the experimental examples were measured to be larger than those in the corresponding comparative examples. As a result, in the case of the particle size, the proportion of the differential in the experimental example was somewhat reduced, It is analyzed that the ratio is slightly increased. As the outer density increases, the strength and weight reduction rate become better. Therefore, it can be understood that the embodiments are more advantageous in comparison with the comparative examples. In the case of the flow rate (F.rate), it can be confirmed that the case of the embodiment is improved to a considerable extent as compared with the case of the comparative example. Particularly, in the case of mixed powders containing graphite in an amount of 5% or more, it was determined that there was no flowability in Comparative Examples 3 and 4, but flowability was measured in Examples 3 and 4. This property facilitates die filling for subsequent compaction and sintering, resulting in improved quality, such as reduced product weight / dimensional variation. This improvement in flowability is due not only to the fact that the lubricant powder is included but also to the structural properties in which the graphite powder and the copper powder are combined by the molten part (binder) of the lubricant powder.

Hereinafter, experimental examples for confirming the improvement of characteristics of a product made of the copper-graphite binding powder of the present invention will be described.

[Experimental Example 1]

<Manufacture of press>

The mixed powder according to Examples 1 to 4 and Comparative Examples 1 to 4 was charged into a die for forming a toroidal green compact having an outer diameter of 12.03 mm, a width of 3 mm and a height of 4 mm, A pressurizer of 6.2 g / cc was manufactured. In the course of 200 continuous molding steps at a rate of 14 per minute, 50 randomly selected weight standard deviations were measured for the single-piece standard (2.12 g 0.02 g).

The results are shown in Table 2 below.

Comparative Example 1 Experimental Example 1 Comparative Example 2 Experimental Example 2 Comparative Example 3 Experimental Example 3 Comparative Example 4 Experimental Example 4
Standard Deviation

0.0062
0.0034
0.0092
0.0053
0.0131
0.0071
0.0145
0.0075

As mentioned above, it has been observed that when the flowability of the mixed powder is improved, the deviation in the center of gravity of the green compact is also reduced and the quality is improved.

 [Experimental Example 2]

<Manufacture of press>

The mixed powder according to Examples 1 to 4 and Comparative Examples 1 to 4 was charged into a die for molding a toroidal green compact having an outer diameter of 22.5 mm, a width of 4.25 mm and a height of 5 mm, Was selected as an arbitrary number of 50 pieces in the process of forming 200 pieces continuously at a rate of 14 pieces per minute.

<Manufacture of sintered body>

Thereafter, the 50 green compacts selected previously were subjected to a preheating zone (450 to 550 degrees, 30 to 60 minutes), a normal temperature (700 to 800 degrees Celsius, 30 to 60 degrees Celsius) 60 minutes) and a sintering furnace having a temperature profile of a cooling zone (about 500 DEG C, 60 to 120 min) for 30 minutes (760 DEG C) to form a sintered body and measuring the outer diameter After that, the outer diameter shrinkage ratio was calculated in comparison with that of the green compact.

The results are shown in Table 3 below.

Comparative Example 1 Experimental Example 1 Comparative Example 2 Experimental Example 2 Comparative Example 3 Experimental Example 3 Comparative Example 4 Experimental Example 4
Standard Deviation

0.0464
0.0283
0.0443
0.0291
0.0505
0.0314
0.0594
0.0351

As mentioned above, it has been observed that when the flowability of the mixed powder is improved, the dimensional deviation of the product after sintering is also reduced, and the quality is improved.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims (11)

A copper-graphite bond powder for use in the production of a slide member comprising a bearing and a bush,
A plurality of copper-graphite binding particles,
The copper-
Particles of copper powder,
Particles of graphite powder for improving lubricity as a slide material after sintering,
And a binder agent for binding the particles of the copper powder and the particles of the graphite powder in a solid state,
Wherein the binder agent is a lubricant having a function of improving the flowability of the copper-graphite binding powder by being positioned between the plurality of copper-graphite binding particles,
The binder agent is a mixture of copper powder and particles of the graphite powder, and the binder powder is a mixture of particles of the copper powder and particles of the graphite powder And the remainder of the initial blend remains in powder form to simultaneously perform the internal lubrication function between the copper-graphite binding particles and the external lubrication between the molding die and the copper-graphite binding powder,
The binder is added in an amount of 0.1 part by weight to 3.0 parts by weight based on 100 parts by weight of the total of the copper-graphite bond powder,
Wherein the copper-graphite binding particles further comprise particles of an alloy powder,
The particles of the alloy powder are bonded to the particles of the copper powder by the binder agent to prevent segregation,
Graphite binding powder characterized in that the alloy powder is made of tin, lead, bismuth, or an alloy thereof.
The method according to claim 1,
Graphite binding powder characterized in that a plurality of said graphite powder particles are bonded to one copper powder particle. delete The method according to claim 1,
Wherein the binder agent is at least one selected from the group consisting of lithium stearate, zinc stearate, Acrawax (C38H76N2O2), kenolube paraffin, aluminum stearate, and paraffin wax Copper-graphite binding powder.
delete delete The method according to claim 1,
Graphite binding powder characterized in that a plurality of particles of said alloy powder are bonded to one of said copper powder particles.
The method according to claim 1,
0.5 to 10.0 parts by weight of the graphite powder, 0.1 to 3.0 parts by weight of the binder, 5.0 to 13.0 parts by weight of the tin powder and the remaining amount of the copper powder, based on 100 parts by weight of the total of the copper-graphite binding powder. - Graphite binding powder.
The method according to claim 1,
Wherein the graphite powder has a copper coating on the surface thereof.
A green compact produced by using the copper-graphite binding powder of claim 1.
A slide material produced using the copper-graphite bond powder of claim 1.

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