KR101981893B1 - Manufacturing method for metal composite and metal composite manufacrured by the same - Google Patents

Abstract

According to one embodiment of the present invention, a high alloy steel powder having an average particle diameter of 3 mu m or more and 20 mu m or less and a copper-containing powder having an average particle diameter of 1/10 or more and 1/2 or less of an average particle diameter of the high alloy steel powder A mixing step of preparing a mixed powder to be mixed; A kneading step of kneading the mixed powder and the thermoplastic organic binder to prepare a feedstock; A forming step of forming a molded body by molding a feedstock; A degreasing step of removing the organic binder from the formed body; And a sintering step of sintering the formed body after the degreasing step to produce a dense sintered body,
Wherein the carbon content of the high alloy steel powder is 0.4 wt% or more and 2 wt% or less, and the weight ratio of the high alloy steel powder and the copper-containing powder is 8: 2 to 6: 4.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for manufacturing a metal composite, and a metal composite produced by the method. BACKGROUND OF THE INVENTION 1. Field of the Invention [0002]

The present invention relates to a method for producing a metal composite and a metal composite produced thereby, and a method for producing a metal complex excellent in hardness and thermal conductivity, and a metal composite produced thereby.

Recently, as the industry develops, the necessity of metal materials having excellent hardness and high thermal conductivity is emphasized. Tool steels and high-speed steels having a high carbon content of 0.4 wt% or more and high alloying elements having a high tendency to form alloy carbides are used as such metal materials. Hereinafter, tool steel and high-speed steel are referred to as high alloy steel. Since high alloy steel is a secondary hardening material due to the formation of alloy carbide during tempering after quenching in heat treatment, it can maintain a considerable hardness even at high temperature compared to other alloy steels. However, high alloy steels have the disadvantage of having low thermal conductivity. As a representative example of high alloy steel, AISI D2 tool steel and M2 high-speed steel have low room temperature thermal conductivity of 20 W / m / K and 19.0 W / m / K, respectively.

As described above, as a method of improving the low thermal conductivity of the high alloy steel, a method of improving the thermal conductivity by adjusting the composition and phase composition of the steel has been proposed. U.S. Patent Publication No. 2014-00023551 discloses a hot tool steel composition as a machining alloy material with improved thermal conductivity by lowering the carbon content to a carbon-carbon range and lowering the addition amount of an alloy element.

Another method is to produce a metal composite using a high alloy steel and a metal having a high thermal conductivity. This method uses a powder molding method. Generally, a molding method using a powder material as a raw material makes it possible to uniformly alloy various components uniformly during a process and precisely form a sintered body, so that it is possible to economically manufacture a sintered body close to a yarn shape while minimizing wastage and post- .

When the powder is produced by a conventional powder metallurgy method followed by press molding and sintering, a raw material powder is selected and used in order to achieve a high molding density. For this reason, instead of using the high alloyed steel powder which has already been alloyed and increased in strength, the alloy powder or the hard phase containing other alloying elements, such as soft iron powder or low alloy steel powder, Powder, etc., and molding is carried out under a high pressure of about 700 MPa or higher. Through this, the contact between the powders can be increased through the plastic deformation during the forming process, and the mechanical bonding can be generated to improve the sinterability.

However, there is a high density gradient due to the friction between the metal powders existing in the molded body produced by the conventional powder metallurgy process or between the metal powders and the inner wall of the mold, punches, etc., resulting in uneven contraction in the sintering process So that the shape is distorted and the production of a high-density sintered body is not easy.

Accordingly, there is a demand for a metal composite material having an improved hardness and thermal conductivity, and a method for producing a precise product using the same.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method for producing a metal composite having excellent hardness and high thermal conductivity using a high alloy steel powder and a copper-containing powder.

According to an embodiment of the present invention, there is provided a high alloy steel powder having an average particle diameter of 3 mu m or more and 20 mu m or less and a copper alloy powder having an average particle diameter of 1/10 or more and 1/2 or less of an average particle diameter of the high alloy steel powder A mixing step of preparing a mixed powder; A kneading step of kneading the mixed powder and the thermoplastic organic binder to prepare a feedstock; A forming step of forming a molded body by molding a feedstock; A degreasing step of removing the organic binder from the formed body; And a sintering step of sintering the formed body after the degreasing step to produce a dense sintered body, wherein the carbon content of the high alloy steel powder is 0.4 wt% or more and 2 wt% or less, and the weight ratio of the high alloy steel powder and the copper- : 2 to 6: 4.

According to an embodiment of the present invention, the high alloy steel powder further comprises silicon, manganese, chromium, molybdenum and vanadium, and the silicon content is 0.1 wt% or more and 0.8 wt% or less with respect to the high alloy steel powder; Manganese content is 0.1 wt% or more and 1 wt% or less with respect to the high alloy steel powder; The chromium content is 2 wt% or more and 15 wt% or less with respect to the high alloy steel powder; The molybdenum content is not less than 0.2 wt% and not more than 8 wt% with respect to the high alloy steel powder; The vanadium content is 0.001 wt% or more and 10 wt% or less with respect to the high alloy steel powder; And the remainder may be iron.

According to an embodiment of the present invention, the high alloy steel powder further comprises at least one metal selected from the group consisting of cobalt, nickel and tungsten, and the cobalt content is 0.001 wt% or more and 5 wt% or less with respect to the high alloy steel powder; The nickel content is 0.001 wt% or more and 3 wt% or less with respect to the high alloy steel powder; The tungsten content can be 0.001 wt% or more and 10 wt% or less with respect to the high alloy steel powder.

According to an embodiment of the present invention, the high alloy steel powder may further include at least one metal selected from the group consisting of silicon, manganese, chromium, cobalt, molybdenum, vanadium, nickel and tungsten.

According to one embodiment of the present invention, the copper-containing powder comprises tin and nickel, and the tin content is 0.1 wt% or more and 15 wt% or less with respect to the copper-containing powder; The nickel content is 0.001 wt% or more and 10 wt% or less with respect to the copper-containing powder; And the remainder may be copper.

According to an embodiment of the present invention, the mixed powder may further include at least one metalloid among carbon, boron and phosphorus, and the metalloid content may be 0.005 wt% or more and 0.3 wt% or less with respect to the mixed powder.

According to one embodiment of the present invention, the volume ratio of the mixed powder and the thermoplastic organic binder in the kneading step may be 6: 4 to 9: 1.

According to one embodiment of the present invention, the forming step can be performed under a pressure of 20 MPa or more and 200 MPa or less.

According to one embodiment of the present invention, the sintering step may be performed in a mixed gas atmosphere in which the volume ratio of nitrogen gas or hydrogen gas to hydrogen gas is 9: 1.

According to one embodiment of the present invention, the sintering step may be performed at a temperature between 1140 ° C and 1250 ° C.

According to an embodiment of the present invention, there is provided a method of manufacturing a sintered body, the method including a heat treatment step of heat treating the sintered body after the sintering step, wherein the heat treatment step comprises austenitizing the sintered body at a temperature of 900 ° C to 1050 ° C, Deg.] C or less.

According to another embodiment of the present invention, there is provided a metal composite produced by a manufacturing method according to an embodiment of the present invention.

The method of manufacturing a metal composite according to an embodiment of the present invention can easily produce a metal composite having improved thermal conductivity and excellent hardness.

The method of manufacturing a metal composite according to an embodiment of the present invention can improve the thermal conductivity of a metal composite produced without a large decrease in hardness in the tempering process.

The metal composite according to another embodiment of the present invention has an advantage of having high hardness and improved thermal conductivity.

1 is a flowchart illustrating a method of manufacturing a metal composite according to an embodiment of the present invention.
2 is a diagram showing an equilibrium state diagram of a binary alloy system of iron and copper.
3 is a view showing the microstructure of the sintered body manufactured in Example 1 of the present invention.
FIGS. 4A and 4B are diagrams showing the texture changes of the sintered body manufactured in Example 4 according to the heat treatment. FIG.
5A and 5B are views showing the microstructure of the sintered body manufactured in Example 6 of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

The terms used in this specification will be briefly described and the present invention will be described in detail.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. Also, in certain cases, there may be a term selected arbitrarily by the applicant, in which case the meaning thereof will be described in detail in the description of the corresponding invention. Therefore, the term used in the present invention should be defined based on the meaning of the term, not on the name of a simple term, but on the entire contents of the present invention.

When an element is referred to as " including " an element throughout the specification, it is to be understood that the element may include other elements, without departing from the spirit or scope of the present invention.

High alloy steels throughout the specification may refer to steels containing carbon, such as tool steels and high speed steels.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart illustrating a method of manufacturing a metal composite according to an embodiment of the present invention.

According to an embodiment of the present invention, there is provided a high alloy steel powder having an average particle diameter of 3 mu m or more and 20 mu m or less and a copper alloy powder having an average particle diameter of 1/10 or more and 1/2 or less of an average particle diameter of the high alloy steel powder A mixing step of preparing a mixed powder; A kneading step of kneading the mixed powder and the thermoplastic organic binder to prepare a feedstock; A forming step of forming a molded body by molding a feedstock; A degreasing step of removing the organic binder from the formed body; And a sintering step of sintering the formed body after the degreasing step to produce a dense sintered body, wherein the carbon content of the high alloy steel powder is 0.4 wt% or more and 2 wt% or less, and the weight ratio of the high alloy steel powder and the copper- : 2 to 6: 4.

According to the method for fabricating a metal composite according to an embodiment of the present invention, the density of the composite, which may be generated when the metal composite is manufactured using the conventional powder metallurgy process and the infiltration process, and shape distortion caused by uneven shrinkage Can be overcome. Further, by using the high alloy steel powder and the copper-containing powder, it is possible to provide a metal composite excellent in hardness and improved in thermal conductivity.

It is possible to use tool steel or high-speed steel powder having a carbon content of 0.4 wt% or more as high alloy steel powder. For example, AISI 440C martensitic stainless steels, D2 tool steels, M2 or T15 high speed steel powders can be used as high alloy steel powders.

That is, the carbon content of the high alloy steel powder according to one embodiment of the present invention is 0.4 wt% or more, and the secondary hardening phenomenon is possible, so that a metal composite having excellent hardness can be produced.

According to an embodiment of the present invention, the high alloy steel powder further comprises silicon, manganese, chromium, molybdenum and vanadium, and the silicon content is 0.1 wt% or more and 0.8 wt% or less with respect to the high alloy steel powder; Manganese content is 0.1 wt% or more and 1 wt% or less with respect to the high alloy steel powder; The chromium content is 2 wt% or more and 15 wt% or less with respect to the high alloy steel powder; The molybdenum content is not less than 0.2 wt% and not more than 8 wt% with respect to the high alloy steel powder; The vanadium content is 0.001 wt% or more and 10 wt% or less with respect to the high alloy steel powder; And the remainder may be iron.

The high alloy steel powder containing carbon, silicon, manganese, chromium, molybdenum, vanadium and iron may further contain at least one metal selected from the group consisting of cobalt, nickel and tungsten. The cobalt content is preferably 0.001 wt % To 5 wt% or less; The nickel content is 0.001 wt% or more and 3 wt% or less with respect to the high alloy steel powder; The tungsten content can be 0.001 wt% or more and 10 wt% or less with respect to the high alloy steel powder.

The copper-containing powder includes tin and nickel, and the tin content is 0.1 wt% or more and 15 wt% or less with respect to the copper-containing powder; The nickel content is 0.001 wt% or more and 10 wt% or less with respect to the copper-containing powder; And the remainder may be copper. When the copper alloy powder containing tin and nickel is used as the copper-containing powder, the thermal conductivity of the metal complex can be slightly reduced, but the strength of the metal complex can be improved. Further, the copper powder itself may be used as the copper-containing powder.

In order to ensure the fluidity of the feedstock and to maximize the densification effect through particle rearrangement by solid-liquid viscous flow in the sintering step, the high alloy steel powder, copper-containing powder and other additives contained in the mixed powder are similar to spherical It may be desirable to use it.

High alloy steel powder and copper-containing powder, for example, a high-alloy metal powder having an average particle diameter of 3 mu m or more and 20 mu m or less and a copper-containing powder having an average particle diameter of 1 mu m or more and 10 mu m or less, Can be manufactured.

By controlling the particle size ratio of the high alloy steel powder and the copper-containing powder as described above, it is possible to prevent large pores from being formed in the sintered body due to the dissolution of copper in the sintering step.

That is, by using the copper-containing powder having a relatively small size as compared with the high alloy steel powder, the filling ratio of the powder mixture can be improved by placing the copper-containing powder in the gap between the loosely packed high alloy steel powders in the molding step. In addition, it is possible to prevent the expansion of the sintered body due to the dissolution of the copper-containing powder having a low melting point in the sintering step, and the copper-containing powder dissolved first in the sintering step forms a liquid phase to fill the gap of the high alloy steel powder during the agglomeration, Densification is improved through particle re-arrangement that flows together with the alloy steel powder, and a high-density sintered body can be produced without forming large pores therein.

Unlike the above, when the average particle size of the high alloy steel powder and the copper-containing powder is similar, the uniformity of the mixed powder may be reduced and a large pore may be formed in the place where the copper-containing powder is located.

According to an embodiment of the present invention, a metal complex can be easily manufactured by using a fine powder mixture and a thermoplastic organic binder and by a degreasing and sintering process.

According to an embodiment of the present invention, the mixed powder may further include at least one metalloid among carbon, boron and phosphorus, and the metalloid content may be 0.005 wt% or more and 0.3 wt% or less with respect to the mixed powder.

By adding at least one of the sub-metals of carbon, boron and phosphorus to the mixed powder, the wettability between the high alloy steel powder and the copper-containing powder contained in the mixed powder can be improved and the densification of the formed body can be improved. Further, it may be preferable to add at least one metalloid among carbon, boron and phosphorus to the mixed powder from the viewpoint of promoting sintering of the formed body and improving the deoxidation effect of removing carbon contained in the copper-containing powder . The content of the metalloid added to the mixed powder may be preferably 0.005 wt% or more and 0.3 wt% or less with respect to the mixed powder.

According to an embodiment of the present invention, the mixed powder further comprises at least one compound powder selected from the group consisting of cobalt alloy powder on Laveth, iron alloy powder on Laveth, TiB ₂ , WC and TiC, The cobalt alloy powder on Laveth may be Co-Mo-Si or Co-Cr-Mo, and the iron alloy powder on Laveth may be Fe-Mo-Si. By using the mixed powder further comprising the compound powder, the high temperature abrasion resistance of the metal composite to be produced can be improved.

According to one embodiment of the present invention, the volume ratio of the mixed powder and the thermoplastic organic binder in the kneading step may be 6: 4 to 9: 1.

The thermoplastic organic binder according to one embodiment of the present invention can be any known one, and the kind of the thermoplastic organic binder to be used is not particularly limited. As the thermoplastic organic binder, for example, a wax-based thermoplastic organic binder for powder injection molding or a commercially available product may be used.

The feedstock prepared by kneading the mixed powder and the thermoplastic organic binder can be molded at a temperature of, for example, 100 ° C or more and 160 ° C or less. A compression molding method, an extrusion molding method, and a powder injection molding method can be used as methods for molding the feedstock. When the powder injection molding method is used in the molding step, the volume ratio of the mixed powder and the thermoplastic organic binder may be 6: 4 to 7: 3. When the warm compression molding method is used, the volume ratio of the mixed powder and the thermoplastic organic binder may be adjusted to a range of 7.5: 2.5 to 9: 1.

The molding temperature in the case of using the powder injection molding method or the warm compression molding method may vary depending on the type of the thermoplastic organic binder and the volume ratio of the mixed powder and the thermoplastic organic binder but may be set in a range of about 100 ° C to 160 ° C have. In the case of forming the feedstock using the warm compression molding method, a pressure of 20 MPa or more and 200 MPa or less may be applied.

According to one embodiment of the present invention, by using a feedstock comprising a thermoplastic organic binder serving as a lubricant, a product having a large aspect ratio or a complicated shape can be molded. In addition, since a density gradient in the formed body is hardly formed, non-uniform contraction in the sintering step can be suppressed and a high-density metal composite can be produced without distortion in shape.

The molding step can be performed at 20 MPa or higher and 200 MPa or lower in order to form a feedstock prepared by kneading a mixed powder containing a high alloy steel powder and a copper-containing powder and a thermoplastic organic binder. The powdery injection molding or hot compression molding of a feedstock having excellent flowability, in which the volume ratio of the mixed powder and the thermoplastic organic binder is in a range of 6: 4 to 9: 1, minimizes the density gradient inside the formed body, Can be minimized.

The degreasing step is a step of removing the thermoplastic organic binder from the formed body, and solvent extraction, heated degreasing, wicking, supercritical fluid degreasing may be used. In the degreasing step, when solvent extraction or supercritical fluid degreasing is used, only a surfactant component such as wax or stearic acid having a low melting point such as paraffin wax can be removed. Therefore, a heating degreasing method is further required to remove the backbone polymer do.

In the sintering step according to an embodiment of the present invention, the copper-containing powder having a low melting point mixed with the high alloy steel powder is melted and liquid-phase sintering is caused. In this process, the melted copper or copper alloy and high alloy steel powder are re-arranged by viscous flow, and high density can be achieved in a short time.

The sintering step may be performed in a mixed gas atmosphere in which the volume ratio of nitrogen gas or hydrogen gas is 9: 1.

By using a mixed gas obtained by adding hydrogen gas to the nitrogen gas, the oxygen component present in the copper-containing powder can be efficiently removed. However, in order to prevent decarburization in the high alloy steel powder, it may be preferable to use a mixed gas containing 10% by volume or less of hydrogen gas.

Since the liquid phase sintering occurs in the sintering step according to one embodiment of the present invention, a high density sintered body having a relative sintering density of 98% or more can be manufactured from the porous state of the sintered body. The sintering step may be performed at a temperature of 1140 DEG C or higher and 1250 DEG C or lower. However, when the sintering temperature is higher than 1250 ° C, the amount of the iron component dissolved in the molten copper is increased to increase the amount of the liquid phase to increase the slump. When the sintering temperature is lower than 1140 ° C, the densification of the sintered body is reduced It is preferable that sintering is performed at a temperature of 1140 DEG C or higher and 1250 DEG C or lower.

According to an embodiment of the present invention, there is provided a method of manufacturing a sintered body, the method including a heat treatment step of heat treating the sintered body after the sintering step, wherein the heat treatment step comprises austenitizing the sintered body at a temperature of 900 ° C to 1050 ° C, Deg.] C or less. The thermal conductivity of the metal composite to be produced can be improved by performing tempering at least once for at least one hour at a temperature of 400 DEG C or more and 650 DEG C or less.

2 is a diagram showing an equilibrium state diagram of a binary alloy system of iron and copper.

Referring to FIG. 2, iron and copper exhibit a certain degree of solubility at high temperatures, unlike W-Cu or Mo-Cu alloys, which are other metal complexes. However, there is a similarity to the other metal complexes in that liquid phase sintering is possible in the presence of molten copper due to a large difference in melting point between copper and iron, and such characteristics can be advantageous for producing a high-density sintered body. In FIG. 2, it can be seen that both the solubility of copper in iron in the solid state and the solubility of iron in copper are greatly reduced when the temperature is lowered. The reduction of the solute capacity as described above is effective for improving the thermal conductivity, and if the formation of the fine precipitate is accompanied, the decrease in the strength due to the reduction of the solute in the matrix can be compensated.

According to one embodiment of the present invention, when a metal composite is manufactured by using a high alloy steel powder and a copper-containing powder in which a secondary curing phenomenon occurs at about 550 ° C in place of iron, the metal composite is tempered at a temperature of from 400 ° C to 650 ° C The thermal conductivity can be improved without decreasing the hardness of the large width. That is, the use of the high alloy steel powder having hardness characteristics in which the secondary hardening phenomenon occurs during the tempering process after the heat treatment and the copper powder having a thermal conductivity of about 15 times or more higher than that of the high alloy steel can improve the hardness and thermal conductivity Metal complexes can be produced.

According to another embodiment of the present invention, there is provided a metal composite produced by a manufacturing method according to an embodiment of the present invention.

The metal composite according to another embodiment of the present invention can have high hardness and improved thermal conductivity. Therefore, the metal composite body according to another embodiment of the present invention can be used for automobile valve seat inserts, particularly automotive power train parts such as valve seat inserts for exhaust gases, valve guides, turbocharger bushings, and plastic injection mold parts, And parts requiring wear resistance.

Hereinafter, the present invention will be described in more detail with reference to examples. These embodiments are merely illustrative and do not limit the technical scope of the present invention.

Example 1

High alloy steel powder having an average particle size (D ₅₀ ) of 8 μm and a composition of Fe-12% Cr-0.4% Mn-0.4% Ni-0.9% Mo-0.4% V-0.5% Si-1.5% C (Manufactured by Atlantic International) having a particle size of not less than 1 占 퐉 and not more than 2 占 퐉 were prepared, and each of the high alloy steel powder and the copper-containing powder was mixed in an amount of 70 wt% , And 30 wt%, respectively. The mixing ratio of the mixed powder to the wax-based thermoplastic organic binder was 8: 2, and the mixture was press-kneaded at 140 ° C to prepare about 120 g of a feedstock. The feedstock was charged into a preheated mold at 120 DEG C and a pressure of 70 MPa was applied to produce a disk-shaped molded body specimen having a diameter of 20 mm and a height of 4 mm. The specimens were placed in an alumina tray and charged into a tubular furnace. The degreasing and sintering were set up in a single heating program, followed by thermal degreasing and sintering in a nitrogen gas atmosphere to produce sintered bodies. At this time, after degreasing in the heating process to about 600 ° C, the sintering temperature was increased to 1210 ° C, and the sintering was performed for 60 minutes.

Example 2

AISI D2 steel powder and copper-containing powder used in Example 1 were used in the same manner and uniformly mixed with a ball mill so that the AISI D2 steel powder, copper-containing powder and phosphorus were respectively 69.95 wt%, 30 wt% and 0.05 wt% . The mixed powder and the wax-based thermoplastic organic binder were mixed to have a volume ratio of 80:20 and press-kneaded at 140 ° C to prepare a feedstock of about 120 g. Compression molding at low pressure was carried out in the same manner as in Example 1 to prepare a disk-shaped molded body specimen having a diameter of 20 mm and a height of 4 mm. The sintered body was sintered at 1210 ℃ and the sintering time was 60 minutes. The sintering temperature was 1210 ℃ and the sintering time was 60 minutes. The sintered body was heated again to 980 占 폚, maintained for 30 minutes, and then heat-treated by heating in a bath of 550 占 폚 for 2 hours.

Example 3

The AISI D2 steel powder and the copper-containing powder used in Example 1 were used in the same manner, and a Tripalloy T-800 (manufactured by Kennametal-Stellite Co., Ltd.) having a -325 mesh size including AISI D2 steel powder, copper- Were uniformly mixed with a ball mill so that the powders were 60 wt%, 30 wt% and 10 wt%, respectively. The mixing ratio of the mixed powder to the wax-based thermoplastic organic binder was 8: 2, and the mixture was press-kneaded at 140 ° C to prepare about 120 g of a feedstock. Compression molding at low pressure was carried out in the same manner as in Example 1 to prepare a disk-shaped molded body specimen having a diameter of 20 mm and a height of 4 mm. The sintered body was sintered at 1210 ℃ and the sintering time was 60 minutes. The sintering temperature was 1210 ℃ and the sintering time was 60 minutes.

Example 4

The AISI D2 steel powder and the copper-containing powder used in Example 1 were used in the same manner and uniformly mixed with a ball mill so that the AISI D2 steel powder, the copper-containing powder and phosphorus were 69.99 wt%, 30 wt% and 0.01 wt%, respectively . The mixing ratio of the mixed powder to the wax-based thermoplastic organic binder was 8: 2, and the mixture was press-kneaded at 140 ° C to prepare about 120 g of a feedstock. Compression molding at low pressure was carried out in the same manner as in Example 1 to prepare a disk-shaped molded body specimen having a diameter of 20 mm and a height of 4 mm. The sintered body was sintered at 1210 ℃ and the sintering time was 60 minutes. The sintering temperature was 1210 ℃ and the sintering time was 60 minutes. The sintered body was heated again to 980 占 폚, maintained for 30 minutes, and then heat-treated at 600 占 폚 for 2 hours in a salt bath three times by tempering.

Example 5

High alloy steel powder having an average particle size (D ₅₀ ) of 10 μm and a composition of Fe-6.25% W-4.97% Mo-4.15% Cr-1.96% V-0.32% Si-0.31% Mn-1.10% C AISI M2 steel powder (manufactured by Epson-Art MIX Co., Ltd., Japan) and a copper-containing powder having a particle size of 1 占 퐉 or more and 2 占 퐉 or less (manufactured by Atlantic Instruments Inc.) were prepared and AISI M2 steel powder, copper- The mixture was homogeneously mixed with a ball mill so as to be 69.95 wt%, 30 wt%, and 0.05 wt%. The mixing ratio of the mixed powder to the wax-based thermoplastic organic binder was 8: 2, and the mixture was press-kneaded at 140 ° C to prepare about 120 g of a feedstock. Compression molding at low pressure was carried out in the same manner as in Example 1 to prepare a disk-shaped molded body specimen having a diameter of 20 mm and a height of 4 mm. The sintered body was sintered at a temperature of 1170 ℃ and the sintering time was 60 minutes.

Example 6

AISI M2 steel powder and copper-containing powder used in Example 5 were used in the same manner. WC having a WC carbide diameter of about 2 탆 was prepared, and AISI M2 steel powder, copper-containing powder, phosphorus and WC were each in an amount of 64.95 wt% , 30 wt%, 0.05 wt%, and 5 wt%, respectively. Compression molding at low pressure was carried out in the same manner as in Example 1 to prepare a disk-shaped molded body specimen having a diameter of 20 mm and a height of 4 mm. The sintered body was sintered at a temperature of 1195 ℃ and sintering time was 60 minutes. The sintering temperature was 1195 ℃ and the sintering time was 60 minutes.

Comparative Example 1

A sintered body was produced in the same manner as in Example 1, except that it was heated and degreased and sintered in an argon gas atmosphere.

Comparative Example 2

AISI D2 steel powder, copper-containing powder, and boron were uniformly mixed in a ball mill so that 84.99 wt%, 15 wt%, and 0.01 wt%, respectively, were produced.

Density and hardness measurements

The densities of the sintered bodies produced in Examples 1 to 6 and Comparative Examples 1 and 2 were measured at room temperature by a water displacement method using the principle of Archimedes. The hardness of the sintered body was measured so as to be represented by Rockwell hardness C scale. The density and hardness of the sintered bodies produced in Examples 1 to 6 and Comparative Examples 1 and 2 are shown in Table 1 below.

Relative density (%) Hardness (HRC) Example 1 99.1 44.3 Example 2 (before heat treatment) 99.6 44.9 Example 3 98.4 39.6 Example 4 (before heat treatment) 99.3 40.0 Example 5 99.9 44 Example 6 99.9 45 Comparative Example 1 94.9 28 Comparative Example 2 88 -

Thermal conductivity and hardness measurement

The thermal conductivity and hardness of the sintered body after the heat treatment of the sintered body manufactured in Example 2 and Example 4 were measured. The thermal conductivity of the sintered body was measured by laser flash method (German quasi-model LFA457) from room temperature to 300 ° C.

The thermal conductivity and hardness of the sintered body prepared in Example 2 after heat treatment are shown in Table 2 below.

Table 3 shows the thermal conductivity and hardness of the sintered body prepared in Example 4 after heat treatment.

Referring to Table 3, since the tempering temperature was slightly higher than the secondary hardening temperature, the hardness value was slightly lower but the thermal conductivity was increased. Also, compared to the case of one tempering, the thermal conductivity increased about 10% when tempering twice, but it was confirmed that the hardness value was lowered. It was confirmed that the three times of tempering under the above conditions did not affect the hardness value or the thermal conductivity.

Microstructure test of sintered body

3 is a view showing the microstructure of the sintered body manufactured in Example 1 of the present invention.

Referring to FIG. 3, it is the D2 steel in which copper is dissolved in granular form labeled with (1), and the copper matrix in which the iron component is solidified in (2). It was confirmed that the sintered body produced in Example 1 had a small amount of pores and the high alloyed steel particles formed a skeleton on the base of the copper alloy and a relatively fine structure was formed.

FIGS. 4A and 4B are diagrams showing the texture changes of the sintered body manufactured in Example 4 according to the heat treatment. FIG.

FIG. 4A is an optical microscope image of a microstructure after heat treatment of the sintered body manufactured in Example 4, and FIG. 4B is a scanning electron microscope backscattering electron image. Referring to FIGS. 4A and 4B, it can be seen that plate martensite is produced in the alloy phase particles, and that relatively coarse carbide is formed by tempering.

5A and 5B are views showing the microstructure of the sintered body manufactured in Example 6 of the present invention.

5A and 5B are micrographs of the optical microscope of the sintered body manufactured in Example 6. Referring to FIGS. 5A and 5B, it can be seen that copper, which is white, is connected to the channel to form a matrix.

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 rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

Claims (11)

Preparing a mixed powder comprising a high alloy steel powder having an average particle diameter of not less than 3 mu m and not more than 20 mu m and a copper-containing powder having an average particle diameter of not less than 1/10 and not more than 1/2 of an average particle diameter of the high alloy steel powder;
A kneading step of kneading the mixed powder and the thermoplastic organic binder to prepare a feedstock;
A shaping step of shaping the feedstock to produce a shaped body;
A degreasing step of removing the organic binder from the molded body;
A sintering step of sintering the formed body after the degreasing step to produce a dense sintered body; And
And a heat treatment step of heat-treating the sintered body,
The carbon content of the high alloy steel powder is 0.4 wt% or more and 2 wt% or less,
The weight ratio of the high alloy steel powder to the copper-containing powder is 8: 2 to 6: 4,
The heat treatment step may include a step of austenitizing the sintered body at a temperature of 900 ° C to 1050 ° C, followed by tempering at a temperature of 400 ° C to 650 ° C,
The high alloy steel powder is secondarily cured in the heat treatment step,
Wherein the high alloy steel powder further comprises silicon, manganese, chromium, molybdenum and vanadium,
The silicon content is 0.1 wt% or more and 0.8 wt% or less with respect to the high alloy steel powder;
The manganese content is 0.1 wt% or more and 1 wt% or less with respect to the high alloy steel powder;
The chromium content is 2 wt% or more and 15 wt% or less with respect to the high alloy steel powder;
The molybdenum content is 0.2 wt% or more and 8 wt% or less with respect to the high alloy steel powder;
The vanadium content is 0.001 wt% or more and 10 wt% or less with respect to the high alloy steel powder; And
The remainder is iron,
In the kneading step, the volume ratio of the mixed powder and the thermoplastic organic binder is 6: 4 to 9: 1,
The molding step is performed under a pressure of 20 MPa or more and 200 MPa or less,
Wherein the sintering step is performed at a temperature of 1140 DEG C or higher and 1250 DEG C or lower.
delete The method according to claim 1,
Wherein the high alloy steel powder further comprises at least one metal selected from the group consisting of cobalt, nickel and tungsten,
The cobalt content is 0.001 wt% or more and 5 wt% or less with respect to the high alloy steel powder;
The nickel content is 0.001 wt% or more and 3 wt% or less with respect to the high alloy steel powder;
Wherein the tungsten content is 0.001 wt% or more and 10 wt% or less with respect to the high alloy steel powder.
The method according to claim 1,
Wherein the copper-containing powder comprises tin and nickel,
The tin content is 0.1 wt% or more and 15 wt% or less with respect to the copper-containing powder;
The nickel content is 0.001 wt% or more and 10 wt% or less with respect to the copper-containing powder; And
And the remainder is copper.
The method according to claim 1,
Wherein the mixed powder further comprises at least one metalloid among carbon, boron and phosphorus,
Wherein the metalloid content of the mixed powder is 0.005 wt% or more and 0.3 wt% or less.
The method according to claim 1,
Wherein the mixed powder further comprises at least one compound powder selected from the group consisting of cobalt alloy powder on Laveth, iron alloy powder on Laveth, TiB ₂ , WC and TiC,
The content of the compound powder is 3 wt% or more and 20 wt% or less with respect to the mixed powder,
Wherein the cobalt alloy powder on the Laveth is Co-Mo-Si or Co-Cr-Mo, and the iron alloy powder on the Laveth is Fe-Mo-Si.
delete delete The method according to claim 1,
Wherein the sintering step is performed in a mixed gas atmosphere in which the volume ratio of nitrogen gas or hydrogen gas to hydrogen gas is 9: 1.
delete 11. A metal composite produced by the production method according to any one of claims 1 to 9.

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