KR102284812B1 - Method for manufacturing sintered body made of composite powder - Google Patents

Abstract

The present invention relates to a method for manufacturing a sintered body made of composite powder having high strength, corrosion resistance and high thermal conductivity. More particularly, the present invention provides a method for manufacturing a sintered body made of composite powder, which mixes iron-based metal powder, copper powder, and a binder to form a sintered body, degreases and sinters the same to obtain ferrous-based metallic rigidity and high thermal conductivity of copper metal at the same time, enables the production of complex-shaped parts, and minimizes the machining process to reduce material loss and enable mass production.

Description

Method for manufacturing sintered body made of composite powder

The present invention relates to a method of manufacturing a sintered body made of a composite powder having a plurality of different characteristics compatible, and specifically, an injection molded body is formed by mixing iron-based metal powder, copper powder, and a binder, followed by degreasing and sintering to obtain iron-based metal powder. In a method for manufacturing a sintered body made of a composite powder that satisfies the mechanical rigidity, simultaneously satisfies the high thermal conductivity of copper metal, enables the manufacture of complex shaped parts, reduces material loss by minimizing the processing process, and enables mass production. it's about

Autonomous vehicles are being applied to parts in various fields such as IT technology, sensor technology, and cameras.

As the fuel efficiency decreases when the vehicle becomes heavy, it is necessary to slim and lighten the electronic device, and as the continuous sensing and data processing speed increase, a lot of energy is consumed. In order to eliminate the generated heat, there is a need for a material with high thermal conductivity, and a material satisfying the strength and corrosion resistance required for a housing material of an electronic device is required.

Republic of Korea Patent Publication No. 10-2018-0113487

The present invention relates to a method of manufacturing a sintered body made of a composite powder having a plurality of different characteristics compatible, and specifically, an injection molded body is formed by mixing iron-based metal powder, copper powder, and a binder, followed by degreasing and sintering to obtain iron-based metal powder. Manufacture of a sintered compact made of composite powder that satisfies mechanical rigidity and corrosion resistance, satisfies the high thermal conductivity of copper metal at the same time, enables the manufacture of complex shaped parts, reduces material loss by minimizing the processing process, and enables mass production The purpose is to provide a method.

A method for manufacturing a sintered body made of a composite powder according to an embodiment of the present invention comprises the steps of: preparing a feedstock, which is a raw material for injection molding, by mixing an iron-based metal powder, a copper powder, and a binder; molding the molded body by injecting the prepared feedstock into a mold having a predetermined shape using an injection molding machine; solvent degreasing the binder of the molded article; Secondary heating and degreasing the solvent degreased molded body in a hot air degreasing furnace; It characterized in that it comprises; sintering the second heat degreased molded body.

The iron-based metal powder is characterized in that any one of stainless steel powder, high carbon steel powder, chromium molybdenum steel powder, high carbon chromium bearing steel powder, and high temperature corrosion resistant steel powder.

The method for manufacturing a sintered body made of a composite powder according to an embodiment of the present invention is characterized in that the particle size of the iron-based metal powder is a spherical powder larger than the particle size of the copper powder. The particle size of the iron-based metal powder: the copper powder has a particle size of 1:1, preferably 1: 1/3 to 3/4.

The iron-based metal powder is a spherical powder having a particle size of 1 to 25 μm, and the copper powder is a spherical powder having a particle size of 1 to 25 μm, preferably a spherical powder having a particle size of 5 to 16 μm of the iron-based metal powder, copper powder Silver is a spherical powder with a particle size of 5 to 12㎛, and the concentration of oxygen is 1,000ppm or less.

The iron-based metal powder contains 60 to 90% by volume, and the copper powder includes 10 to 40% by volume. Preferably, the iron-based metal powder is 65 to 85% by volume, and the copper powder is 15 to 35% by volume.

In the method of manufacturing a sintered body made of a composite powder according to an embodiment of the present invention, the binder is 60 to 75 vol% of POM (polyacetal), at least one wax selected from the group consisting of carnauba wax or paraffin wax 10 to 25% by volume, polycarbonate (PC), polypropylene (PP), polyethylene (polyethylene; PE) characterized in that it consists of 5 to 15% by volume of one or more polymers selected from the group consisting of.

In the method for manufacturing a sintered body made of a composite powder according to an embodiment of the present invention, the solvent degreasing process is performed by placing the product in a water tank maintained at 70 to 90 ° C. The process is characterized in that the binder is removed by hot air degreasing by raising the temperature from room temperature to 600° C. in a hydrogen atmosphere.

In the method for manufacturing a sintered body made of composite powder according to an embodiment of the present invention, after the secondary heating degreasing process, in a hydrogen atmosphere, the copper melting temperature ~ melting temperature + 50 ° C. temperature range for 1 to 3 hours and then cooling It is characterized in that the sintering process is added.

The sintered body manufactured by the manufacturing method of the present invention is characterized in that it is for a housing accommodating the PCB substrate of the electronic component.

The sintered compact manufactured by the manufacturing method of the present invention is characterized in that it is for electromagnetic wave shielding of electronic components.

The present invention relates to the mechanical rigidity and corrosion resistance of iron-based metals by mixing copper (Cu) powder and a binder with iron-based metal powder, molding an injection molded body, degreasing, and sintering to produce a sintered body in which iron-based metal powder and copper powder are mixed. , it can have the high thermal conductivity of copper metal at the same time, and it is possible to manufacture complex shaped parts by minimizing the processing process, and has the effect of lowering the material loss rate and enabling mass production.

In addition, the present invention has the effect of providing a sintered body in which iron-based metal powder and copper powder are mixed, which can be universally used for electronic parts and mechanical parts, etc. having high thermal conductivity and electrical conductivity, and electromagnetic wave shielding properties and soft magnetic properties.

1 is a flowchart showing a method for manufacturing a sintered body made of a composite powder having high strength, corrosion resistance, and high thermal conductivity according to the present invention. It is a schematic diagram before and after sintering in the case of volume %. FIG. 3 is a schematic diagram before and after sintering when the ratio of iron-based metal powder and copper powder according to the present invention is 60% by volume: 40% by volume. It is a graph showing the temperature increase process and the holding time in the sintering process after the secondary heating degreasing process of Examples 1 to 4 among the manufacturing methods. It is a graph showing the temperature increase process and the holding time in the process.

Hereinafter, embodiments of the method for manufacturing a sintered body made of a composite powder having high strength, corrosion resistance, and high thermal conductivity of the present invention will be described in more detail. In addition, in describing the present invention, detailed descriptions of related known general-purpose configurations or functions will be omitted.

Hereinafter, "upper", "downward", "front" and "rear" and other directional terms are defined based on the state defined in the specification.

1 is a flowchart showing a method of manufacturing a sintered body made of a composite powder having improved high strength, corrosion resistance, and high thermal conductivity according to the present invention.

Referring to Figure 1, the method for manufacturing a sintered body made of a composite powder having high strength, corrosion resistance, and high thermal conductivity according to the present invention is a feedstock raw material for injection molding by mixing iron-based metal powder, copper powder, and a binder. preparing a; molding the molded body by injecting the prepared feedstock into a mold having a predetermined shape using an injection molding machine; solvent degreasing the binder of the molded article; Secondary heating and degreasing the solvent degreased molded body in a hot air degreasing furnace; It provides a method of manufacturing a sintered body made of a composite powder having high strength, corrosion resistance, and high thermal conductivity, including; sintering the second heat degreased molded body.

More specifically, the present invention comprises the steps of preparing a raw material iron-based metal powder and copper powder, a binder; kneading the iron-based metal powder, the copper powder, and a binder; molding the molded body by injecting the prepared feedstock into a mold having a predetermined shape using an injection molding machine; degreasing the binder in the molded body by charging a POM (polyacetal) binder in the molded body into a degreasing facility containing normal hexane as a solvent; Secondary degreasing of carnauba wax or paraffin wax binder remaining in the molded body by heating the degreased product to a high temperature; By continuously raising the temperature of the secondary degreased molded body, it is sintered to thermally decompose polycarbonate (PC), polypropylene (PP), and polyethylene (PE), which are polymers for back bone binder, and the melting temperature of copper metal ~ The melting temperature of the copper metal + a sintering step of sintering in a temperature range of 50 ℃; provides a method of manufacturing a sintered body made of a composite powder comprising a.

The iron-based metal powder is any one of stainless steel powder, high carbon steel powder, chromium molybdenum steel powder, high carbon chromium bearing steel powder, and high temperature corrosion resistant steel powder.

In the method for manufacturing a sintered body made of a composite powder having high strength, corrosion resistance, and high thermal conductivity according to an embodiment of the present invention, the particle size of the iron-based metal powder and the particle size of the copper powder are the same, or the particle size of the iron-based metal powder is copper powder It is characterized in that it is a spherical powder larger than the particle size of The particle size of the iron-based metal powder: the copper powder has a particle size of 1:1, preferably 1: 1/3 to 3/4.

The iron-based metal powder is a spherical powder having a particle size of 1 to 25 μm, and the copper powder is a spherical powder having a particle size of 1 to 25 μm, preferably a spherical powder having a particle size of 5 to 16 μm of the iron-based metal powder, copper powder Silver is a spherical powder with a particle size of 5 to 12㎛, and the concentration of oxygen is 1,000ppm or less.

As described above, by adjusting the particle size ratio of the iron-based metal powder and the copper powder, the copper powder located between the iron-based metal powder is dissolved in the sintering step, so that the copper is melted in the pores located between the pores and the iron-based metal powder. By filling the pores with the copper powder, it is possible to prevent the formation of pores in the sintered body, thereby increasing the density after sintering.

That is, in the present invention, by using a copper powder having a relatively small particle size compared to the iron-based metal powder, the filling rate of the mixed powder can be improved by placing the copper-containing powder in the gap between the iron-based metal powders loosely filled in the forming 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 powder dissolved at the sintering temperature in the sintering step forms a liquid phase and fills the gap between the iron-based metal powder during the aggregation process, By improving densification through rearrangement of particles flowing with the iron-based metal powder, a high-density sintered body can be manufactured without forming large pores therein.

2 is a schematic diagram before and after sintering when the ratio of the iron-based metal powder to the copper powder according to the present invention is 80% by volume: 20% by volume, and FIG. 3 is the ratio of the iron-based metal powder to the copper powder according to the present invention is 60 Volume %: It is a schematic diagram before and after sintering in the case of 40% by volume.

Hereinafter, a schematic diagram according to the ratio of the iron-based metal powder and the copper powder of FIGS. 2 and 3 will be described with reference to FIG.

The iron-based metal powder contains 60 to 90% by volume, and the copper powder includes 10 to 40% by volume. Preferably, the iron-based metal powder contains 65 to 85% by volume, and the copper powder contains 15 to 35% by volume.

When the composition ratio of the copper powder is less than 10% by volume, the composition ratio of the copper powder located between the iron-based metal powders is small, and the content of copper melted between the iron-based metal powders is small, so the thermal conductivity is relatively low, but the composition ratio of the copper powder When it is increased to 40% by volume, most of the copper powder is filled in the pores between the iron-based metal powders, so the content of molten copper is increased and the thermal conductivity is relatively high, but when the composition ratio of the copper powder exceeds 40% by volume, the Since the amount of copper powder is excessive and flows to the lower part of the sintered body even after filling all the pores between the iron-based metal powder, the composition ratio of the copper powder is sufficient with a maximum of 40% by volume.

In the method for manufacturing a sintered body made of a composite powder having high strength, corrosion resistance, and high thermal conductivity according to an embodiment of the present invention, the binder includes 60 to 75 vol% of POM (polyacetal), carnauba wax or paraffin wax 10 to 25% by volume of one or more waxes selected from the group, 5 to 15% by volume of one or more polymers selected from the group comprising polycarbonate (PC), polypropylene (PP), and polyethylene (PE) as characterized in that it is composed.

In the method for manufacturing a sintered compact made of a composite powder having high strength, corrosion resistance, and high thermal conductivity according to an embodiment of the present invention, the solvent degreasing process is performed by placing the product in a water tank maintained at 70 to 90 ° C. Degreased for more than an hour, and the secondary heating degreasing process is characterized in that the binder is removed by hot air degreasing by raising the temperature from room temperature to 600° C. under a hydrogen atmosphere.

The method for manufacturing a sintered body made of a composite powder having high strength, corrosion resistance, and high thermal conductivity according to an embodiment of the present invention is, after the secondary heating degreasing process, a hydrogen atmosphere and a melting temperature of copper ~ melting temperature of copper + 50 ° C. It is characterized in that the sintering process of cooling after maintaining in the temperature range for 1 to 3 hours is added.

In the sintering step according to an embodiment of the present invention, the copper powder is melted and liquid phase sintering to fill the pores between the iron-based metal powder occurs, so a high-density sintered body having a relative sintering density of 98% or more can be manufactured from the degreasing body in a porous state. . The sintering step may be performed in a temperature range from the melting temperature of copper to the melting temperature of copper + 50°C.

However, when the sintering temperature is 50°C or higher than the melting temperature of copper, the flowability of the molten copper is excessive and flows downward even after filling the pores between the iron-based metal powders, and the molten copper filled in the pores between the iron-based metal powders of the sintered body The molten copper that was filled in the pores between the iron-based metal powders flows down and flows down, and some pores between the iron-based powders placed on the top are not filled with molten copper, which may cause a problem of lowering the thermal conductivity.

The copper powder preferably has an oxygen concentration of 1,000 ppm or less. When the oxygen concentration of the copper powder is high, the amount of oxide on the surface of the copper powder increases, so that the thermal conductivity and electrical conductivity are lowered, and there is a problem of heat generation. It is desirable to keep the oxygen concentration below 1,000 ppm.

Through the sintering process, the copper powder is melted to cover the surface of the iron-based metal powder, so that the copper metal is connected to each other as a whole of the sintered body.

As such, the mechanical strength and corrosion resistance are maintained in a high state by the iron-based metal powder, and the thermal conductivity can be maintained in a high state by the copper metal surrounding the iron-based metal powder by melting.

Since the sintered body of the present invention is made of a composite powder, it may have a plurality of different characteristics, mechanical strength, corrosion resistance, and thermal conductivity in parallel.

The sintered body produced by the manufacturing method of the present invention is lower than the strength and corrosion resistance of iron-based metals, but has higher strength and corrosion resistance than copper metal, and has lower thermal conductivity than copper metal, but has higher thermal conductivity than iron-based metal you will have the advantage you have.

In other words, the sintered body made of the composite powder of the dissimilar metal powder according to the present invention can be used as a housing for accommodating the PCB substrate of electronic components requiring strength and thermal conductivity within a predetermined range or as an electromagnetic wave shielding material that must shield electromagnetic waves. there will be

Hereinafter, to help the understanding of the present invention, examples will be described in detail. However, the following examples are merely illustrative of the contents of the present invention, and the scope of the present invention is not limited to the following examples. The embodiments of the present invention are provided to more completely explain the present invention to those of ordinary skill in the art.

<Example 1> Preparation of composite powder sintered body

90% by volume of a spherical powder having a particle size of 5 to 16㎛ of stainless steel powder and 10% by volume of a copper powder having a particle size of 5 to 12㎛ and an oxygen concentration of 1,000ppm or less POM 75%, wax 15%, A feedstock for injection molding was prepared by mixing it with a binder having a composition of 10% PE, and then it was put into an injection molding machine and injected into the mold. The injected molded product is charged into a water tank maintained at a solution temperature of 80°C, degreasing is performed for 24 hours while supplying a solvent, Normal Hexane, and then the temperature is raised from room temperature to 600°C in a hydrogen atmosphere to remove the binder by hot air degreasing. In a hydrogen gas atmosphere, a molded article having a relative sintering density of 98.03% was prepared when the molded article was maintained at a copper melting temperature + 30° C. for 2 hours in a sintering furnace and cooled.

<Example 2> Preparation of composite powder sintered body

In Example 2, 80% by volume of stainless steel powder, 20% by volume of copper powder, and a process of heating and degreasing by mixing a binder, temperature of the sintering step, and gas atmosphere were prepared under the same conditions as in Example 1.

The relative sintered density of the sintered compact obtained under these conditions is 98.10%.

<Example 3> Preparation of composite powder sintered compact

In Example 3, 70 vol% of stainless steel powder, 30 vol% of copper powder, and a process of heating and degreasing by mixing a binder, temperature of the sintering step, and gas atmosphere were prepared under the same conditions as in Example 1.

The relative sintered density of the sintered compact obtained under these conditions is 98.15%.

<Example 4> Preparation of composite powder sintered body

Example 4 is 60% by volume of stainless steel powder and 40% by volume of copper powder. The process of heating and degreasing by mixing the binder, the temperature of the sintering step, and the gas atmosphere were prepared under the same conditions as in Example 1.

The relative sintered density of the sintered compact obtained under these conditions is 98.18%.

<Example 5> Preparation of composite powder sintered body

Example 5 was the same as Example 1 until the process of heating and degreasing by mixing stainless steel powder, copper powder, and binder, except that the temperature of the sintering step was different.

For sintering, a final product with a relative sintering density of 98.27% was obtained when the molded product was maintained at 1335° C. for 2 hours in a sintering furnace under a single gas condition of hydrogen gas and cooled.

<Experimental Example 1> Physical property analysis

The tensile strength, thermal conductivity, and corrosion resistance of the molded articles of Examples 1 to 5 were measured and shown in Table 1 below.

The tensile strength was conducted using Instron's model name 4885P, and the cross head speed was 05 mm/min.

The heat conduction wool was measured using the model name LFA457 of Netzsch, Germany.

Example 1 Example 2 Example 3 Example 4 Example 5 note The tensile strength
(300 N/㎟) 458 437 410 388 364 Compared to stainless steel (70-88%) thermal conductivity
(W/m·K) 17.6 25.3 33.1 51.0 52.5 Compared to stainless steel
(113-337%) corrosion resistance 24hr 24hr 24hr 24hr 24hr Contrast stainless steel
(50%)

Looking at Table 1, the tensile strength and hardness are 70-88% of tensile strength compared to commercially available stainless steel, compared to stainless steel It showed thermal conductivity of 113-337% and corrosion resistance of 50% compared to stainless steel.

4 is a graph showing the temperature increase process and the holding time in the sintering process after the secondary heating degreasing process of Examples 1 to 4 of the manufacturing method of the present invention.

5 is a graph showing the temperature increase process and the holding time in the sintering process after the secondary heating degreasing process of Example 5 of the manufacturing method of the present invention.

As shown in the graphs of FIGS. 4 and 5, the binder remaining in the solvent degreased molded body is gradually degreased through a number of different temperature raising processes and holding time at a specific temperature in a hydrogen atmosphere to eliminate the adverse effects caused by the binder remaining during sintering. could

4 is a graph showing the temperature increase process and the holding time in the sintering process after the secondary heating degreasing process of Examples 1 to 4 of the manufacturing method of the present invention.

Copper powder melt is filled between the stainless steel powders through the heating and degreasing molded body of FIG. 4 through 4 steps of temperature raising process and 4 holding times (sintering temperature of 1100° C.), and bonding and densification between the stainless steel powders are made to achieve sintering density can be increased, and mechanical strength, corrosion resistance, and thermal conductivity can be improved.

The copper powder melt is filled between the stainless steel powders through the heating and degreasing molded body of FIG. 5 through the heating process of 4 steps and the holding time (sintering temperature of 1335° C.) 4 times. Although the mechanical strength, corrosion resistance, and thermal conductivity could be improved, the copper melt temperature was high, so the copper filled between the stainless steel powders could not be maintained between the stainless steel powders and flowed down to the bottom.

As the specific parts of the present invention have been described in detail above, for those of ordinary skill in the art, it is clear that these specific descriptions are only preferred embodiments, and the scope of the present invention is not limited thereby. will be.

Accordingly, it is intended that the substantial scope of the present invention be defined by the appended claims and their equivalents.

Claims (6)

preparing a feedstock, a raw material for injection molding, by mixing iron-based metal powder, copper powder, and a binder; molding the molded body by injecting the prepared feedstock into a mold having a predetermined shape using an injection molding machine; Solvent degreasing the binder of the manufactured molded body; Secondary heating and degreasing the solvent-degreasing molded body in a hot air degreasing furnace; Including; sintering the secondary heat degreased molded body;
After the secondary heating degreasing process, a sintering process of cooling after maintaining for 1 to 3 hours in a hydrogen atmosphere and in a temperature range of the melting temperature of copper to the melting temperature of copper + 50 ° C is added. manufacturing method. The method of claim 1,
The method of manufacturing a sintered body made of a composite powder, characterized in that the iron-based metal is 60 to 90 volume %, and the copper powder is 10 to 40 volume %. The method of claim 1,
The iron-based metal is a spherical powder having a particle size of 1 to 25 μm, the copper powder is a spherical powder having a particle size of 1 to 25 μm, and the oxygen concentration is 1,000 ppm or less. The method of claim 1,
The binder is 60 to 75 volume % of POM (polyacetal), 10 to 25 volume % of one or more waxes selected from the group containing carnauba wax or paraffin wax, polycarbonate (PC), polypropylene (PP) ), a method for producing a sintered body made of a composite powder, characterized in that 5 to 15% by volume of one or more polymers selected from the group comprising polyethylene (PE). According to claim 1, In the solvent degreasing process, the product is placed in a water tank maintained at 70 to 90 ° C. and a solvent is supplied to degrease for 24 hours or more, and the secondary heating degreasing process is performed by raising the temperature from room temperature to 600 ° C under a hydrogen atmosphere. A method of manufacturing a sintered body made of a composite powder, characterized in that the binder is removed by hot air degreasing. delete

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