KR101808437B1 - Fe-based alloy for metal injection molding and manufacturing method of the same - Google Patents

Abstract

The present invention relates to an Fe-based alloy for metal powder injection molding and a method of producing the Fe-based alloy for metal powder injection molding, wherein the Fe-based alloy comprises: 2.0-20.0 wt% of nickel (Ni); 0.1-1.0 wt% of silicon (Si); 0.1-0.5 wt% of molybdenum (Mo); 0.1-3.0 wt% of chromium (Cr); and the remaining consisting of iron (Fe) and inevitable impurities. According to the present invention, the Fe-based alloy for metal powder injection molding is excellent in mechanical properties and oxidation resistance; is able to be applied to various product groups through a metal powder injection molding process; and have enhanced mechanical properties using gas spray processes.

Description

FIELD OF THE INVENTION The present invention relates to an Fe-based alloy for metal powder injection molding,

TECHNICAL FIELD The present invention relates to an Fe-based alloy for metal powder injection molding, and more particularly to an Fe-based alloy for metal powder injection molding having enhanced oxidation resistance and an excellent hardness value and a method for producing the same.

Powder injection molding (PIM) process, which is one of near-net shaping molding technology, is a fusion of sintering technology of powder metallurgy industry and injection molding technology of plastic industry. It is used for manufacturing ceramics or metal or composite materials Has recently attracted a lot of attention. Ceramics, cemented carbide, metal, and composite materials, and it is possible to manufacture a three-dimensional complex product which can not be produced by conventional machining, precision casting and machining.

In recent years, the need for various functional characteristics or miniaturization in a wide range of industries such as automobiles, electronics, aerospace, and medical devices has been increasing, and the powder injection molding process is a solution to various functional characteristics and miniaturization. Particularly, the powder injection molding process can be mass-produced in the production of small or micro parts, and the cost can be reduced by about 20 to 30%. In addition, the final product resulting from the powder injection molding process has excellent physical properties and a precise surface roughness.

The powder characteristics of the metal powder injection molding (MIM) process, which is generally used, are spherical and have excellent flowability. The average particle diameter of the powder particles is 10 μm and the particle diameter of about 90% Powder particles of size 30 μm or less are in powder form suitable for metal powder injection molding. It is difficult to control the composition of the sintered material after the mixing and injection molding of a few micron metal powder used for injection molding of a commercialized metal powder, resulting in uneven microstructure and physical property deterioration of the final sintered material. In order to solve the problem of micron size powder, a method using nano size powder which maximizes the driving force of sintering has been applied. The nano-sized powders with increased driving force during sintering have the advantage of fully densifying at low temperatures in a short time and suppressing grain growth, but they have a strong tendency to form agglomerates with increased surface area. Such agglomerate powder generates uneven pore distribution in the formed body during molding to suppress sintering densification.

In the conventional metal powder injection molding, metal powder injection molding is performed by making a powder material having a size of several tens of micro or less through a carbonyl method. However, as gas-atomization researches have been actively conducted recently, an increase in gas temperature, And it is known that it is possible to produce powders having a size of less than 10 ㎛. Therefore, it is necessary to develop a multi-component alloy with improved mechanical properties by manufacturing powders through gas-atomization which is easy to design the multi-alloy system.

1. Korean Patent No. 10-1568383 2. Korean Patent No. 10-1375986

It is an object of the present invention to provide an Fe-based alloy for metal powder injection molding having enhanced oxidation resistance and an excellent hardness value.

It is another object of the present invention to provide a process for producing an Fe-based alloy for metal powder injection molding, the mechanical properties of which are enhanced by using a gas spraying process.

However, these problems are illustrative, and the technical idea of the present invention is not limited thereto.

Technical Solution According to an aspect of the present invention, there is provided an Fe-based alloy for metal powder injection molding comprising 2.0 to 20.0% by weight of nickel, 0.1 to 1.0% by weight of silicon, 0.1 to 0.5% by weight of molybdenum, By weight and 0.1 to 3.0% by weight of chromium (Cr), and the balance of iron (Fe) and unavoidable impurities.

In some embodiments of the present invention, the content of nickel (Ni) may be 10.0 to 20.0 wt%.

In some embodiments of the present invention, the content of chromium (Cr) may be 1.0 to 2.0 wt%.

According to an aspect of the present invention, there is provided an Fe-based alloy for metal powder injection molding comprising 2.0 to 20.0% by weight of nickel (Ni), 0.1 to 1% by weight of silicon (Si), 0.1 to 0.5% by weight of molybdenum 0.1 to 3.0% by weight of chromium (Cr) and 0.05 to 0.3% by weight of carbon (C), and the balance of iron (Fe) and unavoidable impurities.

In some embodiments of the present invention, the content of nickel (Ni) may be 10.0 to 20.0 wt%.

In some embodiments of the present invention, the content of chromium (Cr) may be 1.0 to 2.0 wt%.

In some embodiments of the present invention, the content of carbon (C) may be 0.15 to 0.2% by weight.

In some embodiments of the present invention, the Vickers hardness (Hv) of the Fe-based alloy for metal powder injection molding may be 340 to 423.

According to an aspect of the present invention, there is provided a method of manufacturing an Fe-based metal composite powder for metal powder injection molding, comprising the steps of weighing the Fe-based alloy component and mixing the raw material, Metal composite powder according to the present invention.

In some embodiments of the present invention, the metal composite powder manufacturing step includes the steps of: The mixed alloy raw material is heated to produce a molten metal, and the molten metal is sprayed with a gas to produce a metal composite powder.

In some embodiments of the present invention, there is provided a method of making an alloy, the method comprising: arc melting the mixed alloy raw material to produce a parent alloy in the form of a button; fabricating the ribbon using a rapid solidification spinning method; In the form of a powder.

In some embodiments of the present invention, the metal composite powder may have an average particle size of 20 mu m or less in diameter.

The Fe-based alloy for metal powder injection molding according to the technical idea of the present invention is excellent in mechanical properties and oxidation resistance and can be applied to various product groups through a metal powder injection molding process.

The method for manufacturing an Fe-based alloy for metal powder injection molding according to the technical idea of the present invention can produce an Fe-based alloy for metal powder injection molding with enhanced mechanical properties by using a gas spraying process.

The effects of the present invention described above are exemplarily described, and the scope of the present invention is not limited by these effects.

Fig. 1 is a microstructure obtained by corroding the cross section of a quaternary alloy sintered body of Fe-Ni-1Si-0.5Mo.
2 shows an XRD phase analysis result of a quaternary alloy of Fe-Ni-Si-Mo.
Fig. 3 shows micro-Vickers hardness measurement results of a quaternary alloy of Fe-Ni-Si-Mo.
4 is a graph showing the high-temperature oxidation behavior of a quaternary alloy sintered body of Fe-Ni-Si-Mo.
Fig. 5 is a photograph showing a comparison of the thicknesses of oxide layers after Fe-Ni-Si-Mo high-temperature oxidation experiment of quaternary alloy sintered body.
6 is a microstructure obtained by corroding a 5-element alloy sintered body section of Fe-Ni-Si-Mo-Cr according to an embodiment of the present invention.
FIG. 7 shows XRD analysis results of a Fe-Ni-Si-Mo-Cr binary alloy according to an embodiment of the present invention.
FIG. 8 shows micro-Vickers hardness measurement results of a Fe-Ni-Si-Mo-Cr 5-element alloy according to an embodiment of the present invention.
9 is a graph showing a high-temperature oxidation behavior of a Fe-Ni-Si-Mo-Cr sintered body of a five-element alloy according to an embodiment of the present invention.
FIG. 10 is a photograph showing a comparison of thicknesses of oxide layers after Fe-Ni-Si-Mo-Cr high temperature oxidation experiment of a 5-element alloy sintered body according to an embodiment of the present invention.
Fig. 11 is a microstructure obtained by corroding a 6-element alloy sintered body section of Fe-Ni-Si-Mo-Cr-C according to an embodiment of the present invention.
FIG. 12 shows XRD analysis results of a Fe-Ni-Si-Mo-Cr-C six-element alloy according to an embodiment of the present invention.
FIG. 13 shows micro-Vickers hardness measurement results of a Fe-Ni-Si-Mo-Cr-C hexagonal system alloy according to an embodiment of the present invention.
14 is a graph showing a high-temperature oxidation behavior of a Fe-Ni-Si-Mo-Cr-C sintered body of a six-element alloy according to an embodiment of the present invention.
15 is a photograph showing a comparison of the thicknesses of the oxide layers after the high temperature oxidation experiment of the Fe-Ni-Si-Mo-Cr-C six-element alloy sintered body according to the embodiment of the present invention.
FIG. 16 is a microstructure obtained by corroding a Fe-Ni-Si-Mo-Cr-C six-element alloy according to an embodiment of the present invention and a commercially available Fe-8Ni alloy sintered body for MIM.
17 shows XRD analysis results of a Fe-Ni-Si-Mo-Cr-C 6-element alloy according to an embodiment of the present invention and a commercially available Fe-8Ni alloy for MIM.
18 is a micro-Vickers hardness measurement result of a Fe-Ni-Si-Mo-Cr-C six-element alloy and a commercially available Fe-8Ni alloy for MIM according to an embodiment of the present invention.
19 is a graph showing a high temperature oxidation behavior of a Fe-Ni-Si-Mo-Cr-C six-element alloy and a commercially available Fe-8Ni alloy sintered body for MIM according to an embodiment of the present invention.
FIG. 20 is a photograph showing a comparison of the thicknesses of six-element alloys of Fe-Ni-Si-Mo-Cr-C according to an embodiment of the present invention and the thicknesses of oxide layers after the high temperature oxidation experiment of a commercially available Fe-8Ni alloy sintered body for MIM.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. The scope of technical thought is not limited to the following examples. Rather, these embodiments are provided so that this disclosure will be more thorough and complete, and will fully convey the scope of the invention to those skilled in the art. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items. The same reference numerals denote the same elements at all times. Further, various elements and regions in the drawings are schematically drawn. Accordingly, the technical spirit of the present invention is not limited by the relative size or spacing depicted in the accompanying drawings.

The Fe-based alloy for metal powder injection molding according to the present invention may include nickel (Ni), silicon (Si), molybdenum (Mo) and chromium (Cr), and the balance may be iron (Fe) and unavoidable impurities.

The nickel (Ni) may include 2.0 to 20.0% by weight. Fig. 3 shows micro-Vickers hardness measurement results of a quaternary alloy of Fe-Ni-Si-Mo. As shown in FIG. 3, hardness due to solid solution strengthening tends to increase as nickel (Ni) content increases in a quaternary sintered body (Fe-xNi-1Si-0.5Mo) added with 2.0 to 10.0 wt% .

In particular, the nickel (Ni) may include 10.0 to 20.0% by weight. (Fe-xNi-1Si-0.5Mo) added with 20.0 wt% of nickel (Ni) shows a tendency to decrease in hardness, but when it contains 10.0 to 20.0 wt% of nickel (Ni) Or more.

4 is a graph showing a high temperature oxidation behavior of a quaternary alloy sintered body of Fe-Ni-Si-Mo, and FIG. 5 is a photograph showing a comparison of thicknesses of an oxide layer after a high temperature oxidation experiment of a quaternary alloy sintered body of Fe-Ni-Si-Mo. As shown in FIG. 4, when the nickel (Ni) content is increased, the weight increase is decreased. As shown in FIG. 5, as the Ni content is increased, the oxidation layer is thinned and the oxidation resistance is enhanced.

The silicon (Si) may include 0.1 to 1.0% by weight. When the content of silicon (Si) is excessively added, it has an advantage of increasing the hardness, the elastic limit, the tensile strength, etc. However, it has a disadvantage of decreasing the impact value and elongation. In order to compensate for this disadvantage, the addition of silicon (Si) in an amount of less than 1.0% hardly increases the strength and the elongation, so that the disadvantages can be compensated by adding 0.1 to 1.0% of silicon (Si).

The chrome (Cr) may include 0.1 to 3.0% by weight. Fig. 8 shows micro-Vickers hardness measurement results of Fe-Ni-Si-Mo-Cr 5-element alloys. (Fe-10Ni-1Si-0.5Mo) in which the hardness of chromium (Cr) added quinary system sintered body (Fe-10Ni-1Si-0.5Mo-xCr) Relative to the hardness of < / RTI >

Fig. 9 is a graph showing the high temperature oxidation behavior of a Fe-Ni-Si-Mo-Cr sintered body of a five-component alloy, It is a photograph. As the chromium (Cr) content increases, the weight increase tendency decreases. As the chromium (Cr) content increases, the thickness of the oxide layer decreases. Therefore, oxidation resistance can be enhanced by the addition of chromium (Cr).

In particular, the content of chromium (Cr) may be 1.0 to 2.0% by weight. When the content of chromium (Cr) is 1.0 to 2.0% by weight, the decrease in the amount of weight increase tends to be conspicuous as compared with the case where the content of chromium (Cr) is 0.5% by weight.

The molybdenum (Mo) may include 0.1 to 0.5% by weight. Molybdenum (Mo) together with chromium (Cr) slows down the pearlitic transformation and forms a two-stage transformation region. The addition of 0.5 wt% molybdenum (Mo) (Mo) is added, the tensile strength, elongation and density due to the formation of carbide are reduced. Mo can be added in an amount of 0.1 to 0.5 wt%.

The Fe-based alloy for metal powder injection molding according to the present invention comprises 2.0 to 20.0% by weight of nickel (Ni), 0.1 to 1% by weight of silicon (Si), 0.1 to 0.5% by weight of molybdenum (Mo) By weight and carbon (C) in an amount of 0.05 to 0.3% by weight, and the balance of iron (Fe) and unavoidable impurities.

The content of nickel (Ni) may be 2.0 to 20.0% by weight. As shown in FIG. 3 to FIG. 5, when the high temperature oxidation behavior is confirmed, the weight increase amount tends to decrease as the nickel (Ni) content increases. As the nickel (Ni) content increases, the oxidation layer becomes thinner. In addition, hardness due to solid solution strengthening tends to increase as the content of nickel (Ni) increases in a quaternary sintered body (Fe-xNi-1Si-0.5Mo) containing 2.0 to 10.0 wt% of Ni.

In particular, the nickel (Ni) may include 10.0 to 20.0% by weight. (Fe-xNi-1Si-0.5Mo) added with 20.0 wt% of nickel (Ni) shows a tendency to decrease in hardness, but when it contains 10.0 to 20.0 wt% of nickel (Ni) Or more.

The chrome (Cr) may include 0.1 to 3.0% by weight. As shown in Figs. 8 to 10, the quaternary sintered body (Fe-10Ni-1Si-0.5Mo-xCr) to which chromium (Cr) 0.5Mo), and the weight increase is decreased as the chromium (Cr) content is increased. As the chromium (Cr) content is increased, the thickness of the oxide layer is decreased. The oxidation resistance can be enhanced.

In particular, the content of chromium (Cr) may be 1.0 to 2.0% by weight. When the content of chromium (Cr) is 1.0 to 2.0% by weight, the decrease in the amount of weight increase tends to be conspicuous as compared with the case where the content of chromium (Cr) is 0.5% by weight.

The content of the carbon (C) may be 0.05 to 0.3 wt%. Fig. 13 shows micro-Vickers hardness measurement results of a Fe-Ni-Si-Mo-Cr-C hexagonal system alloy. As shown in FIG. 13, when the content of carbon (C) is 0.05% by weight, it shows an excellent hardness value of 350 Hv or more. When the content of carbon (C) is increased, the hardness increases and the hardness value is 420 Hv or more when it is 0.2% by weight.

In particular, the content of the carbon (C) may be 0.15 to 0.2% by weight. Fig. 14 is a graph showing the high-temperature oxidation behavior of a Fe-Ni-Si-Mo-Cr-C sintered body of a six-element system alloy. (Fe-10Ni-1Si-0.5Mo-2.0Cr-0.2C) added with 0.2 wt% was found to have a composition of (Fe-10Ni-1Si-0.5Mo-2.0Cr) without addition of C, indicating that the hardness and oxidation resistance are excellent.

The Fe-based alloy for metal powder injection molding may have a Vickers hardness (Hv) of 340 to 423.

The method for producing an Fe-based metal composite powder for metal powder injection molding according to the present invention includes the steps of weighing the Fe-based alloy component and mixing the raw materials, and preparing a metal composite powder using the mixed alloy raw material .

The step of preparing the metal composite powder comprises: The mixed alloy raw material is heated to produce a molten metal, and the molten metal is sprayed with a gas to produce a metal composite powder. It is possible to easily use a multi-component alloy by preparing a metal composite powder using a gas atomization method, and the mechanical properties can also be improved.

Arc melting the mixed alloy raw material to produce a parent alloy in the form of a button, making the parent alloy using a rapid solidification spinning method, and pulverizing the ribbon into a powder form .

The metal composite powder may have an average particle size of 20 mu m or less in diameter. And can be produced suitably for metal powder injection molding. Mixing the metal composite powder prepared according to the method for preparing an Fe-based metal composite powder with a binder to form a molding mixture; And molding and sintering the molded mixture by powder injection, so that metal powder injection molding can be performed. The powder injection molding process can be mass-produced in the production of small or micro parts, which can result in a cost reduction of about 20 to 30%. In addition, the final product resulting from the powder injection molding process can have excellent physical properties and precise surface roughness.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof. However, the following examples are merely illustrative of the present invention, and the present invention is not limited to the following examples.

1. Specimen Manufacturing

First, the bulk metal raw materials and purity used for preparing Fe-Ni based parent alloys are commercially available raw materials for reagents and include electrolytic iron (Fe), nickel (Ni), silicon (Si), molybdenum (Mo) , Carbon (C) were used, and button - type parent alloy was manufactured by using arc melting equipment. The amount of the sample used in one dissolution was 10 g.

In order to realize the rapid solidification structure that can be obtained through the gas-atomization process, the button-type master alloy manufactured by the arc melting process is manufactured by melt spinning process such as gas-atomization and ribbon solid specimen Respectively.

In order to pulverize the ribbon produced by the rapid coagulation method, melt spinning process, into a powder form, the ribbon was cut into a specimen having a size of about 0.8 × 0.4 cm, and then a rotary mill (Pulverizer, FRITSCH) The specimen was crushed.

2. Discharge plasma sintering

2.5 g of powder was charged into a graphite mold having a diameter of 10 mm and molded and sintered using a discharge plasma sintering apparatus (Dr. Sinter, Sumitomo Coal Mining, maximum load: 10 tons). During sintering, the graphite mold was maintained at a constant compressive load of 60 MPa, and then heated at a rate of 100 ° C / min from 800 ° C to 800 ° C, and at a rate of 25 ° C / min at a temperature of 900 ° C After holding for 10 minutes, a sintered body was produced.

3. Microstructure analysis

In order to observe the microstructure of the sintered body manufactured by the SPS process, the part to be observed from # 100 to # 4000 using a sand paper was polished so as to have a minute mirror surface, and then, using 1 μm and 0.05 μm Al ₂ O ₃ After polishing, it was corroded with 3% Nital etchant (3 ml HNO ₃ + 97 ml Ethanol) and dried thoroughly. Microstructures were observed using Scanning electron microscopy (Tescan; Mila LHM) equipment.

4. XRD Phase Analysis

Diffraction analysis was performed using an X-ray diffraction analyzer (XRD: MiniFlex 600: Rigaku) to analyze the phase of the sintered body manufactured by the SPS process. The surface of the sintered body to be analyzed was flattened using a sand paper so as to be horizontal and XRD phase analysis was performed using a Cu Kα target (λ = 1.5404 Å). The current was 15 mA and the tube voltage was 40 kV The phase analysis was performed by continuous scanning at a rate of 4 ° / min between 30 ° and 100 ° in the 2θ range.

5. Vickers hardness test

In order to observe the physical properties of the sintered body manufactured using the SPS process, the microstructure of the sintered body was measured with a micro - Vickers hardness tester at a constant interval of 200 g under a load of 15 times, and the average values except for the maximum value and the minimum value were shown.

6. High Temperature Oxidation Experiment

The sintered body produced by the discharge plasma sintering process was maintained at 1000 ℃ for 1 hour, and then was air - cooled in an atmospheric air atmosphere.

(1) Comparative Example 1. A Fe-Ni-1Si-0.5Mo quaternary system

Quaternary alloy alloys were tested for the purpose of improving the physical properties by adding 1.0 Si (wt%) and 0.5 Mo (wt%) in the Fe-Ni binary alloys.

Fig. 1 is a microstructure obtained by corroding the cross section of a quaternary alloy sintered body of Fe-Ni-1Si-0.5Mo. Fe-2Ni-1Si-0.5Mo (wt%) and Fe-5Ni-1Si-0.5Mo (wt%) sintered bodies showed ferrite structure, 1Si-0.5Mo (wt%) sintered body was observed to have martensite structure of acicular structure.

FIG. 2 shows the results of analysis of a quaternary XRD phase of Fe-Ni-Si-Mo produced by a discharge plasma sintering process. The Fe-2Ni-1Si-0.5Mo (wt%) and Fe-5Ni-1Si-Mo0.5 (wt%) sintered bodies showed Ni- The sintered body of 1Si-0.5Mo (wt%) and Fe-20Ni-1Si-0.5Mo (wt%) showed an α-martensite phase in which Ni was solid-dissolved in Fe having a BCC structure having the same crystal structure as that of the equilibrium ferrite.

The sintered body of Fe-Ni-Si-Mo quaternary system prepared by the discharge plasma sintering process was investigated by using 1Si (wt%) and 0.5Mo (wt%) added to the sintered Fe-Ni binary system. The micro-Vickers hardness measurement results are shown in Fig. As a result of the Vickers hardness measurement, it was confirmed that the hardness of Fe-Ni-Si-Mo quaternary sintered body was relatively increased when compared with the hardness of Fe-Ni binary system sintered body.

In the Fe-Ni-Si-Mo quartz sintered body, hardness was increased with increasing Ni content in the sintered body added up to 2, 5 and 10Ni (wt%) but hardness was decreased in the sintered body added with 20Ni (wt% I could confirm. As shown in FIG. 1, it is judged that the grain size is coarser than that of the quaternary system having a Ni content of 20Ni (wt%) and a hardness of 10Ni (wt%).

FIG. 4 is a graph showing a high-temperature oxidation behavior of a quaternary sintered body of Fe-Ni-Si-Mo produced by a discharge plasma sintering process. In order to investigate the oxidation behavior at high temperature, the oxidation was carried out at 1000 ℃ for 1 hour under atmospheric conditions. As a result of the high temperature oxidation test, it was observed that there was a linear oxidation latent period about 17 minutes before the start of oxidation and a parabolic oxidation behavior was observed about 17 minutes later. The Fe-Ni-Si-Mo quaternary system was not observed in the Fe-Ni binary system due to the addition of 1.0 Si (wt%) and 0.5 Mo (wt%). In the high temperature oxidation test of sintered body, the weight increase was decreased with increasing Ni content.

FIG. 5 is a photograph showing the comparison of the thickness of the oxide layer after the high-temperature oxidation experiment. It was found that the increase in weight was insignificant when compared with the Fe-Ni binary sintered body due to the addition of 1.0 Si (wt%) and 0.5 Mo 5Ni-1Si-0.5Mo (wt%) sintered body was decreased than that of the Ni-1Ni-1Si-0.5Mo (wt%) sintered body and the thickness of the oxide film decreased as the Ni content increased I could confirm.

(2) Example 1. Fe-10Ni-1Si-0.5Mo-Cr 5-element system

The hardness of the Fe-Ni-1Si-0.5Mo sintered body of Fe-Ni-1Si-0.5Mo was measured and found to be the highest at the Fe-10Ni-1Si-0.5Mo composition with 10wt% %, And then Cr content, which is an element for improving oxidation resistance, was added.

FIG. 6 is a graph showing the relationship between the Ni content and the Cr content of the Fe-Ni-1Si-0.5Mo quaternary alloy, which was obtained by fixing the Ni content to 10 wt% The microstructure obtained by polishing the sintered body with sand paper and polished with Al2O3 and then corroding the section of the sintered body to observe the Nital 3% corrosion solution.

FIG. 7 shows the results of 5-element XRD analysis of Fe-Ni-Si-Mo-Cr produced by the discharge plasma sintering process. The peak of the crystal phase obtained by XRD analysis was analyzed by sintered body of Fe-Ni-Si-Mo-Cr 5-element alloy using JCPDS program. As a result, it was found that the Ni content was 10 wt% alpha 'martensite phase was observed.

Fig. 8 shows the result of measurement of the microvigic hardness in order to confirm the physical properties of the Fe-Ni-Si-Mo-Cr sintered body produced by the discharge plasma sintering process. The hardness of Fe-Ni-Si-Mo-Cr sintered body was measured to be higher than the hardness of Fe-10Ni-1Si-0.5Mo (wt%) sintered body. However, in the Fe-Ni-Si-Mo-Cr sintered body, the hardness of the 5-element sintered body added with 1.0 Cr (wt%) content was lower than that of the 5-element sintered body containing 0.5 Cr (wt%), The highest hardness value of HV 366.7 was obtained for the pentasic sinter added with 2.0Cr (wt%).

FIG. 9 is a graph showing the high-temperature oxidation behavior of a Fe-Ni-Si-Mo-Cr sintered body produced using a discharge plasma sintering process. In order to investigate the oxidation behavior at high temperature, the oxidation was carried out at 1000 ℃ for 1 hour under atmospheric conditions. As a result of the high temperature oxidation experiments, the parabolic oxidation behavior was shown, and the Fe-Ni-Si-Mo-Cr sintered body of Fe-Ni-Si-Mo-Cr added with a small amount of Cr composition was relatively higher than that of the quaternary sintered Fe- The weight increase over time was reduced. In addition, as the Cr content of the Fe-Ni-Si-Mo-Cr sintered body increases, the weight increase is decreased and the oxidation resistance is increased.

FIG. 10 is a photograph of a comparison of the thicknesses of the oxide layers after the high-temperature oxidation experiment. It is seen that the oxide film thickness of the Fe-10Ni-1Si-0.5Mo-2Cr sintered body is smaller than that of the Fe-10Ni-1Si-0.5Mo-0.5Cr sintered body. The oxidation resistance was increased.

3) Example 2. Fe-10Ni-1Si-0.5Mo-2Cr-0.2C 6-element system

The hardness of the Fe-10Ni-1Si-0.5Mo-Cr sintered body of Fe-10Ni-1Si-0.5Mo-2.0Cr with Cr content of 2.0wt% In order to improve the hardness due to strengthening of solid solution of C element after fixing the Cr content to 2.0wt% by the excellent, the C content was added and the experiment of the hexagonal system alloy was carried out.

FIG. 11 is a graph showing the relationship between the Cr content of the Fe-10Ni-1Si-0.5Mo-Cr alloy and the Fe content of the Fe-10Ni-1Si-0.5Mo-Cr alloy The microstructures of the sintered compacts were observed. The martensite structure was observed.

FIG. 12 shows the results of the analysis of the Fe-Ni-Si-Mo-Cr-C 6-element XRD phase produced by the discharge plasma sintering process. As a result of the phase analysis, Fe with BCC structure was analyzed as α 'martensite phase with Ni solid.

Fig. 13 shows the micro-Vickers hardness measurement results to confirm the physical properties of the hexagonal system according to the addition of the C content to the sintered Fe-Ni-Si-Mo-Cr-C system produced by the discharge plasma sintering process. Vickers hardness showed the tendency of increasing hardness as C content increased due to hardening of solid solution with addition of C, and Fe-10Ni-1Si-0.5Mo-2Cr-0.2C composition showed the highest hardness value as Hv 423 hardness value Respectively.

FIG. 14 is a graph showing a high-temperature oxidation behavior of a Fe-Ni-Si-Mo-Cr-C sintered body produced using a discharge plasma sintering process. Fig. 15 is a photograph showing the comparison of thicknesses of oxide layers after Fe-Ni-Si-Mo-Cr-C high-temperature oxidation experiment of a six-element alloy sintered body.

In order to investigate the oxidation behavior at high temperature, the oxidation was carried out at 1000 ℃ for 1 hour under atmospheric conditions. As a result of the high temperature oxidation test, there was a linear oxidation latent period about 10 minutes before and after about 10 minutes, the S - shaped high temperature oxidation behavior appeared. The change in the amount of increase in weight was slight when comparing the compositions of Fe-Ni-Si-Mo-Cr-C added with 0.05C (wt%) and 0.1C (wt%). The Fe-10Ni-1Si-0.5Mo-2Cr-0.2C composition showed a tendency to decrease compared to the weight increase of Fe-10Ni-1Si-0.5Mo-2Cr composition without addition of C, -0.5Mo-2Cr-0.2C composition was judged to have the best hardness and oxidation resistance.

Comparative Example 2. Commercialized Fe-8Ni powder for MIM

As a result of the previous research, it was judged that the composition of Fe-10Ni-1Si-0.5Mo-2Cr-0.2C had the most excellent hardness and oxidation resistance. The Fe-8Ni (wt%) binary powder for MIM was compared with the hexagonal system.

16 is a graph showing the relationship between the sintering temperature and the sintering temperature of a sintered body obtained by sintering at a conventional sintering temperature and pressure using a discharge plasma sintering process and a six-element system composition of Fe-8Ni (wt%) powder and Fe-10Ni-1Si-0.5Mo-2Cr- Of the microstructure.

FIG. 17 shows the result of analysis of sintered Fe-8Ni (wt%) sintered body and Fe-10Ni-1Si-0.5Mo-2Cr-0.2C sintered body XRD phase by a discharge plasma sintering process. As a result of the XRD analysis, a hexagonal sintered body of Fe-10Ni-1Si-0.5Mo-2Cr-0.2C was found to have an α-martensite phase in which Ni was solid-dissolved in Fe having a BCC structure and a commercially available Fe-8Ni (wt% The γ-phase in which Ni was dissolved in Fe was observed.

18 shows the hardness measurement results of the sintered Fe-8Ni (wt%) sintered body and Fe-10Ni-1Si-0.5Mo-2Cr-0.2C sintered body. As shown in Fig. 18, the hardness of the Fe-10Ni-1Si-0.5Mo-2Cr-0.2C hexagonal sintered body was higher than that of the Fe-8Ni (wt%) powder sintered body.

FIG. 19 is a graph showing a weight increase amount of a sintered Fe-8Ni (wt%) sintered body and Fe-10Ni-1Si-0.5Mo-2Cr-0.2C sintered body according to time. The Fe-10Ni-1Si-0.5Mo-2Cr-0.2C sintered body showed a decrease in the weight increase over time compared with the Fe-8Ni (wt%) sintered body, The oxidation resistance of the 0.5Mo-2Cr-0.2C hexagonal sintered body was considered to be superior to that of Fe-8Ni (wt%) sintered body.

20 shows the thickness of the oxide layer after the high-temperature oxidation behavior of the sintered Fe-8Ni (wt%) sintered body and Fe-10Ni-1Si-0.5Mo-2Cr-0.2C sintered body. The thickness of the oxide layer was lower than that of the Fe-8Ni (wt%) sintered Fe-10Ni-1Si-0.5Mo-2Cr-0.2C sintered body. It is considered that this is due to the increase of oxidation resistance caused by the oxidation.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. Will be apparent to those of ordinary skill in the art.

Claims (12)

(Fe) and the balance of iron (Fe), and the balance of the iron (Fe) and the iron (Fe) It is made of unavoidable impurities,
Vickers hardness (Hv) is 340 to 423,
An Fe-based alloy for metal powder injection molding having a weight increase of not more than 16 mg / cm ² in a high-temperature oxidation test conducted at 1000 ° C for 1 hour in an air atmosphere.
The method according to claim 1,
Wherein the content of nickel (Ni) is 10.0 to 12.0 wt%.
delete (Si), 0.1 to 1.0 wt% of molybdenum (Mo), 1.0 to 2.0 wt% of chromium (Cr), and 0.05 to 0.3 wt% of carbon (C) And the remainder is made of iron (Fe) and unavoidable impurities,
Vickers hardness (Hv) is 340 to 423,
An Fe-based alloy for metal powder injection molding having a weight gain of 14 mg / cm ² or less in a high-temperature oxidation test conducted at 1000 ° C. for 1 hour in an air atmosphere.
5. The method of claim 4,
And the content of nickel (Ni) is 10.0 to 20.0% by weight.
delete 5. The method of claim 4,
And the carbon (C) content is 0.15 to 0.2 wt%.
delete Weighing the Fe-based alloy component of any one of claims 1, 2, 4, 5, and 7 to mix the raw materials; And
And a step of preparing a metal composite powder by using the mixed alloy raw material.
[10] The method of claim 9,
Heating the mixed alloy raw material to prepare a molten metal; And
And spraying the molten metal with a gas to produce a metal composite powder.
[10] The method of claim 9,
Arc melting the mixed alloy raw material to produce a button-shaped master alloy;
Preparing the parent alloy using the rapid solidification spinning method; And
And pulverizing the ribbon in a powder form. The method for producing a Fe-based metal composite powder for metal powder injection molding according to claim 1,
10. The method of claim 9,
Wherein the metal composite powder has a particle size of 20 mu m or less in diameter.

Images