JP2017122276A - Method of manufacturing heat-resistant component using granules - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a heat-resistant component using granules.SOLUTION: A method includes: a step of preparing granules by spraying a mixture including a metal powder and a slurry material into a housing equipped with a disc and rotating the disc; a step of preparing a molded object by compression-molding the granules; a step of preparing a sintered object by sintering the molded object at 1,000 to 1,600°C; and a step of adjusting dimensions by cutting the sintered object, wherein the housing is sealed and hot air at 70 to 200°C is supplied into the housing.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for producing a heat-resistant component using granules.

  Recently, there is an increasing demand for industrial parts with excellent dimensional accuracy and mechanical properties.

  Such industrial parts can be manufactured using powder metallurgy technology or metal powder injection molding technology. The powder metallurgy technique is a technique for producing a metal molded body having a predetermined shape by compressing and molding metal powder.

  FIG. 1 shows a powder metallurgy method. Referring to FIG. 1, the powder metallurgy method may include a forming step, a sintering step, and a cutting step.

  For example, in the powder metallurgy method, (S1) a metal powder is mixed with a binder as a binder and then compressed into an ingot, and then a product is manufactured in a shape as designed through cutting or pressing. (S2) a sintering step in which the product subjected to the molding step is heated in a sintering furnace; and (S3) a cutting step in which the product subjected to the sintering step is ground or cut to a designed size. Can do.

  According to the powder metallurgy method, since a coarse powder having a particle size of 50 μm to 200 μm is used, it is difficult to ensure the mechanical properties of the product, that is, density, strength, hardness, etc. There was a problem that can not be used in.

  In the molding step, when metal powder is put into a mold and compressed, the compression strength can be increased to improve the mechanical properties, but in this case, the mold is damaged, so that the compression strength is increased. There was a limit. Therefore, there is a problem that a subsequent process such as forging or heat treatment is required.

  In the powder metallurgy method, a powder having a coarse particle size (50 μm to 200 μm) must be used to ensure moldability and produce a uniform product. The coarse powder forms large pores in the compact during molding, and such large pores act as a factor that reduces densification of the compact.

  On the other hand, the metal powder injection molding technique uses fine metal particles having a diameter of only about 5 μm to about 10 μm. Attempts have been made to apply fine metal particles used in the metal powder injection molding during the powder metallurgy, but when the fine metal particles with the diameter are applied, the mold is densely filled by the cohesive force between the particles. Therefore, there is a problem that non-uniform density occurs during molding. Moreover, since the filling amount was not constant, the uniformity of the product was lowered.

  And the finer the powder, the more difficult it is to cause plastic deformation, so it receives a lot of stress in the powder state, which is a factor that can cause cracks during heat treatment and is smaller than the tolerance between molds. Since powder induces damage to the mold, it is problematic to apply powder metallurgy with fine powder.

  FIG. 2 is a view showing a metal powder injection molding method. Referring to FIG. 2, the metal powder injection molding method includes (S100) a kneading step, (S200) an injection molding step, (S300) a degreasing step, (S400) a sintering step, and (S500) a cutting step. Can do.

  More specifically, the metal powder injection molding method is a mixing step in which a metal powder and a binder as a binder are mixed by a mixer; the mixture that has passed through the mixing step is injected into an injection molding machine and compression molded. An injection molding stage for producing a product in the shape as designed; a degreasing stage for removing the binder by heating the product after the injection molding stage in a degreasing furnace; a sintering stage for heating the product after the degreasing stage in a sintering furnace And a cutting step of grinding or cutting the product after the sintering step to a designed size.

  The degreasing step is included to ensure the fluidity of the metal powder in the injection molding machine. Also, binders such as waxes and polymers may remain as carbon during heat treatment under inert atmosphere conditions and are therefore removed through a degreasing step.

  In addition, when performing the metal powder injection molding method, the degreasing step requires a troublesome heating from room temperature to 1000 ° C. for 12 to 60 hours. For this reason, there has been a problem that productivity is lowered, fuel cost is increased, and production cost is increased. Patent Document 1 has presented a method for manufacturing a heat-resistant steel part including such a degreasing step.

  Further, the shrinkage rate of the powder metallurgy method is 1% to 5%, whereas the shrinkage rate of the metal powder injection molding method is 12% to 22%, and the shrinkage rate is very large. There is a problem that it is difficult to control.

Korean Registered Patent No. 10-120462

  One aspect of the present invention relates to a method for manufacturing a heat-resistant component using granules.

  In one embodiment, the method for manufacturing a heat-resistant component includes a step of injecting a mixture including a metal powder and a slurry material into a housing provided with a disk, and rotating the disk to produce a granule; Forming a molded body by molding; sintering the molded body at 1000 ° C. to 1600 ° C. to produce a sintered body; and cutting the sintered body to adjust the dimensions; The housing is sealed and supplied with hot air of 70 ° C to 200 ° C.

  In one embodiment, the metal powder includes carbon (C): 0.1 wt% to 3 wt%, silicon (Si): more than 0 and less than 5 wt%, manganese (Mn): more than 0 and less than 15 wt%, phosphorus (P): 0 over 1% by weight, sulfur (S): over 0 over 1% by weight, nickel (Ni): over 0 over 90% by weight, iron (Fe): over 0 over 50% by weight, and chromium ( Cr): More than 0 and 50 wt% or less can be included.

  In one embodiment, the granules may have an average diameter of 20 μm to 200 μm.

  In one embodiment, the metal powder may have an average diameter of 0.01 μm to 50 μm, and the metal powder may have a diameter distribution of 0.001 μm to 100 μm.

  In one embodiment, the mixture may have a solid phase ratio (S / L) of 10% to 45% by volume.

  In one embodiment, the rotational speed of the disk may be 4000 rpm to 20000 rpm.

  In one embodiment, the slurry material may include a solvent and a binder.

  In one embodiment, the solvent may include one or more of water, hexane, acetone, and alcohol having 1 to 10 carbon atoms.

  In one embodiment, the binder may include one or more of polyvinyl butyral (PVB), polyvinyl alcohol (PVA), wax (Wax), and polyethylene glycol (PEG). .

In one embodiment, the compression molding may be performed at a pressure of ^{0.1ton / cm 2 ~10ton / cm 2} .

  An object of the present invention is to provide a method for producing a heat-resistant component capable of producing spherical granules and filling the granules uniformly into the mold.

  Another object of the present invention is to provide a method for producing a heat-resistant component having excellent press formability and excellent mechanical strength of a sintered sintered body.

  Still another object of the present invention is to provide a method for manufacturing a heat-resistant component that has excellent product surface and internal quality and molding density, and that can minimize product shrinkage.

  Still another object of the present invention is to provide a method for producing a heat-resistant component that is excellent in productivity and advantageous in terms of process time and energy.

FIG. 1 shows a powder metallurgy method. FIG. 2 is a view showing a metal powder injection molding method. FIG. 3 is a view showing a method for manufacturing a heat-resistant component according to an embodiment of the present invention. FIG. 4 is a view showing a granule manufacturing method according to an embodiment of the present invention. FIG. 5 is a view showing a granule manufacturing method according to an embodiment of the present invention. FIG. 6 is a view showing a molding machine for producing granules according to an embodiment of the present invention. FIG. 7A is an optical micrograph showing the metal powder used in the example of the present invention, and FIG. 7B is an optical micrograph showing the granule produced by the example of the present invention. . FIG. 8 (a) is an optical micrograph of the granule of the example according to the present invention, FIG. 8 (b) is an optical micrograph of the granule of the comparative example for the present invention, and FIG. 8 (c) is for the present invention. It is an optical microscope photograph of the granule of a comparative example. FIG. 9A is an optical micrograph of the granule of the example according to the present invention, and FIG. 9B is an optical micrograph of the granule of the comparative example with respect to the present invention. FIG. 10A is a photograph of the heat-resistant component of the example according to the present invention, and FIG. 10B is an X-ray photograph of the heat-resistant component of FIG. 10A. FIG. 11A is a photograph showing a heat-resistant component of an example according to the present invention, and FIG. 11B is a photograph showing a heat-resistant component of a comparative example with respect to the present invention. 12A is a photograph showing a heat-resistant component of a comparative example for the present invention, FIG. 12B is a photograph showing a heat-resistant component of an embodiment according to the present invention, and FIG. 12 (a) is a photograph obtained by heat-treating the heat-resistant component of the comparative example, and FIG. 12 (d) is a photograph obtained by heat-treating the heat-resistant component of the embodiment of FIG. 12 (b). FIG. 13A is an electron micrograph showing the microstructure of the heat-resistant component of the comparative example of the present invention, and FIG. 13B is an electron micrograph showing the microstructure of the heat-resistant component of the example according to the present invention. FIG. 13C is an electron micrograph showing the microstructure after heat-treating the heat-resistant component of the comparative example, and FIG. 13D is the microstructure after heat-treating the heat-resistant component of the example. It is the electron micrograph which showed. FIG. 14A is an electron micrograph showing a surface oxide layer formed after heat-treating a heat-resistant component of an example according to the present invention under atmospheric conditions, and FIG. 14B is a continuous view of the heat-resistant component of the example. 4 is an electron micrograph showing a surface oxide layer formed after heat treatment in an annealing furnace.

  Hereinafter, embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily carry out the embodiments. The present invention may be embodied in various different forms and is not limited to the embodiments described herein. In order to clearly describe the present invention in the drawings, portions not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

[Method of manufacturing heat-resistant parts using granules]
One aspect of the present invention relates to a method for manufacturing a heat-resistant component using granules. FIG. 3 is a view showing a method for manufacturing a heat-resistant component according to an embodiment of the present invention. Referring to FIG. 3, the heat-resistant component manufacturing method includes (S10) granule manufacturing stage; (S20) molded body manufacturing stage; (S30) sintered body manufacturing stage; and (S40) cutting stage.

  More specifically, in the method for producing the heat-resistant component, (S10) a step of injecting a mixture containing a metal powder and a slurry material into a housing provided with a disk, and rotating the disk to produce a granule; (S20) A step of filling the granule into a mold and compression-molding to produce a molded body; (S30) sintering the molded body at 1000 ° C. to 1600 ° C. in a sintering furnace and then cooling and sintering. Manufacturing the body; and (S40) cutting the sintered body and adjusting the dimensions.

  Hereinafter, the method for manufacturing the heat-resistant component will be described in detail step by step.

[(S10) Granule production stage]
The step is a step of injecting a mixture containing metal powder and slurry material into a housing provided with a disk, and rotating the disk to produce granules.

  FIG. 4 is a view showing a granule manufacturing method according to an embodiment of the present invention. Referring to FIG. 4, the granules may be manufactured including (S11) a mixture manufacturing stage; and (S12) a drying stage.

[(S11) Mixture production stage]
The step is a step of manufacturing a mixture including a metal powder and a slurry material.

[Metal powder]
In one embodiment, the metal powder may have an average diameter of 0.01 μm to 50 μm. On the other hand, in the present invention, the “diameter” is defined as the maximum length of the metal powder. When applying the metal powder having the average diameter, spherical granules can be easily manufactured, and the granules can be uniformly filled in a mold, and a heat-resistant product having excellent mechanical properties can be manufactured. .

  The diameter distribution of the metal powder may be 0.001 μm to 100 μm (90% or more of the powder). Granules can be easily produced with the diameter distribution.

  In one embodiment, the metal powder may be a metal powder for heat-resistant parts applied to diesel and gasoline turbocharger engines. The metal powder for heat-resistant parts can contain 18% or more of chromium.

  In one embodiment, the metal powder includes carbon (C): 0.1 wt% to 3 wt%, silicon (Si): more than 0 and less than 5 wt%, manganese (Mn): more than 0 and less than 15 wt%, phosphorus (P): 0 over 1% by weight, sulfur (S): over 0 over 1% by weight, nickel (Ni): over 0 over 90% by weight, iron (Fe): over 0 over 50% by weight, and chromium ( Cr): More than 0 and 50 wt% or less can be included. When included in the above range, the mechanical strength of the heat-resistant component of the present invention can be excellent.

  For example, the metal powder includes carbon (C): 0.2 wt% to 0.5 wt%, silicon (Si): 0.75 wt% to 1.3 wt%, manganese (Mn): more than 0. 5 wt% or less, molybdenum (Mo): 0.2 wt% to 0.3 wt%, chromium (Cr): 24 wt% to 27 wt%, nickel (Ni): 19 wt% to 22 wt%, niobium ( Nb): 1% by weight to 1.75% by weight and the balance iron (Fe) and other inevitable impurities. When included in the above range, the mechanical strength of the heat-resistant component of the present invention can be excellent.

  In one embodiment, HK-30 (ASTM standard) can be used as the metal powder. Since HK-30 has excellent heat resistance, it can be used for a high-temperature chemical apparatus or a heat treatment port.

  In one embodiment, the metal powder may have a solid loading (S / L) of 10% by volume to 45% by volume. On the other hand, the solid phase ratio is represented by the volume ratio of the metal powder to the total volume of the mixture. Since the mixing ratio and the moldability are excellent at the solid phase ratio in the above range, the granules can be easily produced. For example, it may be 13 volume% to 40 volume%.

[Slurry material]
The slurry material ensures fluidity of the mixture so that the metal powder can be injected into the housing.

  In one embodiment, the slurry material may include a solvent and a binder.

[solvent]
The solvent may be included for the purpose of ensuring fluidity and mixing properties of the mixture. In one embodiment, the solvent can be volatile. In the present specification, the term “volatile” means that the solvent evaporates in a temperature range of 70 ° C. to 200 ° C. when drying using hot air described later.

  In one embodiment, the solvent may include one or more of water, hexane, acetone, and alcohol having 1 to 10 carbon atoms. When the solvent is used, the fluidity and mixing properties are excellent, and granules can be easily produced.

  In one embodiment, the alcohol having 1 to 10 carbon atoms includes monohydric alcohols such as methanol, ethanol, butanol, pentanol, and hexanol, 1,2-pentanediol, 1,5-pentanediol, hexanediol, and heptane. Dihydric alcohols such as diol, octanediol and decanediol, and trihydric alcohols such as propylene glycol, 1,3-butylene glycol and glycerin can be used. These may be used alone or in combination of two or more.

  In another embodiment, the solvent may be included in an amount of 50 to 90 parts by volume with respect to 100 parts by volume of the mixed slurry. For example, 60 to 70 volume parts may be included. For example, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89 or 90 volumes may be included.

[binder]
The binder may be included for the purpose of forming the metal powder into granules. In one embodiment, the binder may include one or more of polyvinyl butyral (PVB), polyvinyl alcohol (PVA), wax (Wax), and polyethylene glycol (PEG). . When the binder is included, the granule formation effect can be excellent.

  In one embodiment, the binder may be included in an amount of 0.01 to 5 parts by weight with respect to 100 parts by weight of the metal powder. Spherical granules containing in the above volume range can be easily produced. For example, 0.5 to 5 parts by weight may be included. For example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.5, 1, 1. 5, 2, 2.5, 3, 4 or 5 parts by weight may be included.

  In one embodiment, the solvent may include ethanol. In one embodiment, the binder may include polyvinyl butyral (PVB). When applying a slurry material including the solvent and a binder, the effect of preventing oxidation of the metal powder may be excellent.

  In another embodiment, the metal powder and the binder may be included in a weight ratio of 100: 0.01 to 100: 6. When included in the weight ratio, the mixing property, workability, and moldability are excellent, and the granules can be easily produced. For example, it may be included in a weight ratio of 100: 0.5 to 100: 2.

  FIG. 5 is a view showing a granule manufacturing method according to an embodiment of the present invention. Referring to FIG. 5, in one embodiment, the mixture may be prepared by adding metal powder 10 to a solvent 20 and dispersing the mixture, and adding a binder 12.

  In another embodiment, a slurry in which the metal powder 10 is mixed can be manufactured by adding the solvent 20 to the container and then mixing (dissolving) the binder 12 in the solvent 20. Alternatively, the solvent, the binder, and the metal powder may be charged into a ball mill containing balls and mixed to produce a mixture. Further, the slurry can be produced using a normal mixer other than the ball mill. In one embodiment, the mixture may be prepared by mixing using a mixer for 1-2 hours.

[(S12) Drying stage]
The step is a step of injecting the mixture into a housing provided with a disk, and rotating the disk to dry the solvent to produce granules.

  FIG. 6 is a view showing a molding machine 1000 for producing granules according to an embodiment of the present invention. Referring to FIG. 6, the molding machine 1000 may include a housing 200 having a rotatable disk 300.

  For example, the mixture can be sprayed onto the housing 200 provided with the disk 300, and the disk 300 can be rotated to dry the solvent contained in the mixture to produce granules. In one embodiment, the housing 200 is hermetically sealed and can be exhausted by supplying hot air therein.

  As shown in FIGS. 5 (d) and 5 (e), the jetted mixture forms a lump of spherical particles due to surface tension while the disk 300 rotates, and the solvent is dried to form granules 100. Is done.

  In one embodiment, hot air of 70 ° C. to 200 ° C. is supplied to the housing 200. When the disk is rotated while supplying hot air under the above conditions, the binder is not decomposed and the granule formation rate and granule formation rate can be excellent. When hot air of less than 70 ° C. is supplied to the housing, the mixture is not completely dried, so that the shape of the granules becomes poor and the mechanical properties and appearance of the heat-resistant parts are reduced. When excessive hot air is supplied, the binder component in the mixture is decomposed, and the shape of the granule becomes poor, which may deteriorate the mechanical properties and appearance of the heat-resistant component. For example, hot air of 80 ° C. to 150 ° C. can be supplied. For example, hot air of 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 160, 170, 180, 190 or 200 ° C. is supplied Can be done.

  In one embodiment, the rotational speed of the disk may be 4000 rpm to 20000 rpm. Efficient drying can be performed at the rotation speed, and the spherical granule formation rate can be excellent. For example, it can be 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, 10000, 11000, 12000, 13000, 14000, 15000, 16000, 17000, 18000, 19000 or 20000 rpm. .

  In one embodiment, the granules may have an average diameter of 20 μm to 200 μm. The mold filling property and the mechanical properties of the heat-resistant component can be excellent when formed in the above range. For example, it may be 30 μm to 150 μm. Or it may be 30 micrometers-90 micrometers. For example, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, It can be 140, 145, 150, 160, 170, 180, 190 or 200 μm.

  Referring to FIG. 6, the mixture may be dispersed in the form of water droplets from the top to the bottom of the housing 200 (or from the bottom to the top) by centrifugal force generated by the rotation of the disk 300. At this time, the solvent may be dried with the mixture formed in the shape of a sphere to form a sphere-shaped granule. In one embodiment, the granule may be formed in a spherical shape by combining a plurality of metal powder particles by a binding force of a binder and a cohesive force (van der Waals force) of the metal powder.

[(S20) Molded article manufacturing stage]
The step is a step of producing a molded body by filling the granule in a mold and compression molding. In one embodiment, the press mold can be filled and compressed into a predetermined form of ingot.

In one embodiment, the compression molding ^may be performed at a pressure of ^{0.1ton / cm 2 ~10ton / cm 2} . Since the diameter of the granule is 10 times larger than the diameter of the metal powder and has a spherical shape, the fluidity is excellent by gravity. Therefore, the mold can be uniformly filled. This is the same as filling even more uniformly when filling rice grains than filling the mold with flour.

  In one embodiment, a mold filled with the granule can be press-molded to produce a molded body according to the shape of the heat-resistant product. For example, the mold may be filled with granules so that the ingot has a block or disk shape.

  In an embodiment, when the granule is filled into a mold of a press machine so as to form an ingot of a predetermined form and compression-molded, the granule is divided into fine metal powders while the shape of the granule is broken. Can be uniformly filled.

[(S30) Sintered body manufacturing stage]
The step is a step of manufacturing the sintered body by sintering the molded body in a sintering furnace and then cooling.

  In one embodiment, the sintering may be performed at 1000 ° C to 1600 ° C. Within this range, the binder component contained in the mixture can be easily removed, and the mechanical strength and surface characteristics of the sintered body can be excellent. When the sintering is carried out at less than 1000 ° C., the density reduction due to unsintering, the surface characteristics and mechanical properties of the sintered body are reduced, and when the sintering is carried out above 1600 ° C., the shape due to melting Defects can occur and the mechanical properties of the sintered body can be reduced. For example, it can be carried out at 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550 or 1600 ° C.

  In one embodiment, the compact may be heated at the temperature described above in a sintering furnace and then cooled at room temperature to produce a sintered compact.

  The binder component can be decomposed and removed during the sintering. In one embodiment, when polyvinyl butyral is applied to the binder, it can be easily removed in a sintering furnace and process efficiency is excellent, and the mechanical strength and surface characteristics of the sintered body can be excellent.

In one embodiment, the sintering may be performed in an atmosphere of a gas including one or more of hydrogen, nitrogen, and argon. Oxidation due to inflow of oxygen can be prevented when sintering in the gas atmosphere. In one embodiment, the sintering may be performed in an Ar—N ₂ or N ₂ —H ₂ atmosphere.

[(S40) Cutting Stage]
The step is a step of adjusting the dimensions by cutting the sintered body. In one embodiment, the size of the sintered body can be adjusted by cutting the sintered body manufactured in the stage of manufacturing the sintered body to have a target size.

[Heat-resistant parts manufactured by the heat-resistant parts manufacturing method]
Another aspect of the present invention relates to a heat-resistant component manufactured by a method for manufacturing a heat-resistant component using the granules.

  When applying the powder metallurgy method using the granule according to the present invention, the shape of the produced granule is nearly spherical, the particle size of the granule is 20 μm to 200 μm, and the fluidity of the granule is less than 40 sec / 50 g, It has characteristics similar to powder for powder metallurgy and can be easily filled into the mold.

  Moreover, the granulated powder is broken while the granulated powder is pressed, the fine powder can be uniformly filled inside the mold, the relative density after sintering can be increased to 99% or more, and the mechanical properties Can manufacture excellent heat-resistant parts.

  And since the fine metal powder particles are granulated and compressed, they are compressed in the molding stage, so that the internal uniformity can be improved compared to when the metal powder is compressed, and a relatively large sintering driving force is achieved. Since high density can be obtained after sintering, it has excellent mechanical properties over products manufactured by metal powder injection molding or casting method while using powder metallurgy method. You can get a product.

  In addition, since the degreasing process is not required as in the metal powder injection molding method, the manufacturing process is simple, and since heating for degreasing is unnecessary, energy can be saved, and there is also a time saving effect. For this reason, productivity can be improved and production cost can be reduced.

  It can also be seen that the higher the molding density, the smaller the shrinkage after the sintering step. Since the present invention uses fine metal powder and compresses and forms granules, the molding density can be improved over existing powder metallurgy methods, and the shrinkage rate can be easily controlled as compared with metal powder injection molding methods. It can be sintered to dimensions close to the design dimensions after sintering. Therefore, since the work is completed only by the cutting process, the effect of reducing the processing cost and the production cost is excellent.

  Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is merely presented as a preferred example of the present invention, and the present invention is not limited thereby.

[Examples and Comparative Examples]
[Example 1]
A mixture containing metal powder, polyvinyl butyral and ethanol in the contents shown in Table 1 below was prepared. A container having a volume of 1000 ml and a ball mill were prepared. The metal powder, polybutyral and ethanol were applied under the conditions shown in Table 1 below and mixed at room temperature for 1 hour to prepare a mixture.

  As the metal powder, HK-30 product of Parmaco having an average diameter of 5 μm to 9 μm was used. The HK-30 is carbon (C): 0.20 to 0.50 wt%, chromium (Cr): 24 to 27 wt%, nickel (Ni): 19 to 22 wt%, silicon (Si): 0.75 To 1.30% by weight, manganese (Mn): more than 0 and 1.5% by weight or less, molybdenum (Mo): 0.2 to 0.3% by weight, niobium (Nb): 1-1.75% by weight and the balance Iron (Fe) and other inevitable impurities.

  As shown in FIG. 6, the mixture is injected into a molding machine including a hermetically sealed disk having a rotatable disk inside, and hot air at 130 ° C. is applied to the housing while rotating the disk at a rotation speed of 6000 rpm. Feed to produce granules.

The granules were filled into a molding machine and compression molded at a pressure of 100 MPa (1.01 ton / cm ² ) to produce a molded body in the form of a vane ring part used for a turbocharger.

  The molded body is sintered in a high-temperature furnace (possible in a batch furnace or a continuous furnace), and the sintering temperature is sintered at a temperature of 1240 ° C., which is a temperature before the liquid phase is formed, for 2 to 3 hours. A sintered body was manufactured by sintering in a vacuum atmosphere in a batch furnace and in a hydrogen atmosphere in a continuous furnace, and then the sintered body was cut and the dimensions were adjusted to manufacture a heat resistant part.

[Example 2]
A heat-resistant component was manufactured in the same manner as in Example 1 except that a mixture to which the components and contents under the conditions shown in Table 2 below were applied was applied.

[Example 3]
A heat-resistant part was produced in the same manner as in Example 1 except that the compression molding was performed at a pressure of 600 MPa (6.12 ton / cm ² ) during the compression molding.

[Example 4]
A heat-resistant component was manufactured in the same manner as in Example 2 except that the compression molding was performed at a pressure of 600 MPa (6.12 ton / cm ² ) during the compression molding.

[Comparative Example 1]
A heat-resistant component was produced in the same manner as in Example 1 except that 65 ° C. hot air was supplied to the housing to produce granules.

[Comparative Example 2]
A heat-resistant component was produced in the same manner as in Example 1 except that granules were produced by supplying hot air of 215 ° C. to the housing.

[Physical property evaluation of heat-resistant parts]
(1) Relative density, shrinkage rate, apparent density, and granule recovery rate measurement: relative density (relative density) and shrinkage rate (linear) of manufactured heat-resistant parts with respect to Examples 1-4 and Comparative Examples 1-2. Shrinkage), apparent density (g / cc) and granule recovery (%) are shown in Table 3 below.

  Referring to Table 3, since Examples 1 to 4 are formed by compressing granules, the packing density can be higher than that of existing metal (fine powder) powder when filling the mold, and the shrinkage rate can be easily controlled. Therefore, after sintering, it was possible to sinter to a dimension close to the design dimension, and it was found that a heat-resistant part can be manufactured by cutting the sintered body to the minimum.

  On the other hand, in the case of the comparative example 1, since it was not dried, granule powder was not formed, and in the case of the comparative example 2, it turned out that a granule collection rate falls large compared with Examples 1-4.

  FIG. 7A is an optical micrograph obtained by enlarging the metal powder used in Example 1 by 1000 times, and FIG. 7B is an enlarged 100 times granule manufactured by Example 1 of the present invention. It is an optical micrograph. Referring to FIG. 7, it was found that the average diameter of the metal powder was 5 μm to 9 μm, and the granules prepared according to Examples 1 to 3 were manufactured with particles having an average diameter of 30 μm to 90 μm.

  8A is a granule of Example 1, FIG. 8B is a granule of Comparative Example 1, and FIG. 8C is an optical micrograph of the granule of Comparative Example 2. FIG. 9A is an optical micrograph of the granule of Example 1, and FIG. 9B is an optical micrograph of the granule of Comparative Example 1. Referring to FIGS. 8 and 9, the granule of Example 2 was prepared with particles having an average diameter of 30 μm to 90 μm, but the granule of Comparative Example 1 had a granule shape because the mixture was not completely dried. The granule of Comparative Example 2 was found to have a poor granule shape because the binder was decomposed.

  FIG. 10A is a photograph of the heat-resistant component of Example 1 of the present invention, and FIG. 10B is an X-ray photograph of the heat-resistant component of Example 1 described above. Referring to FIG. 10, it was found that the heat-resistant component of Example 1 had excellent appearance and no defects were generated inside the heat-resistant component.

  FIG. 11A is a heat-resistant component of Example 1, and FIG. 11B is a photograph showing the heat-resistant component of Comparative Example 1. Referring to FIG. 11, Example 1 of the present invention was excellent in appearance, but Comparative Example 1 was found to deteriorate in appearance such as cracks.

  (2) Evaluation of heat resistance: In order to evaluate the heat resistance of the heat-resistant component produced according to the present invention, the following evaluation was performed. A heat resistant part was manufactured by casting using the metal powder of Example 1 (Comparative Example 3), and heat resistance was evaluated by heat treating Example 1 and Comparative Example 3 at 820 ° C. for 50 hours. .

  FIG. 12 (a) below shows the heat resistant part of Comparative Example 3, FIG. 12 (b) shows the heat resistant part of Example 1, and FIG. 12 (c) shows the comparative example. FIG. 12D is a photograph of the heat-resistant component of Example 1 heat-treated.

  FIG. 13 (a) below shows the microstructure of the heat-resistant component of Comparative Example 3, and FIG. 13 (b) shows the microstructure of the heat-resistant component of Example 1. FIG. c) shows the microstructure after heat-treating the heat-resistant component of Comparative Example 3, and FIG. 13 (d) is an electron micrograph showing the microstructure after heat-treating the heat-resistant component of Example 1.

  Referring to FIGS. 12 and 13, the microstructure of Example 1 of the present invention (see FIG. 13B) is compared with the microstructure of the cast Comparative Example 3 (see FIG. 13A). It was confirmed that the structure was finely formed, the homogeneity was excellent, and the sigma phase was not detected.

  On the other hand, the sigma phase induces deterioration of heat resistance characteristics and corrosion resistance of the heat resistant parts. The heat-resistant component can be significantly lost in a highly oxidative environment such as nitric acid during sigma phase formation. Therefore, heat-resistant parts for turbochargers limit the area ratio of the sigma phase to less than 2%.

  FIG. 14A shows a surface oxide layer formed after heat-treating the heat-resistant component of Example 1 at 900 ° C. for 500 hours under atmospheric conditions. FIG. 14B shows the heat-resistant component of Example 1 4 is an electron micrograph showing a surface oxide layer formed after heat treatment in a continuous annealing furnace at 900 ° C. for 500 hours.

  Referring to FIGS. 14A and 14B, in the case of Example 1, when the heat treatment is performed under vacuum conditions, the thickness of the surface oxide layer is measured to be 12.405 μm at the maximum, and the heat treatment is performed in a continuous annealing furnace. The maximum thickness of the surface line drawing layer was measured to be 15.405 μm. As a result, it was found that Example 1 satisfies the surface oxide layer thickness limit value of less than 30 μm, which is a heat-resistant component for turbochargers.

  At the time of manufacturing the heat-resistant component according to the present invention, it was found that the granule particles were 10 times or more larger than the metal powder, so that uniform filling was achieved and the density of the heat-resistant component after sintering was uniformly formed.

  Since the particles of the metal powder are granulated and compressed in the molding stage, use a fine metal powder that is evenly filled in the mold and has excellent sintering driving force than when the powder is compressed in the powder metallurgy process. Therefore, it was found that the densification of the structure can be induced during sintering, and there is an advantage that a relatively high density can be obtained as compared with the existing powder metallurgy method.

  Therefore, it was found that a heat-resistant component having excellent mechanical properties such as a metal powder injection molding method can be obtained when manufacturing the heat-resistant component according to the present invention.

  In addition, the present invention does not require a degreasing process required for the metal powder injection molding method, and thus simplification of the process is possible, and heating for degreasing is unnecessary, so that productivity is excellent, process time and It turned out to be advantageous in terms of energy.

  Simple modifications or changes of the present invention can be easily carried out by those having ordinary knowledge in this field, and all such modifications and changes are included in the scope of the present invention.

  This application claims the benefit of priority based on Korean Patent Application No. 10-2015-0187154 filed with the Korean Patent Office on December 28, 2015, and all of the patents disclosed in the relevant Korean patent application documents The contents are included as part of this specification.

(Appendix)
(Appendix 1)
Spraying a mixture comprising metal powder and slurry material into a housing provided with a disk and rotating the disk to produce granules;
Compression molding the granules to produce a shaped body;
Sintering the molded body at 1000 ° C. to 1600 ° C. to produce a sintered body; and cutting the sintered body to adjust the dimensions;
The housing is hermetically sealed and supplied with hot air of 70 ° C. to 200 ° C.,
The manufacturing method of the heat-resistant component characterized by the above-mentioned.

(Appendix 2)
The metal powder includes carbon (C): 0.1 wt% to 3 wt%, silicon (Si): more than 0 and less than 5 wt%, manganese (Mn): more than 0 and less than 15 wt%, phosphorus (P): 0 Excess 1% by weight or less, Sulfur (S): Excess 0, 1% by weight or less, Nickel (Ni): Exceed 0, 90% by weight or less, Iron (Fe): Exceed 0, 50% by weight or less, and Chromium (Cr): Exceed 0 The method for manufacturing a heat-resistant component according to Appendix 1, wherein the heat-resistant component includes 50% by weight or less.

(Appendix 3)
The method for producing a heat-resistant component according to appendix 1, wherein the granule has an average diameter of 20 μm to 200 μm.

(Appendix 4)
The average diameter of the metal powder is 0.01 μm to 50 μm, and the diameter distribution of the metal powder is 0.001 μm to 100 μm.

(Appendix 5)
The method for producing a heat-resistant component according to appendix 1, wherein the mixture has a solid phase ratio (S / L) of 10% by volume to 45% by volume.

(Appendix 6)
The method for manufacturing a heat-resistant component according to appendix 1, wherein the rotational speed of the disk is 4000 rpm to 20000 rpm.

(Appendix 7)
The method for producing a heat-resistant component according to appendix 1, wherein the slurry material includes a solvent and a binder.

(Appendix 8)
The method for producing a heat-resistant component according to appendix 7, wherein the solvent includes one or more of water, hexane, acetone, and an alcohol having 1 to 10 carbon atoms.

(Appendix 9)
Appendix 7 characterized in that the binder includes one or more of polyvinyl butyral (PVB), polyvinyl alcohol (PVA), wax (Wax) and polyethylene glycol (PEG). The manufacturing method of the heat-resistant component of description.

(Appendix 10)
It said compression molding is carried out at a pressure of ^{0.1ton / cm 2 ~10ton / cm 2} , the manufacturing method of the heat-resistant component according to note 1, wherein the.

Claims (10)

Spraying a mixture comprising metal powder and slurry material into a housing provided with a disk and rotating the disk to produce granules;
Compression molding the granules to produce a shaped body;
Sintering the molded body at 1000 ° C. to 1600 ° C. to produce a sintered body; and cutting the sintered body to adjust the dimensions;
The housing is hermetically sealed and supplied with hot air of 70 ° C. to 200 ° C.,
The manufacturing method of the heat-resistant component characterized by this.   The metal powder includes carbon (C): 0.1 wt% to 3 wt%, silicon (Si): more than 0 and less than 5 wt%, manganese (Mn): more than 0 and less than 15 wt%, phosphorus (P): 0 Excess 1% by weight or less, Sulfur (S): Excess 0, 1% by weight or less, Nickel (Ni): Exceed 0, 90% by weight or less, Iron (Fe): Exceed 0, 50% by weight or less, and Chromium (Cr): Exceed 0 The method for producing a heat-resistant component according to claim 1, comprising 50% by weight or less.   The method for producing a heat-resistant component according to claim 1, wherein the granule has an average diameter of 20 μm to 200 μm.   2. The method for manufacturing a heat-resistant component according to claim 1, wherein an average diameter of the metal powder is 0.01 μm to 50 μm, and a diameter distribution of the metal powder is 0.001 μm to 100 μm.   The method for producing a heat-resistant component according to claim 1, wherein the mixture has a solid phase ratio (S / L) of 10% by volume to 45% by volume.   The method for manufacturing a heat-resistant component according to claim 1, wherein a rotational speed of the disk is 4000 rpm to 20000 rpm.   The method for producing a heat-resistant component according to claim 1, wherein the slurry material includes a solvent and a binder.   The method for manufacturing a heat-resistant component according to claim 7, wherein the solvent includes one or more of water, hexane, acetone, and an alcohol having 1 to 10 carbon atoms.   The binder includes one or more of polyvinyl butyral (PVB), polyvinyl alcohol (PVA), wax, and polyethylene glycol (PEG). The manufacturing method of the heat-resistant component as described in 2. Method for producing a heat-resistant component of claim 1 wherein the compression molding is performed at a pressure of ^{0.1ton / cm 2 ~10ton / cm 2} , it is characterized.