Sintered component and method for producing same

Abstract

A sintered component according to one embodiment of the present disclosure is a sintered component obtained by sintering a single compact comprising a metal powder and having a step. In the surface of the recessed corner portion of the step, a brazing filler metal is impregnated in the gaps between the sintered metal powders.

Description

Technical Field

[0001] The present disclosure relates to sintered components and methods of making the same. Background Art

[0002] A method is known in which, for example, metal powder such as Fe-based metal powder is compressed in a die using a lower punch and an upper punch to form a powder compact, and the powder compact is sintered to produce a sintered component. For example, Patent Document 1 discloses a multi-stage forming device for forming a powder compact having steps.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2014-091143 Summary of the invention

[0004] The inventors have found the following problems regarding a sintered component formed by sintering a green compact having a step and a method for producing the same. In a green compact having a step, cracks or insufficient density may occur at the concave corners of the step during compacting of the green compact, resulting in a possibility that the sintered component may have insufficient strength.

[0005] The present disclosure has been made in view of such circumstances, and provides a sintered component and a method for producing the same, which can suppress insufficient strength due to cracks or insufficient density occurring at a concave corner portion of a step in a green compact.

[0006] A sintered component according to one embodiment of the present disclosure is a sintered component formed by sintering a single powder compact having a step and composed of metal powder. On the surface of the concave corner portion of the step, brazing filler metal penetrates into gaps between the sintered metal powders.

[0007] In the sintered component according to one embodiment of the present disclosure, the solder is infiltrated in the gaps between the metal powders after sintering on the surface of the concave corner of the step. Therefore, cracks or insufficient density generated in the concave corner of the step during the molding of the powder compact can be eliminated, and insufficient strength of the sintered component obtained by sintering the powder compact can be suppressed.

[0008] The metal powder may be a Fe-based metal powder, and the brazing filler metal may be a Cu-Ni-Mn-based brazing filler metal. Such a configuration is preferred.

[0009] A method for producing a sintered component according to one aspect of the present disclosure includes: a step of preparing a single powder compact composed of metal powder and having a step; A step of disposing a brazing material on the surface of the concave corner portion of the step; and A step of sintering the green compact provided with the brazing material.

[0010] In a method for manufacturing a sintered component according to one embodiment of the present disclosure, a brazing material is arranged on the surface of a concave corner portion of a step of a powder compact, and the powder compact is sintered. Therefore, during sintering, the molten brazing material penetrates into the gaps between the sintered metal powders on the surface of the concave corner portion. Therefore, cracks or insufficient density generated at the concave corner portion of the step during the molding of the powder compact can be eliminated, and insufficient strength of the sintered component obtained by sintering the powder compact can be suppressed.

[0011] The brazing material may be in a paste state and may be disposed by applying the brazing material to the surface of the concave corner portion of the step. According to such a configuration, the brazing material can be easily disposed on the surface of the concave corner portion of the step.

[0012] The metal powder may be a Fe-based metal powder, and the brazing filler metal may be a Cu-Ni-Mn-based brazing filler metal. Such a configuration is preferred.

[0013] According to the present disclosure, it is possible to provide a sintered component and a method for producing the same, which can suppress insufficient strength due to cracking or insufficient density occurring at a concave corner portion of a step in a green compact. The above and other objects, features and advantages of the present disclosure will be more fully understood from the detailed description and accompanying drawings given below, which are given as examples only and thus should not be considered as limiting the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a perspective view of the sintered component according to the first embodiment. Figure 2 It is a cross-sectional view of the sintered component according to the first embodiment. Figure 3 This is a flowchart showing the method for producing a sintered component according to the first embodiment. Figure 4 This is a cross-sectional structure photograph of a concave corner portion of a step in a sintered component according to an example. Figure 5 This is a cross-sectional structure photograph of a concave corner portion of a step in a sintered component according to a comparative example. Figure 6 yes Figure 4 Reflected electron image in region VI and element mapping images of Fe, Cu, Ni, Mn, and C. DETAILED DESCRIPTION

[0015] Hereinafter, the specific embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the present disclosure is not limited to the following embodiments. In addition, in order to make the description clearer, the following description and drawings are appropriately simplified.

[0016] (First Embodiment) <Structure of sintered parts> First, refer to Figure 1 and Figure 2 , the structure of the sintered component according to the first embodiment will be described. Figure 1 It is a perspective view of the sintered component according to the first embodiment. Figure 2 : is a cross-sectional view of a sintered component according to the first embodiment. As an example, Figure 1 and Figure 2 The sintered component shown is a sintered component for an automobile, more specifically, a planet carrier.

[0017] Examples of automotive sintered parts to which this embodiment can be applied include engine parts such as pulleys, sprockets, oil pump parts, crankshaft and camshaft bearing caps, manual transmission parts such as synchro hubs and shift fingers, and automatic transmission parts such as turbine hubs.

[0018] In addition, the sintered parts involved in this embodiment are not limited to automobile parts, but may also be magnets, motor cores, motor rotors, reactor cores, cutting tools, etc. In addition, the sintered parts involved in this embodiment are Fe-based sintered parts, but may also be sintered parts composed of metal materials mainly composed of Cu, Ni, Co, Ti, W, Mo, etc.

[0019] also, Figure 1 and Figure 2 The right-handed XYZ orthogonal coordinates shown are of course only for the convenience of explaining the positional relationship of the components. Figure 1 In the figures, the positive direction of the Z axis is vertically upward, and the XY plane is a horizontal plane, which is common among the drawings. in addition, Figure 2 The cross-sectional view shown corresponds to Figure 1 A cross-sectional view taken along the II-II cutting line.

[0020] Figure 1 and Figure 2 The sintered component 10 shown includes a base portion 11 and four steps 12 . like Figure 1 and Figure 2 As shown in FIG. 1 , the base portion 11 is a substantially square plate-shaped portion when viewed in the XY plane. The four sides of the base portion 11 are bent so as to extend outward. A circular through hole 11 a is provided in the center of the base portion 11 .

[0021] The step 12 is provided to extend along the four sides of the base 11 and to protrude in the positive direction of the Z axis. Both ends of the step 12 in the longitudinal direction protrude toward the inside of the base 11 (toward the through hole 11 a ). The concave corner portion 12 a of the step 12 is chamfered.

[0022] The sintered component 10 is obtained by sintering a single green compact having a step made of metal powder, that is, the sintered component 10 is not obtained by brazing a plurality of green compacts or sintered bodies.

[0023] On the other hand, the sintered component 10 is manufactured by sintering after placing the brazing material on the surface of the concave corner portion 12a of the step 12 in the powder compact before sintering. Figure 2 As shown, in the surface portion of the concave corner portion 12 a of the step 12 in the sintered component 10 , a penetration portion 13 in which the brazing material is penetrated in the gaps between the sintered metal powders is formed.

[0024] For example, after applying a paste of solder to the surface of the concave corner portion 12a of the step 12, the powder compact is sintered. The paste of solder is a mixture of solder powder composed of a metal material and an organic binder. Alternatively, a powder compact of solder powder composed of a metal material may be arranged on the surface of the concave corner portion 12a. The average particle size D50 of the solder powder is not particularly limited, and is, for example, about 20 μm to 50 μm.

[0025] The brazing filler metal is appropriately selected according to the type of metal powder constituting the powder compact. When the powder compact is composed of Fe-based metal powder, for example, a Cu-Ni-Mn-based brazing filler metal is selected. As the Fe-based metal powder constituting the powder compact, for example, a Fe-based alloy containing a small amount of Cu and C can be used. The average particle size D50 of the Fe-based metal powder constituting the powder compact is not particularly limited, and is, for example, about 20 μm to 300 μm.

[0026] After the Cu-Ni-Mn brazing filler metal melts and penetrates into the gaps between the Fe-based metal powders, the melting point rises due to the reaction with Fe and solidifies again. Therefore, it can stay on the surface of the concave corner 12a in the step 12, and the cracks or insufficient density of the concave corner 12a can be eliminated. Here, the brazing filler metal may also contain, for example, 10% to 20% of Fe-based metal powder constituting the powder compact in addition to the Cu-Ni-Mn brazing filler metal powder. The brazing filler metal is generally referred to as a Cu-Ni-Mn brazing filler metal. However, the Ni concentration may be higher than the Cu concentration, and the brazing filler metal may be referred to as a Ni-Cu-Mn brazing filler metal.

[0027] As described above, when manufacturing the sintered component 10 , cracks or insufficient density may occur in the concave corner portion 12 a as the base of the step 12 during the compacting of the green body. However, in the sintered component 10 according to the present embodiment, during sintering, the molten brazing material penetrates into the gaps between the sintered metal powders on the surface of the concave corner portion 12a of the step 12. Therefore, cracks or insufficient density generated in the concave corner portion 12a of the step 12 during the molding of the powder compact can be eliminated, and insufficient strength of the sintered component 10 obtained by sintering the powder compact can be suppressed.

[0028] In addition, if the density of the powder compact is increased, the strength of the sintered component 10 will be increased, but cracks are likely to occur during the molding of the powder compact. That is, even if the density of the powder compact is increased and cracks occur during molding, the brazing material will penetrate during sintering and can eliminate the cracks or insufficient density. Therefore, the density of the powder compact can be increased, and the strength of the sintered component 10 can be increased.

[0029] Furthermore, the sintered component according to the present embodiment may be formed by sintering a single green compact composed of metal powder and having a step, and the shape, application, etc. are not limited in any way. For example, Figure 1 and Figure 2 In the sintered component 10 shown, the base 11 may be circular in plan view or in other shapes. The through hole 11a provided in the base 11 is not necessary, and the shape of the through hole 11a is not limited to a circle. The position, shape, number, etc. of the step 12 may also be appropriately changed.

[0030] in addition, Figure 2 The penetration portion 13 shown is formed at Figure 1 Although the step 12 shown in the figure is formed on the entire concave corner portion 12a, it can also be formed only on a part of the concave corner portion 12a. For example, it can be formed only on a part of the concave corner portion 12a where cracks or insufficient density are particularly likely to occur. Figure 2 The penetration portion 13 shown. According to such a structure, the amount of brazing material used can be reduced.

[0031] On the other hand, for example, the penetration portion 13 may be formed in a wider range including the concave corner portion 12a so as to extend from the inner surface of the step 12 to the upper surface of the base portion 11. Figure 2 The penetration 13 shown forms a larger area of ​​the penetration 13 . Here, Figure 2 The penetration portion 13 shown is merely schematically shown, and does not accurately show the range, depth, etc. of the penetration portion 13 into which the solder penetrates.

[0032] <Method for Manufacturing Sintered Component According to First Embodiment> Next, refer to Figure 3 , a method for producing a sintered component according to the first embodiment will be described. Figure 3This is a flowchart showing the method for producing a sintered component according to the first embodiment. First, if Figure 3 As shown, a single green compact made of metal powder and having a step 12 is prepared (step ST1). The green compact having the step 12 is not particularly limited, and is produced, for example, by multi-stage molding.

[0033] Next, if Figure 3 As shown, the brazing material is arranged on the surface of the concave corner portion 12a of the step 12 of the powder compact (step ST2). For example, the brazing material is arranged on the surface of the concave corner portion 12a of the step 12 by applying a paste of brazing material to the surface of the concave corner portion 12a of the step 12. Alternatively, a powder compact of brazing material powder composed of a metal material may be arranged on the surface of the concave corner portion 12a. By using a paste of brazing material, the brazing material can be easily arranged on the surface of the concave corner portion of the step.

[0034] Finally, if Figure 3 As shown in FIG. 1 , the powder compact having the brazing material disposed on the surface of the concave corner portion 12a is sintered (step ST3). For example, the powder compact is placed in a sintering furnace, and the powder compact is heated to a predetermined temperature and sintered. Through step ST3, the molten brazing material penetrates into the gaps between the sintered metal powders on the surface of the concave corner portion 12a, forming Figure 2 The impregnation portion 13 is shown.

[0035] As described above, in the method for manufacturing a sintered component according to the present embodiment, a brazing material is placed on the surface of the concave corner portion 12a of the step 12 of the powder compact (step ST2), and the powder compact is sintered to obtain the sintered component 10 (step ST3). Therefore, during sintering, the molten brazing material penetrates into the gaps between the sintered metal powders on the surface of the concave corner portion 12a, forming a Figure 2 As shown in the penetration portion 13. Therefore, cracks or insufficient density generated in the concave corner portion 12a of the step 12 during the molding of the green compact can be eliminated, and insufficient strength of the sintered component 10 obtained by sintering the green compact can be suppressed. [Example]

[0036] Hereinafter, the sintered component 10 and the manufacturing method thereof according to the first embodiment will be described in detail with reference to examples. However, the sintered component 10 and the manufacturing method thereof according to the first embodiment are not limited to the following examples.

[0037] <Example> First, a single powder compact made of Fe alloy (Fe-2.0 mass % Cu-0.9 mass % C) powder and having a step 12 is prepared (step ST1). Figure 1 and Figure 2The same shape as the sintered component 10 shown is formed by multi-stage forming. Here, the green compact is formed so that a predetermined concave corner portion 12a in the step 12 is cracked.

[0038] Next, the brazing material is arranged on the surface of the concave corner portion 12a of the step 12 of the powder compact (step ST2). Specifically, the paste-like brazing material is applied to the surface of the concave corner portion 12a of the step 12. The paste-like brazing material is a mixture of Cu-Ni-Mn alloy (Cu-41.5 mass% Ni-15 mass% Mn-1.8 mass% Si-1.5 mass% B) powder and an organic binder. In addition, the brazing material also contains Fe alloy (Fe-2.0 mass% Cu-0.9 mass% C) powder constituting the powder compact. The mass ratio of the Cu-Ni-Mn alloy powder to the Fe alloy in the brazing material is set to 85:15.

[0039] Next, the powder compact having the brazing material arranged on the surface of the concave corner portion 12a is sintered in a sintering furnace to obtain a sintered component 10 (step ST3). The sintering conditions are set to a temperature of 1120°C and a time of 20 minutes. The sintered component 10 obtained in step ST3 was subjected to cross-sectional structure observation and torsional strength test of the concave corner portion 12 a.

[0040] <Comparative Example> A sintered component was produced in the same manner as in the example except that step ST2 was omitted. As described above, in the manufacture of the sintered component according to the comparative example, no brazing material is used. Figure 2 The shown penetration portion 13 is not formed on the surface of the concave corner portion 12a. The sintered component according to the comparative example was also subjected to cross-sectional structure observation and torsional strength test of the concave corner portion 12 a.

[0041] <Cross-sectional microstructure observation results> Below, refer to Figure 4 and Figure 5 , the results of cross-sectional microstructure observation of the sintered parts according to the examples and comparative examples are described. Figure 4 This is a cross-sectional structure photograph of a concave corner portion of a step in a sintered component according to an example. Figure 5 This is a cross-sectional structure photograph of a concave corner portion of a step in a sintered component according to a comparative example. Figure 4 and Figure 5 All are reflected electron images.

[0042] like Figure 4 As shown, in the sintered component 10 of the embodiment, the brazing material penetrates into the surface of the concave corner portion 12a of the step 12, forming Figure 2The penetration portion 13 is shown. In addition, the penetration portion 13 is formed along the cracks generated during the compacting of the powder body to the inside, and it is confirmed that the cracks have been eliminated.

[0043] On the other hand, Figure 5 As shown, in the sintered component 10 according to the comparative example, cracks were observed on the surface of the concave corner portion 12 a of the step 12 . In addition, Figure 4 The brazing material remaining on the surface of the concave corner portion 12a of the step 12 does not need to be particularly removed, but may be removed.

[0044] Here, Figure 6 yes Figure 4 The reflected electron image in region VI and the element mapping images of Fe, Cu, Ni, Mn, and C. The mapping images of each element were measured by EPMA (Electron Probe Micro Analyzer).

[0045] like Figure 6 As shown in FIG. 1 , in the observation area, there are three Fe-based alloy particles P1 to P3 constituting the powder compact, and it is confirmed that the Cu-Ni-Mn-based brazing filler metal penetrates into the gaps between the Fe-based alloy particles P1 to P3. In addition, near the interface between the Fe-based alloy particles P1 to P3 and the brazing filler metal, the concentrations of Fe, Cu, Ni, Mn, etc. gradually change, and it is presumed that they diffuse mutually.

[0046] <Torsional Strength Test Results> The average value of the torsional strength of the 10 samples of the sintered component 10 involved in the embodiment is 9650 N·m. On the other hand, the average value of the torsional strength of the 10 samples of the sintered component involved in the comparative example is 9320 N·m. As described above, the torsional strength of the sintered component 10 involved in the embodiment is higher by an average value of 300 Nm or more (3% or more) than the torsional strength of the sintered component involved in the comparative example, and all samples meet the reference value of torsional strength.

[0047] As described above, in the sintered component 10 according to the embodiment, during sintering, the molten brazing filler metal penetrates into the gaps between the sintered metal powders on the surface of the concave corner portion 12a of the step 12. Therefore, cracks or insufficient density generated in the concave corner portion 12a of the step 12 during the molding of the green compact can be eliminated, and insufficient strength of the sintered component 10 obtained by sintering the green compact can be suppressed.

[0048] In addition, in the sintered component 10 involved in the embodiment, the density of the powder compact is set higher in such a way that cracks are generated during the forming of the powder compact. As described above, if the density of the powder compact is increased, the strength of the sintered component 10 will be improved. In the sintered component 10 involved in the embodiment, it can be seen that even if the density of the powder compact is increased and cracks are generated during forming, the brazing material will penetrate during sintering and can eliminate the cracks or insufficient density. That is, in the sintered component 10 involved in the embodiment, by increasing the density of the powder compact, the strength can be improved compared with the past.

[0049] According to the disclosure as described above, it is obvious that the embodiments of the present disclosure can be changed in many ways. These changes should not be regarded as departing from the spirit and scope of the present disclosure, and all such modifications obvious to those skilled in the art are intended to be included in the scope of the appended claims.

Claims

1. A sintered component is a sintered component formed by sintering a single powder compact consisting of metal powder and having a step. in, On the surface of the concave corner portion of the step, brazing filler metal penetrates into gaps between the sintered metal powders.

2. The sintered component according to claim 1, wherein: The metal powder is Fe-based metal powder, The solder is a Cu-Ni-Mn solder.

3. A method for manufacturing a sintered component, comprising: a step of preparing a single powder compact composed of metal powder and having a step; A step of disposing a brazing material on the surface of the concave corner portion of the step; and A step of sintering the green compact provided with the brazing material.

4. The method for producing a sintered component according to claim 3, wherein: The brazing material is in a paste state and is disposed by applying the brazing material to the surface of the concave corner portion of the step.

5. The method for producing a sintered component according to claim 3 or 4, wherein: The metal powder is Fe-based metal powder, The solder is a Cu-Ni-Mn solder.

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