JP2010215951A - Sintered composite sliding component and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sintered composite sliding component in which an outer member made of a sintered member having superior wear resistance and corrosion resistance under high temperature is adequately bonded to an inner member made from an molten steel, and to provide a manufacturing method therefor. <P>SOLUTION: This sintered composite sliding component has a total composition comprising, by mass ratio, 23.8-44.3% Cr, 1.0-3.0% Mo, 1.0-3.0% Si, 0.1-1.0% P, 1.0-3.0% C and the balance Fe with unavoidable impurities; includes the outer member made of the Fe-based wear-resistant sintered member which has a density ratio of 95% or more and in which carbides are dispersed in a matrix, and the inner member made from the molten stainless steel; and is integrally formed by fitting and diffusion-bonding the inner member into a pore formed on the outer member. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sintered composite part in which an outer member made of a sintered member and an inner member made of molten steel are integrated by sintered diffusion bonding, and is particularly excellent as a high temperature wear resistance as an outer member. The present invention relates to a sintered composite sliding part to which a sintered member is applied, and a manufacturing method thereof.

  The powder metallurgy method has been applied to various industrial parts because it has advantages such as being able to form a near net shape and producing composite materials that cannot be obtained by melting materials, especially automobile and motorcycle parts. The scope of application is expanding. In such an expansion of the application range, in recent years, for example, parts that require wear resistance and corrosion resistance at high temperatures, such as exhaust device parts (Patent Document 1) and turbocharger parts (Patent Document 2). Is also being applied.

Japanese Examined Patent Publication No. 05-041693 JP 2002-226955 A JP 2008-121058 A

  The sintered material used in the above turbocharger parts has low toughness because of being given wear resistance, and the strength is insufficient depending on the component parts. For this reason, an attempt has been made to configure an outer member that requires wear resistance with a sintered material in combination with a steel material and an inner member that requires strength with a steel material. However, if both members are joined by brazing, there is a risk that the brazing material will melt and the member may fall off when used at a high temperature. In addition, since the sintered material is porous, heat and electrical conductivity are inferior, gas is left in the pores and blowholes are likely to occur in the welded part, and cracking due to transformation strain is likely to occur. Therefore, it is not suitable for welding. Furthermore, when the inner member is press-fitted into the outer member or the outer member is fixed to the inner member by caulking, the sintered material having poor toughness is likely to crack. If the press-fitting allowance is reduced in order to avoid this, the joint strength between the two members is lowered, and there is a risk of dropping during use.

  Accordingly, the present invention provides a sintered composite in which an outer member made of a sintered member excellent in wear resistance and corrosion resistance at high temperatures, which is suitable as a turbocharger component, is well bonded to an inner member made of molten steel. An object of the present invention is to provide a sliding component and a manufacturing method thereof.

  The first sintered composite sliding part of the present invention that achieves the above object has a mass ratio of Cr: 23.8 to 44.3%, Mo: 1.0 to 3.0%, Si: 1.0 to 3.0%, P: 0.1-1.0%, C: 1.0-3.0%, the whole composition consisting of the balance Fe and inevitable impurities, with a density ratio of 95% or more in the base It consists of an outer member made of Fe-based wear-resistant sintered member in which carbides are dispersed and an inner member made of molten stainless steel, and the inner member is fitted and diffused in a hole formed in the outer member. It is characterized by being joined together.

  Moreover, the 2nd sintered composite sliding component of this invention which achieves the said objective is Cr: 19.7-41.9%, Ni: 5.0-15.0%, Mo: 0 by mass ratio. 0.8 to 2.8%, Si: 0.8 to 2.8%, P: 0.1 to 1.0%, C: 1.2 to 4.4%, balance Fe and unavoidable impurities And an outer member made of an Fe-based wear-resistant sintered member in which carbide is dispersed in an austenite base with a density ratio of 95% or more, and an inner member made of molten stainless steel, and the outer member The inner member is fitted into the formed hole and diffused and joined together.

  Furthermore, the manufacturing method of the 1st sintered composite sliding component which achieves the said objective is a method of manufacturing the said 1st sintered composite sliding component, Specifically, by mass ratio, Cr: 25 To an iron-based alloy powder having a composition comprising -45%, Mo: 1 to 3%, Si: 1 to 3%, C: 0.5 to 1.5%, balance Fe and inevitable impurities, P: 10 to 30 mass % Of an iron-phosphorus alloy powder of 1.0-3.3 mass% and graphite powder of 0.5-1.5 mass% added and mixed, the raw material powder is an inner member made of molten steel The outer member shape having a hole portion to be fitted is compacted, and the inner member made of molten stainless steel is fitted into the fitting hole portion of the obtained outer member compact, and then sintered. Then, sintering of the outer member and diffusion bonding of the outer member and the inner member are simultaneously performed and integrated.

  And the manufacturing method of the 2nd sintered composite sliding component which achieves the said objective is a method of manufacturing the said 2nd sintered composite sliding component, Specifically, said 1st sintering In the manufacturing method of composite sliding parts, nickel powder is added to the raw material powder, or Ni is added to the iron-based alloy powder, and Ni is added in an amount of 5.0 to 15.0% by mass with respect to the raw material powder. In addition, the amount of the graphite powder added is 0.8 to 3.0% by mass.

  In the manufacturing method of the sintered composite sliding part of the present invention, as an outer member to be fitted with the inner member, a pre-sintering re-pressure obtained by pre-sintering the green compact and recompressing it instead of the green compact described above When the body is used, the density of the outer member can be further increased, and as a result, the wear resistance and the corrosion resistance can be improved.

  The sintered composite sliding part of the present invention uses a sintered member having wear resistance and corrosion resistance at high temperatures as an outer member, and stainless steel having corrosion resistance at high temperatures as an inner member, and both are integrated by diffusion bonding. Therefore, it has good wear resistance, corrosion resistance and strength even in a high temperature environment, and also has good bonding strength. Moreover, in the manufacturing method of the sintered composite sliding part of this invention, since sintering of an outer member and diffusion joining of an outer member and an inner member are performed simultaneously, said sintered composite sliding part is manufactured with high efficiency. be able to.

  As the outer member of the first sintered composite sliding part of the present invention, the sintered alloy of Patent Document 2 is suitable, specifically, Cr: 23.8 to 44.3% by mass ratio, Mo: 1.0-3.0%, Si: 1.0-3.0%, P: 0.1-1.0%, C: 1.0-3.0%, balance Fe and unavoidable impurities A sintered alloy having a total composition as described above and having a density ratio of 95% or more and in which carbides are dispersed in the matrix is suitable.

  The Cr of the outer member of the first sintered composite sliding part of the present invention contributes to the improvement of the heat resistance and corrosion resistance of the base of the outer member. Cr combines with C to form fine granular carbide uniformly in the base of the outer member, thereby improving the wear resistance of the outer member, and Cr in the base bears corrosion resistance. Provide sufficient wear and oxidation resistance. In order to make the effect of Cr uniformly work in the base of the outer member, Cr is applied in the form of iron-based alloy powder. Here, if the content of Cr in the iron-based alloy powder is less than 25% by mass, the amount of Cr carbide precipitated decreases, the wear resistance of the outer member becomes insufficient, and the heat resistance and corrosion resistance decrease. . On the other hand, if the Cr content exceeds 45% by mass, the compressibility of the powder is significantly impaired. Therefore, the content of Cr in the iron-based alloy powder is 25 to 45 mass%.

  Mo of the outer member of the first sintered composite sliding part of the present invention contributes to improving the heat resistance and corrosion resistance of the base of the outer member, and combines with C to form a carbide to increase the wear resistance of the outer member. Improve. Mo is applied in the form of an iron-based alloy powder so that the effect of Mo is uniformly applied to the entire base as in the case of Cr. If the content of Mo in the iron-base alloy powder is less than 1% by mass, the effect of improving the heat resistance and corrosion resistance of the base is poor, while the effect is not so noticeable even if it exceeds 3% by mass. Therefore, the content of Mo in the iron-base alloy powder is 1 to 3% by mass.

  Si of the outer member of the first sintered composite sliding part of the present invention has an effect of improving the sinterability of the outer member. If the Si content of the iron-based alloy powder is less than 1%, the effect is poor. On the other hand, if it exceeds 3% by mass, the iron-based alloy powder becomes too hard and the compressibility is significantly impaired. Therefore, the content of Si in the iron-based alloy powder is 1 to 3% by mass.

P of the outer member of the first sintered composite sliding part of the present invention generates a Fe-PC liquid phase during sintering together with C to promote densification of the sintered body, thereby increasing the density ratio of the outer member. Is 95% or more.
At the same time, the Fe-PC liquid phase generated from the outer member green compact is wetted by the outer surface of the inner member made of molten stainless steel to promote diffusion bonding between the outer member sintered body and the inner member. In addition, the inner diameter surface of the fitting hole provided in the outer member green compact shrinks, and the inner diameter surface of the outer member green compact fitting hole generates a pressure to tighten the outer diameter surface of the inner member. This pressure promotes diffusion bonding between the two.

  P is added in the form of an iron-phosphorus alloy powder in order to promote the liquid phase formation during the sintering so as to achieve the densification of the outer member and the diffusion bonding between the outer member and the inner member. The amount of iron-phosphorus alloy powder added to the mixed powder is such that when the P content in the overall composition is less than 0.1% by mass, the amount of liquid phase generated is poor, and sufficient densification cannot be achieved, resulting in a density ratio of 95%. On the other hand, if the content of P in the overall composition exceeds 1.0% by mass, the matrix becomes brittle and the corrosion resistance deteriorates.

  C of the outer member of the first sintered composite sliding component of the present invention generates a Fe-PC liquid phase during sintering in order to lower the liquidus temperature, Promotes diffusion bonding of the inner member. C forms a carbide with Cr, Mo, and contributes to an improvement in wear resistance of the outer member. When the content of C in the overall composition is less than 1.0% by mass, these effects are poor. On the other hand, if it exceeds 3.0% by mass, the base of the outer member becomes brittle and the amount of precipitation of carbide increases, so that the counterpart material such as vane is worn or the amount of Cr in the base is reduced. Reduces heat resistance and corrosion resistance. Therefore, the content of C in the overall composition is 1.0 to 3.0% by mass.

  However, when the total amount of C is applied in the form of graphite powder, the iron-base alloy powder becomes a powder in which Cr and Mo are dissolved in the Fe base, and the iron-base alloy powder becomes too hard and the compressibility is impaired. . Further, the use of a large amount of graphite powder also impairs the compressibility of the raw material powder. Therefore, a part of C is applied in the form of iron-based alloy powder, and the remaining C is applied in the form of graphite powder. When a part of C is applied in the form of an iron-base alloy powder, Cr in the iron-base alloy powder, Mo precipitates in the iron-base alloy powder as carbides, and Cr is dissolved in the base of the iron-base alloy powder, Since the amount of Mo is reduced, the compressibility of the iron-based alloy powder can be improved. Furthermore, the compressibility of the raw material powder itself can be improved by supplying the remaining C to the mixed powder in the form of graphite powder. At this time, if the C content of the iron-based alloy powder is less than 0.5% by mass, the amount of Cr and Mo dissolved in the Fe base increases, so the iron-based alloy powder becomes hard and compressible. On the other hand, if the amount exceeds 1.5% by mass, the amount of carbide precipitated in the iron-base alloy powder becomes too large, and conversely, the hardness of the iron-base alloy powder increases. Therefore, the C content of the iron-based alloy powder is 0.5 to 1.5 mass%, and the remaining 0.5 to 1.5 mass% is added to the mixed powder as graphite powder.

  From the above, the raw material powder for the outer member of the first sintered composite sliding part of the present invention has a mass ratio of Cr: 25 to 45%, Mo: 1 to 3%, Si: 1 to 3%, C: 0.5 to 1.5%, balance: iron-based alloy powder composed of Fe and inevitable impurities, P: 10 to 30% by mass, balance: iron-phosphorus alloy powder composed of Fe and inevitable impurities, and graphite powder A mixed powder obtained by adding 1.0 to 3.3 mass% of iron-phosphorus alloy powder and 0.5 to 1.5 mass% of graphite powder to the iron-based alloy powder and mixing them is used.

  By using the above mixed powder and molding and sintering by a conventional powder metallurgy method, Cr: 23.8 to 44.3%, Mo: 1.0 to 3.0%, Si: 1.0 to 3.0%, P: 0.1 to 1.0%, C: 1.0 to 3.0%, the overall composition composed of the balance Fe and inevitable impurities, and the density ratio is 95% or more Thus, the outer member of the first sintered composite sliding part of the present invention in which carbide is dispersed in the base can be produced.

  In particular, since the outer member of the first sintered composite sliding part of the present invention has a density ratio of 95% or more, it is possible to suppress the progress of oxidation and pitting corrosion in the pores, and greatly improve the corrosion resistance. Can be improved. In addition, by dispersing fine granular Cr carbide in the matrix, the wear resistance and oxidation resistance can be improved.

  The outer member of the second sintered composite sliding part of the present invention is a sintered alloy of Patent Document 3, and Ni is given to the outer member of the first sintered composite sliding part to The alloy base is further provided with corrosion resistance and high temperature strength. Specifically, Cr: 19.7-41.9%, Ni: 5.0-15.0%, Mo: 0.8-2.8%, Si: 0.8-2. 8%, P: 0.1 to 1.0%, C: 1.2 to 4.4%, the overall composition consisting of the balance Fe and inevitable impurities, with a density ratio of 95% or more and carbide in the austenite base It consists of a Fe-based wear-resistant sintered member in which is dispersed.

  Ni diffuses into the base of the outer member and strengthens by solid solution, and has the effect of improving the corrosion resistance and high-temperature strength of the wear-resistant member by austenizing the base of the outer member. When the Ni content in the overall composition is less than 5.0% by mass, the effect of Ni is poor. On the other hand, even if the Ni content exceeds 15.0% by mass, the high-temperature strength is not further improved, and the high-temperature corrosion resistance. Decreases. Therefore, the Ni content (addition amount of Ni powder) in the overall composition is set to 5.0 to 15.0 mass%. When Ni having the above action is dissolved in the iron-based alloy powder, it is preferable because the effect of Ni acts uniformly in the base of the outer member, but Ni diffuses relatively quickly into the Fe base. Therefore, you may give to mixed powder with the form of Ni powder.

  On the other hand, when the above amount of Ni is applied to the base of the outer member, the base of the outer member is austenitized to expand the solid solubility limit of C. For this reason, in the outer member of the second sintered composite sliding part of the present invention, it is preferable to increase the C amount as compared with the outer member of the first sintered composite sliding part of the present invention. However, if the amount of C in the overall composition exceeds 4.4% by mass, the matrix becomes brittle and the amount of precipitated carbide increases, so that the counterpart material such as vane is worn or the Cr content in the matrix is reduced. This causes a decrease in heat resistance and corrosion resistance. For this reason, in the outer member of the second sintered composite sliding part of the present invention, the upper limit of the C amount is 4.4 mass%.

  Since the amount of C that can be given to the iron-based alloy powder is 0.5 to 1.5% by mass as described above, an increase in the amount of C is given in the form of graphite powder. For this reason, in the outer member of the second sintered composite sliding part of the present invention, the amount of graphite powder added is 0.8 to 3.0 mass%.

  The raw material powder is compacted into a desired outer member shape having a hole that fits with the inner member to form an outer member compact. Next, the inner member made of molten steel is fitted into the fitting hole of the outer member green compact, and assembled integrally. In addition, as molten steel of an inner member, since corrosion resistance in high temperature is calculated | required, stainless steel molten steel is used.

  Since the outer member green compact undergoes liquid phase shrinkage, it is also possible to set the gap to 1% or less of the diameter of the fitting hole by fitting the inner member into the fitting hole of the outer member green compact. Can be obtained. However, since the axial center of the inner member may be shifted during sintering when the gap is fitted, it is preferable to make the gap as small as possible or make an interference fit. That is, when the inner member having a larger diameter is adjusted and press-fitted into the fitting hole portion of the outer member, it is difficult for the inner member to be misaligned during sintering. Further, when an interference fit is employed, the inner diameter surface of the fitting hole portion of the outer member green compact and the surface of the inner member are closely fitted to each other, so that the degree of adhesion between both is increased. However, since the iron-based alloy powder is harder than pure iron powder and the strength of the outer member green compact is relatively low, when the allowance exceeds 1% of the diameter of the fitting hole, the fitting hole There is a risk that the tensile stress of the part increases and the outer member is damaged.

  The outer member green compact and the inner member assembled together are put into a sintering furnace and sintered. At the time of sintering, in the outer member green compact, the iron-phosphorus alloy powder generates a Fe—PC—C eutectic liquid phase and densifies and shrinks the sintered body. On the other hand, the inner member made of molten steel is thermally expanded by heating. For this reason, during sintering (at a temperature of 800 ° C. or higher), pressure is generated at the interface between the outer member and the inner member, and the two members are in close contact with each other. At this time, the diffusion bonding of both members is performed by the solid-phase diffusion of the component elements of both members at the interface between the outer member and the inner member. As a result, the outer member becomes a sintered member having excellent wear resistance and corrosion resistance at high temperatures, and a sintered composite sliding part in which the outer member and the inner member are firmly integrated is obtained.

  In the above-mentioned sintered composite sliding part, excessive stress does not act on the outer member, and it is possible to avoid the problem of cracks that occur during fitting by press-fitting or caulking. In addition, the outer member and the inner member have high joint strength because they are metallurgically coupled.

  The sintered member, which is an outer member obtained by the above method, has unique pores, and the outer member has a large specific surface area due to the presence of the pores. Since corrosion (oxidation) occurs from the surface, the corrosion resistance can be further improved by reducing the amount of the pores.

  As one of the methods, before fitting with the inner member, the outer member green compact is pre-sintered and re-compressed to produce a pre-sintered re-pressure body. There is a method in which the inner member is fitted into the fitting hole and sintered as described above. Since the compressive strain accumulated in the raw material powder of the green compact is released by the pre-sintering, a pre-sintered re-pressed body having a density higher than that of the green compact is obtained by re-compressing it. By sintering such a material having a high density (a small amount of pores), an outer member having a high density, that is, a small amount of pores and a small specific surface area can be obtained. The pre-sintering temperature is preferably 600 ° C. or higher in order to release the compressive strain accumulated in the raw material powder. On the other hand, if the temperature is too high, growth of necks between the raw material powders starts and it becomes difficult to densify during recompression, so the upper limit is preferably set to 1000 ° C.

  Another method is to use a powder mainly composed of fine powder having a maximum particle size of 46 μm or less as the iron-base alloy powder. When fine powder is used as a raw material powder, bridging is likely to occur and moldability is deteriorated. However, since the specific surface area is increased and the contact portion between the powders that is the starting point of neck growth is increased, Sintering easily proceeds, and the resulting sintered body has a high density. In order to exhibit this effect satisfactorily, the amount of fine powder having a maximum particle size of 46 μm or less in the iron-based alloy powder is preferably 90% or more.

  Furthermore, in the method of achieving densification by improving the sinterability using the above fine powder, when the fine powder is used in the form of a granulated powder granulated in advance to an average particle size of 80 to 150 μm, The problem of deterioration of moldability due to the use of fine powder can be avoided, and further densification can be achieved during sintering.

[First embodiment]
The composition is mass%, Cr: 30%, Mo: 2%, Si: 2%, C: 1%, and the iron-base alloy powder consisting of Fe and inevitable impurities, the composition is P: 20% by mass, And an iron-phosphorus alloy powder consisting of Fe and unavoidable impurities and graphite powder, and adding and mixing these powders in the proportions shown in Table 1, Obtained. These raw powders
(1) Disk shape with a diameter of 30 mm and a height of 10 mm (for wear resistance evaluation)
(2) Ring shape with an outer diameter of 30 mm, an inner diameter of 20 mm, and a height of 5 mm (for bondability evaluation)
(3) Column shape of 10 mm x 10 mm x 60 mm (for tensile strength evaluation)
Were molded at a molding pressure of 600 MPa. Among these (1) to (3) shaped molded body samples, the (2) shaped bondability evaluation sample is used as an outer member green compact after molding, and the inner diameter of the outer member green compact is used. The inner member was fitted into the. As an inner member, a pin made of molten steel equivalent to JIS standard SUS316, machined to have a clearance fit of 10 mm in height and 0.1 mm in outer diameter relative to the inner diameter of the outer member green compact Was used. Thereafter, both the (1) and (3) shaped molded body samples and the molded body fitting sample using the (2) shaped molded body were sintered at 1200 ° C. for 60 minutes in a vacuum atmosphere.

  About the produced (1) shape abrasion resistance evaluation sample, the reciprocating sliding friction test was done and the amount of wear after the test was measured. This reciprocating sliding friction test is a friction test in which the disk-shaped test piece is reciprocally slid while pressing a side surface of a roll (a mating member) having a diameter of 15 mm and a thickness of 22 mm with a predetermined load. In this test, the surface of molten steel equivalent to JIS standard SUS316 is chromized as a roll material (the surface is coated with chromium and a hard iron-chromium intermetallic compound layer is formed to provide wear resistance, seizure resistance, corrosion resistance, etc. Used to improve the process. A reciprocating sliding friction test was performed under the test conditions of load: 50 N, reciprocating sliding frequency: 40 Hz, reciprocating sliding amplitude: 1.0 mm, test time: 30 min, test temperature: 700 ° C.

  Moreover, about the produced sample for bonding property evaluation of (2) shape, the outer member was fixed at room temperature, and the inner member was pressurized to 200 MPa by an autograph. At this time, the load when the inner member and the outer member were broken at the joint interface was measured, and this was taken as the extraction load. In addition, about the sample which was not fractured even if it pressurized to 200 Mpa, the extraction load was described as 200 Mpa or more.

  Furthermore, for the prepared sample for evaluating the tensile strength of the shape (3), after sintering, it was machined into a shape of a tensile test piece, subjected to a tensile test with an autograph while heated to 800 ° C., and pulled at a high temperature. Strength was measured as high temperature strength.

  According to Table 1, compared with the sample No. 01 containing no P, the sample No. 02 having a P content of 0.1% by mass has a sharp decrease in the amount of wear, the extraction load, and the high temperature strength. Has increased significantly. Further, as the P content increases, the wear amount further decreases, the extraction load is remarkably improved, and the high temperature strength is improved. This is because a liquid phase is generated during sintering due to the inclusion of P, and the wear-resistant sintered member (outer member green compact) shrinks and becomes dense during sintering, and the P content increases. This is because the effect increases as the time elapses. However, since P has a function of causing solid dissolution in the Fe base and embrittlement of the Fe base, the sample No. 05 having a P content exceeding 1.0% has an excessive amount of P dissolved in the base. As a result, the base becomes brittle, the high-temperature strength decreases, and the wear amount increases remarkably. From this, it was confirmed that excellent wear resistance and a good bonding state can be obtained by setting the amount of P in the overall composition to 0.1 to 1.0% by mass.

[Second Embodiment]
Using the same iron-base alloy powder, iron-phosphorus alloy powder, and graphite powder as in the first example, adding and mixing the graphite powder in different proportions as shown in Table 2, the total composition listed in Table 2 Raw material powder was obtained. Then, (1) to (3) shaped compacts are produced under the same conditions as in the first example, and the inner member is pressed into the (2) shaped outer member green compact and sintered. The samples No. 06 to 09 were obtained. With respect to these samples, the wear amount, the extraction load, and the high temperature strength were measured in the same manner as in the first example. The results are shown in Table 2 together with the value of the sample No. 03 of the first example.

  As shown in Table 2, the wear of the wear-resistant sintered member sharply decreased and the removal of the sample of sample No. 07 to which 0.5% by mass of graphite powder was added as compared with the sample of sample No. 06 to which no graphite powder was added. The output load has increased remarkably, and the high temperature strength has also increased. This is because the graphite powder promotes liquid phase formation during sintering of the wear-resistant sintered member (outer member green compact), and the outer member green compact shrinks and becomes denser during liquid sintering. Is. Further, as the amount of graphite powder added increases, the amount of wear increases further because the amount of chromium carbide formed increases. However, in the sample of Sample No. 09 in which the amount of graphite powder added exceeds 1.5% by mass, the amount of liquid phase generated was excessive and the mold was deformed, so the subsequent test was stopped. From this, it was confirmed that excellent wear resistance and a good bonding state can be obtained by setting the addition amount of the graphite powder to 0.5 to 1.5% by mass.

[Third embodiment]
Using the same iron-phosphorus alloy powder and graphite powder as in the first embodiment, the iron-base alloy powder in which the Cr content of the iron-base alloy powder in the first embodiment is changed as shown in Table 3, On the other hand, 2.5% by mass of iron-phosphorus alloy powder and 1.0% by mass of graphite powder were added and mixed to obtain a raw material powder having the entire composition shown in Table 3. Then, (1) to (3) shaped compacts are produced under the same conditions as in the first example, and the inner member is pressed into the (2) shaped outer member green compact and sintered. The sample Nos. 10 to 13 were obtained. With respect to these samples, the wear amount, the extraction load, and the high temperature strength were measured in the same manner as in the first example. The results are shown in Table 3 together with the value of the sample number 03 of the first example.

  From Table 3, compared with the sample number 10 whose amount of Cr in the iron-base alloy powder is 20% by mass, the sample numbers 11, 03 and 12 whose Cr amount in the iron-based alloy powder is 25 to 45% by mass are shown. In the sample, the wear of the wear-resistant sintered member is reduced. However, as the amount of Cr increases, the amount of chromium carbide precipitated in the matrix increases, so the high temperature strength tends to decrease. In addition, since the hardness of the iron-based alloy powder increases as the Cr amount increases and the compressibility of the raw material powder decreases, in the sample of Sample No. 13 in which the Cr amount in the iron-based alloy powder exceeds 45% by mass, The influence of this decrease in compressibility became significant, and the molded product could not be molded, and the subsequent test was stopped. In addition, in the range whose Cr amount is 20-45 mass%, any sample is not fractured at a load of 200 MPa, and a good bonded state is obtained. From this, it was confirmed that excellent wear resistance and a good bonding state can be obtained by setting the amount of Cr in the iron-based alloy powder to 25 to 45% by mass.

[Fourth embodiment]
Using the same iron-base alloy powder, iron-phosphorus alloy powder, and graphite powder as in the first example, and newly preparing nickel powder, changing the addition amount of nickel powder at the ratio shown in Table 4 and adding and mixing Thus, a raw material powder having the entire composition shown in Table 4 was obtained. Then, (1) to (3) shaped compacts are produced under the same conditions as in the first example, and the inner member is pressed into the (2) shaped outer member green compact and sintered. The sample Nos. 14 to 20 were obtained. With respect to these samples, the wear amount, the extraction load, and the high temperature strength were measured in the same manner as in the first example. The results are shown in Table 4 together with the value of the sample No. 03 of the first example to which nickel powder is not added.

  From Table 4, when nickel powder is added and Ni is contained, the high-temperature strength of each sample is improved as compared with the sample of sample number 03 not containing Ni. It can also be seen that increasing the amount of Ni increases the high temperature strength as the amount of Ni increases, although the amount of wear increases slightly. However, as the amount of Ni increases, the effect of improving the high temperature strength is diminished, and even if Ni is provided in an amount exceeding 15% by mass, no improvement in the high temperature strength is observed. From this, it is confirmed that the Ni content is effective for improving the high-temperature strength, but even if it exceeds 15% by mass, no further effect is observed, so the upper limit should be 15% by mass. It was.

[Fifth embodiment]
Using the same iron-base alloy powder, iron-phosphorus alloy powder, nickel powder, and graphite powder as in the fourth example, adding and mixing the graphite powder in different proportions as shown in Table 5, mixing together in Table 5 The raw material powder of the whole composition was obtained. Then, (1) to (3) shaped compacts are produced under the same conditions as in the first example, and the inner member is pressed into the (2) shaped outer member green compact and sintered. The sample Nos. 21 to 28 were obtained. With respect to these samples, the wear amount, the extraction load, and the high temperature strength were measured in the same manner as in the first example. The results are shown in Table 5 together with the value of the sample No. 17 in the fourth example.

  From Table 5, the sample No. 21 in which the amount of graphite powder added is less than 0.8% by mass shows a large wear amount. This is because the solid solubility limit of C in the matrix is expanded by containing Ni, and C given in the form of graphite powder is dissolved in the matrix and the amount of chromium carbide formed is reduced. In addition, in the sample of Sample No. 22 to which 0.8% by mass of graphite powder was added, the amount of chromium carbide formed was increased, the amount of wear of the wear-resistant sintered member was decreased, and the amount of graphite powder added was increased. As the amount of chrome carbide increases, the amount of wear decreases significantly. In addition, in the sample of Sample No. 21, since 0.5% by mass of graphite powder is added, the amount of liquid phase generated is sufficient, and an excellent bonded state that does not break even under a load of 200 MPa is obtained. However, as the amount of graphite powder added increases, the amount of liquid phase generated increases in the same manner as in Example 2. In the sample of Sample No. 28 where the amount of graphite powder added exceeds 3.0% by mass. The liquid phase generation amount was excessive and the mold was deformed, and the subsequent test was stopped. From this, when Ni was contained, it was confirmed that excellent wear resistance and a good bonding state can be obtained by adding the graphite powder in an amount of 0.8 to 3.0% by mass.

  The present invention provides a sintered composite sliding part in which an outer member made of a sintered member excellent in wear resistance and corrosion resistance at high temperatures is well joined to an inner member made of molten steel, and a method for manufacturing the same. It is suitable for parts that require high temperature wear resistance and corrosion resistance, such as turbocharger parts.

Claims (5)

  By mass ratio, Cr: 23.8 to 44.3%, Mo: 1.0 to 3.0%, Si: 1.0 to 3.0%, P: 0.1 to 1.0%, C: An outer member comprising an Fe-based wear-resistant sintered member having a total composition of 1.0 to 3.0%, the balance Fe and inevitable impurities, and having a density ratio of 95% or more and in which carbides are dispersed in the matrix; A sintered composite slide characterized by comprising an inner member made of melted stainless steel, wherein the inner member is fitted into a hole formed in the outer member and diffused and joined together. parts.   In mass ratio, Cr: 19.7-41.9%, Ni: 5.0-15.0%, Mo: 0.8-2.8%, Si: 0.8-2.8%, P: Fe group having 0.1 to 1.0%, C: 1.2 to 4.4%, balance Fe and unavoidable impurities in total composition, density ratio of 95% or more and carbide dispersed in austenite base It consists of an outer member made of a wear-resistant sintered member and an inner member made of molten stainless steel, and the inner member is fitted into a hole formed in the outer member and diffused and joined together. A sintered composite sliding part characterized by the above. An iron-based alloy powder having a composition comprising Cr: 25 to 45%, Mo: 1 to 3%, Si: 1 to 3%, C: 0.5 to 1.5%, the balance Fe and inevitable impurities. P: Using a raw material powder in which 10 to 30% by mass of iron-phosphorus alloy powder is added and mixed with 1.0 to 3.3% by mass and graphite powder is added to 0.5 to 1.5% by mass,
The raw material powder is compacted into an outer member shape having a hole to be fitted with an inner member made of molten steel,
After the inner member made of molten stainless steel is fitted into the fitting hole of the obtained outer member green compact, sintering is performed to sinter the outer member, and the outer member and the inner member. A method for producing a sintered composite sliding part, wherein diffusion bonding is performed simultaneously and integrated.   Nickel powder is added to the raw material powder, or Ni is added to the iron-based alloy powder, and Ni is added in an amount of 5.0 to 15.0% by mass with respect to the raw material powder. The method for producing a sintered composite sliding part according to claim 3, wherein the amount of added is 0.8 to 3.0% by mass. After the green compact has been pre-sintered, a re-compressed pre-sintered re-pressed body is formed, and an inner member made of molten steel is fitted into the hole of the pre-sintered re-pressed body, and then sintered. 4. The method for manufacturing a sintered composite sliding part according to claim 3, wherein the outer member is sintered and the outer member and the inner member are simultaneously diffused and integrated.