JP2008144253A - Copper-based slide material and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copper-based slide material which has a high strength as a copper alloy even when a passive oxide film forming element is contained and is suitable for use in a bearing for supporting dynamic load, and its manufacturing method. <P>SOLUTION: In the copper-based slide material, a slide layer is formed by splaying the powder of the copper alloy on a steel base metal and then sintering it. The copper alloy has a composition containing 0.1-10% by mass of at least one of Al, Si, Cr, Ti, V, Ta, Zr, and Nb and the powder thereof is obtained by nitriding atomized powder of the copper alloy at 100-200°C. The slide layer is formed by sintering the copper alloy powders, so that only the passive oxide film forming element existing on the powder surface is stabilized as a nitride without nitriding the copper composition itself. As a result, the powder surface is prevented from being covered with the passive oxide film of an additive element during temperature rising for sintering, so that a firm sintering of copper alloy can be achieved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a copper-based sliding material in which a sliding layer is formed by spraying a copper alloy powder onto a steel back metal and then sintering, and a manufacturing method thereof.

Conventional bearings for internal combustion engines have been made of a sliding material composed of a multilayer sliding material of a copper alloy layer such as lead bronze or phosphor bronze and a steel back metal. Furthermore, as disclosed in Japanese Patent Application Laid-Open No. 2003-269456 (hereinafter referred to as “Patent Document 1”), the Sn content of bronze is increased in order to increase the corrosion resistance of the copper alloy against the lubricating oil for internal combustion engines. Or a method of adding Ni or the like. Further, as a method for producing a copper-based sliding material with a steel backing, a continuous sintering method that is suitable for mass production and can produce a bearing material at a low cost has been used.
JP 2003-269456 A (paragraphs 0007 and 0018, claim 3)

  By the way, in Ni and Sn containing copper alloys, Ni and Sn components, which are less susceptible to sulfidation and oxidation than Cu, are simply dissolved in Cu to improve corrosion resistance. With these copper alloys, bearings for internal combustion engines are used. A copper sulfide film or an oxide film is formed. Since the copper sulfide film and oxide film are sparse and brittle and thick, they are easily broken and removed by sliding with the shaft, and the thick copper sulfide film and oxide film are repeatedly formed, so that the corrosion resistance is insufficient.

  Therefore, it is conceivable to improve the corrosion resistance by adding elements such as Al, Si, Cr, Ti, V, Ta, Zr, Nb, etc. to the copper, but Al, Si, Cr, Ti, When prealloy copper alloy powder added with passive oxide film forming elements such as V, Ta, Zr, Nb, etc. or mixed powder of copper alloy and passive oxide film forming element powder as a raw material is sprayed on a steel back metal and sintered. There is a problem that a copper-based sliding material having sufficient strength cannot be obtained. This is because, when the powder such as bronze dispersed on the steel by the continuous sintering method is sintered in a sintering furnace having a reducing atmosphere such as hydrogen, the oxide film on the copper alloy surface is a reducing gas. The copper alloy powder containing a passive oxide film-forming element is less effective than reduction with a reducing gas, where the metal atoms diffuse and the sintering proceeds at the part where the powders are in contact with each other. Since the formation of the active oxide film is promoted, the powder surface is covered with a dense and strong passive oxide film, so the copper alloy powder is dispersed on the steel and the contact area between the powders is narrow. This is because, in the continuous sintering method in which sintering is performed at a temperature, the sintering phenomenon does not proceed sufficiently, so that a strong sintered material cannot be obtained.

  The present invention has been made in view of the above-described circumstances, and a copper-based sliding material suitable for a bearing that supports a dynamic load and a copper alloy having high strength even when containing a passive oxide film-forming element and its manufacture It is intended to provide a method.

  In order to achieve the above-described object, the invention according to claim 1 is directed to a copper-based sliding material in which a sliding layer is formed by spraying a copper alloy powder onto a steel backing and then sintering the powder. The copper alloy has a composition containing 0.1 to 10% by mass of any one or more of Al, Si, Cr, Ti, V, Ta, Zr, and Nb. A copper alloy powder obtained by nitriding at ˜200 ° C. is sintered as a sliding layer.

  The invention according to claim 2 is the copper-based sliding material according to claim 1, wherein the copper alloy further includes at least one of Sn, Ni, Ag, Zn, Mn, Fe, and Co. It has the composition which contained 0.1-20 mass%, It is characterized by the above-mentioned.

  The invention according to claim 3 is the copper-based sliding material according to claim 1 or 2, wherein the copper alloy further has a composition containing 0.1 to 0.2% by mass of P. It is characterized by that.

  The invention according to claim 4 is the copper-based sliding material according to any one of claims 1 to 3, wherein the copper alloy further contains 1 to 25% by mass of one or more of Bi and Pb. It has the composition which was made.

  Furthermore, the invention according to claim 5 is a powder obtained by atomizing a copper alloy having a composition containing 0.1 to 10% by mass of any one of Al, Si, Cr, Ti, V, Ta, Zr, and Nb. A nitriding step for nitriding at 100 to 200 ° C., a first sintering step for dispersing the copper alloy powder that has undergone the nitriding step on a steel backing metal, and sintering the sliding layer, and the first sintering step Of a copper-based sliding material produced from a rolling process of rolling the sliding layer sintered in roll rolling by a roll rolling, and a second sintering process of re-sintering the sliding layer rolled in the rolling process Features a manufacturing method.

  In the invention according to claim 1, since the nitriding process is performed after the manufacture by the atomizing method, the copper component itself is not nitrided, and only the passive oxide film forming element existing on the powder surface is nitrided. To stabilize. For this reason, it is possible to prevent the powder surface from being covered with the passive oxide film during the temperature rise in the sintering, and to firmly sinter the copper alloys. When this copper-based alloy sliding material is used as a bearing, the bearing surface is covered with a passive oxide film made of Al, Si, Cr, Ti, V, Ta, Zr, and Nb, so that the corrosion resistance is extremely high. Since these passive oxide films do not grow thick, they have high durability. Furthermore, even if the passive oxide film is removed by contact with the shaft, these passive oxide film forming elements are extremely active, and a passive oxide film is rapidly formed. Note that Al, Si, Cr, Ti, V, Ta, Zr, and Nb are effective in improving the corrosion resistance of the copper alloy even if added by 0.1% by mass. The nitride on the surface of the copper alloy powder becomes too much, and the sintered strength of the copper alloy begins to weaken. The nitriding temperature is preferably 100 ° C. to 200 ° C. in order to nitride only the passive oxide film forming element present on the extreme surface of the powder.

  As in the invention according to claim 2 or claim 3, as a copper alloy for atomized powder, at least one of Sn, Ni, Ag, Zn, Mn, Fe, and Co is 0.1 to 20 By setting it as the composition containing 0.1 mass% and / or the composition containing 0.1-0.2 mass% of P, material strength can be raised, without impairing the effect of this invention.

  As in the invention according to claim 4, as a copper alloy for atomized powder, the composition further contains 1 to 25% by mass of one or more of Bi and Pb, so that the effect of the present invention is not impaired. Can be increased.

  By the manufacturing method of the invention according to claim 5, the copper-based sliding member described in claim 1 can be manufactured by the continuous sintering method. This is because, generally, in the sintering of the dispersed copper alloy powder, element diffusion occurs only on the surface of the powder at the beginning of the temperature rise, and a sintered joint is formed at the contact portion of the powder. Thereafter, when the temperature rises, volume diffusion occurs through the sintered joint, and the sintered joint grows thick and becomes a strong sintered state. However, copper alloy powder containing extremely active elements that form a passive oxide film reacts with oxygen remaining in the sintering furnace atmosphere even when sintered in a reducing atmosphere such as hydrogen, and on the powder surface. Will form a passive oxide film. The diffusion rate of the copper element on the powder surface is slow at the beginning of the temperature rise, and before the sintered joint is formed, a dense passive oxide film is formed over a wide area of the powder surface, preventing the formation and growth of the sintered joint. Therefore, a strong sintered state cannot be obtained. On the other hand, the copper alloy composition powder used in the manufacturing method of the present invention is nitrided after being manufactured by the atomizing method, so that the copper component itself is not nitrided and is a passive body present on the powder surface. Stabilization is achieved by using only an oxide film forming element as a nitride. For this reason, it is possible to prevent the powder surface from being covered with the passive oxide film during the temperature rise in the sintering, and to firmly sinter the copper alloys.

  Hereinafter, preferred embodiments of the present invention will be described. FIG. 1 is a process diagram for explaining a manufacturing method for manufacturing a copper-based sliding material according to the present invention, and FIG. 2 is a cross-sectional view of the copper-based sliding material manufactured by the manufacturing method shown in FIG. FIG.

  In FIG. 1, the manufacturing method for manufacturing the copper-based sliding material according to the present embodiment includes 0.1 to 10 of at least one of Al, Si, Cr, Ti, V, Ta, Zr, and Nb. A copper alloy powder obtained by atomizing a copper alloy having a composition containing mass% is nitrided at 100 to 200 ° C. for a predetermined time, and the nitrided copper alloy powder is sprayed on a steel back metal (for example, a steel strip), under predetermined conditions. After sintering in the primary sintering furnace, cooling and densifying the copper alloy sintered layer by roll rolling, then sintering again in the secondary sintering furnace (for example, the same sintering conditions as in the primary sintering furnace) After sintering under the condition), the copper-based sliding material is manufactured by cooling.

  Here, Al, Si, Cr, Ti, V, Ta, Zr, and Nb are effective in improving the corrosion resistance of the copper alloy even when added in an amount of 0.1% by mass. Due to the excessive amount of nitride on the surface of the copper alloy powder, the sintered strength of the copper alloy begins to weaken. The nitriding temperature is preferably 100 ° C. to 200 ° C. in order to nitride only the passive oxide film forming element present on the extreme surface of the powder.

  Moreover, the copper alloy for atomizing contains 0.1-20 mass% of any one or more of Sn, Ni, Ag, Zn, Mn, Fe, Co, and / or P in 0.1 The material strength can be increased by the composition containing 0.2% by mass, and the lubricity can be improved by the composition containing 1 to 25% by mass of one or more of Bi and Pb. it can. Furthermore, hard particles such as carbides, nitrides, oxides, borides, and silicides can be added in order to improve wear resistance. Since these compounds are not substances that change during nitriding, they do not affect the effects of improving the corrosion resistance and improving the sintering strength of this embodiment.

  As shown in FIG. 2, the copper-based sliding material manufactured by the above-described manufacturing method is a two-layered copper-based sliding material 1 in which a copper alloy layer 3 is laminated as a sliding layer on a steel back metal 2. Produced.

  Next, the copper-based sliding material manufactured by the manufacturing method according to the present invention will be described with reference to Table 1. Example No. in Table 1 A copper alloy powder (−60 mesh) having the composition shown in 1 to 13 was prepared by an atomizing method, and then subjected to nitriding treatment in a nitrogen atmosphere and heated to the nitriding treatment temperature shown in Table 1 and held for 3 minutes (nitriding treatment) Process). This powder is spread on a steel strip having a thickness of 1.5 mm to a thickness of 0.8 mm, and is continuously passed through a sintering furnace at 800 ° C. to 950 ° C. in a hydrogen gas atmosphere (the first sintering step). Then, after cooling and roll rolling (rolling step) to densify the sintered layer, it was sintered again under the same conditions (secondary sintering step). 1 to 13 copper-based sliding materials were produced.

  On the other hand, Example No. Comparative Example Nos. 1 to 13 corresponding to the compositions 1 to 13, respectively. No. 14 to 26 copper alloy powders were prepared by the atomizing method, and were not subjected to nitriding treatment. Sintered under the same conditions as in Nos. 1-13, Comparative Example No. 14 to 26 copper-based sliding materials were produced.

  Example No. 1-13, Comparative Example No. 14 to 26 copper-based sintered materials are processed into JIS No. 6 tensile test pieces (however, both ends of the tensile test pieces are bonded to a sliding layer with a steel strip for chucking with a testing machine). The alloy was subjected to a tensile test to determine the tensile strength and elongation value of each. The results are also shown in Table 1.

  Comparative Example No. For Examples 14 to 26, Example Nos. Having the same composition were used. 1 to 13 are both higher in tensile strength and elongation by 2 times or more. When the fracture surface of the specimen subjected to the tensile test is analyzed with an electronic probe microanalyzer, oxides of Al, Si, Cr, Ti, V, Ta, Zr, and Nb are extensively analyzed on the fracture surface of the comparative product. It was. This is presumably because a passive oxide film of Al, Si, Cr, Ti, V, Ta, Zr, and Nb was formed on the powder surface during sintering, which inhibited the sintering. Since this passive oxide film serves as a starting point for destruction, both the tensile strength and the elongation value are low.

  On the other hand, the oxides of Al, Si, Cr, Ti, V, Ta, Zr, and Nb were also analyzed slightly in the fracture surface of the example product, but a wide range of oxides serving as the starting point of the fracture. There is no film formation. This is because the Al, Si, Cr, Ti, V, Ta, Zr, and Nb on the surface of the raw material copper alloy powder are stabilized as nitrides by nitriding and then sintered, so that these elements are passively oxidized during sintering. This is probably because the formation of a film on the powder surface was suppressed.

  The copper-based sliding material of the present invention is suitable for a bearing that supports a dynamic load because both the tensile strength and elongation are high even if it contains a passive oxide film forming element. In addition, copper or a copper alloy containing no Al, Si, Cr, Ti, V, Ta, Zr, or Nb as an intermediate layer between the copper alloy sintered material and the steel for increasing the bonding strength with the steel (for example, An intermediate layer by plating or sintering of Cu-Sn-Ni alloy or the like may be provided.

It is process drawing for demonstrating the manufacturing method for manufacturing the copper-type sliding material which concerns on this invention. It is a schematic diagram of the cross section of the copper-type sliding material manufactured with the manufacturing method of FIG.

Explanation of symbols

1 Copper sliding material 2 Steel backing metal 3 Sliding layer

Claims (5)

In copper-based sliding material in which a sliding layer is formed by spraying a copper alloy powder on a steel backing and then sintering it,
The copper alloy has a composition containing 0.1 to 10% by mass of any one or more of Al, Si, Cr, Ti, V, Ta, Zr, and Nb,
A copper-based sliding material obtained by sintering, as a sliding layer, a copper alloy powder obtained by nitriding the atomized powder of the composition at 100 to 200 ° C.   The copper alloy further has a composition containing 0.1 to 20% by mass of any one or more of Sn, Ni, Ag, Zn, Mn, Fe, and Co. Copper-based sliding material.   The copper-based sliding material according to claim 1 or 2, wherein the copper alloy further has a composition containing 0.1 to 0.2 mass% of P.   The copper-based sliding material according to any one of claims 1 to 3, wherein the copper alloy further has a composition containing 1 to 25 mass% of one or more of Bi and Pb. . A nitriding step of nitriding a powder obtained by atomizing a copper alloy having a composition containing at least one of Al, Si, Cr, Ti, V, Ta, Zr, and Nb in an amount of 0.1 to 10% by mass at 100 to 200 ° C. When,
A first sintering step of dispersing the copper alloy powder that has undergone the nitriding step on a steel back metal and sintering the sliding layer;
A rolling step of rolling the sliding layer sintered in the first sintering step by roll rolling;
A second sintering step for re-sintering the sliding layer rolled in the rolling step;
The manufacturing method of the copper-type sliding material manufactured from this.

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