JP5377557B2 - Copper-based sliding material - Google Patents

Description

  The present invention relates to a copper-based sliding material excellent in fatigue resistance and seizure resistance, and more particularly to a copper-based sliding material suitable as a material for half bearings, bushes, thrust washers, etc. in automobiles, industrial machines and the like.

  Conventionally, a copper-based sliding material used for a plain bearing for an internal combustion engine is generally manufactured by a continuous sintering method. This continuous sintering method is a manufacturing method in which a Cu alloy powder is continuously sprayed on a steel strip and subjected to continuous sintering and rolling. Also, copper-based sliding materials for slide bearings are required to be Pb-free in order to comply with recent environmental regulations, and those using a sintered Cu alloy containing Bi as an alternative material for Pb. It has been proposed (see, for example, Patent Documents 1 to 5).

Japanese Patent No. 3421724 US 2003/0068106 A1 Special table 2010-535287 JP-A-4-28836 JP-A-5-263166

  By the way, in recent years, crankshafts of internal combustion engines tend to be rotated at higher speeds, and sliding bearings are required to have better seizure resistance. In order to obtain good seizure resistance when using the above-described sintered Cu alloy containing Bi as a copper-based sliding material for a slide bearing, the sintered Cu alloy contains Bi by 10 mass% or more. It is desirable.

  By the way, in patent documents 1-3, although sintering of Cu alloy containing Bi is carried out by a continuous sintering method, whether or not this sintered Cu alloy has good strength is the inclusion of Bi. It is greatly influenced by the quantity. Specifically, as shown in FIG. 4A, when Cu alloy powder is spread on the steel strip, there are many gaps in the Cu alloy layer. Further, as shown in FIG. 4B, Bi is present in the Cu alloy powder, and when the temperature is raised in the subsequent primary sintering step, Bi melts near 271 ° C. to become a liquid phase. Then, when the sintering temperature is reached and the cooling is started, the shrinkage rate of the Cu alloy is higher than that of Bi, so Bi is extruded from the Cu alloy powder as shown in FIG. It flows out into the gap between the powders. As Bi flowing out to the gap spreads along the Cu alloy powder surface, Bi grains in the Cu alloy layer are coarsened as shown in FIGS. 3 and 4D. FIG. 3 shows the structure of the Cu alloy after the rolling and secondary sintering steps are further performed on the sintered Cu alloy after the primary sintering shown in FIG. The phenomenon that the Bi grains become coarse is particularly affected when Bi is contained in the Cu alloy layer in an amount of 10% by mass or more. Since Bi hardly dissolves in the Cu alloy, it exists alone in the Cu alloy layer, and the strength of Bi is significantly lower than that of the Cu alloy. In a bearing that receives a dynamic load, as described in paragraph [0030] of Patent Document 2, cracks occur starting from grain boundaries between coarse Bi or Bi and a Cu alloy, and fatigue failure of the Cu alloy layer occurs. Is prone to occur.

  Patent Documents 2 and 3 propose bearings in which the composition of the Cu alloy layer for the bearing is Cu—Sn—P—Bi, and the base of the Cu alloy is a solid solution of Cu, Sn, and P. When this bearing is subjected to a sliding load during use, Sn in the Cu alloy substrate moves to the sliding surface of the bearing, and a layer containing a large amount of Sn is formed on the sliding surface. It describes that seizure is improved. However, when Sn is concentrated on the surface of the Cu alloy that becomes the sliding surface of the bearing, the Cu alloy near the sliding surface becomes hard and seizure resistance decreases.

  On the other hand, according to Patent Documents 4 and 5, a Cu alloy powder containing Bi is produced by a mechanical alloying method, and this Cu alloy powder is used for a relatively low temperature (400 to 800 ° C., more preferably 400 to 700 ° C.). ), It is described that a copper-based sliding material having fine Bi grains can be obtained. However, if the sintering is performed at a temperature of 800 ° C. or lower in the continuous sintering method, the adhesion between the steel back metal and the Cu alloy layer cannot be sufficiently obtained, so that the fatigue resistance is lowered. Further, when sintering is performed at a temperature exceeding 800 ° C., the adhesion with the steel back metal is good, but as described in Patent Document 4, the sintering of the Cu alloy powder proceeds too much, and the Cu alloy layer The Bi grains inside become coarse.

  The present invention has been made in view of the above-described circumstances, and its object is to suppress the coarsening of Bi grains in a Cu alloy layer produced by a continuous sintering method, and to improve fatigue resistance and resistance. An object of the present invention is to provide a copper-based sliding material having excellent seizure properties.

In order to achieve the above-described object, in the invention according to claim 1, a copper-based sliding material comprising a steel back metal layer and a Cu alloy layer, wherein the Cu alloy layer contains 6 to 12 mass% of Sn, Bi In a copper-based sliding material containing 11 to 30% by mass of P and 0.01 to 0.05% by mass of P, with the balance being Cu and inevitable impurities, the Bi has a mass ratio with the Sn of Bi / Sn. = 1.7 to 3.4, the mass ratio with P is Bi / P = 500 to 2100, and a Cu-Sn-P compound is dispersed in the Cu alloy layer, whereby the Cu alloy layer Bi grains having an average particle area of 60 to 350 μm ² are dispersed in a cross section in a direction parallel to the thickness direction.

  In a second aspect of the present invention, in the copper-based sliding material according to the first aspect, the Sn has a mass ratio with the Bi of Bi / Sn = 2.1 to 3.1, and the Cu alloy. It is characterized by containing 6.8-9 mass% in the layer.

  According to a third aspect of the present invention, in the copper-based sliding material according to the first or second aspect, the Cu alloy layer further includes a total amount of at least one selected from the group consisting of Ni, Fe, and Ag. It is characterized by containing 0.1 to 10% by mass.

In the invention which concerns on Claim 4, in the copper-type sliding material in any one of Claim 1 thru | or 3, the said Cu alloy layer is further carbide, nitride, silicidation whose average particle diameter is 1-10 micrometers. It contains 0.1 to 10% by mass of an inorganic compound composed of any one of a product and an oxide .

  In the invention according to claim 1, it is known that when Bi is added to the copper-based sliding material, good sliding characteristics can be obtained. However, the Cu alloy layer contains 11 to 30% by mass of Bi. And achieves high sliding characteristics. On the other hand, if the Bi content is less than 11% by mass, the sliding characteristics are not sufficient and the seizure resistance is lowered. On the other hand, if the Bi content is more than 30% by mass, the fatigue resistance is lowered.

Moreover, in the invention which concerns on Claim ¹ , it discovered that the average particle | grain area of Bi grain | grains could be finely controlled with 60-350 micrometers ² by disperse | distributing a Cu-Sn-P type compound to Cu alloy layer. This is presumed to be due to the following mechanism. The copper-based sliding material of the present invention is manufactured by continuously spreading a Cu alloy powder on a steel strip and repeating sintering and rolling. First, in the spreading step, as shown in FIG. 2A, after the Cu alloy powder is spread on the steel strip, the Cu alloy layer is in a porous state. Further, as shown in FIG. 2B, Bi is present in the Cu alloy powder. When the temperature is raised in the subsequent sintering step, Bi melts in the vicinity of 271 ° C. to become a liquid phase. And if sintering is performed at 800-900 degreeC and cooling is started in the subsequent cooling process, since the thermal contraction rate of Cu alloy is higher than Bi and Cu alloy contracts earlier, Bi is Cu alloy. It is extruded from the powder and flows into the gap between the Cu alloy powders. At this time, shrinkage of the Cu alloy is suppressed by precipitating the Cu—Sn—P-based compound on the Cu alloy. In this way, by relaxing the difference in thermal shrinkage between the Cu alloy and Bi, it is possible to prevent the liquid phase of Bi from being pushed out of the Cu alloy powder as shown in FIG. It becomes the organization shown in 2 (d). Thereafter, by rolling and sintering for densification, Bi grains can be finely dispersed in the Cu alloy layer as shown in FIG.

  Further, the Cu—Sn—P-based compound is precipitated on the Cu alloy by the following mechanism. First, at the sintering temperature (800 to 900 ° C.), a larger amount of Sn and P can be dissolved in the Bi liquid phase than at normal temperature (20 ° C.). Diffuses into the phase. Thereafter, when the temperature is lowered in the cooling step, Sn and P are supersaturated in the Bi liquid phase, and Sn and P diffuse from the Bi liquid phase into the Cu alloy. For this reason, Sn and P are concentrated near the interface between the liquid phase of Bi and the Cu alloy. At this time, when the cooling rate from 800 ° C. to 450 ° C. in the cooling step is fast, Sn and P are dissolved in a supersaturated state in the Cu alloy, but the cooling rate from 800 ° C. to 450 ° C. is 4 to 4 ° C. By cooling for 10 minutes, it becomes possible to precipitate a Cu-Sn-P-based compound on the Cu alloy. As a result, the difference in thermal shrinkage between Bi in a liquid phase with that of the Cu alloy is relaxed, and the liquid phase of Bi remains in the Cu alloy powder, so that the coarsening of Bi grains can be suppressed.

  As described above, it is possible to suppress the coarsening of the Bi grains by precipitating the Cu—Sn—P compound in the Cu alloy, but the Cu—Sn compound and the Sn—P compound are precipitated. May be. In addition, when only a Cu-Sn compound was deposited by the same method as described above using a Cu-Sn-Bi alloy, the effect of suppressing the coarsening of Bi grains was not obtained.

  In addition, Cu—Sn—P-based compounds are deposited on the Cu alloy, and the Cu alloy prevents Sn from being dissolved in a supersaturated state, thereby preventing Sn from concentrating on the bearing surface in a sliding environment. And it can suppress that seizure resistance falls. When Sn is present in a supersaturated state in the Cu alloy, Sn is unstable and easily moved, and a concentrated Sn layer is formed on the bearing surface in a sliding environment. On the other hand, when a Cu—Sn—P-based compound is deposited on a Cu alloy, Sn existing in a supersaturated state in the Cu alloy decreases, so that a concentrated Sn layer is formed on the bearing surface in a sliding environment. Therefore, it has good seizure resistance.

In the invention according to claim 1, it is preferable that the mass ratio of Bi and Sn is Bi / Sn = 1.7 to 3.4, and the mass ratio of Bi and P is Bi / P = 500 to 2100. And found to have excellent fatigue resistance. Thus, by controlling the mass ratio of Bi and Sn and the mass ratio of Bi and P, it becomes possible to precipitate a Cu-Sn-P-based compound in the Cu alloy, and the average particle area of Bi grains is 60 to 60. It can be controlled to 350 μm ² . Moreover, when the mass ratio (Bi / Sn) of Bi and Sn is smaller than 1.7, the content of Sn is larger than Bi. Sn is more easily diffused into Bi than P, and in the sintering process, the Bi liquid phase is in a state where Sn is saturated and dissolved, and it becomes difficult for P to diffuse into the Bi liquid phase. For this reason, the Cu—Sn—P-based compound is not precipitated in the Cu alloy, and the effect of suppressing the coarsening of the Bi grains cannot be obtained. On the other hand, if the mass ratio of Bi to Sn (Bi / Sn) is larger than 3.4, the content of Sn is too small relative to Bi, so the amount of precipitation of the Cu—Sn—P-based compound is not sufficient, The effect of suppressing the coarsening of Bi grains cannot be obtained.

  When the mass ratio of Bi to P (Bi / P) is smaller than 500, the P content is larger than Bi. For this reason, the Bi liquid phase is in a state where a large amount of P is dissolved in the sintering process, and a part of the P surplus in the Bi liquid phase in the subsequent cooling process is bonded to the steel backing metal and the Cu alloy. By forming a steel back metal and a brittle Fe-P compound in the vicinity of the surface, the fatigue resistance is lowered. On the other hand, if the mass ratio of Bi to P (Bi / P) is greater than 2100, the P content is too small relative to Bi, so the amount of precipitation of the Cu—Sn—P compound is not sufficient, and Bi grains The effect which suppresses the coarsening of is not acquired.

  Moreover, in the invention which concerns on Claim 1, although Sn contains 6-12 mass% in Cu alloy, when content of Sn is less than 6 mass%, Sn will be solid-solved in Cu alloy and Sn will be contained. There will be no surplus. For this reason, the Cu—Sn—P-based compound is not precipitated in the Cu alloy, and the effect of suppressing the coarsening of the Bi grains cannot be obtained. On the other hand, if the Sn content exceeds 12% by mass, a large amount of Cu—Sn liquid phase is generated in the sintering process, and the Cu alloy powder partially flows. For this reason, it cannot suppress that the liquid phase of Bi flows out from Cu alloy powder, and the effect which suppresses the coarsening of Bi grain cannot be acquired.

  Moreover, in the invention which concerns on Claim 1, although 0.01-0.05 mass% of P is contained in Cu alloy, when content of P is less than 0.01 mass%, P will be contained in Cu alloy. It is dissolved and P does not become excessive. For this reason, the precipitation amount of the Cu—Sn—P compound is not sufficient, and the effect of suppressing the coarsening of Bi grains cannot be obtained. On the other hand, if the content of P exceeds 0.05% by mass, the Bi liquid phase is in a state where a large amount of P is dissolved in the sintering process, and the Bi liquid phase is excessive in the subsequent cooling process. A part of the formed P forms a brittle Fe—P compound with the steel back metal in the vicinity of the bonding surface between the steel back metal and the Cu alloy, so that the fatigue resistance is lowered.

Moreover, in the invention which concerns on Claim ¹ , it discovered that it had favorable fatigue resistance by controlling the average area of Bi grain disperse | distributed to Cu alloy layer to 60-350 micrometer < ² >. The average particle area of Bi is the average value of the area of each Bi grain in the cross section in the direction parallel to the thickness direction of the Cu alloy layer. Bi has a significantly lower strength than Cu alloys, and Bi grains are often the starting point of fatigue. When the average area of the Bi grains is controlled to be larger than 350 μm ² , cracks are generated in the coarsened Bi grains, and the fatigue resistance is significantly lowered.

  Moreover, in the invention which concerns on Claim 2, the mass ratio of Bi and Sn shall be Bi / Sn = 2.1-3.1, and Sn is 6.8-9 mass% contained, Good seizure resistance It was found to have sex. This is presumed to be due to the following mechanism. In addition to Cu-Sn-P compounds, Cu-Sn compounds and Sn-P compounds are precipitated in the Cu alloy. However, since these compounds are harder than the Cu alloy, a large amount of the Cu alloy is precipitated. Cu alloy becomes too hard. On the other hand, when the precipitation amount of these compounds is small, Sn is dissolved in a supersaturated state in the Cu alloy, and a concentrated layer of Sn is formed on the bearing surface in a sliding environment, so that portion is cured. . For this reason, the adaptability of the bearing surface is lost in a sliding environment, and seizure resistance is lowered.

  As described above, when the mass ratio of Bi and Sn (Bi / Sn) increases, the amount of Cu-Sn-P compound deposited decreases, and a concentrated Sn layer is formed on the bearing surface in a sliding environment. It becomes easy and the part becomes easy to harden. On the other hand, when the mass ratio of Bi and Sn (Bi / Sn) is reduced, the amount of precipitation of the Cu—Sn—P compound increases, but the amount of precipitation of the Cu—Sn compound and Sn—P compound also increases, resulting in a Cu alloy. Becomes easy to cure. Under such circumstances, by setting the mass ratio of Bi and Sn to Bi / Sn = 2.1 to 3.1, Sn is not dissolved in the Cu alloy in a supersaturated state, and the sliding environment Under this, it becomes difficult to form a concentrated Sn layer on the bearing surface. Moreover, since the precipitation amount of the Cu—Sn compound and Sn—P compound in the Cu alloy is also small, the Cu alloy is hard to be hardened and can have good seizure resistance.

  In addition, when the mass ratio of Bi and Sn is Bi / Sn = 2.1 to 3.1, when the Sn content is increased, not only the precipitation amount of the Cu—Sn—P compound but also the Cu—Sn compound The amount of precipitation increases. As a result of the experiment, the present inventor has found that the Sn content is 9% by mass or less, thereby having the best seizure resistance. On the other hand, it is preferable that the Sn content is small. However, if the Sn content is less than 6.8% by mass, the amount of precipitation of the Cu—Sn—P compound is too small, and the seizure resistance is lowered.

  Further, as in the invention according to claim 3, in order to reinforce the Cu alloy layer, at least one kind selected from the group consisting of Ni, Fe, and Ag may be contained in a total amount of 0.1 to 10% by mass. . When the total content is less than 0.1 mass, the Cu alloy layer is not sufficiently strengthened. Moreover, when these content increases in total exceeding 10 mass%, Cu alloy layer will become weak and fatigue resistance will fall.

  Moreover, in order to reinforce a Cu alloy layer like the invention which concerns on Claim 4, you may contain 0.1-10 mass% of inorganic compounds. As this inorganic compound, carbide, nitride, silicide, oxide, or the like can be used. An inorganic compound having an average particle diameter of 1 to 10 μm can be used. When the content of the inorganic compound is less than 0.1% by mass, the Cu alloy layer is not sufficiently strengthened. On the other hand, when the content of the inorganic compound exceeds 10% by mass, the inorganic compound particles aggregate in the Cu alloy layer, so that the strength decreases.

It is a schematic diagram which shows the structure | tissue of a Cu-Sn-P-Bi type Cu alloy layer. It is a figure for demonstrating the behavior of Bi in the preparation process of a Cu-Sn-P-Bi type Cu alloy layer. It is a schematic diagram which shows the structure | tissue of the conventional Cu-Bi type Cu alloy layer. It is a figure for demonstrating the behavior of Bi in the preparation process of the conventional Cu-Bi type Cu alloy layer.

  About Examples 1-17 and Comparative Examples 1-13 using the Cu alloy containing Bi which concerns on this embodiment, while measuring the average particle area of Bi grain | grains, the bearing fatigue test was done. Moreover, about Examples 1-17 and the comparative example 1, the bearing seizure test was done. Table 1 shows the compositions (mass%) of Examples 1 to 17 and Comparative Examples 1 to 13, the mass ratio of Bi and Sn (Bi / Sn), and the mass ratio of Bi and P (Bi / P). Examples 1-17 used the Cu alloy powder produced with the composition shown in Table 1 with the atomizing method, sprayed the powder on a strip steel, repeated sintering, and rolled, and produced the sliding material. Sintering was performed at a temperature of 830 ° C., and the Cu—Sn—P-based compound was precipitated on the Cu alloy by lowering the temperature from 830 ° C. to 450 ° C. in 7 minutes in the cooling step after sintering. This sliding material was processed into a semicylindrical shape to produce a sliding bearing.

  Comparative Example 1 is a Cu alloy described in Patent Documents 2 and 3, and the manufacturing method of the example is that the temperature is lowered from 830 ° C. to 450 ° C. in 2 minutes in the cooling step after sintering. Sliding bearings having the compositions shown in Table 1 were prepared by a method in which Sn and P were dissolved in a supersaturated state in the alloy and only the point that the Cu-Sn-P compound was not precipitated was different. Comparative Example 2 is a Cu alloy described in Patent Document 1, and a plain bearing having a composition shown in Table 1 was manufactured by the same manufacturing method as that of the example. Further, Comparative Examples 3 and 4 are Cu alloys described in Patent Documents 4 and 5, and Cu alloy powders prepared by the mechanical alloying method with the composition shown in Table 1 are used. Scattering, sintering and rolling were repeated to produce a sliding material. In the sintering process, the comparative example 3 was sintered at a temperature of 700 ° C. and the comparative example 4 was sintered at a temperature of 830 ° C. This sliding material was processed into a semicylindrical shape to produce a sliding bearing. In Comparative Examples 5 to 13, sliding bearings having the compositions shown in Table 1 were produced by the same production method as in the Examples.

  Next, with respect to the produced slide bearing, an image near the center in the thickness direction in a cross section in a direction parallel to the thickness direction of the Cu alloy layer using an electron microscope is 200 times (observation field: Cu alloy layer). The film was photographed with a length of 200 μm in the thickness direction and a rectangular range defined by a length of 300 μm in the direction perpendicular to the thickness direction of the Cu alloy layer, and the image was analyzed by a general image analysis method (analysis software: Image) -Pro Plus (Version 4.5); manufactured by Planetron Co., Ltd.) was used to measure the area of each Bi grain and calculate the average. This value was taken as the average particle area of Bi grains, and the measurement results are shown in Table 1. Moreover, Examples 1-17 confirmed that the Cu-Sn-P type compound was disperse | distributing to the Cu alloy layer using general TEM analysis.

  Table 2 shows the test conditions of the bearing fatigue test. In Examples 1 to 17 and Comparative Examples 1 to 13, a bearing fatigue test was performed under the test conditions shown in Table 2 using a bearing tester. Moreover, Examples 1-17 and the comparative example 1 implemented the bearing seizure test on the test conditions shown in Table 3 with a bearing tester. The test results are shown in Table 1. The limit pressure at which no fatigue occurred in the sample is shown in the fatigue resistance column of Table 1, and the limit pressure at which no seizure occurred in the sample is shown in the seizure resistance column.

  Examples 1-17 have favorable fatigue resistance compared with Comparative Examples 1-13. In Examples 1 to 17, the mass ratio of Bi and Sn is Bi / Sn = 1.7 to 3.4, and the mass ratio of Bi and P is Bi / P = 500 to 2100. As explained, it becomes possible to precipitate a Cu—Sn—P-based compound on the Cu alloy in the Cu alloy powder in the cooling step after sintering. As a result, the difference in thermal shrinkage between the Cu alloy in the Cu alloy powder and Bi in the liquid phase is alleviated, and the Bi liquid phase remains in the Cu alloy powder. The fatigue resistance of the alloy layer can be increased.

  Examples 1 to 17 all have good seizure resistance as compared to Comparative Example 1, but Examples 1, 4, 5, and 13 to 17 among Examples 1 to 17 have particularly good seizure resistance. It has sex. In Examples 1, 4, 5, 13 to 17, the mass ratio of Bi and Sn is Bi / Sn = 2.1 to 3.1, and Sn is contained in an amount of 6.8 to 9 mass%. [0024] As described in [0024], Sn is not solid-solved in the Cu alloy in a supersaturated state, and it is difficult to form a concentrated Sn layer on the bearing surface in a sliding environment. Moreover, since there are also few precipitation amounts of the Cu-Sn compound and Sn-P compound in Cu alloy, Cu alloy is hard to harden | cure and the seizure resistance of Cu alloy layer can be improved.

Example 16 contains Ni, Fe, and Ag in the Cu alloy, and Example 17 contains an inorganic compound (Mo ₂ C in this example) in the Cu alloy, but is the same as in Examples 1-15. , Bi grain coarsening can be suppressed and the fatigue resistance of the Cu alloy layer can be increased. Moreover, Cu alloy is hard to be hardened and the seizure resistance of the Cu alloy layer can be improved.

  In Comparative Example 1, compared with Example 1, the average particle area of Bi grains is large, resulting in poor fatigue resistance and seizure resistance. In Comparative Example 1, the composition of the Cu alloy is the same as that of Example 1, but the cooling rate in the cooling step is faster than that of Example 1, and Sn and P are dissolved in a supersaturated state in the Cu alloy. Cu—Sn—P based compounds are not precipitated. For this reason, Bi flows out into the gap between the Cu alloy powders without mitigating the difference in thermal shrinkage between the Cu alloy and Bi, and thus the Bi grains are coarsened and fatigue resistance is reduced. Further, by forming a Sn concentrated layer on the bearing surface in a sliding environment, the portion is cured and seizure resistance is reduced.

  In Comparative Example 2, the average particle area of Bi grains is large and fatigue resistance is inferior compared with Example 1. In Comparative Example 2, since Cu is not contained in the Cu alloy, the Cu—Sn—P compound is not precipitated, and the Cu—Sn compound is precipitated. For this reason, Bi flows out into the gap between the Cu alloy powders without mitigating the difference in thermal shrinkage between the Cu alloy and Bi, and thus the Bi grains are coarsened and fatigue resistance is reduced.

  In Comparative Example 3, compared with Example 1, the average particle area of the Bi grains is about the same, but the fatigue resistance is inferior. This is because the sintering temperature was as low as 700 ° C. and the adhesion between the Cu alloy layer and the steel strip was not sufficient. Moreover, compared with Example 1, the comparative example 4 has the result that the average particle | grain area of Bi grain was large and its fatigue resistance was inferior. This is because the sintering temperature is as high as 830 ° C., the sintering of Cu alloy powders proceeds too much, and the effect of refining Bi grains when mechanical alloying powder is used is lost.

  In Comparative Example 5, the mass ratio (Bi / Sn) between Bi and Sn is larger than that of the example. That is, since the Sn content is small with respect to Bi and the precipitation amount of the Cu—Sn—P compound is not sufficient, the average particle area of Bi grains is large and fatigue resistance is reduced. In Comparative Example 6, the mass ratio (Bi / Sn) between Bi and Sn is smaller than that of the example. That is, the content of Sn is larger than Bi, and the liquid phase of Bi is in a saturated state by dissolving only Sn in the sintering process, so that it is difficult for P to diffuse into the liquid phase of Bi. Cu—Sn—P based compounds are not precipitated. As a result, the average grain area of the Bi grains is large and the fatigue resistance is reduced.

  In Comparative Example 7, the mass ratio (Bi / P) of Bi and P is smaller than that of the example. That is, since the P content is large relative to Bi and a large amount of P is dissolved in the Bi liquid phase in the sintering process, a part of the P surplus in the Bi liquid phase in the cooling process is a part of the steel. A fragile Fe-P compound is formed with the backing metal. As a result, the average particle area of Bi grains is small, but the fatigue resistance is reduced. In Comparative Example 8, the mass ratio (Bi / P) of Bi and P is larger than that of the example. That is, since the P content is small relative to Bi and the precipitation amount of the Cu—Sn—P-based compound is extremely small, the average particle area of Bi grains is large and the fatigue resistance is low.

  The comparative example 9 has more Bi content than an Example. Since Bi has a significantly lower strength than Cu alloys, the average particle area of Bi grains is small, but fatigue resistance is reduced.

  In Comparative Example 10, the Sn content is higher than that of the Example, and a large amount of Cu-Sn liquid phase is generated in the sintering process. The phase flows out. As a result, the average grain area of the Bi grains is large and the fatigue resistance is reduced. In Comparative Example 11, the Sn content is lower than that in the Examples, and all Sn is dissolved in the Cu alloy, so that no Cu—Sn—P based compound is precipitated. As a result, the average grain area of the Bi grains is large and the fatigue resistance is reduced.

  In Comparative Example 12, the P content is higher than that in the Examples, and P is excessively dissolved in the Bi liquid phase in the sintering process. Not only Cu—Sn—P compounds but also steel backing metal and brittle Fe—P compounds are formed. As a result, the average grain area of Bi grains is small, but the fatigue resistance is lowered. Moreover, since the comparative example 13 has less P content than an Example and the precipitation amount of a Cu-Sn-P type compound is not enough, the average particle area of Bi grain | grains is large and fatigue resistance is falling.

  The copper-based sliding material according to the present embodiment can be applied to a sliding bearing for an internal combustion engine and a sliding bearing material for various industrial machines. The copper-based sliding material according to the present embodiment is also used as a multilayer bearing in which an overlay layer is formed on a Cu alloy layer.

Claims (4)

A copper-based sliding material comprising a steel back metal layer and a Cu alloy layer, wherein the Cu alloy layer has Sn of 6 to 12% by mass, Bi of 11 to 30% by mass, and P of 0.01 to 0.05% by mass. In the copper-based sliding material containing, the balance consisting of Cu and inevitable impurities,
The Bi has a mass ratio with the Sn of Bi / Sn = 1.7 to 3.4, and a mass ratio with the P of Bi / P = 500 to 2100,
In the Cu alloy layer, Cu—Sn—P-based compounds are dispersed, whereby Bi grains having an average particle area of 60 to 350 μm ² are dispersed in a cross section parallel to the thickness direction of the Cu alloy layer. A copper-based sliding material characterized by having   The mass ratio of the Sn to the Bi is Bi / Sn = 2.1 to 3.1, and 6.8 to 9 mass% is contained in the Cu alloy layer. Copper-based sliding material.   The copper system according to claim 1 or 2, wherein the Cu alloy layer further contains 0.1 to 10% by mass in a total amount of at least one selected from the group consisting of Ni, Fe, and Ag. Sliding material. The Cu alloy layer further contains 0.1 to 10% by mass of an inorganic compound composed of any one of carbide, nitride, silicide, and oxide having an average particle diameter of 1 to 10 μm. The copper-based sliding material according to claim 3.

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