Process for production of sintered copper alloy sliding material and sintered copper alloy sliding material

Abstract

Seizure resistance and wear resistance of CuBiIn copper-alloy sliding material are enhanced by forming a soft phase of as pure as possible Bi. Mixed powder of CuIn cuprous alloy powder and CuBi containing Cu-based alloy powder is used. A sintering condition is set such that Bi moves outside particles of said CuBi containing Cu-based powder and forms a Bi grain-boundary phase free of In, and In diffuses from said CuIn containing Cu-based powder to said CuBi containing Cu-based powder.

Claims

1. A sintered copper-alloy sliding material containing, by mass percentage, from 0.3 to 15% of In, from 0.5 to 30% of Bi, and from more than 2.0 to 15% of Sn plus In, balance comprising Cu and inevitable impurities, wherein the sintered structure comprises a Cu matrix and Bi grain-boundary phase free of In, and further an In-concentrated region is not formed in the Cu matrix.

Description

BEST MODE FOR CARRYING OUT THE INVENTION

(1) The following powders are mixed with a blender to prepare powder mixtures having a composition shown Table 1.

(2) (1) CuBi powder (Bi contentfrom 10 to 60 mass %, average particle diameter80 m)

(3) (2) CuIn powder (In contentfrom 5 to 30 mass %, average particle diameter80 m)

(4) (3) CuSn powder (Sn contentfrom 5 to 40 mass %, average particle diameter80 m)

(5) (4) CuBiSn powder (Bi contentfrom 5 to 20 mass %, Sn contentfrom 5 to 20 mass %, average diameter80 m)

(6) (5) CuInSn powder (In contentfrom 5 to 15 mass %, Sn contentfrom 5 to 15%, average particle diameter80 m)

(7) The powders (1) and (2) are used in Example Nos. 3, 6, 7, 9, 11 and 12 of Table 1. One of the powders (1) and (5), the powders (1), (2) and (3), the powders (2) and (4), the powders (2), (3) and (4) and the powders (4) and (5) is used in the other examples. Single powder was used in each of the Comparative Examples.

(8) TABLE-US-00001 TABLE 1 Recip- Seizure rocating Test- Sliding Cu Seizure Test Alloy Surface Wear Composition (mass %) Hardness Pressure- Amount Cu Bi In Sn (Hv) (MPa) (m) A 1 Bal. 0.5 0.3 0.5 89 12 3.3 2 Bal. 0.5 2.5 12.5 153 13.5 2.8 3 Bal. 0.5 15.0 147 15 2.0 4 Bal. 5.0 0.3 14.5 142 13.5 2.2 5 Bal. 5.0 2.5 5 128 15 2.4 6 Bal. 5.0 15.0 154 16.5 1.7 7 Bal. 15.0 0.3 105 15 2.8 8 Bal. 15.0 2.5 12.5 128 16.5 1.9 9 Bal. 15.0 15.0 141 18 2.2 10 Bal. 30.0 0.3 14.5 120 16.5 3.1 11 Bal. 30.0 2.5 127 18 3.3 12 Bal. 30.0 15.0 142 18 2.9 13 Bal. 5.0 2.5 5 138 15 2.2 14 Bal. 5.0 2.5 12.5 142 16.5 2.1 15 Bal. 0.5 2.5 5 138 13.5 2.9 16 Bal. 15.0 2.5 5 118 15 2.9 B 1 Bal. 72 3.0 7.4 2 Bal. 5.0 108 9.0 4.3 3 Bal. 5.0 70 9.0 4.5 4 Bal. 5.0 107 4.5 5.1 5 Bal. 15 152 10.5 3.3 6 Bal. 15.0 161 4.5 3.9 7 Bal. 5.0 4.0 115 10.5 4.7 8 Bal. 15.0 5.0 88 10.5 5.7 9 Bal. 5.0 2.5 5.0 105 10.5 5.2 Remarks. AInventive Examples. BComparative Examples

(9) A starting material powder to be sintered was dispersed on a backing steel sheet to a thickness of 1000 m. Sintering was carried out twice in an electric furnace under conditions of 750 degrees C. for 30 minutes. Rolling was carried out between the sintering processes, so as to compress the sintered layer. Bimetal form specimens having a 500-m thick sintered layer was thus obtained and subjected to the following tests.

(10) FIG. 1 shows the observation result of an Example 5 material under EPMA. The EPMA apparatus employed was a JXA-8100 manufactured by Nihon Denshi. The Cu phase of matrix exhibits uniform concentration corresponding to approximately 90 mass % in matrix phase. In addition, Cu and Bi are co-present. In and Sn are so uniformly present in the Cu phase. The concentrations of In and Sn correspond to approximately 2.5 mass % and approximately 5 mass %, respectively. These concentrations are considerably lower than the Cu concentration and are uniform in the matrix. That is, variation in the Sn and In concentrations is approximately in the same degree as that of the Cu concentration. Meanwhile, the Bi phase exhibits high concentration amounting to 70-100 mass % and Bi is co-present with neither In nor Sn.

(11) Seizure Resistance Test

(12) FIG. 2 illustrates a cooling-medium atmosphere test. Load was successively increased by 1.5 MPa at every fifteen minutes. In the drawing, 1 denotes a specimen, 2 denotes an opposite material (Fe hemisphere), and 3 denotes a pump.

(13) Wear Resistance Test (Reciprocating Sliding Test)

(14) Kind of oil: Ice machine oil

(15) Oil temperature: Room temperature

(16) Load: 980 N

(17) Frequency: 7 Hz

(18) Stroke: 10 mm

(19) As is shown in Table 1, the seizure resistance and wear resistance of Comparative Example 9, in which a single CuBiInSn powder is used, are inferior to those in which the mixed powders are used. Since either or both of Bi or In are not added in Comparative Examples 1-8, either or both of wear resistance or seizure resistance is inferior to those of the inventive examples. In addition, concentration distribution of the In and Sn is uniform in the examples, while the BiIn concentrated phase and the concentrated In phase are formed in Comparative Example 9.

INDUSTRIAL APPLICABILITY

(20) The sintered sliding material according to the present invention can be preferably used for a swash plate of a swash-plate type compressor, a bearing metal of an internal combustion engine, a thrust bearing of a turbo charger, a washer of LSD, a bush of a connecting rod's small end, and the like.

BRIEF DESCRIPTION OF DRAWINGS

(21) FIG. 1 EPMA images showing concentrations of the respective elements of Cu-5% Sn-3% In-6% Bi alloy according to an inventive example.

(22) FIG. 2 Drawing of a cooling-medium tester