Pb-Free Copper-Alloy Sliding Material

Abstract

[PROBLEMS] To provide a Cu—Bi—hard substance base sintered alloy in which the respective properties of Bi and hard substance can be satisfactorily exerted. [MEANS FOR SOLVING PROBLEMS] There is provided a Ph free copper base sintered alloy, comprising 1 to 30% of Bi and 0.1 to 10% of hard substance particles of 10 to 50 μm average diameter, (1) wherein a Bi phase having an average particle diameter smaller than that of the hard substance particles is dispersed in a matrix of Cu, or wherein with respect to a Bi phase in contact with the hard substance particles, the ratio of presence of hard substance particles exhibiting a ratio of hard substance particle contact length to entire circumference of Bi phase of 50% or less is 70% or greater based on the total number of hard substance particles.

Description

BRIEF EXPLANATION OF DRAWINGS

[FIG. 1] a photograph (200 times) showing a microscopic structure of the sintered copper alloy according to an example of the present invention.

[FIG. 2] a photograph (500 times) showing a microscopic structure of the sintered copper alloy according to the example of the present invention.

[FIG. 3] a photograph (200 times) showing a microscopic structure of the sintered copper alloy according to a comparative example.

[FIG. 4] a photograph (500 times) showing a microscopic structure of the sintered copper alloy according to the comparative example.

In FIGS. 1 and 2 are shown the microscopic photographs of the inventive example No. 4 at magnification of 200 times and 500 times, respectively. Similarly, in FIGS. 3 and 4 are shown the microscopic photographs of the comparative example No. 3 at the magnification of 200 times and 500 times, respectively. It is apparent that in the former FIGS. 1 and 2, the contact ratio of the hard matters and the Bi phase is small, while in the latter FIGS. 3 and 4 the contact ratio of the hard matters and the Bi phase is large.

INDUSTRIAL APPLICABILITY

The sintered copper alloy according to the present invention can be used for various bearings, for example AT (automatic transmission) bush and piston-pin bush. The high levels of conformability, wear resistance, seizure resistance and fatigue resistance achieved by the present invention are effectively utilized for these applications.

Claims

1. A Pb-free copper-based sintered alloy, characterized in that it has a composition containing from 1 to 30% by mass of Bi and from 0.1 to 10% by mass of hard matter particles having from 10 to 50 μm of average particle diameter, the balance consisting of Cu and unavoidable impurities, and, further, the Bi phase having smaller average particle diameter than that of the hard matter particles is dispersed in the Cu matrix.

2. A Pb-free copper-based sintered alloy, characterized in that it has a composition containing from 1 to 30% by mass of Bi, at least one of a group consisting of from 1 to 15% by mass of Sn, from 0.1 to 5% by mass of Ni, and 0.5% by mass or less of P, from 0.1 to 10% by mass of hard matter particles having from 10 to 50 μm of average particle diameter, the balance consisting of Cu and unavoidable impurities, and, further Bi phase having smaller average particle diameter than that of the hard matter particles is dispersed in the Cu matrix.

3. A Pb-free copper-based sintered alloy, characterized in that it has a composition containing from 1 to 30% by mass of Bi and from 0.1 to 10% by mass of hard matter particles having from 10 to 50 μm of average particle diameter, the balance consisting of Cu and unavoidable impurities, and, further, the hard matter particles having 50% or less of a contact length ratio with the Bi phase based on the total circumferential length of the hard matter, which is in contact with said Bi phase, are present in a ratio of 70% or more based on the entire number of the hard matter particles.

4. A Pb-free copper-based sintered alloy, characterized in that it has a composition containing from 1 to 30% by mass of Bi, at least one of a group consisting of from 1 to 15% by mass of Sn, from 0.1 to 5% by mass of Ni, and 0.5% by mass or less of P, and from 0.1 to 10% by mass of hard matter particles having from 10 to 50 μm of average particle diameter, the balance consisting of Cu and unavoidable impurities, and, further the hard matter particles having 50% or less of a contact length ratio with the Bi phase based on the total circumferential length of the hard matter particles, which are in contact with said Bi phase, are present in a ratio of 70% or more based on the entire number of the hard matter particles.

5. A Pb-free copper-based sintered alloy according to any one of claims 1 through 4, wherein said hard matter particles is an Fe compound, such as Fe2P, Fe3P, FeB, Fe2B and Fe3B.