A green compact according to the present invention is a green compact, which is obtained by compaction-molding raw material powder containing metal powder as a main raw material, the green compact including an oxide film formed between particles of the raw material powder forming the green compact, the oxide film binding the particles of the raw material powder to each other, in which the metal powder to toe used includes metal powder showing a circularity R at a cumulative frequency of 80% of 0.75 or more, the circularity R being expressed by Equation (1), where S represents a two-dimensional projected area of the metal powder and L represents a two-dimensional projected circumferential length of the metal powder.

[00001]$\begin{array}{cc}R=4.Math.\pi \times \frac{S}{L^2}& \left(1\right)\end{array}$

This disclosure relates to a manufacture method of a bushing, a bushing and an excavator to alleviate the problems of insufficient lubricity and wear resistance of the bushing. The bushing includes an inner ring and an outer ring. The manufacture method of the bushing includes the following steps: grinding a first mixed powder containing Fe, Al, Ti, Cr and V, nitriding the ground first mixed powder to form a nitrogen-rich stable compound powder, and then carrying out molding by pressing and sintering the nitrogen-rich stable compound powder to form the outer ring; grinding a second mixed powder containing Fe and Mo, sulfurizing the ground second mixed powder to form a sulfurized powder containing FeS and MoS.sub.2, and carrying out molding by pressing the sulfurized powder to form the inner ring; and placing the inner ring in the outer ring and carrying out sintering to obtain the bushing.

The present application relates to a plain bearing, or a part thereof and to a method for producing same, characterised in that the plain bearing at least partially consists of a CuCrZr alloy. The application also relates to the use of the CuCrZr alloy as a plain bearing material.

Provided is a Cu-based sintered bearing comprising: 15-36 mass % of Ni; 3-13 mass % of Sn; 0.05-0.55 mass % of P; and 0.02-4 mass % of C in total, the balance consisting of Cu and inevitable impurities, wherein the content of C forming an alloy with a matrix within Cu—Ni-based main phase grains is 0.02-0.10 mass %.

A sintered sliding material with excellent corrosion resistance, heat resistance, and wear resistance is provided. The sintered sliding material has a composition made of: 36-86 mass % of Ni; 1-11 mass % of Sn; 0.05-1.0 mass % of P; 1-9 mass % of C; and the Cu balance including inevitable impurities. The sintered sliding material is made of a sintered material of a plurality of grains of alloy of Ni—Cu alloy or Cu—Ni alloy, the Ni—Cu alloy and the Cu—Ni alloy containing Sn, P, C, and Si; has a structure in which pores are dispersedly formed in grain boundaries of the plurality of the grains of alloy; and as inevitable impurities in a matrix constituted from the grains of alloy, a C content is 0.6 mass % or less and a Si content is 0.15 mass % or less.

Provided is a slide bearing (bearing sleeve (8)), comprising an oxidized green compact in which particles (11) of metal powder are bonded to each other by an oxide film (12) formed on surfaces of the particles (11). The oxidized green compact has a bearing surface (A, B) configured to slide, through intermediation of a lubricating film, relative to a mating member (shaft member (2)) to be supported. The bearing surface (A, B) has a large number of opening portions (13a), and the large number of opening portions (13a) and inner pores (13b) are interrupted in communication therebetween by the oxide film (12).

A sintered metal bearing is formed through sintering of a compact obtained through compression molding of raw-material powder. The sintered metal bearing includes chamfered portions that are respectively formed at least along outer rims of both end surfaces of the sintered metal bearing, and a dynamic pressure generating portion formed on an inner peripheral surface of the sintered metal bearing by sizing. An axial dimension of each of the chamfered portions is set larger than a radial dimension of the each of the chamfered portions, and a difference in axial dimension between the chamfered portions on one end side and another end side in an axial direction of the sintered metal bearing is set larger than a difference in radial dimension between the chamfered portions on the one end side and the another end side in the axial direction.

A sintered bearing includes, on an inner peripheral surface, a cylindrical portion and a one-side increased-diameter portion, which are provided so as to be continuous in the axial direction. An end portion of one side in the axial direction of the cylindrical portion and an end portion of another side in the axial direction of the increased-diameter portion coincide, and the cylindrical portion and the increased-diameter portion are molded by performing sizing on a sintered compact having a tubular shape, which is introduced into a die.

There is provided a sintered bearing having high rotational accuracy and low rotational fluctuation. This bearing includes a bearing surface (4a), and is made of a sintered compact (4″) produced by molding and sintering a raw material powder (10) containing a partially diffusion-alloyed powder (11) in which a copper powder (13) is partially diffused on a surface of an iron powder (12), a tin powder (14) as a low-melting-point metal powder, and a graphite powder as a solid lubricant powder. The sintered bearing has a radial crushing strength greater than or equal to 300 MPa.

Dynamic pressure bearing (10), including: a green compact (10′), as a base material, of raw material powder including metal powder capable of forming an oxide coating; and dynamic pressure generating portions (A1 and A2) formed through die molding on an inner peripheral surface (8a) forming a radial bearing gap with an outer peripheral surface (2a1) of a shaft to be supported, that is, a shaft member (2). An oxide coating (11) is formed between particles of the metal powder by subjecting the green compact (10′) to steam treatment, and the dynamic pressure bearing (10) has a radial crushing strength of 150 MPa or more.