A powder metallurgically produced, wear-resistant, and highly thermally conductive copper-based sintered alloy as matrix is disclosed. The sintered alloy includes a powder mixture of a copper-base powder, of a hard phase with a total share of 8 to 40% by weight, of a solid lubricant with a total share of 0.4 to 3.8% by weight, of a pressing additive with a total share of 0.3 to 1.5% by weight, and production-related impurities. The powder mixture includes at least 55% by weight of the copper-base powder.

To provide: a silicon nitride sintered body having excellent mechanical property, in particular fracture toughness, and having long lifetime of a product into which the silicon nitride sintered body is processed; a rolling element using the silicon nitride sintered body; and a bearing. The silicon nitride sintered body contains a rare earth element and an aluminum element. The silicon nitride sintered body contains 6-13 wt % of the rare earth element in terms of oxide, and 6-13 wt % of the aluminum element in terms of oxide, relative to the total weight of the silicon nitride sintered body. The silicon nitride sintered body contains an inclusion (I) in a surface layer portion that is a region within 2 mm from a surface of the silicon nitride sintered body. A ratio of a total sectional area of the inclusion (I) to a total sectional area of the surface layer portion is 0.05% or more.

According to an embodiment, a silicon nitride sintered body includes silicon nitride crystal grains and a grain boundary phase. In a case where Raman spectroscopy of a 20 μm×20 μm region at any cross section of the silicon nitride sintered body is performed, seven or more peaks are detected within a range of not less than 400 cm.sup.−1 and not more than 1200 cm.sup.−1, and the most intense peak of the seven or more peaks is not in a range of not less than 515 cm.sup.−1 and not more than 525 cm.sup.−1. Favorably, at least three of the seven or more peaks exist within a range of not less than 530 cm.sup.−1 and not more than 830 cm.sup.−1. It is favorable for at least one of the seven or more peaks to be within a range of not less than 440 cm.sup.−1 and not more than 460 cm.sup.−1.

A sliding member of the present invention includes a base material and a coating layer that is formed on the base material. The coating layer includes a particle aggregate that contains precipitation hardened copper alloy particles. The precipitation hardened copper alloy particles contain cobalt (Co) and silicon (Si) The sliding member has high coating strength and superior wear resistance.

A roller ball assembly is provided. The assembly includes a primary roller ball supported by a support element that is composed of a superhard material. The assembly includes a cup defining a cavity within which the support clement is positioned. A cap is coupled with the cup and positioned to retain the primary roller ball within the cavity. Also, a cup is disclosed for supporting roller halls. Additionally, disclosed are system and apparatus incorporating the assembly, as well as to methods of making and using the same.

A rolling bearing having an inner raceway and an outer raceway and a plurality of rolling elements arranged therebetween. The rolling bearing is media-lubricated or oil-free lubricated. The lubricant forms an elasto-hydrodynamic lubricant film between the rolling elements and the raceways. At first use of the rolling bearing, at least one surface of the rolling bearing is coated with a protective fluid, preferably an oil-based preservative fluid. Also, a refrigerant compressor having such a rolling bearing.

The sliding member according to the embodiment includes a silicon nitride sintered body that includes silicon nitride crystal grains and a grain boundary phase, in which a percentage of a number of the silicon nitride crystal grains including dislocation defect portions inside the silicon nitride crystal grains among any 50 of the silicon nitride crystal grains having completely visible contours in a 50 μm×50 μm observation region of any cross section or surface of the silicon nitride sintered body is not less than 0% and not more than 10%. The percentage is more preferably not less than 0% and not more than 3%.

A roller ball assembly is provided. The assembly includes a primary roller ball supported by a support element that is composed of a superhard material. The assembly includes a cup defining a cavity within which the support element is positioned. A cap is coupled with the cup and positioned to retain the primary roller ball within the cavity. Also, a cup is disclosed for supporting roller balls. Additionally, disclosed are system and apparatus incorporating the assembly, as well as to methods of making and using the same.

Two hybrid ball bearings and a compressor bearing arrangement with two hybrid ball bearings for a rotatable support of a rotor of the compressor versus a stator of the compressor. The two hybrid ball bearings are arranged face-to-face or back-to-back, are configured with an optimal axial clearance depending on the inner diameter of a ring-shaped inner raceway element one of the hybrid ball bearings respectively a pitch diameter of one of the two hybrid ball bearings for a long bearing life in connection with an optimal compressor operating performance.

A sliding member includes: a base material; a solid lubricant layer arranged on a surface of the base material; a defect layer having a material defect, disposed in the solid lubricant layer, and being changeable into an ultra low friction layer by mechanical stress more easily than changing from the solid lubricant layer to the ultra low friction layer; and a ultra low friction layer covering a surface of the defect layer.