To provide a composition for a heat cycle system, which comprises a working fluid for heat cycle which has a low global warming potential and high stability, and which can replace R410A, and a heat cycle system employing the composition. A composition for a heat cycle system, which comprises a working fluid for heat cycle containing trifluoroethylene, and a stabilizer for preventing deterioration of the working fluid for heat cycle, such as an oxidation resistance-improving agent, a heat resistance-improving agent or a metal deactivator, and a heat cycle system employing the composition for a heat cycle system.

An oil composition comprising a first component having pendant groups, a second component having two or more terminal carbon chains, and optionally a third component, where a single molecule of the second component can form shearable stable structure with two molecules of the first component via van der Waals force between pendant groups and the terminal carbon chains. Shear stability of the oil can be improved if the total concentration of the heavy fraction of the shearable stable structure is controlled at a low concentration.

An oil composition comprising a first component having pendant groups, a second component having two or more terminal carbon chains, and optionally a third component, where a single molecule of the second component can form shearable stable structure with two molecules of the first component via van der Waals force between pendant groups and the terminal carbon chains. Shear stability of the oil can be improved if the total concentration of the heavy fraction of the shearable stable structure is controlled at a low concentration.

A composition comprising a sheared antifoam solution/mixture with a mean particle size from about 0.01 microns to about 0.5 microns and a maximum particle size of less than about 1 micron. In this composition the sheared antifoam solution/mixture comprises antifoam solution/mixture comprising an antifoam and a base stock.

To provide a composition for a heat cycle system having favorable lubricating properties and comprising a working fluid for heat cycle which has a low global warming potential and which can replace R410A and a heat cycle system employing the composition. A composition for a heat cycle system comprising a working fluid for heat cycle containing trifluoroethylene, and a refrigerant oil (for example, an ester refrigerant oil, an ether refrigerant oil, a polyglycol refrigerant oil or a hydrocarbon refrigerant oil), and a heat cycle system employing the composition for a heat cycle system.

A method including substituting an atmosphere in a space, in which a sliding surface formed of a metal or a ceramic material, and a slid surface are disposed, with a gas atmosphere containing a hydroxyl group-containing compound and at least one of hydrogen and nitrogen, and relatively sliding the sliding surface against the slid surface by a Hertzian contact stress of 1.0 GPa or more in the space under the gas atmosphere containing the hydroxyl group-containing compound at least one of hydrogen and nitrogen. As a result, it is possible to form, on the sliding surface, a low-friction coating that stably exhibits a significantly low friction coefficient, for example, of 10.sup.4 order (less than 0.001).

Provided is a lubricating oil composition for a refrigerator which uses a base oil including as the main component at least one kind of oxygen-containing compounds selected from polyoxyalkylene glycols, polyvinyl ethers, copolymers of poly(oxy)alkylene glycols or monoethers thereof and polyvinyl ethers, polyol esters, and polycarbonates. The lubricating oil composition for a refrigerator is used for a refrigerator that uses, as a refrigerant, a fluorine-containing organic compound, which is a refrigerant applicable to current car air conditioner systems or the like and has a specific polar structure, and has favorable sealing property, a low coefficient of friction factor in a sliding part, and excellent stability as well as excellent compatibility with the refrigerant.

Inside a sealed container (101) of a refrigerant compressor (100), lubricating oil (103) having a kinematic viscosity at 40 C. of 0.1 mm.sup.2/S to 5.1 mm.sup.2/S is stored, and an electric element (106) and a compression element (107) are accommodated. The compression element (107) is provided with, as a shaft part, a crankshaft (108) comprising a main shaft (109) and an eccentric shaft (110), and as bearing parts, a main bearing (114) that axially supports the main shaft (109) and an eccentric bearing (119) that axially supports the eccentric shaft (110). At least one surface of the main shaft (109) and the eccentric shaft (110) is subjected to a surface treatment, e.g., formation of an oxide film, having a hardness equal to or greater than that of a bearing part (the main bearing (114) or the eccentric bearing (119)). Satisfactory reliability in sliding parts can thereby be achieved even if lubricating oil having lower viscosity is used.

raction fluid additive combination that is usable with any traction fluids base stock is provided. To optimize the traction, low temperature viscosity and shear stability performance, a combination of a polyisobutene and a polymethacrylate may be added to a base oil to obtain a traction fluid with good low temperature viscosity without degrading the shear strength properties of the fluid. To minimize foaming of the traction fluid, a combination of one, two, or more anti-foaming agents may be added to the fluid in addition to a standard additive package.

The present invention relates to compositions for use in refrigeration, air-conditioning, and heat pump systems wherein the composition comprises a fluoroolefin and at least one other component. The compositions of the present invention are useful in processes for producing cooling or heat, as heat transfer fluids, foam blowing agents, aerosol propellants, and fire suppression and fire extinguishing agents.