The invention relates to a multi-component composite sulfide solid lubricating film prepared by sulfurizing the surface of a high-entropy alloy. The high-entropy alloy is composed of five metal elements of Co, Cr, Fe, Ni and Mo or six metal elements of Co, Cr, Fe, Ni, Mo and W. The multi-component composite sulfide solid lubricating film of the invention is mainly applied to the friction pair surface of mechanical equipment, the lubricating film and the sulfurized base have high bonding strength, and multi-component composite sulfide solid lubricating films containing different sulfide lubricating phases can be chose and prepared according to the service environment of equipment.

A coffee lubricant having nanoparticles is provided. It consists of 36 to 40 wt % of glycerin, 1 to 7 wt % of gum arabic, 0.3 to 1.3 wt % of nanoparticles, and remaining part of coffee biofuel. In which, the nanoparticles are CuO. The coffee biofuel is extracted from coffee dregs and has a viscosity of 60 to 70 cSt at a temperature of 40 degrees Celsius. It can reduce the friction coefficient and operating temperature. In addition, it can replace the mineral oil.

A coffee lubricant having nanoparticles is provided. It consists of 36 to 40 wt % of glycerin, 1 to 7 wt % of gum arabic, 0.3 to 1.3 wt % of nanoparticles, and remaining part of coffee biofuel. In which, the nanoparticles are CuO. The coffee biofuel is extracted from coffee dregs and has a viscosity of 60 to 70 cSt at a temperature of 40 degrees Celsius. It can reduce the friction coefficient and operating temperature. In addition, it can replace the mineral oil.

A lubricating grease composition includes a base oil, a thickener, and a solid lubricant, wherein the base oil is a synthetic hydrocarbon oil with a kinematic viscosity of 600 to 2000 mm.sup.2/s at 40 C., the thickener is a barium complex soap, and the solid lubricant is an inorganic fine particle with Mohs hardness of 3 to 6 and an average particle size of 10 to 40 m.

A lubricating grease composition includes a base oil, a thickener, and a solid lubricant, wherein the base oil is a synthetic hydrocarbon oil with a kinematic viscosity of 600 to 2000 mm.sup.2/s at 40 C., the thickener is a barium complex soap, and the solid lubricant is an inorganic fine particle with Mohs hardness of 3 to 6 and an average particle size of 10 to 40 m.

[Object] An object of the present invention is to provide a high-aspect-ratio plate-like alumina particle having low aggregability and high dispersibility and a method for producing the particle.

[Solving Means] The above problem is solved by providing a plate-like alumina particle including a step of firing an aluminum compound in the presence of a shape-controlling agent and a molybdenum compound serving as a fluxing agent. The above problem is solved also by providing a method for producing a plate-like alumina particle, the method including a step in which the aluminum compound and the molybdenum compound react with each other to form aluminum molybdate and a step in which the aluminum molybdate is decomposed to obtain the plate-like alumina particle.

[Object] An object of the present invention is to provide a high-aspect-ratio plate-like alumina particle having low aggregability and high dispersibility and a method for producing the particle.

[Solving Means] The above problem is solved by providing a plate-like alumina particle including a step of firing an aluminum compound in the presence of a shape-controlling agent and a molybdenum compound serving as a fluxing agent. The above problem is solved also by providing a method for producing a plate-like alumina particle, the method including a step in which the aluminum compound and the molybdenum compound react with each other to form aluminum molybdate and a step in which the aluminum molybdate is decomposed to obtain the plate-like alumina particle.

Disclosed herein is a sliding member for an internal-combustion engine of an automobile or the like. The sliding member has excellent sliding properties due to high oleophilicity of its sliding surface achieved by adjusting the surface texture of a resin layer forming the sliding surface, which makes it possible to effectively prevent wear or seizure of the sliding member and a counterpart sliding member thereof. The sliding member includes a resin layer provided on a surface of a base material, in which the resin layer has a surface roughness of 1.05 or more, preferably 1.07 or more. The mean spacing (s) between local peaks of the resin layer may be in the range of 2 m or more but 12 m or less, but may be preferably in the range of 2 m or more but 10 m or less. Further, the mean height (Rc) of the resin layer may be in the range of 0.5 m or more but 5.0 m or less, but may be preferably in the range of 0.5 m or more but 3.0 m or less.

Disclosed herein is a sliding member for an internal-combustion engine of an automobile or the like. The sliding member has excellent sliding properties due to high oleophilicity of its sliding surface achieved by adjusting the surface texture of a resin layer forming the sliding surface, which makes it possible to effectively prevent wear or seizure of the sliding member and a counterpart sliding member thereof. The sliding member includes a resin layer provided on a surface of a base material, in which the resin layer has a surface roughness of 1.05 or more, preferably 1.07 or more. The mean spacing (s) between local peaks of the resin layer may be in the range of 2 m or more but 12 m or less, but may be preferably in the range of 2 m or more but 10 m or less. Further, the mean height (Rc) of the resin layer may be in the range of 0.5 m or more but 5.0 m or less, but may be preferably in the range of 0.5 m or more but 3.0 m or less.

A coffee lubricant having nanoparticles is provided. It consists of 36 to 40 wt % of glycerin, 1 to 7 wt % of gum arabic, 0.3 to 1.3 wt % of nanoparticles, and remaining part of coffee biofuel. In which, the nanoparticles are CuO. The coffee biofuel is extracted from coffee dregs and has a viscosity of 60 to 70 cSt at a temperature of 40 degrees Celsius. It can reduce the friction coefficient and operating temperature. In addition, it can replace the mineral oil.