Provided is a raw material powder for powder metallurgy, capable of preventing stains, surface defects and decarburization of a sintered body, improving strength and density thereof. The raw material powder for powder metallurgy is for use in the production of a sintered body that is sintered at a temperature of not lower than 500° C., composed of a mixture of a metal powder and a lubricant, in which the lubricant is melamine cyanurate or terephthalic acid. Alternatively, the raw material powder for powder metallurgy is for use in the production of a sintered body that is sintered at a temperature of not lower than 500° C, composed of a mixture of a metal powder, a first lubricant and a second lubricant, in which the first lubricant is melamine cyanurate or terephthalic acid, while the second lubricant is preferably erucic acid amide or stearic acid amide.

One aspect of the present invention is a lubricant to be incorporated into a powder metallurgical mixed powder containing an iron-based powder. The lubricant includes a flaky organic material having an average particle diameter of from 0.1 μm to less than 3 μm. Another aspect of the present invention is a powder metallurgical mixed powder which contains an iron-based powder and the lubricant. Yet another aspect of the present invention is a method for producing a sintered compact. The method includes the step of mixing materials to give a powder metallurgical mixed powder containing an iron-based powder and the lubricant. The powder metallurgical mixed powder is compacted using a die to give a powder compact. The powder compact is sintered to give a sintered compact.

An industrial oil composition contains a mineral or a synthetic oil as a base oil, and a neutral phosphite ester derivative represented by the following formula (B) and a 2,6-di-t-butylphenol derivative represented by the following formula (C) as antioxidants. In the formula (B), R.sup.b21 to R.sup.b24 each independently represent an aliphatic hydrocarbon group of 10 to 16 carbon atoms. In the formula (C), R.sup.c1 represents a straight-chain or a branched alkyl group of 1 to 12 carbon atoms.

##STR00001##

##STR00002##

One aspect of the present invention is a lubricant to be incorporated into a powder metallurgical mixed powder containing an iron-based powder. The lubricant includes a flaky organic material having an average particle diameter of from 0.1 m to less than 3 m. Another aspect of the present invention is a powder metallurgical mixed powder which contains an iron-based powder and the lubricant. Yet another aspect of the present invention is a method for producing a sintered compact. The method includes the step of mixing materials to give a powder metallurgical mixed powder containing an iron-based powder and the lubricant. The powder metallurgical mixed powder is compacted using a die to give a powder compact. The powder compact is sintered to give a sintered compact.

The present invention provides a steel wire rod having a lubricating coating film, which can achieve both workabilities such as wire drawability, spike property and ball ironing property, and corrosion resistance such as long-term rust prevention property; and a method for producing the same. Disclosed are a steel wire rod having a coating film containing no phosphorus, wherein the coating film includes a lower layer coating film composed of oxide and/or hydroxide of zirconium and having a film thickness of 1.0 to 200 nm, and an upper layer coating film containing silicon and tungsten, in order from a steel wire rod side, a mass ratio of tungsten/silicon being in a range of 1.3 to 18; and a method for producing the above steel wire rod, which includes bringing an aqueous chemical conversion treatment solution, which has a pH in a range of 2.5 to 5.0 and contains a water-soluble zirconium compound dissolved therein, into contact with a surface of a steel wire rod to form a lower layer coating film.

The invention provides a solid lubricant in the form of film containing a triazine compound or the salt thereof, such as melamine cyanurate or the like.

The invention pertains to certain (per)fluoropolyether triazine derivatives comprising at least one triazine group and at least one fluoropolyoxyalkene chain (chain R.sub.f) comprising a fluorocarbon segment having ether linkages in main chain, said chain R.sub.f comprising at least one hydroxyl group, to a method for their manufacture and to their use in lubrication, in particular for lubricating sliding or moving parts of magnetic recording media.