The present invention concerns a friction piece (10) suitable for operating in a lubricated medium at a temperature higher than 200 C. The piece (10) comprises a metal surface (12) and an external coating (14) composed of tungsten carbide doped with nitrogen WC(N) with an atomic ratio of nitrogen between 5 and 12%. The invention also relates to a mechanical system (1) comprising such a piece (10). The invention also relates to a method for implementing such a piece (10).

An aqueous acidic composition for treating metal surfaces, the composition including the following components: a) at least one water soluble or water dispersable anionic polyelectrolyte; b) at least one organofunctional silane including one or more reactive functional groups selected from the group including amino, mercapto, methacryloxy, epoxy and vinyl; c) at least one water dispersible solid wax wherein the weight ratio between components a:b is in the range of 1:2-4:1, based on dry matter; the weight ratio between components (a+b):c is in the range of 1:3-3:1, based on dry matter, and wherein components a and b may be presentat least partiallyas their graft reaction product. Another aspect is a treating method using this composition and use of the thus treated metal surface.

A connecting element for a tubular component, the connecting element being overlaid with a coating including a principal layer constituted by a nickel-phosphorus alloy, a tubular component including one or more such connecting elements, and a method for producing such a connecting element.

A sliding spline shaft device of the present invention includes a male spline and a female spline that is fitted to the male spline in an axially slidable manner, and at least one of the splines has a surface processed layer. The surface processed layer includes an undercoat layer, an intermediate layer containing phosphate, and a topcoat layer containing solid lubricant, in this order. The undercoat layer contains iron nitride and/or iron carbide. Thus, the surface of a base material has high hardness. As a result, microscopic deformation of the sliding surface is reduced, and increase in a real contact area is suppressed, whereby stick-slip is prevented.

A lubricant composition includes a base lubricant and a plurality of lubricant additive molecules. Each molecule includes a surface active group attractable to a target surface, wherein the surface active group comprises a carboxyl group, a siloxyl group, an amine group, or a mixture thereof, and a carbon containing component connected to the surface active group, wherein the carbon containing component comprises a carbon ring, wherein the surface active group and the carbon containing component are adapted such that the carbon film is formed in situ on the target surface of the target machine only when tribological energy activates the lubricant additive to unravel the carbon containing component under a pressure and a temperature during operation.

A lubricated mechanical polishing (LMP) process is provided that uses hard nanoparticles of less than 5 nm diameter dispersed in a fluid lubricant as a polishing slurry to produce an ultra-smooth surface on a hard metallic or non-metallic substrate with a sub-nanometer surface roughness substantially less than that produced by silica chemical mechanical polishing.

A lubricant composition includes a base lubricant and a plurality of lubricant additive molecules. Each lubricant additive molecule includes a surface active group attractable to a target surface, and a carbon containing component connected to the surface active group, for providing a carbon source to form a carbon film on the target surface. A method for in situ forming of a carbon film using the lubricant composition, includes adding the lubricant composition into a target machine such that the lubricant composition is in contact with a target surface of the target machine, and operating the target machine to cause a temperature and a pressure at the target surface so that the carbon containing component is unraveled thereon to form a carbon film on the target surface during the operation.

Methods for treatment shaped bodies are described herein. The methods generally include contacting at least one shaped body with an aqueous acidic composition to form a conversion layer on a surface of the at least one shaped body, wherein the surface includes iron or steel and a carbon content in a range of 0 to 2.06 wt. % and a chrome content in a range of 0 to <10 wt. % and wherein the surface is optionally galvanized or alloy galvanized. The aqueous acidic composition includes water; from 2 to 500 g/L oxalic acid; and from 0.01 to 20 g/L of at least one catalyst based on guanidine, nitrate or combinations thereof, wherein a pickling removal of the aqueous acidic composition is in a range of 1 to 6 g/m.sup.2.

Disclosed herein is a method of pretreatment of a metallic substrate for a subsequent metal cold forming process. The method includes at least steps (1) and (2), namely providing at least one substrate having at least one surface at least partially made of at least one metal (step (1)), contacting the at least one surface of the substrate provided in step (1) with an aqueous lubricant composition (B) (step (2)), where the aqueous lubricant composition (B) includes besides water at least constituents (b1) to (b4) and optionally (b5).

Further disclosed herein are a pretreated metallic substrate obtained by the method, a method of cold forming of a metallic substrate, and an aqueous lubricant composition (B).

The invention concerns a threaded portion of a tubular element for a threaded tubular connection having an axis of revolution, the portion comprising a threading extending over its outer or inner peripheral surface, and a first sealing surface on the peripheral surface, the first sealing surface being capable of producing metal-metal interference with a corresponding second sealing surface belonging to a complementary threaded portion. The threading and the first sealing surface are coated with a metallic anti-galling layer wherein zinc (Zn) is the major element by weight, the metallic anti-galling layer being at least partially coated with a lubricant layer comprising a resin and a dry solid lubricant powder dispersed in the resin.