Abstract: A steel product having a composition which contains by mass C: 0.01 to 1.9%, Si: 0.01 to 1.9%, Mn: 5.0 to 24.0% with balance consisting of Fe and unavoidable impurities and a steel product described above which further contains Cr: 18.0% or below and/or Ni: 12.0% or below in addition to the above essential elements. The above steel products may each further contain Al: 1% or below and/or N: 0.3% or below and the above steel products may each further contain one or more elements selected from among Nb, Ti, Zr, Mo and Cu in a total amount of 4.0% or below. The steel products can sufficiently follow the thermal expansion of a cylinder made of an aluminum alloy and thus enables the production of a piston ring which is suitable for use as a piston ring to slide on the inner face of a cylinder bore made of an aluminum alloy in an internal combustion engine and which can retain excellent sealing properties.

Abstract: According to an embodiment of the present invention a piston ring for internal combustion engines for use with a piston and a cylinder, is provided that has an external circumferential sliding surface adapted to slid against the internal wall of the cylinder. The piston ring has an ion-plating deposition layer formed over the externtal circumferential sliding surface, the deposition layer having pores and being made of a mixture of a first chromium nitride of CrN type and a second chromium nitride of Cr2N type. The mixing ratios in the mixture are more than 45.5 and less than 98.0 weight percent for the first chromium nitride and the balance portion for the second chromium nitride. According to another embodiment of the present invention, a piston ring for internal combustion engines for use with a piston and a cylinder, is provided that has an external circumferential sliding surface adapted to slid against the internal wall of the cylinder.

Abstract: The present invention provides a sliding member, of which the surface cavities do not disappear even after progress of wear of the sliding surface, which permits maintenance of a satisfactory seizure resistance, and has better seizure resistance, wear resistance and strength properties than in a sliding member having a porous chrome plating layer formed thereon in the conventional art. The sliding member of the invention has a laminated hard Cr plating layer comprising a plurality of hard Cr plating layers laminated on the sliding surface. Micro-cracks are formed on each hard Cr plating layer surface, and the micro-cracks of each hard Cr plating layer form micro-pores independent in the film-forming direction. On the cross-section of the laminated hard Cr plating layer, the porosity should be within a range of from 0.5 to 4.5%.

Abstract: An object of the present invention is to provide a sliding member which is coated a film having superior wear resistance, superior scuffing resistance and a superior property not to increase an amount of wear on an opponent material (an opponent attacking property). This object can be achieved by providing a sliding member coated by a Cr—B—N alloy film 4 on an outer surface 3 thereof. In this case, it is preferable that the Cr—B—N alloy film is formed through a physical vapor deposition, particularly ion plating, vacuum deposition, or sputtering. Further, it is preferable that the boron (B) content is within the range of 0.05-20 wt.%.

Abstract: A laminated chromium plating layers providing improved wear resistance and fatigue strength for use in mechanical parts of an internal combustion engine. The lamination is formed on a base body and contains a plurality of high hardness chromium plating layer and a plurality of low hardness chromium plating layer, and each high hardness chromium plating layer is formed upon each low hardness chromium plating layer to provide the lamination of alternating high hardness chromium plating layer and low hardness chromium plating layer.

Abstract: A piston ring combination including at least one compression ring and at least one oil ring. If a plurality of compression rings are provided, an outer peripheral surface of at least a top ring is formed with a first ion plating layer. The oil ring has a pair of side rails whose outer peripheral surfaces are formed with second ion plating layers. These layers are formed of Cr—N mixture. The first ion plating layer has a porous structure with a porosity ranging from 3 to 10% and a hardness ranging from 1000 to 1500 Hv. The second ion plating layer has a dense structure with a porosity ranging from 0 to 3% and a hardness ranging from 1800 to 2200 Hv.

Abstract: A piston ring combination including at least one compression ring and at least one oil ring. If a plurality of compression rings are provided, an outer peripheral surface of at least a top ring is formed with a first ion plating layer. The oil ring has a pair of side rails whose outer peripheral surfaces are formed with second ion plating layers. These layers are formed of Cr-N mixture. The first ion plating layer has a porous structure with a porosity ranging from 3 to 10% and a hardness ranging from 1000 to 1500 Hv. The second ion plating layer has a dense structure with a porosity ranging from 0 to 3% and a hardness ranging from 1800 to 2200 Hv.

Abstract: An object of the present invention is to provide a sliding member which is coated a film having superior wear resistance, superior scuffing resistance and a superior property not to increase an amount of wear on an opponent material (an opponent attacking property). This object can be achieved by providing a sliding member coated by a Cr--V--B--N alloy film 4 on an outer surface 3 thereof. In this case, it is preferable that the Cr--V--B--N alloy film is formed through a physical vapor deposition, particularly ion plating, vacuum deposition, or sputtering. Further, it is preferable that V (Vanadium) content is within the range of 0.1-30 wt. % and the boron (B) content is within the range of 0.05-20 wt. %.

Abstract: The present invention is directed to a method of applying a magnetic thin film on a substrate by alloy electroplating in which the alloy content in the deposition is defined by an electric current density in the course of the plating operation. The magnetic thin film is superior in uniformity and formability on a complicated substrate. The method comprises the step of changing the electric current density from a low value to a high value, and vice versa at predetermined intervals during plating to laminate different alloy-content plated layers into a multilayer thin film, and improving the magnetic characteristics of the film by heat treatment.

Abstract: A piston ring developed to prevent aluminum deposition and adhesion thereon is disclosed. The piston ring includes a ring-shaped piston ring main body including upper, lower, outer circumferential surfaces. An anti-abrasion surface treatment layer is formed on at least the lower surface of the main body, and a polybenzimidazole resin coating film including a solid lubricant, is formed on a surface of the anti-abrasion surface treatment layer.

Abstract: A composite plating bath prepared by adding an agent of boron compounds, such as trimethylamine-borane, dimethylamine-borane and sodium borohydride, by an amount of 0.1 to 10 grams/liter, preferably 1 to 8 grams/liter to a usual nickel electroplating bath having an aqueous acidic solution of at least one nickel salt and micron size particles of at least one water-insoluble material.

Abstract: A piston ring for use in an internal combustion engine. The piston ring includes a base body, a nitriding layer formed at an outer peripheral surface portion of the base body, and a composite Ni-B diffusion plating layer formed over the nitriding layer. The composite Ni-B diffusion plating layer has a thickness ranging from 0.5 to 20 micron meters. Since the nitriding layer is provided on at least the sliding surface of the piston ring, high durability of the piston ring can be attained because of the high wear resistivity of the nitriding layer. Further, since a Ni-Bi composite dispersion plating layer is formed over the nitriding layer, abnormal wearing due to scuffing is avoidable at an initial working phase because of the high scuffing resistance of the composite plating layer.