Example nanoparticles may include an iron-based core, and a shell. The shell may include a non-magnetic, anti-ferromagnetic, or ferrimagnetic material. Example alloy compositions may include an iron-based grain, and a grain boundary. The grain boundary may include a non-magnetic, anti-ferromagnetic, or ferrimagnetic material. Example techniques for forming iron-based core-shell nanoparticles may include depositing a shell on an iron-based core. The depositing may include immersing the iron-based core in a salt composition for a predetermined period of time. The depositing may include milling the iron-based core with a salt composition for a predetermined period of time. Example techniques for treating a composition comprising core-shell nanoparticles may include nitriding the composition.

A system for coating an interior surface of a heat exchanger includes a tank for storing the coating solution, a pump, a source line for supplying the coating solution to the heat exchanger, and a return line for returning the remainder of the coating solution to the tank. The system can include a pre-treatment line for supplying a pre-treatment solution to the heat exchanger and a water line for supplying water to the heat exchanger. An air compressor can be coupled to the heat exchanger to force the coating solution, the pre-treatment solution, or the water from the heat exchanger.

With the method according to the invention, mould parts for casting moulds for light metal casting can be treated such that the danger of crack formation in the region of the surface sections of the mould part coming into contact with the light metal melt during casting is reduced to a minimum. This is achieved in that by means of nitriding treatment on the mould part a nitride-hardened edge layer adjoining its free surface is generated which is harder than the inner core region of the mould part and comprises a diffusion layer adjoining the core region and a compound layer located on the diffusion layer and adjoining the free surface of the mould part and in that at least one section of the surface of the mould part is mechanically processed by machine hammer peening, in the case of which a hammer tool, which, at a certain impact frequency, carries out an impact movement along a movement axis which is aligned in relation to the free surface at a certain acute angle, is guided continuously over the free surface of the mould part following a track determined in a preceding design step such that the compound layer is removed by the impacting stress in the impact region of the hammer tool.

With the method according to the invention, mould parts for casting moulds for light metal casting can be treated such that the danger of crack formation in the region of the surface sections of the mould part coming into contact with the light metal melt during casting is reduced to a minimum. This is achieved in that by means of nitriding treatment on the mould part a nitride-hardened edge layer adjoining its free surface is generated which is harder than the inner core region of the mould part and comprises a diffusion layer adjoining the core region and a compound layer located on the diffusion layer and adjoining the free surface of the mould part and in that at least one section of the surface of the mould part is mechanically processed by machine hammer peening, in the case of which a hammer tool, which, at a certain impact frequency, carries out an impact movement along a movement axis which is aligned in relation to the free surface at a certain acute angle, is guided continuously over the free surface of the mould part following a track determined in a preceding design step such that the compound layer is removed by the impacting stress in the impact region of the hammer tool.

A method for manufacturing a forged article, capable of improving the durability of a die for forging is provided. The method, includes forging a steel material by using a die, by spraying or applying a water-soluble polymer lubricant containing 0.01 to 0.98 mass % of a water-soluble sulfate onto a working surface of the die, the die being made of a raw material having a constituent composition of by mass %, of 0.4 to 0.7% of C, 1.0% or less of Si, 1.0% or less of Mn, 4.0 to 6.0% of Cr, 2.0 to 4.0% of (Mo+½W), 0.5 to 2.5% of (V+Nb), 0 to 1.0% of Ni, 0 to 5.0% of Co, 0.02% or less of N, and a remnant composed of Fe and impurities, and having hardness of 55 to 60 HRC, and the die including a nitrided layer or a nitrosulfidized layer on the working surface thereof.

Materials, methods and techniques relate to steel alloys. In some instances, steel alloys can include chromium, molybdenum, vanadium, copper, nickel, manganese, niobium, aluminum, and iron. In some instances, exemplary steel alloys are subjected to solution carburizing, tempering, and/or plasma nitriding. Exemplary steel alloys are typically precipitation strengthened carburizable and nitridable steel alloys.

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 FeNi ordered alloy includes a plurality of particles having a L1.sub.0 type ordered structure. A size of the particles is in a range between 200 nm and 500 nm. A volume fraction of a pore in the particles with respect to a volume of the particles having an unit of vol. % is 5% or less.

A sliding member (1) includes an iron and steel-based sintered compact containing chromium, molybdenum, and carbon and having a content of chromium, of 5 mass % or less. The sliding member (1) includes: a compound layer (11) which has a sliding surface (1a) and is formed mainly of an iron and steel nitride; and a diffusion layer (12) which is adjacent to the compound layer (11) and has an iron and steel structure into which nitrogen and carbon diffuse. The concentrations of carbon and nitrogen in the diffusion layer (12) are gradually reduced with increasing depth from the sliding surface (1a).

A sliding member (1) includes an iron and steel-based sintered compact containing chromium, molybdenum, and carbon and having a content of chromium, of 5 mass % or less. The sliding member (1) includes: a compound layer (11) which has a sliding surface (1a) and is formed mainly of an iron and steel nitride; and a diffusion layer (12) which is adjacent to the compound layer (11) and has an iron and steel structure into which nitrogen and carbon diffuse. The concentrations of carbon and nitrogen in the diffusion layer (12) are gradually reduced with increasing depth from the sliding surface (1a).