In a scroll fluid machine, a thinned section (26) is provided in correspondence with a position at which the wrap height of a spiral wrap (15B, 16B) changes due to a step part. The thinned section (26) is provided on the front-side surface or the rear-side surface of a tooth tip section of at least one of the spiral wraps (15B, 16B) of at least one of partner scrolls (15, 16) respectively engaging with scrolls (15, 16). The thinned section (26) is provided in the direction in which the wrap thickness decreases so as to extend over at least a reduced-machining-accuracy area (27), which is an area where the machining becomes discontinuous due to at least a change in the wrap height. Thus, a contact failure between the spiral wraps (15B, 16B) is avoided in the area where the machining accuracy relatively decreases as a result of increasing the machining speed, thereby achieving both improved productivity and maintained performance.

In a Ni-base alloy, an area-equivalent diameter D is calculated. D is defined by D=A.sup.1/2 from an area A of a largest nitride in a field of view when an observation area S.sub.0 is observed. This process is repeated in n fields of view for measurement, where n is the number of the fields of view for measurement, so as to acquire n pieces of data on D, and the pieces are arranged in ascending order D.sub.1, D.sub.2, . . . , D.sub.n to obtain a reduced variate y.sub.j. The obtained values are plotted on X-Y axis coordinates, where an X axis corresponds to D and a Y axis corresponds to y.sub.j. In a regression line y.sub.j=a×D+b, y.sub.j is obtained when a target cross-sectional area S is set to 100 mm.sup.2. When the obtained y.sub.j is substituted into the regression line, the estimated nitride maximum size is ≦25 μm in diameter.

A nickel superalloy has the following composition, the concentrations of the different elements being expressed as wt-%: Formula (I), the remainder consisting of nickel and impurities resulting from the production of the superalloy. In addition, the composition satisfies the following equation, wherein the concentrations of the different elements are expressed as atomic percent: Formula (II).

A method is provided for designing and producing fiber-reinforced polymer (FRP) pistons. Pistons made with FRP have a lower mass than prior art metal pistons conferring advantageous engine efficiency and stability. FRP pistons also increase the thermal efficiency of engines by having a lower thermal conductivity, with tighter piston-to-bore clearance, and/increased air-fuel ratio than pistons of metal. The technical parameters of the piston are identified, and a piston body blank is produced. The blank is then machined, a bearing surface for the pin bore is created, the piston blank is optionally coated, is optionally subjected to Heavy Metal Ion Implantation (HMII) treatment and is subjected to sodium silicate impregnation to produce the final pistons.

A nickel superalloy has the following composition, the concentrations of the different elements being expressed as wt-%: Formula (I), the remainder consisting of nickel and impurities resulting from the production of the superalloy. In addition, the composition satisfies the following equation, wherein the concentrations of the different elements are expressed as atomic percent: Formula (II).

A vacuum pump and a vacuum pump rotor blade that can effectively limit deposition of reaction products are provided. The vacuum pump includes a rotating shaft held rotationally, a drive mechanism for the rotating shaft, a first rotor blade made of a first material, a second rotor blade made of a second material having higher heat resistance than the first material, and disposed further toward a downstream side than the first rotor blade, and a casing enclosing the rotating shaft, the first rotor blade, and the second rotor blade. The second rotor blade is disposed, via a heat insulating portion, on the first rotor blade.

A dry vacuum pump has a stator (2) and two rotors (5) that are accommodated in at least one compression chamber (3) of the stator (2), the rotors (5) being configured to rotate synchronously in opposite directions so as to drive a gas to be pumped between an intake and a delivery of the vacuum pump. The rotors (5) and the compression chamber (3) of the stator (2) are coated with a nickel-phosphorus coating (11) comprising between 9% and 14% phosphorus and having a thickness greater than 20 μm, the nickel-phosphorus coating (11) having undergone a hardening heat treatment comprising a step of heating to a treatment temperature greater than 250° C. for a treatment duration greater than one hour, so as to have a hardness greater than 700 HV.

The purpose of the present invention is to enhance the creep characteristics of an Ni-based alloy. The present invention relates to a Ni-based alloy characterized by having a composition containing, in terms of wt %, 15.00-25.00% Cr, 5.00-15.00% Co, 1.00% to less than 12.00% Mo, 1.50-2.50% Ti, 1.00-2.00% Al, 0.20-1.00% Nb, and 0.0010-0.10% C, and in terms of mass ppm, 10-200 ppm P, 30-250 ppm B, and 30-200 ppm N, the remainder comprising Ni and unavoidable impurities.

The purpose of the present invention is to enhance the creep characteristics of an Ni-based alloy. The present invention relates to a Ni-based alloy characterized by having a composition containing, in terms of wt %, 15.00-25.00% Cr, 5.00-15.00% Co, 1.00% to less than 12.00% Mo, 1.50-2.50% Ti, 1.00-2.00% Al, 0.20-1.00% Nb, and 0.0010-0.10% C, and in terms of mass ppm, 10-200 ppm P, 30-250 ppm B, and 30-200 ppm N, the remainder comprising Ni and unavoidable impurities.

In a scroll fluid machine, a thinned section (26) is provided in correspondence with a position at which the wrap height of a spiral wrap (15B, 16B) changes due to a step part. The thinned section (26) is provided on the front-side surface or the rear-side surface of a tooth tip section of at least one of the spiral wraps (15B, 16B) of at least one of partner scrolls (15, 16) respectively engaging with scrolls (15, 16). The thinned section (26) is provided in the direction in which the wrap thickness decreases so as to extend over at least a reduced-machining-accuracy area (27), which is an area where the machining becomes discontinuous due to at least a change in the wrap height. Thus, a contact failure between the spiral wraps (15B, 16B) is avoided in the area where the machining accuracy relatively decreases as a result of increasing the machining speed, thereby achieving both improved productivity and maintained performance.