Abstract: An etching method includes: forming a second film on a workpiece target including a processing target film, a layer including a plurality of convex portions formed on the processing target film, and a first film that covers the plurality of convex portions and the processing target film exposed between the plurality of convex portions; etching the second film in a state where the second film remains on a portion of the first film that covers a side surface of each of the plurality of convex portions; and etching the first film in a state where the second film remains on the portion of the first film that covers the side surface of each of the plurality of convex portions, thereby exposing a top portion of each of the plurality of convex portions and the processing target film between the plurality of convex portions.

Abstract: The present invention provides a pressure vessel for hydrogen in which the development of cracking in the pressure vessel for hydrogen can be effectively inhibited and that is excellent in terms of safety, reliability, and durability. The present invention pertains to a pressure vessel for hydrogen in which a plastic region is present on the inner face side of a hydrogen pressure vessel main body, an elastic region is present on the outer face side, and compressive residual stress is generated on the inner face, wherein preferably: the equivalent plastic strain remaining on the inner surface of the hydrogen pressure vessel main body is 1% or below; the plastic region on the inner face side measures 50% or less of the wall thickness in the radial direction of the hydrogen pressure vessel main body; and the steel used has a tensile strength of at least 725 MPa.

Abstract: An accumulator vessel (10) includes a screwable portion (3) and a lid portion (2) that is positioned at an axially inner side of the screwable portion and an axially inner surface configures a pressure bearing plane. The lid portion includes a protruding portion (22) extending axially outward on an inner circumferential side, and the protruding portion configured to abut against an axially inner end side of the screwable portion to separate an axially inner surface of the screwable portion on an outer circumferential side thereof apart from an axially outer surface of the lid portion on an outer circumferential side thereof.

Abstract: An etching method includes: forming a second film on a workpiece target including a processing target film, a layer including a plurality of convex portions formed on the processing target film, and a first film that covers the plurality of convex portions and the processing target film exposed between the plurality of convex portions; etching the second film in a state where the second film remains on a portion of the first film that covers a side surface of each of the plurality of convex portions; and etching the first film in a state where the second film remains on the portion of the first film that covers the side surface of each of the plurality of convex portions, thereby exposing a top portion of each of the plurality of convex portions and the processing target film between the plurality of convex portions.

Abstract: In a processing method according to one exemplary embodiment, a first nitrified region of a workpiece is etched. The first nitrified region is provided on a first protrusion made of silicon. The workpiece further has a second protrusion, a second nitrified region, and an organic region. The second protrusion is made of silicon. The second nitrified region contains silicon and nitrogen and is provided on the second protrusion. The organic region covers the first and second protrusions and the first and second nitrified regions. In the processing method, the organic region is partially etched to expose the first nitrified region. Then, a silicon oxide film is formed to cover the surface of an intermediate product produced from the workpiece. Then, the silicon oxide film is etched to expose an upper surface of the first nitrified region. Then, the first nitrified region is isotropically etched.

Abstract: In a processing method according to one exemplary embodiment, a first nitrified region of a workpiece is etched. The first nitrified region is provided on a first protrusion made of silicon. The workpiece further has a second protrusion, a second nitrified region, and an organic region. The second protrusion is made of silicon. The second nitrified region contains silicon and nitrogen and is provided on the second protrusion. The organic region covers the first and second protrusions and the first and second nitrified regions. In the processing method, the organic region is partially etched to expose the first nitrified region. Then, a silicon oxide film is formed to cover the surface of an intermediate product produced from the workpiece. Then, the silicon oxide film is etched to expose an upper surface of the first nitrified region. Then, the first nitrified region is isotropically etched.

Abstract: An accumulator vessel (10) includes a screwable portion (3) and a lid portion (2) that is positioned at an axially inner side of the screwable portion and an axially inner surface configures a pressure bearing plane. The lid portion includes a protruding portion (22) extending axially outward on an inner circumferential side, and the protruding portion configured to abut against an axially inner end side of the screwable portion to separate an axially inner surface of the screwable portion on an outer circumferential side thereof apart from an axially outer surface of the lid portion on an outer circumferential side thereof.

Abstract: A main cooling circuit is formed by an engine, a radiator and a first pump. A hot water circuit is formed by the engine, a heater core and the first pump. A heat storing water circuit is connected between a bifurcating point of the hot water circuit and the engine, wherein a second pump and a heat storage tank are provided in the heat storing water circuit. Engine cooling water stored in the heat storage tank is circulated by the second pump, so that the hot water is supplied to the engine before the engine operation is started. The engine cooling water is also circulated by the second pump during the engine operation, so that hot water is stored in the heat storage tank.