Abstract: A bonded substrate includes a quartz substrate and a piezoelectric substrate which is bonded on the quartz substrate and on which a surface acoustic wave propagates, wherein the quartz substrate and the piezoelectric substrate are bonded by covalently coupling at a bonding interface, and an orientation of the quartz substrate and an orientation of the piezoelectric substrate intersect with each other on an orthogonal direction side or in the range of 65 degrees to 115 degrees in a bonding surface direction.

Abstract: A method of manufacturing a bonded substrate, which has a quartz substrate and a piezoelectric substrate bonded, includes irradiating a bonding surface of the quartz substrate and a bonding surface of the piezoelectric substrate with ultraviolet light under a pressure lower than atmosphere pressure. After the irradiation, the bonding surface of the quartz substrate and the bonding surface of the piezoelectric substrate are brought into contact. And the quartz substrate and the piezoelectric substrate are pressurized in a thickness direction to bond the bonding surfaces.

Abstract: An optical modulator, a substrate for an optical modulator, a method of manufacturing an optical modulator, and a method of manufacturing a substrate for an optical modulator that can reduce a propagation loss are provided. An optical modulator 1 according to an embodiment includes: a base substrate 10; a waveguide substrate 20 disposed over the base substrate 10 and including an electro-optic effect; a waveguide 23 formed on the waveguide substrate 20 for performing optical modulation; and an electrode 40 configured to apply a voltage to the waveguide 23. Here, the base substrate 10 and the waveguide substrate 20 are made of the same material, the waveguide 23 is formed inside the waveguide substrate 20, and a refractive index of the waveguide substrate 20 is larger than a refractive index of the base substrate 10.

Abstract: A bonded substrate includes: a quartz substrate cut at an intersection angle with a crystal X-axis; and a piezoelectric substrate laminated on the quartz substrate. Preferably, a cut angle of the quartz substrate has an angle in the range of 85 to 95 degrees with respect to the crystal X-axis. Preferably, the surface acoustic wave propagation direction of the quartz substrate has an angle of 15 to 50 degrees with respect to a crystal Y-axis. Preferably, as a piezoelectric substrate, lithium niobate or lithium tantalate is used. Preferably, the piezoelectric substrate has a thickness h having a relationship of 0.02 to 0.11? with respect to a wavelength ? of a surface acoustic wave.

Abstract: A bonded substrate includes a quartz substrate and a piezoelectric substrate which is bonded on the quartz substrate and on which a surface acoustic wave propagates, wherein the quartz substrate and the piezoelectric substrate are bonded by covalently coupling at a bonding interface, and an orientation of the quartz substrate and an orientation of the piezoelectric substrate intersect with each other on an orthogonal direction side or in the range of 65 degrees to 115 degrees in a bonding surface direction.

Abstract: An optical modulator, a substrate for an optical modulator, a method of manufacturing an optical modulator, and a method of manufacturing a substrate for an optical modulator that can reduce a propagation loss are provided. An optical modulator 1 according to an embodiment includes: a base substrate 10; a waveguide substrate 20 disposed over the base substrate 10 and including an electro-optic effect; a waveguide 23 formed on the waveguide substrate 20 for performing optical modulation; and an electrode 40 configured to apply a voltage to the waveguide 23. Here, the base substrate 10 and the waveguide substrate 20 are made of the same material, the waveguide 23 is formed inside the waveguide substrate 20, and a refractive index of the waveguide substrate 20 is larger than a refractive index of the base substrate 10.

Abstract: A first object of the present invention is to provide a method for efficiently growing a nitride single crystal even under low pressure conditions. The present invention relates to a method for producing a nitride single crystal, comprising growing a nitride crystal on the surface of a seed crystal having a hexagonal crystal structure by setting a pressure in a reaction vessel having the seed crystal, a nitrogen-containing solvent, a mineralizer containing a fluorine atom, and a raw material placed therein to 5 to 200 MPa and performing control so that the nitrogen-containing solvent is in at least either a supercritical state or a subcritical state.

Abstract: A method of manufacturing a bonded substrate, which has a quartz substrate and a piezoelectric substrate bonded, includes irradiating a bonding surface of the quartz substrate and a bonding surface of the piezoelectric substrate with ultraviolet light under a pressure lower than atmosphere pressure. After the irradiation, the bonding surface of the quartz substrate and the bonding surface of the piezoelectric substrate are brought into contact. And the quartz substrate and the piezoelectric substrate are pressurized in a thickness direction to bond the bonding surfaces.

Abstract: There is provided a bonded substrate including: a quartz substrate; and a piezoelectric substrate which is bonded on the quartz substrate and on which a surface acoustic wave propagates, wherein the quartz substrate and the piezoelectric substrate are bonded at a bonding interface through covalent bonding, and a surface acoustic wave element having a higher phase velocity and a higher electromechanical coupling factor than conventional one is obtained by disposing an interdigital electrode on a principal surface of the piezoelectric substrate.

Abstract: Provided is a Cu-containing low alloy steel having excellent balance between strength and low-temperature toughness. The Cu-containing low alloy steel has a chemical composition comprising, by mass %, C: 0.01 to 0.08%, Si: 0.10 to 0.40%, Mn: 0.80 to 1.80%, Ni: 0.80 to 2.50%, Cr: 0.50 to 1.00%, Cu: 0.80 to 1.50%, Mo: 0.20 to 0.60%, Al: 0.010 to 0.050%, Nb: 0.030 to 0.080%, and N: 0.005 to 0.020%, and further comprising Ca: 0.010% or less as needed, and consisting of Fe and inevitable impurities as the balance; has a 0.2% yield strength of 525 MPa or higher. The Cu-containing low alloy steel has a ductile-brittle fracture appearance transition temperature (FATT) as measured by the 2 mm V-notch Charpy impact test of ?70° C. or less.

Abstract: A first object of the present invention is to provide a method for efficiently growing a nitride single crystal even under low pressure conditions. The present invention relates to a method for producing a nitride single crystal, comprising growing a nitride crystal on the surface of a seed crystal having a hexagonal crystal structure by setting a pressure in a reaction vessel having the seed crystal, a nitrogen-containing solvent, a mineralizer containing a fluorine atom, and a raw material placed therein to 5 to 200 MPa and performing control so that the nitrogen-containing solvent is in at least either a supercritical state or a subcritical state.

Abstract: The present invention relates to an Fe—Ni-based alloy having excellent high-temperature characteristics and hydrogen embrittlement resistance, which has a composition containing, in terms of % by mass, C: 0.005% to 0.10%, Si: 0.01% to 0.10%, P: 0.015% or less, S: 0.003% or less, Ni: 23.0% to 27.0%, Cr: 12.0% to 16.0%, Mo: 0.01% or less, Nb: 0.01% or less, W: 2.5% to 6.0%, Al: 1.5% to 2.5%, and Ti: 1.5% to 2.5%, the balance being Fe and other unavoidable impurities.

Abstract: A first object of the present invention is to provide a method for efficiently growing a nitride single crystal even under low pressure conditions. The present invention relates to a method for producing a nitride single crystal, comprising growing a nitride crystal on the surface of a seed crystal having a hexagonal crystal structure by setting a pressure in a reaction vessel having the seed crystal, a nitrogen-containing solvent, a mineralizer containing a fluorine atom, and a raw material placed therein to 5 to 200 MPa and performing control so that the nitrogen-containing solvent is in at least either a supercritical state or a subcritical state.

Abstract: There is provided a bonded substrate including: a quartz substrate; and a piezoelectric substrate which is bonded on the quartz substrate and on which a surface acoustic wave propagates, wherein the quartz substrate and the piezoelectric substrate are bonded at a bonding interface through covalent bonding, and a surface acoustic wave element having a higher phase velocity and a higher electromechanical coupling factor than conventional one is obtained by disposing an interdigital electrode on a principal surface of the piezoelectric substrate.

Abstract: The present invention relates to an Fe—Ni-based alloy having excellent high-temperature characteristics and hydrogen embrittlement resistance, which has a composition containing, in terms of % by mass, C: 0.005% to 0.10%, Si: 0.01% to 0.10%, P: 0.015% or less, S: 0.003% or less, Ni: 23.0% to 27.0%, Cr: 12.0% to 16.0%, Mo: 0.01% or less, Nb: 0.01% or less, W: 2.5% to 6.0%, Al: 1.5% to 2.5%, and Ti: 1.5% to 2.5%, the balance being Fe and other unavoidable impurities.

Abstract: A first object of the present invention is to provide a method for efficiently growing a nitride single crystal even under low pressure conditions. The present invention relates to a method for producing a nitride single crystal, comprising growing a nitride crystal on the surface of a seed crystal having a hexagonal crystal structure by setting a pressure in a reaction vessel having the seed crystal, a nitrogen-containing solvent, a mineralizer containing a fluorine atom, and a raw material placed therein to 5 to 200 MPa and performing control so that the nitrogen-containing solvent is in at least either a supercritical state or a subcritical state.

Abstract: The present invention relates to a multilayer overlay welding section in which a first layer of an overlay welding section to be formed on the bearing contact surface of a high Cr steel turbine rotor includes C: 0.05 to 0.2%, Si: 0.1 to 1.0%, Mn: 0.3 to 1.5%, Cr: 4.0 to 7.7%, and Mo: 0.5 to 1.5% with a remainder including Fe and unavoidable impurities, a multilayer overlay welding section in which, in addition to the above layer, an upper layer welding section includes C: 0.05 to 0.2%, Si: 0.1 to 1.0%, Mn: 0.3 to 2.5%, Cr: 1.0 to 4.0%, and Mo: 0.5 to 1.5%, and a welding material therefor and a process for producing the multilayer overlay welding section.

Abstract: Using information about the position, orientation, and shape of a crack appeared in a judged material and information about the structure of the judged material as parameters, the stress intensity factor KI of the crack is found. Based on the stress intensity factor KI, hydrogen embrittlement cracking of the judged material is judged. The crack growth rate and possibility of brittle fracture can be judged by comparing the stress intensity factor KI with the critical stress intensity factor KIH for crack initiation or the critical stress intensity factor KIC-H for brittle fracture about the temper embrittled steel which absorbs approximately 2.0 ppm hydrogen.

Abstract: The multi-tube heat exchanger includes a bundle of tubes which form fluid passages of first heat exchanging fluid, an outer shell which covers the bundle of tubes and form a fluid passage of second heat exchanging fluid, and a baffle plate which is arranged inside the outer shell in a direction intersecting an axial direction of the bundle of tubes and provided with a plurality of through holes through which respective tubes of the bundle are passed. Each of the through holes has such a shape that a portion of an outer peripheral face of the tube comes into contact with a portion of an inner peripheral face of the through hole, and a gap for passing the second heat exchanging fluid is formed between the other portion of the inner peripheral face and the outer peripheral face of the tube. It is possible to support the tubes with high dimensional accuracy, and to enhance heat exchanging efficiency by decreasing fluid resistance.

Abstract: Using information about the position, orientation, and shape of a crack appeared in a judged material and information about the structure of the judged material as parameters, the stress intensity factor KI of the crack is found. Based on the stress intensity factor KI, hydrogen embrittlement cracking of the judged material is judged. The crack growth rate and possibility of brittle fracture can be judged by comparing the stress intensity factor KI with the critical stress intensity factor KIH for crack initiation or the critical stress intensity factor KIC-H for brittle fracture about the temper embrittled steel which absorbs approximately 2.0 ppm hydrogen.