Abstract: Provided is a heat-resistant Ir alloy, which is further improved in Vickers hardness while maintaining satisfactory processability. Specifically, provided is a heat-resistant Ir alloy, including: 5 mass % to 30 mass % of Pt; 0.5 mass % to 5 mass % of Ta; and 0.003 mass % to 0.15 mass % of at least one kind selected from the group consisting of: Sc; Hf; and W, with the balance being Ir.

Abstract: Provided is an Ir alloy which is excellent in high temperature strength while ensuring oxidation wear resistance at high temperature. The Ir alloy consists of: 7 mass % or more, and less than 10 mass % of Rh; 0.5 mass % to 5 mass % of Ta; 0 mass % to 5 mass % of at least one kind of element selected from among Co, Cr, and Ni; and Ir as the balance, wherein a total content of the Ta and the at least one kind of element selected from among Co, Cr, and Ni is 5 mass % or less.

Abstract: A spark plug includes a first discharge chip and a second discharge chip which faces the first discharge chip and works to produce an electrical spark therebetween. At least one of the first and second discharge chips is made from material containing iridium, platinum, and tantalum. An amount of platinum in the material is in a range of 5 Wt % to 30 Wt %. An amount of tantalum is in a range of 0.3 Wt % to 7.5 Wt %. Use of such material enhances a wear resistance of the spark plug.

Abstract: Provided is an Ir alloy, which is further improved in Vickers hardness. Specifically, provided is a heat-resistant Ir alloy, including: 5 mass % to 30 mass % of Rh; 0.5 mass % to 5 mass % of Ta; and 0.003 mass % to 0.15 mass % of at least one kind selected from the group consisting of: Sc; Hf; and W, with the balance being Ir.

Abstract: Provided is an Ir alloy wire, which is further improved in oxidation wear resistance while ensuring a Vickers hardness. The Ir alloy wire includes: 5 mass % to 30 mass % of Rh; and 0.5 mass % to 5 mass % of Ta, wherein an average value A for an aspect ratio (crystal grain length/crystal grain width) of a structure of the alloy wire in a range of a depth of 0.05 mm or less from a surface of the alloy wire satisfies 1?A<6.

Abstract: Provided is an Ir alloy which is excellent in high temperature strength while ensuring oxidation wear resistance at high temperature. The Ir alloy consists of: 7 mass % or more, and less than 10 mass % of Rh; 0.5 mass % to 5 mass % of Ta; 0 mass % to 5 mass % of at least one kind of element selected from among Co, Cr, and Ni; and Ir as the balance, wherein a total content of the Ta and the at least one kind of element selected from among Co, Cr, and Ni is 5 mass % or less.

Abstract: Provided is an Ir alloy, which is further improved in Vickers hardness. Specifically, provided is a heat-resistant Ir alloy, including: 5 mass% to 30 mass% of Rh; 0.5 mass% to 5 mass% of Ta; and 0.003 mass% to 0.15 mass% of at least one kind selected from the group consisting of: Sc; Hf; and W, with the balance being Ir.

Abstract: Provided is an Ir alloy wire, which is further improved in oxidation wear resistance while ensuring a Vickers hardness. The Ir alloy wire includes: 5 mass % to 30 mass % of Rh; and 0.5 mass % to 5 mass % of Ta, wherein an average value A for an aspect ratio (crystal grain length/crystal grain width) of a structure of the alloy wire in a range of a depth of 0.05 mm or less from a surface of the alloy wire satisfies 1?A<6.

Abstract: An Ir alloy is excellent in high temperature strength while ensuring oxidation wear resistance at high temperature. The heat-resistant Ir alloy includes: 5 mass % to 30 mass % of Rh; 0.3 mass % to 5 mass % of an element group A made of at least one kind of element selected from among Ta and Re; and 0 mass % to 5 mass % of an element group B made of at least one kind of element selected from among Co, Cr, and Ni, wherein the heat-resistant Ir alloy includes 5 mass % or less of the element group A and the element group B in total, and wherein, when the at least one kind of element in the element group A includes Re, the at least one kind of element in the element group B is Co alone, Cr alone, or two or more kinds selected from Co, Cr, and Ni.

Abstract: A spark plug electrode is provided, in which an electrode member in which a total of 0.3 to 7.5 wt % of at least one of Ta and Nb is added to an IrRh alloy is provided at a discharge part.

Abstract: A spark plug electrode is provided, in which an electrode member in which a total of 0.3 to 7.5 wt % of at least one of Ta and Nb is added to an IrRh alloy is provided at a discharge part.

Abstract: A center electrode is held in insulating glass, in which a tip end portion of the center electrode protrudes. A ground electrode has a connection part connected to a housing. The ground electrode forms a spark discharge gap between the center electrode and the ground electrode. The ground electrode has a ground base material that includes the connection part and a ground protrusion part that protrudes from the ground base material toward the center electrode and forms the spark discharge gap between the center electrode and the ground electrode. An angle between a ground discharge surface of the ground protrusion part and a side surface of the ground protrusion part is a right angle or an acute angle. At least a portion of the side surface of the ground protrusion part and at least a portion of a side surface of the ground base material are flush with each other.

Abstract: A spark plug includes a ground electrode that is curved to oppose a tip end surface of a center electrode. A predetermined virtual plane that passes through a center axis of the spark plug along the curved ground electrode faces a flow direction of airflow. The ground electrode includes a main body including: an opposing surface on a first side facing the tip end surface of the center electrode; and a sloped surface on a second side opposite the first side. The main body satisfies 10 [°]?Dg?70 [°], 1.0 [mm]?Th, and 1.5 [mm]?Wd, where Dg is a slope angle of the sloped surface relative to the opposing surface, Th is a thickness of the main body in an insertion direction of the center electrode, and Wd is a width of the ground electrode in a direction perpendicular to the virtual plane.

Abstract: A spark plug includes a ground electrode that is curved to oppose a tip end surface of a center electrode. A predetermined virtual plane that passes through a center axis of the spark plug along the curved ground electrode faces a flow direction of airflow. The ground electrode includes a main body including: an opposing surface on a first side facing the tip end surface of the center electrode; and a sloped surface on a second side opposite the first side. The main body satisfies 10 [°]?Dg?70 [°], 1.0 [mm]?Th, and 1.5 [mm]?Wd, where Dg is a slope angle of the sloped surface relative to the opposing surface, Th is a thickness of the main body in an insertion direction of the center electrode, and Wd is a width of the ground electrode in a direction perpendicular to the virtual plane.

Abstract: A center electrode is held in insulating glass, in which a tip end portion of the center electrode protrudes. A ground electrode has a connection part connected to a housing. The ground electrode forms a spark discharge gap between the center electrode and the ground electrode. The ground electrode has a ground base material that includes the connection part and a ground protrusion part that protrudes from the ground base material toward the center electrode and forms the spark discharge gap between the center electrode and the ground electrode. An angle between a ground discharge surface of the ground protrusion part and a side surface of the ground protrusion part is a right angle or an acute angle. At least a portion of the side surface of the ground protrusion part and at least a portion of a side surface of the ground base material are flush with each other.

Abstract: There is provided a spark plug for an internal combustion engine with a simple configuration capable of ensuring stable ignitability regardless of mounting posture to the internal combustion engine. The spark plug includes a housing, an insulator, a center electrode, and a ground electrode. The ground electrode includes an erecting part that is erected from a tip part of the housing to a tip side and an inclined part that is bent from the tip of the erecting part to the center electrode side to extend obliquely toward a tip side. An end edge of the ground electrode on an opposite side to the housing side is a tip of the inclined part. The erecting part satisfies w/t?1, w?1.9 mm, and t?2.3 mm, where t is a dimension in an alignment direction of the erecting part and the center electrode, and w is a dimension in a width direction orthogonal to each of the alignment direction and a plug axial direction. An inclination angle ? of the inclined part with respect to the plug axial direction satisfies 30°???60°.

Abstract: An Ir alloy is excellent in high temperature strength while ensuring oxidation wear resistance at high temperature. The heat-resistant Ir alloy includes: 5 mass % to 30 mass % of Rh; 0.3 mass % to 5 mass % of an element group A made of at least one kind of element selected from among Ta and Re; and 0 mass % to 5 mass % of an element group B made of at least one kind of element selected from among Co, Cr, and Ni, wherein the heat-resistant Ir alloy includes 5 mass % or less of the element group A and the element group B in total, and wherein, when the at least one kind of element in the element group A includes Re, the at least one kind of element in the element group B is Co alone, Cr alone, or two or more kinds selected from Co, Cr, and Ni.

Abstract: A spark plug for an internal combustion engine includes a cylindrical housing, a cylindrical insulator, a center electrode, and a ground electrode. The ground electrode includes an upright part and an inclined part. The upright part is a portion vertically provided on a tip end part of the housing to a tip end side. The inclined part is a portion that is bent from the tip of the upright part toward the center electrode side, and is extended toward an oblique tip end side. The inclined part has a ground end face, an opposed face, and a corner curved face. The corner curved face is a face that smoothly connects the ground end face and the opposed face. The corner curved face has a curved shape. The curvature radius R of the corner curved face satisfies 0.3 mm?R?0.7 mm. The inclination angle ? of the inclined part with respect to a plug axial direction (Z) satisfies 30°???60°.

Abstract: A spark plug for an internal combustion engine includes a cylindrical housing, a cylindrical insulator, a center electrode, and a ground electrode. The ground electrode includes an upright part and an inclined part. The upright part is a portion vertically provided on a tip end part of the housing to a tip end side. The inclined part is a portion that is bent from the tip of the upright part toward the center electrode side, and is extended toward an oblique tip end side. The inclined part has a ground end face, an opposed face, and a corner curved face. The corner curved face is a face that smoothly connects the ground end face and the opposed face. The corner curved face has a curved shape. The curvature radius R of the corner curved face satisfies 0.3 mm?R?0.7 mm. The inclination angle ? of the inclined part with respect to a plug axial direction (Z) satisfies 30°???60°.

Abstract: When one of a center chip and a ground chip of a spark plug is defined as a first chip and another one is defined as a second chip, a discharge starting ridge line, which is a straight ridge line that forms a boundary between two surfaces having different normal line directions, is formed in a portion closest to the second chip in the first chips, and a distance from the discharge starting ridge line to the second chip is configured to be equal at a portion where the first chip and the second chip are opposed to each other.