| 摘要 |
This invention inhibits growth of oxide scale at an interface between a noble-metal tip and an electrode base material. A melt section (26) has a melt-flow region (28) along the entire circumference of the outside surface of the noble-metal tip (27). In an electrode cross section that contains a central axis, letting D represent the length of a line segment (S) corresponding to the end surface of the noble-metal tip (27), L1 and L2 are imaginary straight lines each at a distance of 9D/20 from the central axis, P1 and P2 are the intersections between said lines (L1 and L2) and the interface between the noble-metal tip and the melt section, L3 is an imaginary straight line connecting said intersections (P1 and P2), P3 is the end of the aforementioned line segment (S) on the same side as line L1, P4 is the end of said line segment (S) on the same side as line L2, L4 and L5 are imaginary straight lines that pass through ends P3 and P4 and are parallel to the central axis, P5 is the end of the melt-flow region (28) on line L4, P6 is the end of the melt-flow region (28) on line L5, and P7 and P8 are the intersections between lines L4 and L5 and line L3. The distance (X1) between intersection P7 and end P5 and the distance (X2) between intersection P8 and end P6 are each greater than or equal to 0.092 mm. |
