| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that, when spark discharge is made to flow by a strong air stream generated within a gas cylinder, spark discharge being generated in a noble metal chip 5 may "leap" to a melting part 6 and the melting part 6 may be worn.SOLUTION: At a welding spot of an electrode base material 3 and the noble metal chip 5, the melting part 6 is formed by welding. An insulator α is provided in a boundary part between a surface of the noble metal chip 5 and a surface of the melting part 6. As one example, the insulator α is precipitated from the melting part 6 during welding. As a specific example, welding is performed by using the electrode base material 3 or the noble metal chip 5 to which powder-state alumina is applied. The powder-state alumina is precipitated in an end of the melting part 6 that is molten, cooled and solidified, such that the insulator α is provided between the surface of the noble metal chip 5 and the surface of the melting part 6. Leaping spark from the noble metal chip 5 to the melting part 6 is prevented by interposing the insulator α between the surface of the noble metal chip 5 and the surface of the melting part 6, such that the spark discharge can be prevented from leaping to the melting part 6 even if a high-speed stream is generated within the gas cylinder. |
