| 摘要 |
PURPOSE:To contrive to lengthen the catalytic effect of a glow plug having a catalyst layer, by providing a middle layer made of nearly pure cobalt, nickel or chrome, between a noble metallic catalyst layer and the base material of a sheath tube. CONSTITUTION:A plug body 1 is mainly constituted of a heater 13 which is laid n a sheath tube 11 together with ceramic powder 12, a housing 14 to fix one end of the sheath tube 11 to the plug body 1, and a center electrode 15 which is inserted into the sheath tube 11 along the center line of the tube in the axial direction. In this case, the housing 14 and the center electrode 15 are unitarily fixed to the plug body 1, electrically insulated by a ceramic material. The glow plug is constituted of the plug body 1 and the sheath tube 11, on which outer surface a metallic middle layer 2 made of cobalt of 5-30 micron thick is formed by a dielectric plating, and a noble metallic catalyst layer 3 made of platinum of 2,000Angstrom thick is formed on the surface of the middle metallic layer 2 by a method of spatter-spraying. |
