PURPOSE: To exactly measure the oxygen in an exhaust gas contg. unburned components by providing an electrode consisting of a platinum group metal including platinum and rhodium and oxygen ion conductive solid electrolyte on an oxygen ion conductive solid electrolyte.
CONSTITUTION: The reference electrode is formed by molding a plate-shaped solid electrolyte by using a zirconia solid electrolyte and printing a conductive material essentially consisting of platinum on the inner side face facing the air passage thereof. On the other hand, a 1st electrode plate consisting of the powders of the conductive material essentially consisting of platinum powder and the zirconia solid electrolyte is printed on the outer side face and further, the 2nd electrode paste consisting of rhodium powder and zirconia solid electrolyte powder is printed thereon; thereafter, the printing is dried and calcined. A porous protective film is then formed thereon by plasma thermal spraying of a ceramics material essentially consisting of spinel, following which the said layer is subjected to a hydrogen reduction treatment.
ISHIGURO FUJIO
KATO NOBUHIDE
