| 摘要 |
PROBLEM TO BE SOLVED: To obtain a potential difference type NOx sensor low in sensor impedance, having a noble metal electrode good in electrode conductivity and excellent in NOx sensitivity characteristics by using an alloy electrode consisting of platinum and rhodium or a thermet electrode consisting of platinum, rhodium and zirconia as a gas detection electrode of a sensor. SOLUTION: A sensor is formed by using a green sheet 1 of zirconia doped with 8 mol. of Y2 O3 as an oxygen ion conductor. The green sheet is formed by a doctor blade method and has a thickness of 0.3 mm. This green sheet is cut into a sample size of 4×6 mm to be used. As a material of a detection electrode 2, paste prepared by adding a predetermined amt. of an org. binder and a predetermined amt. of an org. solvent to an alloy powder of Pt and Rh to knead them therewith is prepared. The addition amt. of Rh is set to 5% by wt. of the total amt. of Pt and Rh. Zirconia is further added to this paste in order to adjust electrode porosity. Pt is applied to a reference electrode 3 by paste printing so as to form a pair on the surface of the zirconia sheet 1 along with the detection electrode 2 and zirconia for adjusting an electrode structure is dispersed and added in the same way as the detection electrode 2. |
