PROCEDE DE PRODUCTION D'UN ELEMENT DETECTANT L'OXYGENE EN ELECTROLYTE SOLIDE DE STRUCTURE FEUILLETEE DU TYPE A CELLULE DE CONCENTRATION

L'INVENTION CONCERNE UN PROCEDE DE PRODUCTION D'UN ELEMENT DETECTANT L'OXYGENE DU TYPE A CELLULE DE CONCENTRATION.SELON L'INVENTION, EN PLUS D'UNE COUCHE DE BLINDAGE 12, D'UNE COUCHE FORMANT ELECTRODE DE REFERENCE 16, D'UNE COUCHE D'UN ELECTROLYTE SOLIDE CONDUCTEUR DE L'ION OXYGENE 18 ET D'UNE PREMIERE COUCHE FORMANT ELECTRODE DE MESURE 20, ON FORME UNE SECONDE COUCHE FORMANT ELECTRODE DE MESURE 24 AYANT UNE STRUCTURE MICROSCOPIQUEMENT POREUSE ET PERMEABLE AUX GAZ, SUR LA SURFACE EXTERNE DE LA PREMIERE COUCHE 20 PAR DEPOT PHYSIQUE A LA VAPEUR D'UN METAL, CETTE COUCHE 24 ETANT ELLE-MEME FORME EN DEUX COUCHES 23 ET 25.L'INVENTION S'APPLIQUE NOTAMMENT A L'INDUSTRIE AUTOMOBILE. A method of producing an oxygen sensing element which is essentially an oxygen concentration cell in the form of a lamination of relatively thin layers. The first step of the method is to prepare a lamination of a ceramic shield layer, an inner or reference electrode layer, a solid electrolyte layer and an outer or measurement electrode layer which is formed by sintering metal particles applied to the solid electrolyte layer surface in the form of a paste or slurry and dried. Then an additional measurement electrode layer, preferably not thicker than 1.0 micron, is formed on the outer surface of the sintered measurement electrode layer by a physical vapor deposition technique such as ion plating, sputtering or vacuum evaporation. Preferably this electrode layer is formed by a two-stage vapor deposition process wherein the first stage deposition is terminated before the deposited layer becomes thicker than 0.5 microns. The addition of the vapor-deposited measurement electrode layer improves the responsiveness and durability of the oxygen sensing element.