Patent ID: 6706317
Filing Date: 2004-03-16
Classification: G01N

Abstract:
A method for manufacturing a gas sensing element which has a cup-shaped solid electrolytic body having a reference gas chamber formed therein, an inside electrode provided on an inner surface of said solid electrolytic body, an outside electrode provided on an outer surface of the solid electrolytic body, and a porous layer formed so as to cover said outside electrode, said manufacturing method comprising:a step of forming said solid electrolytic body; a step of providing said inside electrode on a predetermined portion of said inner surface of said solid electrolytic body and providing said outside electrode on a predetermined portion of said outer surface of said solid electrolytic body; and a step of dipping said solid electrolytic body into a slurry which is prepared for forming said porous layer by using a dipping apparatus, wherein said dipping apparatus comprises: a dipping tank for storing said slurry which is prepared for forming said porous layer, a viscosity adjusting tank equipped with a viscosity sensor for measuring a viscosity of said slurry and a viscosity adjusting mechanism for adjusting the viscosity of said slurry based on a sensing value of said viscosity sensor, a fluid passage for connecting said dipping tank and said viscosity adjusting tank, and a circulating pump provided in said fluid passage for forcibly circulating said slurry between said dipping tank and said viscosity adjusting tank, wherein said dipping step includes: a step of dipping said solid electrolytic body into said slurry stored in said dipping tank while said slurry is forcibly circulated between said dipping tank and said viscosity adjusting tank by said circulating pump, a step of forming a slurry film on a predetermined portion of said solid electrolytic body through this dipping treatment, and a step of sintering said slurry film to form said porous layer.