Article and method of forming porous coating on electrode layer of concentration cell type oxygen sensor

摘要

A porous coating, which is effective in restricting the flow of a gas under measurement relatively to the electrode layer of the sensor and protecting the electrode against detrimental influences, is formed by spraying fine particles of a heat-resistant and chemically stable material at a high temperature onto the electrode surface to form a porous layer with pores of a moderate size, then impregnating the porous layer with an aqueous dispersion of fine particles of a similar material followed by baking the impregnated layer, so that the finished coating has pores of appropriate size and total volume.