Method to apply multiple layers, including an electrode layer, on a sintered or pre-sintered ion conductive solid electrolyte body

Method of making a solid electrolyte ion conductive gas sensing element having

• a solid ion conductive electrolyte body (1) having two surface portions, one of which is adapted for exposure to the gas to be sensed
• a layer of electrode material (2) on one surface portion of the body;
• a layer of electrode material on the second surface portion of the body;
• a cover layer of porous ceramic material on the layer of electrode material on said one surface portion of the body;
• and
• a cover layer of porous ceramic material on the layer of electrode material on said second surface portion of the body,
• comprising the steps of
• providing a pre-sintered ion conductive solid electrolyte body having said two surface portions,
• applying a layer of the electrode material on one surface portion of said body;
• applying a layer of the electrode material on the second surface portion of said body;
• applying a cover layer of ceramic material which, when sintered, becomes porous, on the layer of electrode material on one surface portion of said body;
• applying a cover layer of ceramic material which, when sintered, becomes porous on the layer of electrode material on the second surface portion of said body;
• and
• then in one step, sintering the electrode layers and the cover layers, by heating the body with the electrode layers and the cover layers applied thereon to a temperature in which the sintering process of the electrode layers at least commences and the ion conductive body and the cover layer are completely sintered.