Gas sensor element, gas sensor, and manufacturing method for gas sensor element

A manufacturing method for a gas sensor element, the gas sensor element including:

• a pump cell including a first surface, a second surface, a first electrode on the first surface, and a second electrode on the second surface;
• a second ceramic layer including the pump cell;
• a first ceramic layer defining a measurement chamber into which a gas to be measured flows, the first electrode facing the measurement chamber;
• a porous body covering the second electrode, the porous body including, as a main component, a component having a sintering start temperature;
• and
• a dense layer defining a void and not allowing the gas to be measured to pass therethrough, the second electrode and the void being connected through the porous body,
• the manufacturing method comprising:
• a lamination step of forming an unfired laminate which is the gas sensor element before firing, and
• a firing step of firing the unfired laminate to produce the gas sensor element, after the lamination step, wherein
• in the gas sensor element, a reinforcing layer which is porous and includes, as a main component, a component having a sintering start temperature, the sintering start temperature of the main component of the reinforcing layer being lower than the sintering start temperature of the main component of the porous body, the reinforcing layer interposed between the second electrode and the porous body at a position overlapping the void in a thickness direction of the porous body, and
• the lamination step includes:
• filling a region in an unfired dense layer which becomes the void after firing, with a vanishing material which vanishes due to firing, and
• forming an unfired reinforcing layer between an unfired second electrode and an unfired porous body.