Methods of making gas sensors and sensors formed therefrom

Abstract

In one embodiment, a method of making a sensor comprises: forming a slurry comprising a metal oxide, a binder, an acetate, and a reducing material, applying the slurry to at least a portion of a sensing element comprising two electrodes with an electrolyte disposed therebetween, and calcining the slurry to form a protective coating. In one embodiment, a gas sensor, comprises: a sensing element comprising a sensing electrode and a reference electrode having an electrolyte disposed therebetween, and a protective coating disposed over the sensing electrode, wherein the protective coating comprises aluminum oxide, an alpha alumina and about 2 wt % to about 15 wt % solid solution, based upon the total weight of the protective coating.

1 - 16 . (canceled)  
   
   
       17 . A gas sensor, comprising: 
 a sensing element comprising a sensing electrode and a reference electrode having an electrolyte disposed therebetween; and    a protective coating disposed over the sensing electrode, wherein the protective coating comprises aluminum oxide, an alpha alumina and about 2 wt % to about 15 wt % solid solution, based upon the total weight of the protective coating.    
   
   
       18 . The sensor of  claim 17 , wherein the aluminum oxide is selected from the group consisting of theta-alumina, gamma-alumina, delta-alumina, and combinations comprising at least one of the foregoing aluminum oxides.  
   
   
       19 . The sensor of  claim 17 , wherein the solid solution is selected from the group consisting of aluminum-zirconium solid solution, aluminum-titanium solid solution, a titanium-zirconium solid solution, and a titanium-aluminum-zirconium solid solution.  
   
   
       20 . The sensor of  claim 17 , wherein the zirconia particles have a diameter, measured along a major axis, of less than or equal to about 2 nanometers.  
   
   
       21 . The sensor of  claim 17 , wherein the protective coating has a thickness of about 90 micrometers to about 200 micrometers.