Ceramic Composite Thermocouples for High Temperature Applications

A temperature sensing article comprising:

• at least one inner layer embedded within an outer layer;
• wherein the at least one inner layer is comprised of a first leg and a second leg;
• wherein the first leg is comprised of a first composite mixture of an undoped or doped LaCrO3 in contact with a refractory oxide in a volumetric ratio ranging from about 70:30 to about 95:5, respectively;
• wherein the second leg is comprised of a second composite mixture of an undoped or doped LaCrO3 in contact with a refractory oxide in a volumetric ratio ranging from about 70:30 to about 95:5, respectively;
• wherein the first leg and the second leg are in electrical contact with each other to form a junction;
• wherein the first composite mixture and the second composite mixture are different compositions such that a thermoelectric voltage is generated between the first leg and the second leg;
• wherein the doped LaCrO3 is represented by the formula La0.7Ca0.3CrO3;
• wherein the outer layer is comprised of a refractory oxide;
• wherein the refractory oxide is comprised of Al2O3, Cr2O3, ZrO2, SiO2, MgO, CaO, Fe2O3, P2O5, or combinations thereof;
• and
• wherein the temperature sensing article is a monolithic structure.

A thermocouple sensor preform comprising:

• a first leg;
• a second leg;
• a sacrificial substrate;
• wherein the first leg is comprised of a first composite mixture of an undoped or doped LaCrO3 in contact with a refractory oxide in a volumetric ratio ranging from about 70:30 to about 95:5, respectively;
• wherein the second leg is comprised of a second composite mixture of an undoped or doped LaCrO3 in contact with a refractory oxide in a volumetric ratio ranging from about 70:30 to about 95:5, respectively;
• wherein the first leg and the second leg are disposed on the sacrificial substrate and are in electrical contact with each other to form a junction;
• wherein the first composite mixture and the second composite mixture are different compositions such that a thermoelectric voltage is generated between the first leg and the second leg;
• wherein the doped LaCrO3 is represented by the formula La0.7Ca0.3CrO3;
• wherein the refractory oxide is comprised of Al2O3, Cr2O3, ZrO2, SiO2, MgO, CaO, Fe2O3, P2O5, or combinations thereof;
• and
• wherein the sacrificial substrate disintegrates at a temperature lower than the sintering temperature of the first composite mixture and the second composite mixture.