Semester
Fall
Date of Graduation
2024
Document Type
Dissertation
Degree Type
PhD
College
Statler College of Engineering and Mineral Resources
Department
Mechanical and Aerospace Engineering
Committee Co-Chair
Edward M. Sabolsky
Committee Member
Konstantinos Sierros
Committee Member
Xueyan Song
Committee Member
Xingbo Liu
Committee Member
Charter Stinespring
Abstract
In order to test and monitor the operational stability and conditions of various energy, transportation, and manufacturing systems and their components, accurate sensors capable of operating at temperatures over 1000 °C in various environments for long durations are required. In addition, many of these harsh environmental systems do not permit sensors to be directly inserted into the environment, so the sensors need to be embedded into the surrounding support or thermal protective materials. Some technological and industrial applications that require the use of harsh environment conditions sensing include nuclear and chemical reactors, jet engines, heavyduty gas turbines, rotating bearings in aircraft engines, and solid oxide fuel cells (SOFC). For use in solid-stated sensor designs, various high-temperature conductorssuch as noble refractory metals, nitrides, carbides, and silicides have been applied for this purpose; however, those materials are not stable at high temperatures and under different working atmospheres. Other systems such as conductive oxides have been selected as potential conductors for harsh environment sensors development. Lanthanide chromite perovskites (LaCrO3, LC), and various dopant schemes of this composition, exhibit a group of physical properties that satisfy those expected for high temperature sensing applications, such as high melting point, good electrical conductivity at high temperatures, chemical stability under reducing and oxygen-rich atmospheres. In the current dissertation, the physical properties of pure and doped LC were characterized at temperatures up to 1500 oC under different working atmospheresto apply these materials to various solid-state sensor designs. Most previous literature for these compositions limited their studies toSr-, Ca-, Sr-/Mn co-doped LaCrO3 materials at the levels of 10-40 mol% up to 1500 oC under oxidizing, reducing, and variant partial oxygen pressure atmospheres. This work included defining the electronic band structure and band gap energies trends experimentally and through DFT modeling. In addition, the thermoelectric properties were also measured for various doped LaCrO3 compositions and composites (which contained secondary refractory phases). The data acquired was utilized to fabricate thermoelectric sensor devices (thermocouples) which were tested in various temperature regimes and environments for the first time. Finally, the chemical and microstructural stability of these materials were characterized after hightemperature operation, where specifically the electrical and thermoelectrical degradation mechanisms were studied and modeled to better define the working life of such sensors in real industrial and commercial applicationssuch as coal boilers and high-temperature chemical reactors monitoring.
Recommended Citation
Mena, Javier A., "Processing, Stability, and High-Temperature Properties of Doped LaCrO3-Based Refractory Ceramics and Composites for Harsh Environments Sensing Applications" (2024). Graduate Theses, Dissertations, and Problem Reports. 12668.
https://researchrepository.wvu.edu/etd/12668
Included in
Ceramic Materials Commons, Condensed Matter Physics Commons, Engineering Physics Commons, Inorganic Chemistry Commons, Other Materials Science and Engineering Commons, Semiconductor and Optical Materials Commons