Influence of neutron irradiation on the microstructures and electrical properties of polymer derived ceramic sensing material

Principal Investigator
Name:
Cheryl Xu
Email:
nsuf@inl.gov
Phone:
(208) 526-6918
Experiment Details:
Experiment Title:
Influence of neutron irradiation on the microstructures and electrical properties of polymer derived ceramic sensing material)
Work Description:
The objective of this project is to perform neutron irradiation damage test on one kind of polymer derived SiAlCN ceramics (PDC). If our hypothesis is correct -- the microstructures and electrical properties are maintained under irradiation -- such material will later be designed as a temperature sensor in nuclear reactor for in-core temperature measurement. Irradiation experiments will be performed at PULSTAR reactor at North Carolina State University (NCSU). The detailed plans of irradiation condition and material property characterization are listed below: • Neutron flux with a dose as 1012 n/cm2/sec. • Ambient temperature at 90 F. • Sample size: 30*10*3 mm. • Irradiation durations are set as 10 hours, 30 hours and 50 hours. • For each set of irradiation test, three samples with same material composition and same size will be tested to ensure result’s repeatability. • Before and after irradiation test, Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) will be used to characterize to see if there is any microstructural change. • Before and after irradiation test, X-Ray Diffraction (XRD) will be performed to see if there is any lattice structure change. • Before and after irradiation test, electrical resistivity will be measured from room temperatures to high temperature (e.g., 500 oC). The two relationship curves before and after the irradiation test will be drawn and compared to see if they match, and if yes, in the next step, such material will be used to design a temperature sensor. It will be the task for the next phase.
Abstract
The objective of this project is to perform neutron irradiation damage test on one kind of polymer derived SiAlCN ceramics (PDC). If our hypothesis is correct -- the microstructures and electrical properties are maintained under irradiation -- such material will later be designed as a temperature sensor in nuclear reactor for in-core temperature measurement (It will be the goal for the next phase). In this phase of project, irradiation experiments will be performed at PULSTAR reactor at North Carolina State University (NCSU). Temperature sensors for nuclear reactor applications are subject to high temperature, high pressure, and irradiation challenges. Currently, wired thermocouples are the most common temperature sensor used in nuclear reactors. The current nuclear field has made significant advances in thermocouple design, but there are still limitations in durability and increased expense in instrumented test assemblies. In our previous work, we have been able to demonstrate that SiAlCN materials pertains good semiconducting behaviors and good thermal resistance up to 1050 oC. Both leaded and wireless sensors have been designed and experimented with excellent accuracy for a duration of time (10 hours). Even more appealing, the crystallinity and composition of SiAlCN materials can be adjusted and controlled to modify the electrical conducting properties and sensitivity gauging factor. This proposed work intends to test the irradiation stability of such ceramic sensing materials, and if successful, in the next step, we will design a temperature sensor based on such material for nuclear reactor temperature measurement. Irradiation stability is one of the most important factors to ensure the performance of the PDC sensor material for nuclear application. PDCs are mostly used at non-crystalline state, which makes them less brittle. PDCs also exhibit a more stable structure than crystalline SiC and Si3N4, which is inferred from their higher creep resistance and higher thermal stability. Unlike conventional materials, the PDCs consist of nano-domains created by intertwined graphene (aromatic carbon) sheets about 1-5nm in size. The unique structure of PDCs can effectively promote defect recombination to mitigate radiation damage. During this task, we will assess the irradiation tolerance, microstructural stability and electric properties of PDC material to understand the radiation effects on its sensing capability. In total, it will take six months to perform this research, including (1) sample preparation, (2) material property characterization before irradiation test, (3) perform Irradiation test, (4) material property characterization after irradiation test, data analysis, and material properties comparison, and (5) finishing documentation and research summary. Scanning Electron Microscope (SEM) and Optical Microscopes (OM) will be used to examine the surface of irradiated samples. X-Ray Diffraction (XRD) will be used to investigate the possible irradiation induced crystallinity change in the sample, in which case, further Transmission Electron Microscopy (TEM) investigations will be used. Based on the radiation test results and PIE analysis, further optimization on material composition and fabrication process will be performed to ensure its irradiation stability in such harsh nuclear environment.