Jiang, Junhua. Ion-Irradiation and Microstructural Change Studies of Glassy Carbon

Principal Investigator
First Name:
Junhua
Last Name:
Jiang
Institution:
Idaho National Laboratory
Title:
Chemical Scientist
Team Members:
Name: Institution: Expertise: Status:
Junhua Jiang Idaho National Laboratory Electrochemistry, Energy storage, Nanomaterials, Process development, Fuel fabrication and characterization Other
Yaqiao Wu Boise State University TEM, Cladding, Metallurgy, Mechanical Properties, Irradiation Effects, Martensite Steel, APT, austenitic, Stainless Steel, magnetic materials, Characterization, nanostructure, Spent Nuclear Fuel, Iron Based Alloy, Graphite, uranium compounds, TRISO Fuel Faculty
Lin Shao Texas A&M University Radiation Effects, Sensors, ion beam analysis Faculty
Experiment Details:
Experiment Title:
Ion-Irradiation and Microstructural Change Studies of Glassy Carbon
Describe the work that you are proposing in detail. Please include as many specifics as possible (e.g., dose, dose rate, ion energy, types of ions, beam line x-ray energy, irradiation temperature, analysis temperature, atmosphere, etc.):
This project proposes to conduct three tasks: (1) ion-irradiation of glassy carbon; (2) PIE studies of the irradiated material by XRD/SEM/TEM/FIB/Raman; and (3) Mechanical property studies of the irradiated sample by nanoindentation. The irradiation of the material will be performed on a 2 MV accelerator with a carbon ion beam. Three irradiated samples will be prepared at 400 oC and in a vacuum by applying three different fluences: 5 dpa, 25 dpa, and 100 dpa. The irradiated samples will be examined by Raman at Texas A&M, and other methods at CAES. For Raman studies, the intensity ratio of two peaks (G band at around 1580 cm-1 and D band at around 1350 cm-1) or their frequency integrated intensity ratio of these two peaks scales will be measured to estimate the degree of graphitic ordering in glassy carbon, and the crystallite size of ordered graphite phases. The quantitative analysis of XRD patterns corresponding to (002), (100) and (110) diffraction of carbon nanocrystallites allows the calculation of five structural parameters including amorphous carbon fraction (Xa), aromaticity (fa), interlayer spacing (d002), nanocrystallite lateral size (La), and thickness (Lc). Based on the calculation, the changes of carbon nanostructure caused by irradiation will be studied, based on the correlation between the five parameters and the fluence. The results will be further examined by the SEM//TEM methods. TEM lamellas will be prepared by using FIB lift-out technique. Crash-and-float technique will be an alternative way for making TEM specimens if the FIBing process would affect the glassy carbon structure. Electron tomography will be utilized for 3D imaging/reconstruction of nano-scale to microscale irradiation-induced changes including pore changes. The 3D image reconstruction methods can be used to construct visual and mathematical models of the structures across the breadth of scales. The nanoindentation studies of the irradiated samples will allow to measure the mechanical properties (elastic modulus and hardness) and examine their surface morphology changes, which can be correlated to the material’s microstructures disclosed above.
Technical Abstract
Glassy carbon has received increasing attention for being studied as a promising core material for advanced nuclear technologies. Compared to extensive studies of the irradiation effects in nuclear graphite, the influences of neutron or ion irradiation on the mechanical, electrical, and thermal properties of glassy carbon have been rarely reported. It has unique physical and chemical properties substantially different from those of graphite. The neutron or ion irradiation of the materials is likely to cause considerable changes of its physicochemical and mechanical properties, and even its transformation into graphitic materials. The PIE studies by several established methods will allow to disclose their microstructure and develop the relationship between the structure, property, and irradiation conditions. The systematic studies of irradiation effects in glassy carbon are important for boosting the design and development of high-performance fuel elements for advanced nuclear technologies and deepening our understanding of physicochemical property changes of the glassy carbon materials in nuclear environments. This project will initiate a preliminary systematic study and begin experiments to irradiate the glassy carbon material and examine the microstructural changes of the irradiated material.