TEM/STEM observation of ZrC coating layer for advanced high-temperature gas-cooled reactor fuel, Part II

Aihara, Jun ; Ueta, Shohei   ; Yasuda, Atsushi; Ishibashi, Hideharu; Mozumi, Yasuhiro; Sawa, Kazuhiro; Motohashi, Yoshinobu*

The ZrC coating layer was fabricated with bromide process at JAEA. In a later stage of the project, we have successfully kept nominal deposition temperature almost constant. Microstructures of the ZrC layers, of which nominal deposition temperatures were able to measure, were characterized by means of TEM and STEM and the results were compared and discussed with those obtained for different batches including those reported in a previous study. The ZrC grains were oriented in the ZrC layers deposited at about 1630 K. This feature was rather different from that reported in the previous study. The formation of fairly different PyC structures was found on the PyC/ZrC boundary as well as around the pores existing near the boundary. Fibrous carbons were observed on the PyC/ZrC boundary produced in a batch deposited at a higher temperature (nominal temperature was 1769 K); no such fibrous carbons were found in a batch deposited at a lower temperature (nominal temperature was 1632 K).