A SiC-CuC-Cu insulator for MHD generator channels

Summary Form only given, as follows. The authors have tested improved SiC-CuC-Cu elements and shown their effectiveness as regards permissible heat flux, safe thermal shock conditions, electrical leakage, and breakdown between adjacent elements. To clarify the design specifications for the new elements, they examined the parameters generating degradation or destruction of the element. Under operating conditions exceeding permissible levels, considerable deterioration due to the reaction of potassium with SiC and severe ablation were observed. EPMA observation of post-test samples under permissible conditions showed diffusion and formation of a carbon-rich layer on the working surface. A direct relationship between the penetration of potassium and sulfur and the deterioration was not clear, even after 20 h. The crystal structure of SiC showed no change under permissible operating conditions. However, crystal granulation occurred, and peeling of the corner portions and a decrease of bond strength in the CuC compliant were observed when the permissible surface temperature was exceeded.<>