Compatibility of BeO ceramics for MHD generator insulating wall

Long life insulating walls for open cycle MHD generating channels have been developed. These insulating walls are made of BeO ceramic elements, and were subjected to thermal shock test, corrosion test and current application durability test using a material test rig capable of a heat input of 1.2 MW. Under the conditions of Tsub(W)<=3500C and phi<=180 W/cm2, the experimental formula Tsub(W)=(b/lambdasub(eff)J+0.78)phi+20 obtained for the surface temperature vs. heat flux relationship demonstrates that excellent insulating walls can be constructed with BeO ceramic elements. Under these experimental conditions, six kinds of BeO ceramics including trially prepared materials were subjected to durability tests. It was shown that the commercial product of 95% purity and trially prepared ceramics made by placing a laminating mixture of MgO and Spinel on the surface of the above mentioned commercial product were excellent. (T.O.)