Thermal cycling behavior of YBCO high temperature superconductor thick films

Thermal cycling behavior of YBCO high temperature superconductor thick films coated on different ceramic substrates was studied. It was found that the YBCO superconductor thick film coated on MgO substrate has a better thermal cycle resistance than Al/sub 2/O/sub 3/ substrate; the cycle number for initiating thermal fatigue crack significantly decreases as the thermal cycling temperature range increases. Film thickness was found to have an influence on thermal cycling resistance for thicknesses in the range of 70 to 100 /spl mu/m. A simple thermal mechanical model is employed to describe the thermal stress, and the thermal cycles of failure of YBCO thick films.