Investigation of the mechanical properties of ceramic breeder materials

Abstract In order to characterize ceramic breeder materials for fusion reactors, mechanical properties were measured on Li 2 SiO 3 , Li 4 SiO 4 , and also on some LiAlO 2 samples for comparison. Literature data on thermal conductivity and thermal expansion of all breeder materials considered were compiled to compare their presumable sensitivity to thermal stresses. The highest level of thermal shock resistance is predicted for LiAlO 2 , and the lowest level for Li 4 SiO 4 . Thermal shock tests, made by dipping pellets into a hot metal melt, confined the relation for LiAlO 2 and Li 4 SiO 4 . Young's modulus was determined by ultrasound velocity measurement, and fracture strength was measured on pellet samples under compression. The scatter in compressive strength is exceptionally large, partly due to various grain size, and does not suggest a definite ranking of the different breeder materials. Compressive creep tests were made at temperatures of 750–950°C for about 100 h each. An extrapolated creep rate of 10 −6 /h was used to estimate a conservative temperature limit of total microstructure stability.