Flexural strength of ceramic materials exposed to Pb-16Li at elevated temperatures

Flow channel inserts (FCI) are functional components designed to minimize the magnetohydrodynamic pressure drop and also serve as a thermal and tritium permeation barrier. In the simplified design of the FCI component, the ceramic is directly exposed to contact with Pb-16Li at elevated temperature. As the FCI must withstand mechanical stresses resulting from the thermal gradient during the demanding operation, the assessment of mechanical response of ceramic in contact with Pb-16Li is essential. Pristine Al 2 O 3 and SiSiC were subjected to three-point bending at room temperature and at 650 °C in argon. While SiSiC showed no change in flexural strength at both temperatures, flexural strength of Al 2 O 3 decrease when the test temperature was increased. Inspection of the fracture surfaces revealed mixture of intergranular and transgranular brittle fracture for both materials in investigated temperature range. Pre-exposed samples were tested at 650 °C in liquid Pb-16Li to assess the effect of mechanical strength degradation caused by Pb-16Li. Testing of the pre-exposed Al 2 O 3 samples showed the similar flexural strengths to the unexposed ones. In the case of SiSiC, the sample exposure resulted in decrease of the flexural strength. The analysis of the pre-exposed tested samples revealed deteriorated surface by Pb-16Li only in the case of SiSiC.