Effects of neutron irradiation on glass ceramics as pressure-less joining materials for SiC based components for nuclear applications

This paper reports on the microstructure and properties of two glass–ceramics based on SiO2–Al2O3–MgO (SAMg) and SiO2–Al2O3–Y2O3 (SAY), which have been designed to be used as pressure-less low activation joining materials for SiC/SiC and SiC based components for nuclear applications. Glass–ceramic pellets (SAY and SAMg) were irradiated for approximately 1 year in the reactor core of the LVR-15 research reactor at Nuclear Research Institute Rez, Czech Republic, at about 50 °C, 6.92 × 1024 n/m2 (E > 1 MeV, about 1 dpa in steel); SiC/SiC composites joined by SAY were irradiated about 1 year at High Flux Reactor (HFR), Petten, The Netherlands, 550 °C, 9–11 × 1024 n/m2 (E > 1 MeV, about 1.4–1.8 dpa in C), 600 °C, 16–22 × 1024 n/m2 (E > 1 MeV, about 2.6–3.3 dpa in C) and 820 °C 31–32 × 1024 n/m2(E > 1 MeV, about 5 dpa in C). Optical microscopy with image analysis and scanning electron microscopy (SEM) with X-ray microanalysis (EDS) were used to investigate the glass–ceramics morphology and composition, showing a remarkable similarity before and after neutron irradiation for both glass–ceramics. Comparison of bending strength for irradiated and non-irradiated SAY joined SiC/SiC indicate that the mechanical strength is unaffected by irradiation at these conditions.