Strength and Young's modulus of silicon carbide layers of HTGR fuel particles at high temperatures

Strength and Young's modulus of chemically vapor deposited silicon carbide layers of coated fuel particles for high temperature gas-cooled reactors (HTGR) were measured from room temperature up to 1480deg C (1753 K) in helium atmosphere. The diametrical compression test was applied to micro-specimens of ring shaped SiC. Young's modulus decreased slightly from room temperature up to around 1200degC (1473 K) and decreased rapidly above this temperature. The strength remained almost unchanged from room temperature up to around 1300deg k 9107013442C (1573 K) and decreased rapidly above this temperature. The fracture surfaces indicated that fracture mechanisms changed from transgranular to intergranular, which corresponded with the rapid decrease in strength. (orig.)