Active Brazing of Silicon Carbide with Rapidly Quenched TiZrCuBe Filler Metal

The Zr35Ti25Cu12Be28 rapidly quenched filler metal has been used to obtain a durable and reliable SiC/SiC brazed joint. With the SEM, EDX and XRD methods, the following phases were found and confirmed in the brazed seam: (Zr,Ti)2Cu, ZrBe2, TiBe2. The microstructural studies have revealed the absence of the noticeable reaction layer in the brazed joint. The shear strength tests have shown that the SiC/SiC joint failure occurred by a brittle failure with a formation of a crack and its propagation through the silicon carbide and the brazed joint/SiC interface. But despite this high shear strength of 201 MPa was obtained with 810 °C, 10 min brazing mode. Unbrazing tests with heating to 1450 °C of SiC/SiC joints indicated that the dissolution of the silicon carbide proceeded and a formation of the ZrSi matrix with TiC, ZrC inclusions occurs in the brazed joint, which is the consequence of an increasing filler metal reactivity with temperature.