Solid‐State Diffusion Bonding of Carbon–Carbon Composites with Borides and Carbides

Abstract

Solid‐state diffusion bonding of carbon–carbon (C─C) composites by using boride and carbide interlayers has been investigated. The interlayer materials used in this study were single‐phase borides (TiB2 or ZrB2), eutectic mixtures of borides and carbides (ZrB2+ ZrC or TiB2+ B4C), and mixtures of TiB2+ SiC + B4C produced in situ by chemical reactions between B4C, Ti, and Si or between TiC, Si, and B. The double‐notch shear strengths of the joints produced by solid‐state reaction sintering of B4C + Ti + Si interlayers were much higher than those of joints produced with other interlayers. The maximum strength was achieved for C─C specimens bonded at 2000°C with a 2:1:1 mole ratio of Ti, Si, and B4C powders. The reaction products identified in the interlayers, after joining, were TiB2, SiC, and TiC. The joint shear strength increased with the test temperature, from 8.99 MPa at room temperature to an average value of 14.51 MPa at 2000°C.