Refractory eutectic assisted bonding (REABond) technology for joining of high temperature silicon carbide‐based composite materials

Abstract

Continuous ceramic fiber‐reinforced ceramic composite materials are targeted for high temperature thermostructural components in aerospace. Advanced joining and integration technologies are enabling for the fabrication of large and complex shaped ceramic matrix composite components. Silicon rich refractory eutectic phase compositions in silicon‐chromium (Si‐18 at% Cr), silicon‐titanium (Si‐16 at% Ti), and silicon‐hafnium (Si‐8.5 at% Hf) systems were investigated for joining studies. The Si‐8.5 at% Hf system was down‐selected and further evaluated for joining silicon carbide fiber bonded composite (SA‐Tyrannohex) and additional fiber‐reinforced composite materials. Microstructural analysis of polished cross‐sections using optical microscopy and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) was used to evaluate the joint quality and determine the composition of the reaction formed phases. Joints along the full length of the paired substrates were observed to be well adhered, uniform, and free of gaps and pores. Single lap offset testing conducted at room temperature, 750°C, and 1200°C showed very good strengths when the fibers in the SA‐Tyrannohex material were perpendicular to the joint interface. However, when the fibers were orientated parallel to the joining plane, failures were premature due to the low interlaminar strength of the SA‐Tyrannohex material and occurred away from the joint interface.