Titanium-based brazing alloy for bonding oxide/oxide CMCs for steelmaking industry applications

In this work, a Ti-based high-entropy alloy was used to join Al2O3f / Al2O3-ZrO2 ceramic matrix composites, intended for use as radiant tube furnace components in energy-intensive industries such as steelmaking. The brazing cycle was conducted in a vacuum tubular furnace up to 1050 °C. The brazing material consisted of brazing alloy powders mixed with a water-based binder. Process parameters studied included the weight percentages of the binder, the pressure applied on the joints, and additional heat treatments to obtain successful brazed CMCs. Morphological characterizations were conducted to analyze the brazed joints and the microstructure of the filler metal. Mechanical shear tests at room temperature were performed to assess the apparent shear strength of the brazed joints, measuring 49 ± 8 MPa of apparent shear strength for butt-configuration joints with failure mode caused by the delamination of the composite. Additionally, direct-flame exposure tests were conducted to evaluate the brazed joints in combustion environments.