Effects of the Mn–Co spinel coating on BaZr0.1Ce0.7Y0.1Yb0.1O3-δ/AISI 441 reactive air brazed joint: Microstructure, strength, and stability

Reactive air brazing (RAB) holds great potential for joining BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb) electrolytes with stainless steel interconnects. But this technique inevitably results in many brittle compounds along the BZCYYb interface and excessive oxidation at the steel interface. Herein, we successfully address the above issues by introducing the Mn–Co spinel coating. The coating prevents the reaction of Cr with the electrolyte and reduces brittle compounds along the BZCYYb interface, thereby elevating the joint strength by 31%. Also, it completely separates CuO and the stainless steel, thus inhibiting the excessive oxidation on the steel surface. Furthermore, the coating remains dense in both oxidizing and reducing atmospheres at 600 for 300 h, significantly enhancing the long-term stability of joints.