Brazing ZTA ceramic and Ti6Al4V alloy directly in air: Excellent oxidation resistance at 800 °C

The Ag-2mol.% CuO braze is adopted to successfully join the zirconia toughened alumina ceramic to the surface aluminized Ti6Al4V directly in air. Fine interfaces are formed between the reactive air brazing braze and the matrix on both sides. Nano-scale diffusion layers are observed at the Ag/ZTA interface. Too low brazing temperatures (≤970 °C) result in the insufficient wettability of Ag–CuO on ceramic, while excessively high temperatures (1030–1090 °C) lead to the over-oxidation of coated Ti6Al4V. A balance is achieved at 1000 °C, at which joints reach the highest shear strength (～56.8 MPa). The oxidation tests at 800 °C for 120 h prove that joints possess excellent oxidation resistance.