Air-reactive cladding assisted brazing of Y2O3-MgO nanocomposite ceramic to TC4 alloy: Interfacial reaction mechanism and mechanical property

Y 2 O 3 -MgO nanocomposite ceramic, as a novel infrared window material, exhibits superior properties compared to traditional infrared window materials. To realize its engineering application in high-speed aircraft such as unmanned aerial vehicles, the reliable joining between Y 2 O 3 -MgO nanocomposite ceramic and TC4 alloy is a key challenge. In this study, the surface of Y 2 O 3 -MgO nanocomposite ceramic was first clad in air using an Ag-CuO-Al 2 O 3 filler, which achieved uniform spreading on the ceramic. Subsequently, vacuum brazing was successfully performed between the clad Y 2 O 3 -MgO nanocomposite ceramic and TC4 alloy using AgCu filler. The microstructure and mechanical properties of the brazed joints were studied in detail. The air-reactive cladding technique significantly improved wettability, reducing the wetting angle of the filler metal on Y 2 O 3 -MgO nanocomposite ceramic from 104° to 27°. The brazed joint interface treated with the Ag-CuO-Al 2 O 3 cladding exhibited sound metallurgical bonding without defects. The main phases identified in the Y 2 O 3 -MgO ceramic-side reaction layer were Cu 2 Y 2 O 5 , Mg 0.78 Cu 0.22 O and Y 4 Al 2 O 9 . Analysis and calculations reveal that Cu 2 Y 2 O 5 and Mg 0.78 Cu 0.22 O are respectively formed by the reaction of CuO with Y 2 O 3 and MgO, while Y 4 Al 2 O 9 results from the reaction between Al 2 O 3 and Y 2 O 3 . The typical interfacial microstructure was: Y 2 O 3 -MgO/Cu 2 Y 2 O 5 +Mg 0.78 Cu 0.22 O+Y 4 Al 2 O 9 /Cu x Ti 6-x O+Ag(s,s.)/Ti(s,s.)+Ti 2 Cu/TC4. The joint achieved a maximum shear strength of 66 MPa under optimal parameters of 24 mol% CuO in the cladding layer and a brazing parameters of 860 °C for 20 min. • This work developed a novel surface modification method for Y 2 O 3 -MgO ceramic: air-reactive cladding technique. • The air-reactive cladding technique reduces the contact angle of the filler metal on Y 2 O 3 -MgO ceramic from 104° to 27° • Both Y 2 O 3 and MgO participate in interfacial metallurgical reaction despite high thermodynamic stability. • Shear strength of the brazed joint is increased by 200% due to sufficient interfacial metallurgical reaction..