Interfacial characterization and mechanical properties of reactive air brazed ZrO2 ceramic joints with Ag–CuO–Al2TiO5 composite filler metal

Abstract

The Al2TiO5 particles reinforced Ag–CuO–Al2TiO5 composite filler metal prepared by mechanical milling was applied to reactive air braze ZrO2 ceramic to itself. The effect of Al2TiO5 particle content and brazing parameters on the interfacial microstructure and mechanical properties of the joints was systematically analyzed. Moreover, the stability of joint microstructure and the variation of bonding properties were investigated by subjecting them to prolonged heat treatment at 800 °C. The results show that the shear strength of the reactive air brazed joints at 1050 °C for 30 min with 10 wt % Al2TiO5 additives reached 104 MPa, which was 112% higher than that of the joints brazed with single Ag–CuO filler metal. The added Al2TiO5 particles were decomposed into TiO2, which was further reacted with ZrO2 ceramic to form ZrTiO4 phase and blocky Al2O3 phase in the Ag matrix and thus generating the particle-reinforced brazing seam. The variation of joint shear strength caused by brazing parameters and Al2TiO5 contents was analyzed from the viewpoints of the wettability of composite filler, microstructural evolution of joint and formation of void defect. When the ZrO2 ceramic was brazed with Ag–CuO-10 wt % Al2TiO5 at an optimized parameter of 1050 °C for 30 min, the joint shear strength did not decrease obviously after oxidation at 800 °C for 100 h because of the good high-temperature stability of the joint microstructure.