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In this work, crystallization, thermal expansion and wetting behavior of ZnO–Al 2 O 3 –SiO 2 (ZAS) glass were first investigated. The results showed that ZnAl 2 O 4 was precipitated from ZAS glass after crystallization treatment. Crystallization increased the coefficient of thermal expansion (CTE) of ZAS glass ceramic due to the high CTE of ZnAl 2 O 4. In addition, ZAS glass exhibited good wettability on the surface of MgAl 2 O 4 substrate. On this basis, ZAS glass was used to join MgAl 2 O 4 ceramic, and the microstructure and mechanical properties of joints obtained with different cooling methods were investigated. The flexural strength of joints was related to the content of ZnAl 2 O 4 crystals in the brazing seams. Additional nucleation and crystallization treatment during cooling process improved the crystallinity of brazing seam, resulting in better matching of the CTE of brazing seam with that of MgAl 2 O 4 ceramic. The maximum flexural strength of joints reached 201 MPa, which was equivalent to the strength of MgAl 2 O 4 ceramic. [ABSTRACT FROM AUTHOR]

Effects of ZrO 2 content on the crystallization kinetics, formation mechanism of voids and mechanical property of Dy 2 O 3 –Al 2 O 3 –SiO 2 glass were studied. The crystallization method of DAS glasses transforms from surface crystallization into bulk crystallization with an increase in ZrO 2 content from 0-3% to 6–9%. When ZrO 2 content is 0–3%, the crystalline phases of DAS glass ceramics are Dy 2 Si 2 O 7 and Al 2 O 3 , accompanied by formation of voids. When ZrO 2 content is 6–9%, the DAS glass ceramics consist of Dy 2 Si 2 O 7 , Al 2 O 3 and ZrO 2. At the same time, no voids are found in the glass ceramics. Therefore, formation of voids during crystallization can be attributed to combined effect of the crystallization method and the density difference before and after crystallization. In addition, for glassy samples, the flexural strength increases from 80.4 MPa to 219.3 MPa with an increase in ZrO 2 content from 0% to 9%. Moreover, crystallization further improves the mechanical properties of the DAS glass ceramics with bulk crystallization method. [ABSTRACT FROM AUTHOR]