Joining ZTA ceramic by using Dy2O3-Al2O3-SiO2 glass ceramic filler

In this paper, a novel Dy2O3-Al2O3-SiO2 (DAS) glass ceramic was designed and prepared for joining zirconia toughened alumina (ZTA) ceramic. The crystallization, thermal expansion behavior and wetting behavior of the DAS glass filler were studied. The effect of cooling rate and joining temperature on the microstructure and flexural strength of joints was investigated. The results show that slow cooling rate (15 degrees C/min) leads to crystallization of brazing seam, which causes the formation of pores in the joints due to the large density difference between the glass and the crystalline phases. The dissolution of ZrO2 from ZTA substrate into the filler during joining process improves the mismatch of the coefficient of thermal expansion (CTE) between the brazing seam and substrate. The maximum flexural strength of 535 MPa is obtained when the joining temperature and cooling rate are 1475 degrees C and 50 degrees C/min, respectively.