Research On Lamination And Co-sintering Technology And Its Effect On Deformation Behavior Of Multi-layer Ceramics

With the rapid growth of vehicle population, environmental pollution caused by carexhaust is becoming more and more serious. So the research of car exhaust oxygen sensor,NOx sensor, ammonia sensor is becoming a hot spot issue all around the world. Thesetypes of sensing device usually use YSZ as solid electrolyte, Al₂O₃as insulating layer, andthen co-sinter with other functional layers to crank out. However, there is huge mismatchof sintering shrinkage and thermal expansion between YSZ and Al₂O₃, which could resultin various defects between them in the co-sintering process, such as delamination,cracking and warping deformation. These defects can cause great difficulties topreparation of the sensing device. Therefore, this paper focused on sintering shrinkagedifference between YSZ and Al₂O₃, by improving technology and methods to reduce thisshrinkage mismatch. Its purpose was to prepare YSZ and Al₂O₃multi-layer heterogeneousceramic without macro-warpage or micro-crack.Firstly, the author studied the shrinkage difference between YSZ and Al₂O₃, and foundthat changing the loadage of green tape and adding sintering aids could increase theshrinkage of Al₂O₃and reduce the shrinkage mismatch between the two.The author studied the screen printing process to prepare different thickness of theAl₂O₃insulating layer. Study found that the thickness of the insulating layer increasedwith the screen printing times, decreased with the amount of the blade pressure, increasedwith the loadage of slurry, and the printing difference in both sides of YSZ green body canbe ignored.The author investigated the effect of lamination on deformation behavior ofYSZ/Al₂O₃/YSZ multi-layer ceramic, and found that ethanol is the best laminatingmedium. Improvement of laminating method-adding YSZ screen printing layer, could getfavorable combination of YSZ/Al₂O₃/YSZ interface, which used the degassing effect ofscreen printing and mechanical meshing between two layers.At last, the co-sintering deformation behavior of YSZ and Al₂O₃has been studied.YSZ and Al₂O₃multi-layer heterogeneous ceramic with macro-warpage smaller andmicro-crack free was been prepared, by adding the YSZ-20and YSZ-80transition layer and pressure restriction sintering method.