Al2O3/Y-TZP and Y-TZP materials fabricated by stacking layers obtained by aqueous tape casting

Abstract

A processing method for production of multilayer ceramics by laminating stacked green ceramic tapes with help of adhesive layer and pressing at room temperature was extended. Ceramic tapes with two compositions within the system alumina/yttria stabilized zirconia (YTZP) (alumina–40 vol.% Y-TZP and 100 vol.% Y-TZP), obtained from aqueous ceramic slurries by tape casting procedure were employed in this work. The optimum conditions to fabricate pieces made of six tapes with same composition, and to obtain defect free sintered materials, by varying the level of pressure applied, was investigated. For this purpose, previously selected composition of adhesive layer and type of pre-treatment of tapes were used. The analysis of engineering stress–apparent strain curves recorded during the lamination process was done to control the formation of cracks within the pieces under pressure. Optimization of the pressure range was performed by the analysis of the green density change as a function of pressure. The cross section observation by optical and scanning electron microscopy of sintered ceramic pieces was carried out to assure the control of the process. Fabricated pieces were subjected to testing by Impulse Excitation Technique (IET) and Vickers indentation in order to evaluate the adequacy of the fabrication procedure and to analyse the possible effects of interfaces. Dense pieces with maximum sizes of the defects of the same level as those of the microstructural ones and without interface effects on the elastic and mechanical behaviour were obtained.