Study Of The ZrO₂/Al₂O₃ Laminated Compound Ceramics

Laminated ceramics is a kind of obdurability material, which is imitative of the framework of shell in the nature. The special superposition of the laminated ceramics make the researcher can proceed designing inside the layer and among layers from the macro-aspect, and synthesize the new material with the superiority performance. Based on the design ways of multi-layered ceramics and the advisement of the effect of transformation-toughened, thermal-mismatched, dispersion-toughened of particle of ZTA and PSZ, the paper produced a three-layer ZrO2/Al2O3 ceramics-30wt%Al2O3 + ZrO2 or 45wt%Al2O3 + ZrO2 in the two surfaces, 5wt%Al2O3 + ZrO2 in the center. The surface thickness is approximately 300~500. Through scan electronic microscopy and mechanical property instruments, the relationship of the process, microstructure and mechanical property of the three-layer ZrO2/Al2O3 ceramics was systematically studied.In this research , we used non-pressure sintering process, adjusted the surface compositions and lowered the heating rate, and finally obtained >98% relative density in the condition of 1650℃×1h. The product of 45wt%Al2O3 + ZrO2 surface composition has high mechanical properties: 682 Mpa bending strength, 15.5Gpa hardness,8.26Mpa.m1/2 fracture toughness, higher 30%~50% than those of mono-layer ceramics. Meanwhile, further study showed that molding-pressure and the method of pressing will directly affect the density of embryo products and products.In this paper, we obtain the dense products by the two-direction pressing and at the pressure of 250~300Mpa. The result of experimentation of thermal-shock showed that the critical temperature difference of the three-layer ZrO2/Al2O3 ceramics was above 450℃,higher 200℃ than those of monothic ceramics. The 38×6.5×5mm laminated ceramics revealed superiority performance to the extend in the experimentation of thermal simulation.The result of SEM reveals that the laminar ceramics is a kind of wave interface structure, the particles of ZrO2 and Al2O3 combine densely. At the effect of transformation-toughened, thermal-mismatched, dispersion-toughed of particle etc., the toughness of the laminar ceramics improves greatly.The analysis of thermal shock stability of the monothic ceramics and laminar ceramics showed that the monothic ceramics of 5wt%Al2O3 + ZrO2 and the laminar ceramics (30wt%Al2O3 + ZrO2 or 45wt%Al2O3 + ZrO2 in the two surfaces) revealed the ascend resistance-curve and the performance of flaw-tolerate. The thermal shockstability of laminar ceramics of 45wt%Al2O3 + ZrO2 in the two surface is higher approximately 50% than those of monothic ceramics.