Enhanced mechanical properties by grain boundary strengthening in ultra-fine-gra

2019-10-10 11:46:23

ceramics fracture grain TZP sinter

责任者: He, Y.J.;Winnubst, A.J.A.;Sagel-Ransijn, C.D.;Burggraaf, A.J.;Verweij, H. 单位: Fac. of Chem. Technol., Twente Univ., Enschede, Netherlands 来源出处: Journal of the European Ceramic Society(J. Eur. Ceram. Soc. (UK)),1996//,16(6):601-12 摘要: The mechanical properties of ceramics with the compositions of 5 mol% YO1.5-TZP (ZY5) and 4 mol% YO1.5-4 mol% CeO2-TZP (ZY4Ce4) were investigated. Nanocrystalline powders of both TZPs were synthesized by a gel precipitation technique. Powder compacts were made by cold isostatic pressing, and were then pressureless sintered or sinter-forged to dense TZP ceramics (density: 96-99%) with grain sizes of 180 nm. Shear deformation during sinter-forging was found to favourably affect densification and microstructure. The mechanical properties of both types of ultra-fine-grained TZP ceramics were examined up to 760°C. The results point towards an improved grain boundary structure and the elimination of residual flaws obtained by the sinter-forging technique. The sinter-forged samples exhibited a higher Vicker hardness compared to that of pressureless sintered specimens. After sinter-forging the fracture energy value was found to be 325 J/m2 and the fracture toughness to be 10 MPa m1/2. A Weibull modulus of 21 was obtained for the sinter-forged samples which was significantly higher than the value of 8 for the pressureless sintered specimens. The enhancement of reliability is obviously connected to a decrease in the average size and concentration of flaws caused by inhomogeneous powder particle packing due to the presence of irregular agglomerates 关键词: ceramics;densification;fracture toughness;grain boundaries;grain size;hardening;hardness;nanostructured materials;powder technology;precipitation (physical chemistry);shear deformation;sintering;zirconium compounds;mechanical properties;grain boundary strengthening;compositions;nanocrystalline powders;ultra-fine-grained tetragonal ZrO2 polycrystal ceramics;YO1.5-CeO2-tetragonal ZrO2 polycrystals;gel precipitation technique;powder compacts;cold isostatic pressing;dense tetragonal ZrO2 ceramics;grain sizes;shear deformation;pressureless sintered specimens;densification;microstructure;grain boundary structure;residual flaws;sinter-forging technique;fracture energy value;fracture toughness;Weibull modulus;inhomogeneous powder particle packing;irregular agglomerates;YO1.5-CeO2-ZrO2;ZrO2