氧化锆陶瓷气泡缺陷对其断裂韧度的影响

Effect of bubble defects on fracture toughness of zirconia ceramics

为研究氧化钇稳定氧化锆陶瓷(Y-TZP)气泡缺陷在烧结前后的遗传性及气泡缺陷对材料断裂韧度的影响,采用X射线显微镜对3mol%氧化钇稳定四方多晶氧化锆陶瓷(3Y-TZP)烧结前后的气泡缺陷进行观测,得到缺陷变化规律,然后分别测试了天然缺陷和人为引入体缺陷状态下,不同氧化钇掺量的3Y-TZP、4YTZP、5Y-TZP陶瓷的弯曲强度,并计算威布尔模量和断裂韧度,在SEM下观察各组的破坏模式。研究结果表明:烧结作用可修复氧化锆陶瓷的气泡缺陷,修复率约为74.12%,当直径小于10μm时,修复率高达97.22%,当直径大于40μm时,修复率仅为20%,烧结后80%以上的气泡缺陷直径不超过20μm;氧化锆陶瓷的弯曲强度随氧化钇掺量的增加而降低,引入体缺陷显著降低了氧化锆陶瓷的弯曲强度,其中4Y-TZP陶瓷稳定性最佳,强度仅降低8.64%,5Y-TZP陶瓷对缺陷最敏感,强度降低22.58%;断裂韧度随氧化钇掺量的增加而降低,引入体缺陷的深度(a)和半宽度(c)会影响氧化锆陶瓷的断裂韧度,断裂韧度随a/c的增大,先增大后减小,在a/c≈1.5时达到峰值。

To study the change law of bubble defects before and after the sintering of yttria-stabilized tetragonal zirconia(Y-TZP)ceramics and the influence of bubble defects on fracture toughness of materials,the flaws of 3Y-TZP ceramic before and after sintering were observed by X-ray microscope,and the variation law of defects was obtained.Then,testing the bending strength of 3Y-TZP,4Y-TZP,and 5Y-TZP ceramic with different yttrium oxide content under the condition of natural defects or artificially introduced volume defects,and calculating the Weibull modulus and fracture toughness.The failure modes of each group were observed under SEM.The results show that sintering can repair the bubble defects of zirconia ceramics,and the repair rate is about 74.12%.When the diameter is less than 10μm,the repair rate is up to 97.22%.When the diameter is more than 40μm,the repair rate is only 20%.The diameter of more than 80%of bubble defects after sintering shall not exceed 20μm.The bending strength of zirconia ceramics decreases with the increase of yttrium oxide content.The introduction of volume defects significantly reduce the bending strength of zirconia ceramics,of which 4Y-TZP ceramic has the best stability,and the strength decreased by only 8.64%.5Y-TZP ceramic is the most sensitive to defects,and the strength decreased by 22.58%.The fracture toughness decreases with the increase of yttrium oxide content.The depth(a)and half-width(c)of the introduced volume defect will affect the fracture toughness of zirconia ceramics.The fracture toughness increases first and then decreases with the increase of a/c,reaching a peak value when a/c≈1.5.