ZTA陶瓷ZrO_2的韧化机制与断裂特征

TOUGHENIG MECHANISMS AND FRACTUE CHARACTERISTICS OF ZrO_2 IN ZTA CERAMICS

选用无压烧结和热压烧结两种系列不同成分配比的ＺｒＯ＿２韧化Ａｌ＿２Ｏ＿３（ＺＴＡ）陶瓷，在较宽的力学性能范围内研究７ｒＯ２的韧化机制对材料强度、韧性的贡献及其与断裂特征之间的关系。压痕裂纹揭示出ＺｒＯ＿２的不同韧化机制有不同的开裂特征：微裂纹韧化的材料，压痕裂纹弯曲行进，并且沿着ｍ－ＺｒＯ＿２颗粒与基体的交界面扩展；相变韧化的材料，压痕裂纹穿越ｔ－ＺｒＯ＿２颗粒。此特征能很好地解释：微裂纹韧化可以提高材料的断裂韧性，但有可能降低材料的断裂强度，相变韧化既可以提高材料的断裂韧性，又可以提高材料的断裂强度。

Two series of ZTA ceramics ( sintered with and without hot-pressing) of different compositionwere chosen to analyze the contributlon of the toughening mechanisms of ZrO_2 to the fracture strength and thefracture toughness of the materials and to study the relationship between the toughening rnechanism and fracturecharacteristics of ZrO_2. Indentation cracks show that different totighening mechanisms can produce differentcrack paths: crack propagations are deflected and branched alonig the m-ZrO_2 particle-matrix interfaces for mate-rials toughened by microcracks ; crack propagations can go through t-ZrO_2 grains for materials toughened bytransformation. The two cracking characteristics can be used to explain the following facts : microcrack toughen-ing can increase the fracttire toughness , but may decrease the fracture strength ; transformation toughening cannot only raise greatly the fracture toughness but also increase the fracture strength.