Al_2O_3-TiC/Al_2O_3-TiC-CaF_2叠层陶瓷拉拔模具坯体的叠层结构优化分析

Laminated Structure Optimization Analysis of Al_2O_3-TiC/Al_2O_3-TiC-CaF_2 Laminated Ceramic Drawing Die Blank

采用真空热压烧结的方式制备出Al2O3-TiC/Al2O3-TiC-CaF2叠层陶瓷拉拔模具坯体。通过显微压痕强度实验,研究Al2O3-TiC层和Al2O3-TiC-CaF2层的叠层厚度和层厚比对陶瓷材料硬度和断裂韧性的影响,并且用有限元方法对叠层陶瓷材料烧结过程中的残余应力进行分析。结果表明:Al2O3-TiC/Al2O3-TiC-CaF2叠层陶瓷拉拔模具坯体具有良好的层间界面,晶粒结合紧密;在模具坯体叠层部分总高度不变的情况下,当叠层数目为5,层厚比(Al2O3-TiC层:Al2O3-TiC-CaF2层)为1∶1时,叠层陶瓷拉拔模具坯体的硬度值和断裂韧性值达到最大,分别为18.2±0.3 GPa和5.7±0.2 MPa·m1/2;在烧结冷却过程中,由于不同材料层的热膨胀系数和弹性模量而引起的残余应力是该叠层陶瓷拉拔模具坯体具有良好机械性能的原因。

Al2O3-TiC/Al2O3·TiC-CaF2 laminated ceramic drawing die blanks were prepared by vacuum hot pressing sintering method. The microscopic indentation-strength experiments of laminated ceramic drawing dies were conducted to research the relationship between the laminated structure （laminated number and laminated thickness ratio ） and the hardness and fracture toughness. The finite element analysis method was taken to analyze the residual stress of the laminated ceramics drawing die blanks generated during the sintering process. The results showed that the interfaces of Al2O3-TiC/Al2O3·TiC-CaF2 laminated ceramic drawing die blanks bonded well and crystal particles jointed closely. With an invariable total height of the laminated parts, when the laminated number is 5 and laminated thickness ratio （AlEO3-TiC： AIEO3-TiC-CaF2 ） is 1： 1, the laminated drawing die blanks possess better mechanical properties （hardness value is 18.2 ± 0.3 GPa, fracture toughness value is 5.7 ±0.2 MPa· m1/2）. The residual stress caused by different thermal expansion coefficient and elastic modulus of different composites layers during the cooling process make contribution to the better mechanical properties of the laminated ceramics.