LaMgAl_(11)O_(19)-Al_2O_3复相陶瓷的制备及其力学性能的研究

Fabrication and Mechanical Properties of LaMgAl_(11)O_(19)-Al_2O_3 Composite Ceramics

以板片状结构的LaMgAl11O19作为第二相来对Al2O3陶瓷进行增韧补强,采用无压烧结工艺在1650℃下保温4 h制备了LaMgAl11O19-Al2O3复相陶瓷,研究了LaMgAl11O19的添加量对LaMgAl11O19-Al2O3复相陶瓷的物相组成、体积密度和力学性能的影响,并结合复相陶瓷试样断面的SEM照片分析了其强韧化机理。研究表明,添加一定量的LaMgAl11O19后,LaMgAl11O19-Al2O3复相陶瓷材料的抗弯强度和断裂韧性均有明显提高,当添加LaMgAl11O19的质量分数为10%时,LaMgAl11O19-Al2O3复相陶瓷的抗弯强度和断裂韧性分别为321 MPa和5.03 MPa.m1/2,其中片状晶的拔出效应、裂纹偏转作用以及裂纹分支等增韧机制发挥了主导作用。

LaMgAl11O19-Al2O3 composite ceramics toughened and reinforced by LaMgAl11O19 platelets were fabricated by pressureless sintering at 1650 ℃ for 4 h.Then the effects of plate-like LaMgAl11O19 additions on the phase composition,microstructure of fracture surface and mechanical properties of composites were investigated.The results demonstrate that the mechanical properties of LaMgAl11O19-Al2O3 composite ceramics were improved evidently in comparison to the pure Al2O3 ceramic,when the additions of LaMgAl11O19 increased to 10 wt%,the flexural strength and fracture toughness of composite ceramics reached 321 MPa and 5.03 MPa·m1/2,respectively.The predominant toughening mechanisms were attributed to the pull-out effect of plate-like LaMgAl11O19 grains,crack deflection and crack branching.