镍掺杂对α-Al_2O_3烧结过程、微观结构及力学性能的影响

Effects of Ni-doping on the Sintering Process,Microstructure and Mechanical Properties of α-Al_2O_3

首先采用非均相沉淀包裹法制备金属镍包裹α-Al2O3复合微球粉体,然后采用热压烧结制备了Al2O3/Ni金属陶瓷。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)对复合粉体及热压烧结产物的成分和结构进行了表征,利用阿基米德法测量了复合陶瓷的密度,分别通过三点弯曲法和单边切口横梁法对陶瓷试条的抗弯强度和断裂韧性进行评估。研究发现:金属镍的引入活化了α-Al2O3的烧结,镍粒子均匀地分布在氧化铝的晶界上,增加了弱界面,提高了氧化铝的断裂韧性,最高可达7.62MPa·m1/2。

Ni coated α-Al2O3 composite microspheres are first synthesized by heterogeneous precipitation coating method, and then Al2O3/Ni cermets are prepared by hot press-sintering of the as-prepared Ni-coated α-Al2O3 powders. The microstructural features of the resultant Al203-Ni cermets and the crystalline phases of precipitated precursors, reduced powders and sintered cermets are characterized by scanning electron microscope （SEM）, energy dispersive spectroscopy（EDS）, and X-ray diffractometer （XRD）. The relative densities of cermets are measured by Archimedes＇ method, and the flexural strength and fracture toughness are estimated by the three-point bending and single-edge-notched beam methods. The results exhibit that the Ni-doping activated the sintering of α-Al2O3, and Ni particles are uniformly distributed at the interface of alumina grains, which increase the weak interfaces, and enhance the fracture toughness of alumina, achieving a maximum value of 7.62 MPa · m^1/2.