高纯致密氧化镁陶瓷的常压和真空烧结  

High Purity and Fully Dense MgO Ceramic by Conventional and Vacuum Sintering

作　　者：陈淼琴 何金江[1] 张玉利[1] 丁照崇[1] 贺昕[1] Chen Miaoqin;He Jinjiang;Zhang Yuli;Ding Zhaochong;He Xin(Beijing Engineering Research Center, Grikin Advanced Materials Co., Ltd., General Research Institute for Nonferrous Metals, Beijing 100088, China)

机构地区：[1]北京有色金属研究总院有研亿金新材料有限公司北京市高纯金属溅射靶材工程技术研究中心

出　　处：《稀有金属》2018年第4期402-407,共6页Chinese Journal of Rare Metals

基　　金：北京市科技新星项目(Z1511000003150102)资助

摘　　要：MgO为重要的功能型材料,磁隧道结（MTJ）以MgO薄膜作为势垒层时在室温下具有巨大的隧穿电阻效应。实验采用冷等静压（CIP）工艺将高纯MgO粉末（纯度〉99.99%）压制成相对密度为60%左右的坯体,再在500℃充分煅烧后分别进行常压烧结和真空烧结。通过优化烧结工艺参数,可制备得到用于溅射沉积MgO薄膜的高纯高致密MgO陶瓷靶。为了探讨烧结温度、保温时间、烧结气氛对MgO陶瓷致密化和晶粒生长的影响,对烧结后的MgO陶瓷进行取样,并对试样进行金相（OM）观察、X射线衍射（XRD）测试、断面扫描电镜（SEM）观察。结果表明：与常压烧结气氛相比,真空烧结气氛能明显提高MgO陶瓷的致密度,且在烧结中后期封闭气孔形成后真空烧结的作用更显著;在真空气氛进行1500℃保温4 h烧结,可得到相对密度为99.12%,平均晶粒尺寸11.71μm的高纯MgO陶瓷;真空烧结的MgO陶瓷晶粒尺寸更均匀,尺寸标准差低于4.8μm,晶粒沿（200）方向择优生长的趋势更明显,而常压烧结的MgO陶瓷晶粒尺寸分布范围较广,晶粒的择优生长趋势不明显。MgO is an important functional material and magnetic tunnel junctions（MTJs） used MgO films as the barrier layer have a large tunneling magnetoresistance in room temperature.MgO compacts with a relative density of 60 ± 2% were prepared by cold-isostatic pressing（CIP） and high purity MgO powder（purity 99.99%） was used.The compacts were heat treated at 500°C before sintering in vacuum or air.Then fully dense and high purity MgO ceramic targets used for depositing MgO films were fabricated by optimizing sintering parameters.The effects of sintering temperature,time and atmosphere on densification and grain growth behavior were investigated by analyzing the MgO specimens through optical microscope（OM）,X-ray diffraction（XRD） and scanning electron microscope（SEM）.The results showed that the relative densities of MgO ceramics sintered in vacuum were more significantly improved than those sintered in air,especially at the final stage.High purity MgO ceramics with a relative density of 99.12% and an average grain size of 11.71 μm was obtained at 1500 ℃ for 4 h in vacuum.The grain size of MgO sintered in vacuum,having a standard deviation less than 4.8 μm,was more homogenous and exhibited a more clearly preferred orientation of（200） than those sintered in air.

关 键 词：MgO陶瓷 常压烧结 真空烧结 致密化 

分 类 号：TK174[动力工程及工程热物理—热能工程]