国产煅烧氧化铝粉体改性和自发凝固成型

Modification and Spontaneous Coagulation Casting of Domestic Calcined Alumina Powder

Al_(2)O_(3)陶瓷具有机械性能优异、耐酸碱腐蚀和性价比高等优点,是广泛应用的结构陶瓷。国产煅烧Al_(2)O_(3)粉体存在团聚严重和钠钾杂质含量高等问题,导致国内高品质Al_(2)O_(3)陶瓷制备严重依赖进口粉体。本工作首先采用球磨的方式对国内某公司Al_(2)O_(3)粉体进行解团聚,粉体的中位粒径D 50从1.88μm降低到0.90μm;之后,通过水洗降低粉体中杂质含量,Na含量从140×10^(-6)降低到60×10^(-6),接近国外同级别粉体水平;最后,以MgO和MgAl_(2)O_(4)为烧结助剂,采用自发凝固成型制备Al_(2)O_(3)陶瓷素坯。发现MgO引起浆料黏度增大,而MgAl_(2)O_(4)不影响浆料黏度,并且两者都能降低烧结温度和抑制晶粒异常长大,平均晶粒尺寸从41.10μm降低到10.64μm,提升了Al_(2)O_(3)陶瓷的力学性能。通过解团聚和除杂处理,国产Al_(2)O_(3)粉体能够达到与同级别性能最好的日本住友Al_(2)O_(3)粉体相当水平。

Al_(2)O_(3) ceramics are the most widely used structural ceramics because of excellent mechanical properties,acid and alkali corrosion resistance and high quality-price-ratio.Due to serious agglomeration and high content of sodium and potassium impurities in domestic calcined Al_(2)O_(3) powder,the preparation of Al_(2)O_(3) ceramics with high performance relies heavily on imported powder.In this work,the Al_(2)O_(3) powder produced by a domestic company was firstly disaggregated using ball milling,and the median particle size D 50 of the powder was reduced from 1.88μm to 0.90μm.Afterwards,the impurity content in the powder was reduced by washing with water,and the Na content was reduced from 140×10^(-6) to 60×10^(-6),which was close to the level of the same grade powder abroad.Finally,Al_(2)O_(3) ceramic green bodies were prepared by spontaneous coagulation casting using MgO and MgAl_(2)O_(4) as sintering aids.It is found that the addition of MgO increases the slurry viscosity,while MgAl_(2)O_(4) does not affect that,and both can effectively reduce the sintering temperature and inhibit the grain growth.And the average grain size is reduced from 41.10μm to 10.64μm,which improves the mechanical properties of Al_(2)O_(3) ceramics.Through disaggregation and purification,the domestic Al_(2)O_(3) powder can reach the same level as the Japanese Sumitomo Al_(2)O_(3) powder with the best performance in the same grade.