以溶胶-凝胶法制备镁铝尖晶石(以下简称“尖晶石”)粉末, 掺入0~2.5wt%的LiF, 经球磨后, 测试混合粉末的物相组成. 采用热压(HP; 32 MPa/1550℃)及热压结合热等静压(HP/HIP; 热等静压工艺条件为150 MPa/1700℃)工艺制备出尖晶石透明陶瓷. 分析测试了掺入不同LiF的尖晶石陶瓷的结构和红外透过率, 采用感应耦合等离子体(Inductively Coupled Plasma, 或ICP)方法测定了LiF掺杂后的粉料和透明陶瓷中的Li离子含量. 实验显示, LiF的加入促进了尖晶石晶粒长大和气孔的排除, 并促进了尖晶石陶瓷烧结的致密化进程. 添加1.0wt%~1.5wt% LiF的尖晶石透明陶瓷具有最高的红外透过率. LiF在尖晶石陶瓷中形成残余物质, 添加过量的LiF对尖晶石陶瓷的光学性能会产生不利影响.
The influence of LiF as a sintering aidditive on the infrared transmissivity of magnesia alumina spinel (MgAl2O4; spinel, briefly) transparent ceramics was investigated. Spinel powders prepared by Sol-Gel method, were mixed with LiF of 0-2.5wt%, and then ball milled, tested by XRD for their phase compositions. Hot press (HP) or hot press combined with hot isostatic press (HP/HIP) technique was applied to sintering the powder mixtures into spinel ceramics, while HP under 32 MPa at 1550℃, and HIP under 150 MPa at 1700℃. The structures and infrared transmissions of the ceramic bodies were examined by SEM and IR spectrometer, respectively. Li contents in the spinel powder mixtures and in the resulted ceramics were detected by inductively coupled plasma (ICP) technique. The incorporation of LiF in the starting spinel powders facilitates the growth of grains and the expulsion of pores during sintering. And it shows LiF promotes the sintering of spinel ceramics. Spinel ceramics with LiF contents of 1.0wt%-1.5wt% exhibit optimal infrared transmissivity. While excess LiF acts adversly on the optical performances of spinel ceremics due likely to its remnant or derivative in the ceramic bodies.
参考文献
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