烧结工艺对纳米晶种微晶陶瓷刚玉磨料结构与性能的影响

Effect of Sintering Process on Structure and Properties of Microcrystalline Ceramic Corundum Abrasive with Nano-Seed

采用溶胶-凝胶技术合成Al_(2)O_(3)刚玉前驱体,以SiO_(2)-MgO-CaO为助烧剂,α-Al_(2)O_(3)纳米粉体为晶种,利用传统烧结技术制备微晶陶瓷刚玉(SG)磨料。借助透射电镜(TEM)、X射线衍射(XRD)及热重-量热扫描(TG-DSC)等技术分析了晶种的特性和凝胶前驱体的热学性能,探讨了烧结温度和烧结时间对SG磨料微观结构和力学性能的影响。结果表明,纳米α-Al_(2)O_(3)晶种的添加使θ→α-Al_(2)O_(3)相变温度降低了250℃。单颗粒抗压强度和密度随烧结温度的升高和烧结时间的延长先增大后减小,晶粒形貌由等轴晶转变为片状晶。在1 320℃烧结45 min制备的SG磨料的单颗粒抗压强度和密度分别为40.2 N和3.88 g/cm^(3),平均晶粒粒径为0.56μm,优于用传统烧结技术制备的微米晶种磨料样品。

Al_(2)O_(3) corundum precursor was synthesized by sol-gel technology,and microcrystalline ceramic corundum(SG) abrasive was prepared by traditional sintering technology with SiO_(2)-MgO-CaO as sintering aids and α-Al_(2)O_(3) nano-powder as crystal seed.The characteristics of seed and thermal properties of gel precursor were analyzed by means of transmission electron microscopy(TEM),X-ray diffraction(XRD) and thermogravimetric-calorimetric scanning(TG-DSC).The effects of sintering temperature and holding time on microstructure and mechanical properties of SG abrasive were studied.The results show that α-Al_(2)O_(3) nano-seed makes the transition temperature of θ→α-Al_(2)O_(3) decrease by 250 ℃.With increasing sintering temperature and holding time,the single particle compressive strength and density increase first and then decrease,and the grain morphology changes from equiaxed crystal to platelike crystal.Sintering at 1 320 ℃ for 45 min,the single particle compressive strength and density of SG abrasives reach 40.2 N and 3.88 g/cm^(3),respectively,and the average particle size is 0.56 μm,which is superior to micron seed abrasive samples prepared by traditional sintering technology.