前驱体煅烧法制备CeO_(2)颗粒及其抛光性能的研究

Preparation and Polishing Properties of CeO_(2)Particles Fabricated by Precursor Calcination Method

以Ce(OH)_(3)为前驱体,采用前驱体煅烧法制备CeO_(2)抛光粉。通过调节煅烧温度、升温速率和保温时间获得的具有不同比表面积的CeO_(2)颗粒样品,将样品球磨破碎,制备出中位粒径为(1.0±0.1)μm的CeO_(2)抛光液。通过分析CeO_(2)抛光液对K9玻璃的抛光切削量和表面粗糙度Ra值来评价其抛光性能,采用比表面仪(BET)、X射线衍射仪(XRD)、扫描电镜(SEM)、透射电镜(TEM)和原子力显微镜(AFM)等表征手段对样品的比表面积、物相组成、微观组织结构和抛光玻璃表面粗糙度进行分析,结果表明:前驱体Ce(OH)_(3)煅烧可以制备具有立方萤石结构、尺寸均匀的纳米级CeO_(2)抛光粉,煅烧温度的升高,保温时间的延长和升温速率降低均会使CeO_(2)颗粒的比表面积减小。CeO_(2)颗粒的比表面积是其抛光性能的关键,比表面积越小切削能力越强,本实验样品对K9玻璃的切削量最大可达900 nm·min^(-1),此外,比表面积对玻璃抛光质量也有重要影响,在比表面积为5 m^(2)·g^(-1)时,获得的玻璃表面粗糙度小,玻璃表面质量高。

As an important rare earth oxide functional material,CeO_(2)powder had been widely used as polishing material in recent years.The unique chemical mechanical polishing performance of CeO_(2)provided a new idea for the global planarization of optical glass,silicon crystal and other materials,and became an important polishing product in the field of precision optics.At present,the precursor calcination method had become one of the main methods for batch production of CeO_(2)powder because of its simple process,low production cost and large-scale application.Under different calcination process conditions,the specific surface area of CeO_(2)particles prepared under the same calcination process conditions was quite different due to different temperature zones in roller kiln and different holding time.The effect of CeO_(2)particles with the same specific surface area on the polishing performance was still unclear,so it was a hot research direction to study the relationship between the specific surface area and the polishing performance,and then improve the calcination process to obtain uniform CeO_(2)particles with appropriate specific surface area to improve the polishing performance.In this paper,Ce(OH)_(3)was used as the precursor material.During the experiment,appropriate amount of Ce(OH)_(3)was directly calcined in muffle furnace.The calcination process was adjusted by setting different calcination temperature,heating rate and holding time.After the calcination of raw material,the powder particles of calcined product were refined.According to the material water mass ratio of 1:3 and the material ball mass ratio of 1:10,appropriate amount of calcined samples were put into YFFX16/13 QYC stirring ball mill.The ball milling was carried out in YC type stirring ball mill.The rotation speed of the ball mill was set at 35 r·min^(-1).The particle size distribution of CeO_(2)was monitored by Malvern 2000 E laser particle size analyzer.When the median diameter of CeO_(2)particles D50=(1.0±0.1)μm,the ball milling was stopped and the slurry was taken out.After that,the slurry was filtered through a 5μm filter bag,adjusted to the appropriate pH value with 0.5 mol·L-1 KOH solution,and added an appropriate amount of suspension dispersant sodium polyacrylate to prepare a polishing solution with a solid content of 5%.The K9 glass was polished by reed 9 B polishing machine.CeO_(2)particles with different properties obtained by different calcination processes were refined,and the slurry with solid content of 5%was prepared to polish K9 glass on a double-sided polishing machine.The thickness reduction of K9 glass after 30 min was recorded.The cutting amount of polishing fluid was quantified by MRR to characterize the polishing efficiency of CeO_(2)polishing fluid.The surface morphology of glass before and after polishing was observed by atomic force microscope(AFM),and the surface roughness was used to evaluate the surface quality of glass.The specific surface area of the particles was measured by H300-2000 A automatic nitrogen adsorption specific surface analyzer(BET);the phase of the calcined products was analyzed by Panaco X‘Pert Powder 003 diffractometer(XRD);the micro morphology of the particles was characterized by JEOL JEM-2100 F field emission transmission electron microscope(TEM)and JEOL7001 F field emission scanning electron microscope(SEM);the morphology of the particles was characterized by edge The surface roughness of polished glass was measured by AFM.The results showed that under different calcination conditions,the particle properties of CeO_(2)powders were obviously different.When the calcination temperature of raw materials increased,the maximum temperature holding time prolonged or the heating rate slowed down,the CeO_(2)grains would grow rapidly,the agglomeration of the grains was enhanced,the particle size became larger,and the CeO_(2)grains were more complete,the grain defects were significantly reduced,and the specific surface area of the particles was reduced.The smaller the specific surface area was,the higher the MRR value was.However,when the specific surface area of CeO_(2)was 5 m^(2)·g^(-1),the roughness(Ra)value of K9 glass was the smallest,and the glass had a smooth surface.CeO_(2)with CaF2 structure could be prepared by simple direct calcination method,using Ce(OH)_(3)as precursor and calcining temperature above 700℃.The calcination process had an important influence on the structure and morphology of CeO_(2)powder.When calcined at 900℃,the massive particles were more uniform and regular,forming more dense CeO_(2)aggregate particles.Higher calcination delay,longer holding time and higher heating rate could obtain CeO_(2)particles with smaller specific surface area.The specific surface area of CeO_(2)particles was closely related to its polishing performance.When the specific surface area of CeO_(2)particles was 5 m^(2)·g^(-1),the roughness(Ra)value of K9 glass polished surface was the smallest,and the glass had a smooth surface.Therefore,CeO_(2)powder with large specific surface area could be used for large cutting amount,and CeO_(2)powder with reasonable specific surface area could be used for polishing when high quality surface was needed.