Synthesis And Chemical Mechanical Polishing Performance Of Compound Cerium Oxide

Chemical mechanical polishing (CMP) is one of the most popular planarization technologies in the precision optics manufacturing industry, while the chemical composition and physical character of the abrasive have a very important influence on the CMP process. Therefore, the research made a study of changing the physical and chemical characters of the particles by doping, and the synthesized particles were used for optical glass and LCD glass polishing.The reason and regularity of increasing the removal rate were investigated, it can provide a new perspective to design and prepare composite polishing powder with high performance.A series of tin-cerium mixed oxides with different compositions were successfully synthesized by wet-solid mechanical chemical processing (MCP) using SnC12·2H2O and Ce2(CO3)3·8H2O as starting reagents, ammonia as precipitator. The effect of Sn-Ce ratio and calcination temperature on the phase composition and particle size were investigated. The results showed that the crystal phase of synthesized mixed oxides includes cubic ceria and tetragonal tin dioxide. With the calcination temperature increasing from 800℃to 900℃and 1000℃, the crystallinity of mixed oxides increased; however, the material removal rate (MRR) showed a little decrease. The enhancement of MRR was observed for the samples synthesized at 800℃with tin molar fraction over 50%. The optimal Sn-Ce molar ratio is related to the type of glass polished,5:5 for ZF7 glass and 6:4 for K9 glass.A series of CeO2-based polishing powders containing different amount of La and Pr were synthesized by co-precipitation using Ce(NO3)3,La(NO3)3,Pr(NO3)3 as raw materials, ammonia as precipitator, and their polishing performance was investigated. A dependence of Pr concentration on the MRR values of polishing K9 glass and LCD glass was observed and the highest MRR values,343.9nm/min for K9 glass and 136.1nm/min for LCD glass,.were achieved using a composite oxide with Ce/La/Pr=70:29:1, With the increase of content of Pr,, the morphology of particles of as-synthesized powders became to rod-like, which eliminates the positive effect on CMP. Composite CeO2 polishing powders co-doping with different amount of fluorine were synthesized by co-precipitation and wet-solid mechanical chemical processing (MCP) using NaF as raw materials, and their MRR,particle size,TPR,XRD and Zeta potential were investigated. The results showed that the fluorine-doped CeO2-based composite oxides could successfully synthesized by co-precipitation, with the increase of fluorine content, the MRR for K9 glass and LCD glass increased at first and then decreased. The optimum content of fluorine doped into the CeO2-based composite oxides was found to be 5.16%wt with the highest MRR values 409.2nm/min for K9 glass and 167.7nm/min for LCD glass., The morphology of as-synthesized powders is spherical with high Zeta potential and moderate particle size (1μm). While it is difficult to obtain fluorine-doped ceria by mechanical chemical processing, and no contribution for the improvement of polishing rate was observed.