Research On Polishing Technology For CSI Crystals

In the nineteen-eighties,Cs I(Tl)crystal in the field of optical applications of the strengths was discovered.As the application of CsI(TI)was expanded to more field,It is very important to obtain good surface quality to meet the needs of the application.However,due to the soft,easy to hydrolysis,sensitive to temperature and light changes of Cs I(TI),it is difficult to process.In the traditional processing,CsI(TI)is polished by the polishing slurry with abrasive.A larger material removal rate can be obtained by the traditional processing because of the existence of abrasive.However,because of poor dispersion of solid abrasive,the surface scratches and pits would be lead in traditional processing to deteriorate the quality of the polished surface.In order to meet the needs of practical application,it is necessary to improve the original CsI(TI)crystal ultra-precision machining method.Meanwhile,it is more important to explore new ultra-precision method of CsI(TI)crystal.In this paper,a new technique is proposed for CsI(TI)by using its characteristic of hydrolysis.The main contents of this dissertation are summarized as follows: The development of CsI(TI)crystal and the development of chemical mechanical polishing(CMP)are reviewed.On the basis of the chemical properties of CsI(TI),The new hydrolysis polishing technology for CsI(TI)crystal was put forward.The composition and the ratio of different components in the polishing slurry were studied,and the polishing processing technology was developed.The hydrolysis action of polishing slurry was verified and the better performance of the polishing slurry was obtained.The effects of polishing time,polishing speed and polishing pressure on the material removal rate and surface roughness of CsI(TI)were investigated.The optimized combination of process parameters was obtained.The experiments of the traditional no hydrolysis polishing CsI(TI)crystal were conducted.CeO2 and SiO2 particles were selected in the single-factor experiments.The effects of different abrasive grain solids,polishing disc rotation and polishing pressure and other input variables on the material removal rate and surface roughness of CsI(TI)crystals without hydrolysis were studied.The optimized combination of process parameters was obtained though the contrast tests.Then,the surface morphology after hydrolysis-free polishing and hydrolysis-polishing were compared and analyzed,the results shown that: The performance of hydrolytic polishing was better.