| Aluminum alloy has been widely used in aerospace optical system for its advantages of good processing performance,light weight and low cost.After single point diamond turning(SPDT),aluminum alloy mirrors that meet the requirements of infrared band can be obtained directly,but it is hard for its surface figure and surface quality to meet the requirements of visible light band.In the long-term research,The combination polishing technology was proposed to improve the surface figure and quality of aluminum mirror.However,aluminum alloy is soft and active in chemical properties,which is difficult to be processed in polishing process.Surface defects are highly prone to occur during processing,and surface crystallization as well as low efficiency during chemical mechanical polishing(CMP)are also serious.These problems have largely limited the manufacturing precision and application of aluminum mirrors.Therefore,it is of great significance to carry out research on the surface quality control technology for aluminum mirror polishing to meet the requirements of the near infrared,visible light and even ultraviolet bands.Based on the requirements of high-precision aluminum mirrors,this paper solves the problems in view of the perspective of interface chemistry,micro-material removal and advanced manufacturing methods,aiming to solve the key problems of polishing the surface quality control for aluminum mirror polishing.It can provide support for highprecision mirror processing of aluminum.The main research work of the thesis includes the following aspects.1.The surface crystallization mechanism and suppression method of aluminum mirror polishing process were studied.The advanced detection methods were used to analyze the elemental composition and classification of white matter on the surface,combined with interface reaction theory,Visual MINTEQ chemical morphology distribution simulation and experimental verification,the mechanism and influencing factors of crystallization formation were analyzed.The corresponding solutions are proposed from the process conditions and methods,and the goal of improving the surface quality without generating crystallization is achieved.2.The technology of high precision polishing and polishing efficiency improvement of aluminum mirror CMP was studied.The theoretical research of aluminum mirror technology and the law of surface rickets are summarized.The material removal model is established from the perspective of micro-abrasive granules.The factors affecting the current process efficiency are found out.A new method of variable parameter polishing is proposed.The polishing efficiency is improved,and the post-treatment method is further improved to prevent introduction of rickets during surface cleaning.3.A new technique for ultra-fast laser cleaning of the surface after Magnetorheological finishing(MRF)was studied.After testing the surface photothermal properties before and after magnetorheological finishing,a laser cleaning scheme was proposed.Further laser selection and parameter determination were carried out through theoretical analysis and experimental verification.Finally,the femtosecond laser was selected for surface cleaning.After cleaning,The surface was evaluated from two aspects of surface quality and reflectivity. |
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