Study On Ultrasmooth And Low Defect Polishing For Silica Workpiece Using Nanoparticle SiO₂ Jet Technology

Nanoparticle SiO₂ jet polishing is a method based on the material removal in elastic mode,which can achieve ultra-smooth and low defect processing.At present,single-hole processing is often used in nanoparticle SiO₂ jet polishing.This method?s efficiency is low.Currently in order to improve efficiency,the multi-nozzle structure is designed.The layout of hole and clearance control of multi-nozzle has very high requirements.In addition,the research of nanoparticle SiO₂ jet polishing is mainly limited in super-smooth surface processing and rarely used to deal with the surface of the broken defects and pollution defects.This paper mainly focuses on two problems of low processing efficiency and low defect processing to study.The main contents include:According to the characteristics of jet polishing,collision model is established.By using the model,the boundary conditions between elastic domain,plastic domain and brittle domain are divided.The size of the polished particles is selected by boundary conditions and machining effect.Then,polishing liquid is selected by the stability of the polishing liquid and whether the impurities can be introduced from polishing liquid.At last,through analyzing of nanoparticle SiO₂ jet polishing removal mechanism,the process can be divided into chemical adsorption and broken of the weakening of the atomic bonds.Nanoparticle SiO₂ jet polishing can realize atomic level removal by removing mechanism.Based on the removal mechanism of the nanoparticle SiO₂ jet polishing and the function of the experimental platform analyzed,experimental device is designed.The main part of device is nozzle structure.Firstly,the simulation of single nozzle is carried out.According to the single-hole flow field distribution,the simulation of slit nozzle is built.The effect of pressure,gap and aspect ratio on the flow field distribution of slit nozzle is studied.By comparing the pressure,shear force and turbulence intensity acting on the surface of the element,the appropriate parameters of slit nozzle is selected.The combined liner nozzle structure is designed.The experiment proves that the combined liner nozzle can improve the machining efficiency under the same pressure.The application of devices for nanoparticle SiO₂ jet polishing.The fused silica element is fabricated by using nanoparticle SiO₂ jet polishing device.The main work is focused on the ultra-smooth and low defect polishing for fused silica.In ultra-smooth processing,the surface roughness of the fused silica reduces rapidly by nanoparticle SiO₂ jet polishing process.In low defect processing,breadth depth ratio of hertz scratches in the removal of a certain depth and the anti-laser damage ability of fused silica increase.After processing technique of magneto rheological,the content of iron and cerium on the surface is decreased after nanoparticle SiO₂ jet polishing process.At the same time,the quality of surface improves.The research will help promote the development of nanoparticle SiO₂ jet polishing technology.The combined nozzle design provides a method to improve the removal efficiency.In addition,the study of low defects processing,especially for the removal of pollution elements,will shed some light on future research.