Material Removal Mechanism Of Optical Glass During Chemical Mechanical Polishing By Fixed Abrasive Pad

With the development of optics, optoelectronics and digital products, K9optical glass has beenwidely used in many fields. And the surface quality is required strictly. K9glass is a kind ofhard-brittle materials and easy to brittle failure. It is difficult to obtain super-smooth surface bytraditional processing technology. In recent years, Fixed-Abrasive Chemical Mechanical Polishing(FA-CMP) technology has been received more and more attention for its easy process-control, highefficiency, low costs, no pollution, et al. In this paper, the influence of polishing slurry on the surfacehardness of K9glass has been analyzed by micro-hardness method. And the mechanical and chemicalfunction during the material removal process was separated by adopting weight loss measurements,when fixed abrasive polishing pad works on K9glass. The surface roughness and the materialremoval rate in polishing of K9glass were analyzed by the orthogonal experiment method so as toguide the Technologic processes and optimize the grinding and polishing technology of K9glass. Themain work and results are as follows:(1) The influence of polishing slurry on the surface hardness of K9glass has been studied.The K9glass were soaked by deionized water or polishing slurry and the vickers hardness andcreasing diagonal length were measured and compared. According to the numerical the metamorphiclayer thickness of K9glass were calculated. Results show that chemical reaction could take placebetween polishing slurry and K9glass, and forms a denatured layer which is softer than host materialon the surface of K9glass. When soak time increases, the thickness of the denatured layer alsoincreases but the increasing trend gradually slow down.(2) The material removal mechanism of K9glass during chemical mechanical polishing by FixedAbrasive Pad (FAP) was searched.The mechanical and chemical function during the material removal process was separated as: thechemical action of the polishing slurry, the mechanical action of abrasive, the mechanical action ofmatrix, the chemical mechanical interaction between abrasive and slurry, the chemical mechanicalinteraction between matrix and slurry. The material removal rate of each component was analyzed, itis considered that the chemical mechanical interaction between abrasive and slurry is dominant inchemical mechanical polishing and the material removal, accounts for about80%(3) The grinding of K9glass process on The CETR CP-4polishing machine was optimized.The surface roughness and the material removal rate in grinding K9glass were analyzed by theorthogonal experiment method. So as to guide the technologic processes such as: reduction rate,grinding pressure, grinding fluid flow to optimize the grinding technology of K9glass. The grindingtechnology of K9glass was: grinding pressure55MPa, reduction rate145（rpm）/150（rpm）, grinding fluid flow60ml/min. The material removal rate of K9glass is3186nm/min and the surface roughnessis19.6nm.(4) The polishing of K9glass process on The CETR CP-4polishing machine was optimized.The surface roughness and the material removal rate in polishing K9glass were analyzed by theorthogonal experiment method. So as to guide the technologic processes such as: reduction rate,polishing pressure, polishing fluid flow, to optimize the polishing technology of K9glass. Thepolishing technology of K9glass was: polishing pressure13MPa, reduction rate195（rpm）/20（0rpm）,polishing fluid flow30ml/min. The material removal rate of K9glass is72nm/min and the surfaceroughness is1.94nm.