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摘要
Hydrodynamic effect polishing (HEP), in which the material is removed in elastic region by chemical impact reaction, can effectively remove the surface/subsurface damage to get an ultrasmooth surface. However subsurface damage contains scratches and machining residual stress are hidden below the surface and can't be easily detected. The subsurface/surface properties such as hardness and elastic modulus have direct relationship with the subsurface damage. Therefore, a nano-imprint method analysis of the optical subsurface quality was presented to evaluate the hydrodynamic effect polishing process effect. Polishing experiment was conducted on a conventional pad pre-polished silica glass. The surface before and after polishing process was firstly observed by atomic force microscope and ZYGO white-light interferometer. The observation shows the surface damage such as the scratches and bump structures are completely removed by HEP process, and the surface roughness rms value decreased to near 0.3 nm. To evaluate the subsurface damage, nano-imprint was conducted on the processed and unprocessed area under different load with different impressed depth. The imprint results show the processed surface become soft and easily be impressed, while the unprocessed surface becomes hard. The processed and unprocessed surface shows the same impress depth when impressed depth exceeded 200 nm. Analysis shows the surface becomes hard under the effect of the residual stress in subsurface damage which is generated in the traditional machining process with material removal in brittle or plastic mode. Material is removed in elastic mode by chemical impact reaction in HEP, and the surface/subsurface damage can be effectively removed. It demonstrates that HEP processed surface properties are much close to the bulk material.
- 出版日期2018
- 单位中国人民解放军国防科学技术大学; 湖南大学
