Experimental investigation on polishing of ultrasmooth surface in nanoparticle colloid jet machining

Abstract

In this paper, a nanoparticle colloid jet machining system has been developed for shaping and polishing ultra smooth surfaces of brittle materials. Nanoparticle colloid jet machining is an ultra smooth surface processing technique which utilizes surface chemical reaction between work surface atoms and nanoparticles in alkaline colloid to remove the uppermost surface atoms. The purpose of the paper is to investigate the surface removal mechanism and process of optical glass in nanoparticle colloid jet machining. Removal experiments have been conducted to show the removal process. A K9 glass sample with a regulated surface profile has been polished and flattened in nanoparticle colloid jet machining. The roughness of the K9 glass surface has been reduced from 31.6 nm RMS to less than 1 nm RMS. Atomic force microscopy (AFM) were used to observe the surface microscopic morphological characteristics of K9 glass sample processed by nanoparticle colloid jet machining. The observation results show that the protuberant sites on the work surface are preferentially removed in nanoparticle colloid jet machining. Power spectral density analyses have been done to evaluate the performance of the nanoparticle colloid jet machining. The PSD curves show that the surface has been flattened within spatial wavelength of 0.04~10 μm after nanoparticle colloid jet machining.