No abstract

No abstract

This article first presents the performance of Electrorheological Fluid (ER fluid). Thus, a new-style machining technique based on ER effect to form a tiny grinding wheel is developed for superfine machining. By adding abrasive particles to ER, an array of stable chains of ER particles can be shaped when an electric field is applied and abrasive particles are fixed to these chains structure. When the tip of tool is rotated, the abrasive particles rotate with the flow and a superfine grinding process come into being. This process is expected to be applicable to the aspheric surface machining of micro miniature components made of optic glass or other hard-brittle materials.

Chemical reaction rate of SiC wafer surface usually determines the material removal rate (MRR) in chemical mechanical polishing (CMP). In this paper, systemic experiments are carried out to discover the relationship between Fe catalyst with different forms or valence and chemical reaction rate based on Fenton reaction. Experimental results show that the MRR changes little using Fe powder or hydrogen peroxide (H2O2) alone, but the MRR of SiC will increase largely by adding them both that will produce Fenton reaction. The MRR continues to increase slightly when Fe2+ ions is employ as catalyst, but that is much lower when utilizing Fe3+ ions. Moreover, SiC wafer with a smaller surface roughness and better quality can be obtained when using Fe powder as catalyst in Fenton reaction. The results indicate that the Fenton reaction can effectively improve the polishing efficiency of SiC substrate and Fe powder is more suitable for polishing of SiC than ferrous or ferric salt in CMP based on Fenton reaction.

Experiment was performed to examine the plane polishing of SiC single crystal wafer by using the chemical magnetorheological finishing (CMRF) technique. The influence of some process parameters such as the concentration of diamond abrasive particles, the concentration of carbonyl iron powder and the machining gap in CMRF were studied comparing with the magnetorheological finishing (MRF) method. The results show that the surface roughness of polished SiC single crystal by the CMRF is slightly lower than that by the MRF. Polishing liquid with different components and processing parameters affects the coupling effect of mechanical removal and chemical removal in CMRF, and a better coupling effect can produce a better surface quality in CMRP. In the MRF, the surface roughness of SiC single crystal is lower for a higher concentration of carbonyl iron powder (CIP). However, in the CMRF, the CIP’s concentration may change the contact state between the catalyst and SiC, and the CIP’s concentration of about 20% can produce a better surface roughness of SiC. The machining gap between the polishing disk and the workpiece surface determines the processing effect, and the machining gap of 1.0 mm is suitable for the polishing of SiC in the MRF and CMRF.