| Summary: | 碩士 === 中正理工學院 === 兵器系統工程研究所 === 85 === Single crystal silicon is usually considered to be extremely brittle and exhibits little ductility in machining. During the indentation tests, cracks appeared around the impression at load as little as five grams and the crystallographic direction had strong influence on the crack initiation and propagation. In the present research, diamond tools were employed to turn single crystal silicon. The effect of cutting speed, feed, cut depth and crystallographic orientations on ductile-brittle transition were investigated. The results showed, given the same machining conditions, [OTO], [010], [100], [TOO] and [112], [211], [121] are the relatively easy to fracture directions on Si (100) surfaces and Si (111) surfaces respectively. While rapid tool wear and poor surface finish were obtained when brittle mode machining were dominant, surfaces with Ra better than 5nm and no obvious tool wear were achieved by using ductile mode machining. This means that the effective cut depth and the crystallographic orientations have profound effects on the material removal mechanisms involved and surfaces finish. It is possible for single crystal silicon to be machined in a ductile manner under some carefully chose machining conditions.
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