Micro and Precision Grinding Technique and Functional Behavior Development of Micro-structured Surfaces

Due to the difficult control of machined micro-structured form-accuracy of hard and brittle materials such as monocrystalline silicon, optical glass and so on, a micro-grinding is developed. It utilizes the micro-tip shape of diamond wheel and the micro-grit cutting-edges on its working surface to machine the micro-groove array on hard and brittle material surface. To explore its function behaviors, it is applied to the substrate surfaces of thin film solar cell, silicon chip and graphite blades, their photovoltaic properties, wettability and pump efficiency are measured and investigated, respectively. The machining results show that the micro-grinding may produce an accurate and smooth micro-structured surface. The applications show that the thin film solar cell with micro-lens structured substrate exhibits higher conversion efficiency and fill factor in weak light and scattered light, thus it may be used to make electricity without solar irradiation. When the silicon surface is machined to be a micro-grooved structure, an increase in micro-groove depth leads to an increase in the contact angle of droplet, and gradient micro-grooved surface may drive the micro-motion of droplet. In oil pump, when the micro-grooved depth is decreased from 500 mu m to 100 mu m in the case of micro-grooved graphite blades, the work efficiency is increased gradually, finally greater than the traditional one. Therefore, the accurate and smooth micro-structured surface may produce high value-added functions.