A Study on Ultrasonic Assisted Polishing on Hard and Brittle Materials

[[abstract]]硬脆材料因具有優良的機械、光學及化學性質，已被廣泛地應用於光電高科技製品、醫學工程及電子資訊等產業上。然其加工效率、加工精度及加工成本等的優劣關係著其附加價值的高低。本研究利用自行設計超音波振動輔助硬拋光（hard polishing）與軟拋光（soft polishing）實驗裝置加工硬脆材料。研究中以99.7%高純度氧化鋁平板為加工件，實驗設計採用中央合成設計法（CCD）分別建構拋光實驗。並選取施加壓力、磨盤轉速、磨料溶液濃度、加工時間及超音波功率等加工參數。進而探討加工機制、表面粗度改善率與材料移除量之變化，及超音波振動與加工參數間的交互作用關係。並對加工後之氧化鋁進行表面微結構之分析。 研究結果顯示超音波振動輔助硬拋光能有效提高表面粗度改善率與材料移除率。在表面粗度改善率3分鐘幾乎都有60%的提升，且表面粗糙度可達Ra 0.1μm左右。材料的移除率也因超音波的振動，而有大幅度的提升。在超音波振動輔助軟拋光方面，發現需配合其他加工參數才能有較佳的表面粗度改善率，且表面粗糙度可達Ra 0.06μm左右。氧化鋁加工後表面微結構方面，有賴於超音波的高能量振動，減少表面裂縫成長機會，且能較快得到較佳的表面狀態。因此加了超音波振動輔助可獲得高精度的加工尺寸，並提升加工效率減少加工成本。[[abstract]]Because hard fragile material has fine mechanical , optics and chemical property has already been widely applied to Hi-Tech industry products of photoelectricity, medical project industry and electronic information industry, etc. But its manufacturing efficiency, precision of machining, and the cost are concerning the level of its additional value. This research utilizes and designs ultrasonic vibration auxiliary hard polishing and soft polishing experimental provision and processes the hard fragile material by oneself. This study uses the central composite design (CCD) method for the design of the experiment to build and construct the polishing experiment respectively, and the 99.7% aluminum oxide sheet for as work piece. It selects the parameters such as processing pressure, platen speed, solide content, machining time, and ultrasonic power. And subject then probe into the change which process the mechanism, surface roughness improvement value and material removal quantity, and ultrasonic vibration and processing the reciprocation relation among the parameters. And subject to the analysis of carrying on the surface micro-structure of alumina after processing. The result of study shows the auxiliary hard polishing of ultrasonic vibration can improvement surface roughness improve value and material removal quantity. Nearly all there is 60% improvement in 3 minutes in surface roughness improvement, and the roughness of surface can reach about 0.1μm . Except that the vibration because of being ultrasonic of the rate of the moving of the material, and there is improvement by a large margin. In the auxiliary soft polishing respect of ultrasonic vibration, discover needing to cooperate with to be other and process the parameter and have better surface roughness improvement value, and the roughness of surface can reach about 0.06μm. The surface is micro-structure, depending on ultrasonic high-energy vibration after the aluminum oxide is processed, reduce surface crack grow up chance, can get better surface state comparatively fast. So it is auxiliary to add ultrasonic vibration and can obtain high-accuracy dimension, improve the efficiency of processing and reduce the process cost