電鍍鎳及電鍍鎳-鑽奈米複合材料之疲勞特性研究

Abstract

本論文主要利用微機電製程技術及電鍍技術，製作電鍍鎳及電鍍鎳-鑽奈米複合材料之懸臂樑結構，並採用微力試驗機搭配微探針頂推懸臂樑自由端的方式，對懸臂樑進行彎曲及疲勞試驗，以探討電鍍鎳及電鍍鎳-鑽奈米複合材料之疲勞特性的差異。 在試片設計上，本論文於懸臂樑上增加一接觸孔設計，可方便微探針對位，及避免微探針與試片表面接觸時的滑動。此一接觸孔設計，為彎曲及疲勞試驗時因接觸滑動所引起的誤差，找到了一個簡易的解決方法。 在彎曲試驗中，以電鍍鎳及電鍍鎳-鑽奈米複合材料所製成的長130 μm、厚15 μm懸臂樑結構，於試驗所得的F-δ圖，可得材料的比例限對應的位移分別為18 μm及22 μm，以作為疲勞試驗的最大位移量，且由電鍍鎳-鑽奈米複合材料製作而成之懸臂樑的剛性及楊氏係數略高於電鍍鎳，與前人的研究結果相符。 在疲勞試驗中，由試驗所得的S-N曲線可知，當材料受到相同比例的週期性位移負載時，如約89% δmax時，電鍍鎳材料的疲勞壽命比電鍍鎳-鑽奈米複合材料高約5倍。而受相同位移負載時，例如16 μm時，電鍍鎳材料的疲勞壽命比電鍍鎳-鑽奈米複合材料高約3倍，利用奈米壓痕機量測得知的楊氏係數計算力量及應力，在受到相同的力量時，例如50 mN時，電鍍鎳材料的疲勞壽命比電鍍鎳-鑽奈米複合材料高約3倍，而受相同週期性應力也是。電鍍鎳及電鍍鎳-鑽奈米複合材料的疲勞比分別為0.69及0.46。

In this study, cantilever beams are fabricated by electroplated Ni and Ni-diamond nanocomposite. A MTS micro-force testing machine (Tytron 250) with a probe is adopted for bending test and fatigue test. In the test beam design, a cantilever beam with a contact hole is included to improve the quality of the test data. In the bending test, a load-displacement curve is obtained and the Ni-diamond nanocomposite is about 1.2 times the proportional limit of the pure electroplated nickel. In addition, the stiffness, as well as the Young’s modulus, of Ni-diamond nanocomposite is higher than pure electroplated nickel, and this result is insistent with previously reported results. In the fatigue test, the S-N curve is obtained. The Young’s modulus of electroplated Ni and Ni-diamond nanocomposite are measured by the means of the nanoindentation test. In the same proportional loading of maximum displacement (ex. 89% δmax), the pure electroplated nickel is about 5 times the fatigue life of Ni-diamond nanocomposite. When the same displacement is applied (ex. 16 μm), the pure electroplated nickel is about 3 times the fatigue life of Ni-diamond nanocomposite. Similarly, when the same force is applied (ex. 50 mN), as well as the stress, the pure electroplated nickel is about 3 times the fatigue life of Ni-diamond nanocomposite. In addition, the endurance ratio of pure electroplated Ni and Ni-diamond nanocomposite are 0.69 and 0.46, respectively.