改良式真空潛弧製程製備奈米複合流體之性質研究

A Study on the Properties of Nano Composite Fluid Prepared by Using Improved Vacuum Submerged Arc Machining

葉宇軒(Yu-Hsuan Yeh)

指導教授 ： 張合

國立臺北科技大學/機電學院/機電整合研究所/碩士(2007年)

摘要

本文旨在探討以自行發展之改良式真空潛弧系統製備四組不同之奈米複合流體及其性質分析；改良式真空潛弧系統相較於前一代所發展之製備系統，具有電弧加熱系統功率大，電弧穩定性佳及控制部份技術成熟等優點。本實驗分成兩大部分以分別探討四組複合流體，第一部分為製程參數實驗，在實驗中將正負電極為純銅與純鐵，在崩潰電壓為250V、工作壓力為30torr、介電液溫度0℃的環境條件下，針對電流與放電休止幅兩項參數以試誤法取得較佳的加工參數製備出的銅/鐵奈米複合流體；再依序將正負電極分別改為純銀與純鐵、純銀與純鎳及純銀與純鈷，與第一組同樣的條件下經實驗取得個別較佳加工參數製備出的銀/鐵、銀/鎳、銀/鈷奈米複合流體。第二部分。將由較佳製備參數所產出的奈米複合流體，進行形貌外觀、成分分析、表面電位及熱傳導性質實驗與磁性檢測；在奈米顆粒的形貌部分，經實驗發現Ag、Cu、Fe、Ni等未氧化的顆粒皆呈現近似圓形，而若與水中的氧結合形成氧化物，奈米顆粒則會朝特定方向成長，在銅/鐵奈米複合流體中FeO為四方體結構、Cu2O的顆粒是針葉狀，在銀/鐵奈米複合流體中FeO則為多邊形結構；而介面電位檢測方面， 結果顯示經本製程所產出的奈米複合流體除銀/鐵奈米複合流體這一組較容易聚集沉澱外，其他三組中銀/鈷奈米複合流體的pH值為7，表面電位為21.21mV，銀/鎳奈米複合流體的pH值6.5表面電位為21.04mV而銅/鐵奈米複合流體的pH值為7時表面電位約在-30mV，且此三組流體顆粒皆能維持懸浮性2週以上，懸浮性較佳；熱傳導實驗部分，四組奈米複合流體中以銀/鎳奈米複合流體在增進熱傳上效果最佳，在溫度30℃及流體重量濃度0.4﹪條件下熱傳導係數增進達26﹪；磁檢測方面，除了銀/鐵奈米複合流體外，其他三組奈米顆粒皆屬順磁性，且這四組奈米複合材料都是屬軟磁性。

關鍵字

真空潛弧 ； 熱傳係數增進率 ； 磁滯曲線 ； 順磁性 ； 表面電位

並列摘要

The purpose of this study is to discuss the preparation of four sets of nano composite fluid prepared by using the improved vacuum submerged arc machining developed by this study, as well as their properties. Compared with the previous generation system, this improved system has advantages of high electric arc heating power, stable electric arc, and sophisticated control technology. This experiment was divided into two parts to discuss four sets of composite fluids. The first part was parameters experiment, which using pure copper and iron as the positive and negative electrodes, respectively, under the condition of 250V of breakdown voltage, 30torr of working pressure, and 0℃ of dielectric temperature, to obtain appropriate processing parameters for electric current and pulse off-time with trial and error method for preparation of copper/iron nano composite fluid. The positive and negative electrodes were then changed to pure silver and pure iron, pure silver and pure nickel, and pure silver and pure cobalt, and nano composite fluids of silver/iron, silver/nickel, and silver/cobalt prepared by the appropriate processing parameters under the same experimental conditions as of the first group. The second part was to test the appearance, ingredient analysis, surface potential, thermal conduction properties, and magnetism of the nano composite fluid prepared from the parameters. The experiment found that unoxidized particles, Ag, Cu, Fe, and Ni appeared round. If combined with oxygen in water as oxides, the nano particles would grow toward certain directions. In copper/iron nano composite fluid, FeO appeared cubic, Cu2O appeared coniferous. In silver/iron nano composite fluid, FeO was polygonal. In dielectric potential detection, the nano composite fluid was likely to aggregate and deposit, except for silver/iron set. In other sets, the pH of silver/cobalt nano composite fluid was 7, surface potential was 21.21mV; the pH for silver/nickel nano composite fluid was 6.5, surface potential was 21.04mV; the pH for copper/iron nano composite fluid was 7, surface potential was -30mV. The fluid particles of the three sets could all maintain suspension of 2 weeks or more. For thermal conduction, the silver/nickel, nano composite fluid showed the best thermal conduction. Under temperature of 30℃ fluid weight conduction of 0.4%, the thermal conduction increase was 26%. For magnetic detection, except for silver/iron nano composite fluid, the nano particles of other three sets were paramagnetic, and all four sets were soft magnetic nano composite materials.

並列關鍵字

SANSS ； thermal conductivity ratio ； hysteresis curves ； paramagnetic ； zeta

參考文獻

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