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  • 學位論文

水基潤滑液之奈米添加劑:銀與硒系統之研究

Water-Based Lubricant Additive: Study on the System of Silver and Selenium

指導教授 : 王崇人
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摘要


我的研究分為兩大部分,第一部分為探討水基潤滑液奈米添加劑之散熱性對於磨潤表現的影響,在此選擇奈米銀粒子做為添加劑的主體,並針對添加劑的尺寸調控做初步的評估;第二部分則是針對奈米添加劑形貌與磨擦係數的關係,這部分選擇零維與一維的奈米硒粒子做為添加劑的主體。 提升散熱的部分是以奈米銀粒子做為添加劑的主體,此粒子係分散於非離子型界面活性劑的環境下且濃度為5 wt%,其粒徑約為4.0 ±1.5 nm,並可藉由純水稀釋以調整濃度,此外,我們也針對添加劑的穩定性進行追蹤測試,結果發現原始5 wt%的成品以及以純水稀釋至0.5 wt%的樣品皆能在室溫下儲存至少兩個月。至於磨潤測試方面,我們分別將不同濃度的奈米銀粒子添加於水溶液與乳化液兩種環境下進行塊對環(block-on-ring)的試驗(荷重及轉速分別為80 N及250 rpm,測試時間為2400 sec),結果顯示在水溶液的環境下,當粒子濃度達 0.25 wt%時,相對於純水,摩擦係數減少約30 %,工件溫升更是降低60 %;至於乳化液的系統,則是針對乳化油濃度與粒子濃度兩個變數進行探討,結果顯示隨添加粒子濃度的增加,摩擦係數則是略降後升,以含有 5 wt%乳化油的潤滑液為例,當粒子濃度達0.08 wt% 時,摩擦係數減少 40%,工件溫升則降低50%,這部分推測是奈米銀粒子的貢獻,但隨添加劑濃度上升,由光顯可以觀察到含有0.5 wt% 粒子及5 wt%乳化油的潤滑液,其油滴數量明顯減少,推測是其粒徑變得太小以致於無法在光顯中觀察到,進而在磨潤時的油膜不易生成,造成摩擦係數上升。在金的成長溶液系統,金奈米粒子的粒徑可調控在10 nm 至 50 nm,而在銀的系統中,銀奈米粒子的粒徑可調控在20 nm 至 60 nm。 關於添加劑形貌的影響則是以零維與一維奈米硒做為添加劑的主體,選用粒徑約為 25 nm的硒奈米球,與短軸約為 25 nm,長軸分別為100、 200、400、600 和 1000 nm等不同長度的一維奈米硒做比較,結果發現零維結構磨潤表現較佳,而一維奈米硒隨長度愈長,磨擦係數則有上升的情形,磨擦係數最大的變化量約升高40 %,原因推測是由於顆粒間的作用力程度不同而造成填補效率差異。

並列摘要


The main theme of my thesis lies in the investigation for the effect of nanoadditives in water-based lubrication. Two nanoparticle systems were chosen to study (i) the effect in the decrease of the temperature rise during lubrication and (ii) the nanoparticle shape dependence in lubrication. The former effect was studied by choosing silver nanoparticles aqueous dispersions with or without emulsified oil (EO) added. The shape-dependence was investigated by the use of selenium nanoparticle systems of Se nanospheres and Se nanorods with different mean lengths. In addition, I demonstrated a preparation scheme employed to prepare gold nanoshells in the basis of the AgNPs systems. A non-ionic surfactant (Heptaethylene glycol monododecyl ether, SL70) system was chosen to prepare silver nanoparticles aqueous dispersions for the increase of the heat dissipation performance in water-based lubrication. The AgNP was chosen due to its softness and high thermal conductivity. The AgNPs in SL70 dispersions was prepared to give5 wt% in Ag with the mean diameters ca. 4.0±1.5 nm. The tribological tests were measured under the block-on-ring measurements. The results for AgNPs aqueous dispersions without EO show that as the concentrations of AgNPs were 0.25 wt% or higher, the frictional coefficient (FC) decreased to 70% and work peace temperature-rising (TR) dropped to 40% from those in water. In the cases of AgNPs dispersions coexisted with the EO, The results showed that the FC decreased slowly then increased at a critical turning point with specific AgNP concentration. This critical concentration differs in different wt% of EO. Take the lubricant with 5 wt% EO as an example, 0.08 wt% AgNPs decreased the FC from 0.11 to 0.07 (roughly 60%) and restrict the TR down to 5 ℃ from 10 ℃ for the case without AgNPs added. However, the trade-off for introducing excess amount of AgNPs comes from the fact that it seems to be able to destroy the oil droplets of EO and to decrease their sizes into much smaller values, which make them much more water soluble and further prevents the formation of interfacial oil film in lubrication. This interpretation was supported by the evidences obtained in optical microscope measurements. The oil droplet sizes were almost the same in the cases of 5 wt% EO without AgNPs and 0.08 wt% AgNPs-5 wt% EO. The oil droplets disappeared in the case of 0.5wt% AgNPs-5 wt% EO. On the other hand, I also studied the shape-dependent lubrication by Se nanoparticles as additive. For the 0-D NPs, the diameter is about 25 nm; For the 1-D NPs, the short length is ca. 25 nm, the long length are 100, 200, 400, 600 and 1000, respectively. The results show that 0-D NPs have better tribological performance than 1-D NPs. What’s more, as the aspect ratio increased, the FC is raised. The largest percentage that FC increased is about 20% (from 0.14 to 0.17). We suggest that the difference between 0-D and 1-D SeNP is owing to the degree of interparticle interactions, which is stronger in 1-D SeNP than 0-D SeNP.

參考文獻


38. Ho, C. Y.; Powell, R. W.; Liley, P. E., Thermal Conductivity of the Elements. Journal of Physical and Chemical Reference Data 1972, 1 (2), 279-421.
1. Bartz, W. J., Lubricants and the environment. Tribology International 1998, 31 (1–3), 35-47.
2. Peng, Y.; Hu, Y.; Wang, H., Tribological behaviors of surfactant-functionalized carbon nanotubes as lubricant additive in water. Tribol Lett 2007, 25 (3), 247-253.
3. Bartz, W. J., Ecotribology: Environmentally acceptable tribological practices. Tribology International 2006, 39 (8), 728-733.
5. Sakurai, T.; Ikeda, S.; Okabe, H., The Mechanism of Reaction of Sulfur Compounds with Steel Surface During Boundary Lubrication, Using S35 as a Tracer. A S L E Transactions 1962, 5 (1), 67-74.

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