微元件考慮顆粒與液體之表面力對界面微接觸性能的影響及其應用在表面形貌之評估與選用

The Effects of Surface Forces on Contact Characteristics and the Topographical Evaluation of Microparts in Considering of Particle and Liquid Film

陳誌賢(Chih-Hsien Chen)

國立虎尾科技大學/工程學院/動力機械工程研究所/碩士(2005年)

摘要

在微機電元件中，慣性力隨著元件本身之重量急遽減少而降低，以致兩元件間表面波峰尖端之表面力對界面性能有顯著影響，尤其在表面粗糙度降低至奈米等級時更顯現其對微機電元件界面性能的重要性。其中間隙、磨擦與磨損的控制是微運動元件最關心的難題。在微機械或精密機械具有相對運動之接觸表面間，實際上常存有不同外來粒子、磨屑或液體膜等，因此本文建立一個界面存有顆粒、液體及表面具有粗糙度的三體微接觸黏附模式，以了解顆粒及液體表面效應在兩接觸界面間對接觸特性的影響。過去表面和表面及表面和顆粒兩種不同的黏附力模式，可利用此三體黏附力模式簡化得到。
本文亦利用此新模式推導可預測微元件之黏附磨擦與砂磨磨損之公式，以同時考慮材料、顆粒大小、負荷、試件表面粗度與表面能對脫離力、真實接觸面積、磨擦力、平衡間隙、黏附力與毛細力的影響。結果顯示微機件界面間之間隙與力量控制，除了在極小表面能或極污染表面外，深受黏附力影響，有時需用外力壓近兩相對表面，有時需要拉離相對表面方可達到微機件需要之適當間隙。本文亦設計製造不同表面粗糙度之表面，探討其加工表面形貌對微元件之真實接觸面積、黏附力及毛細力的影響效應，以取得較佳之表面形貌，提供專業參考選用。此表面粗度、表面能、顆粒大小、間隙、磨擦與磨損六者之相互關係可由本文之分析得知，因此本文理論分析結果與實作表面可作為各項微機件製造與設計之參考。

並列摘要

In the microelectromechanical system (MEMS), inertial force is reduced as the weight of the component reduces rapidly. Surface forces occurs at the peaks of the asperities on interface and is pronounced when the surface roughness effect is small, due to the nanometer level. In the MEMS and precision machine, particles and liquid films are often presented at contact interfaces. In this paper, a three-body adhesion model for rough surfaces with particles and liquid films are proposed in order to understand the effects of particles and liquid films between surfaces on contact characteristics. Both transitional surface-to-surface and particle-to-surface two-body microcontact adhesion model simulations can be obtained according to the simplification of this model.
The new adhesion model was also used to analysis the friction and wear between rough surface in MEMS and precision machine. The effects of surface roughness, material, lead, particle size, surface energy of surface and particles on pull-off force, friction coefficient, equilibrium gap, real contact area, wear and capillary force investigated. Moreover, in order to design the optimal surface, the effects of adhesion and capillary force of surface micromaching on the real contact area of microparts are investigated. It is shown that the separation and the applied load between the interfaces of microparts were considerably affected by the adhesion, except under small surface energy or contaminated surfaces. The results show that, in some cases, it needs external force to close the opposite surface or external load was needed to separate it to reach the appropriate separation in other cases. The relationship between surface roughness, particle size, surface energy, separation, friction and wear between the contacting surfaces can be obtained in this paper. The analytical results particle manufacture surface can to be a base for manufactory and design of microparts.

參考文獻

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