Session: 03-28-01: Joint Session on Recent Advances in Advanced Materials Processing and Tribology

Paper Number: 95163

95163 - Effects of Surface Finish and Molecular Structure on the Lubricating Ability of Borate-Based Protic Ionic Liquids 

Friction and wear are inherent problems in mechanical systems, leading to about 23% world's total energy usage. Most of the losses are caused by friction and another fraction is attributable to the replacement of machinery components. However, energy losses could be reduced by up to 40% using high-performance lubricants. This would not only bring significant monetary advantages but would mean a reduction of emissions, achieving a more sustainable and environmentally friendly development.
In order to meet these objectives, Ionic liquids (ILs) have been studied for more than two decades as potential high performance lubricants and additives. Ionic liquids (ILs) are a class of synthetic salts with melting points below 100 °C due to their asymmetric chemical structure. This feature confers them remarkably interesting physicochemical properties such as: chemical and thermal stability, high electrical and thermal conductivity, high viscosity, and low volatility. Moreover, the delocalized charge in their functional groups enables them to react with metal surfaces through the formation of protective layers that prevent them against contact.
ILs are generally categorized based on the nature of their cation into aprotic ionic liquids (APILs) and protic ionic liquids (PILs). Even though aprotic ionic liquids have been proved as neat lubricants and additives with great performance. The presence of halogen elements in their chemical composition could cause corrosion to the contacting metals. Additionally, their applicability is limited as a consequence of the complexity of their synthesis. On the contrary, protic ionic liquids (PILs) can be easily obtained through proton transfer from a Brønsted acid to a Brønsted base. This way, they can be tailored by varying the species of the cations and anions to satisfy specific requirements
In this study, two borate-based PILs, N-methylethanolamine 1,2-dodecanediolborate and N’N-dimethylethanolamine 1,2-dodecanediolborate, were synthesized, with same anion and different ammonium cation, using a simple and affordable way. Their ionic structures were confirmed by proton nuclear magnetic resonance (1H NMR). In addition, the lubricating abilities of these PILs were investigated as neat lubricants on steel–steel contact at room temperature, using a custom-designed ball-on-flat reciprocating tribometer that complies with ASTM G133-05. Each protic ionic liquid (PIL) was tested using grinded and polished steel disks and two levels of normal force and frequency.
Results showed that the surface finish and molecular structure of the PIL have an important influence on the lubricating performance of these ordered fluids. Wear mechanisms on steel surfaces and surface interactions were discussed from optical and SEM microscopies, and EDS analysis.

Presenting Author: Patricia Iglesias Rochester Institute of Technology

Presenting Author Biography: She earned her Ph.D. in mechanical engineering with focus on tribology from the Polytechnic University of Cartagena (Spain). Dr. Iglesias also worked as a post-doctoral researcher in the Center for Materials Processing and Tribology at Purdue University. Currently, she is an associate professor and the director of the Tribology Laboratory in the Kate Gleason College of Engineering at the Rochester Institute of Technology. Her research focuses on wear and friction of materials, ionic liquids as lubricants and additives of lubricants, bio-lubricants, nanostructured materials, and textured surfaces. Dr. Iglesias has extensive experience working on tribology and has published 35 peer-reviewed articles and more than 38 conference proceedings in the area.

Authors:

Alfonso Sierra Rochester Institute of Technology
Hope Scott Rochester Institute of Technology
Darwin Pray Rochester Institute of Technology
Zachary Polus Rochester Institute of Technology
Patricia Iglesias Rochester Institute of Technology