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Sayali Satam_Final Dissertation.pdf (4.54 MB)

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Optimization of Wet Friction Systems Based on Rheological, Adsorption, Lubricant and Friction Material Characterization

Satam, Sayali S
http://orcid.org/0000-0002-1098-1071
http://rave.ohiolink.edu/etdc/view?acc_num=akron1503358825451407

Abstract Details

2017, Doctor of Philosophy, University of Akron, Polymer Engineering.
Improved friction characteristics and reduced wear are desired in most of the contacting surface systems. With this motivation, our work is focused on two different applications. First application involves improving friction characteristics of automobile wet clutch system by exploiting `lubricant additive-friction material’ interaction and material modification aspects. The second part is focused on reducing friction and wear in boundary lubrication using multiwalled carbon nanotube (MWCNTs) as a lubricant additive. Wet clutch is an integral part of a transmission system in automobiles. Positive slope of the friction coefficient versus sliding speed curve along with a high dynamic friction coefficient value indicate ideal friction characteristics for smooth clutch engagement between the friction material (FM – also called “friction paper”) and the reaction plate (steel) in the presence of automatic transmission fluid (ATF). The first part of our work involved adsorption analysis of ATF additives on friction material components (filler and fiber) using DSC and UV/VIS techniques. Adsorption behavior was further correlated with rheological and friction phenomena. Shear stress and strain rate obtained from rheological testing were correlated with friction and sliding speed, respectively, as obtained from friction characteristics testing. It was observed that ATF causes shear thickening while base oil causes shear thinning behavior when mixed with FM filler. Higher rate of increase of shear stress with shear rate (i.e., enhanced shear thickening) is expected lead to higher friction coefficient with sliding speed. Following up on this hypothesis, the filler component of the friction paper was found to show shear thickening behavior and improved friction characteristics, as compared to its fiber component. Further concentrating on the filler component, we used three different fillers (diatomaceous earth and a proprietary clay) to top-coat the friction paper. It was observed that filler coating increases direct contact between the steel and the filler during clutch engagement, thus improving the friction characteristics due to the shear thickening effect. It was further found that the filler with the highest rate of increase in shear stress with shear rate in the presence of ATF, showed the best friction characteristics as compared to other two fillers as well as the non-coated FM. Due to our consideration of filler coating the friction paper, which may reduce its permeability, effect of oil permeability of filler coated FM surface on friction characteristics and FM durability were also studied. FM surface porosity was varied using parameters such as fiber/filler ratio in base layer FM composition, FM density and coating thickness. FM base layer composition was optimized comparing aramid and aramid/cotton compositions at different densities. In the last part of our work, phosphonium ionic liquid was used as an additive for MWCNT dispersion in non-polar lubricant. Ionic liquid adsorption on MWCNT walls was studied using DSC, FTIR and rheological techniques. Ionic liquid stabilized dispersion of nanotubes in lubricant was confirmed from UV/VIS and TEM. Addition of MWCNTs in lubricant resulted in decreased friction coefficient and wear in boundary lubrication for steel-steel contact as compared to base oil.
Erol Sancaktar, Dr. (Advisor)
Sadhan Jana, Dr. (Committee Member)
Xiong Gong, Dr. (Committee Member)
Mesfin Tsige, Dr. (Committee Member)
Gary Doll, Dr. (Committee Member)
Rashid Farahati, Dr. (Committee Member)
148 p.
Engineering; Materials Science; Nanotechnology; Polymers
Rheology, Adsorption, Wet Friction Material, Automatic Transmission Fluid, ATF, Boundary Lubrication Regime, Filler, Fiber, Coating, Friction Coefficient, Sliding Speed, Wear, Carbon Nanotubes

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Citations

  • Satam, S. S. (2017). Optimization of Wet Friction Systems Based on Rheological, Adsorption, Lubricant and Friction Material Characterization [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1503358825451407

    APA Style (7th edition)

  • Satam, Sayali. Optimization of Wet Friction Systems Based on Rheological, Adsorption, Lubricant and Friction Material Characterization. 2017. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1503358825451407.

    MLA Style (8th edition)

  • Satam, Sayali. "Optimization of Wet Friction Systems Based on Rheological, Adsorption, Lubricant and Friction Material Characterization." Doctoral dissertation, University of Akron, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1503358825451407

    Chicago Manual of Style (17th edition)

akron1503358825451407
498
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This open access ETD is published by University of Akron and OhioLINK.