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Self-Lubricated Hybrid Polymeric Composites for Water Lubricated Bearing Applications: Effect of Hygrothermal Aging on Wear Mechanism and Friction Behavior
Luleå University of Technology, Department of Engineering Sciences and Mathematics. (Tribology)
2017 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

One of the greatest concerns in nowadays industries i.e. hydropower is to be environmentally friendly which push industries to change boundaries and replace mineral and synthetic oils used with more bio degradable lubricant such as water in various components such as bearing used in hydropower plant. Realization of this concept however poses many challenges including the choice of bearing materials that can provide desirable tribological behavior for extended lifespan under operating conditions that are poses because of water properties.

Due to considerably lower viscosity of water (0.66 cSt at 40 oC) compared to that of turbine oils (32-68 cSt at 40 oC), water lubricated bearings are likely to operate in boundary/mixed lubrication regime for relatively longer periods. Therefore choice of the materials and their tribological behavior are very important for the proper performance and extended lifespan of such bearings operating in boundary/mixed lubrication regime.

Polymer composites water uptake’s behavior in hygrothermal condition seems to be quite complex phenomenon. The state of filler/matrix interface is believed to influence the nature of diffusion modes. Significant fillers weakening often appear at the interface of polymer during the hygrothermal ageing, which affects the moisture uptake kinetics and mechanical properties. The importance of temperature at the time of conditioning plays an important role in environmental degradation of such composite materials.

There has been quite extensive research done on tribological behavior of PTFE and its composites in both dry condition and water lubricated condition, however, effect of hydrothermal aging on tribological behavior of such a composites has been barley studied. This paper outlines the influence of hygrothermal aging on failure of hybrid polymeric composite due to degradation mechanisms. For doing so, an attempt has been made to evaluate the deleterious effect of temperature and humidity on frictional and wear behavior of hybrid PTFE composites during hygrothermal conditionings.

Prepared samples of PTFE composites were immersed in distilled water at different temperatures (21-23 oC and 80 oC) for 132 days of aging and different tests such astribo-test, thermal analysis (DSC/TGA), wettability analysis, FTIR and surface characterization (SEM/EDX) were performed prior and posterior to hydrothermal aging helping reveal the influence of hygrothermal aging on tribological behavior. 

Place, publisher, year, edition, pages
2017.
Keywords [en]
tribology polymer PTFE Hygrothermal Ageing friction wear
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
URN: urn:nbn:se:ltu:diva-66223OAI: oai:DiVA.org:ltu-66223DiVA, id: diva2:1151456
Educational program
Mechanical Engineering, master's level (120 credits)
Supervisors
Examiners
Available from: 2017-11-14 Created: 2017-10-23 Last updated: 2018-01-13Bibliographically approved

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