Surface engineered systems for industrial applications must be able to withstand the harsh inservice environments that they will be operated under. Localised testing on the nanoscale is a method commonly used to probe such systems at very high temperatures, varying humidity and even under liquid environments. However little or no research has been directed towards investigating their behaviour under low temperature conditions. In this study a novel sub-ambient temperature nanomechanical testing instrument has been designed and developed. It allows testing of materials under the temperature range from 20 oC to minus 30 oC. The instrument employs peltier coolers to provide vibration free measurements and a custom purging chamber has been designed to prevent condensation of water vapour on the sample surface during the sub-ambient testing. The study demonstrated the need for dual cooling of both the sample and indenter to ensure drift free measurements are obtained under sub-ambient regimes. A section of the research is dedicated to the testing of polymeric materials. A range of tests were performed from nanoindentation through to probing of time and environmental dependence parameters. In particular creep was studied at ambient temperatures on a range of engineering polymers and also on Nylon’s which were submerged in a fluid cell. The prototype was constructed and validation tests carried out to ensure its performance on standard samples. Next the mechanical properties and creep behaviour of an atacticpolypropylene through its glass transition temperature was examined. Further experiments were carried out focusing on tribological testing of surface engineered systems with the new prototype providing interesting results on DLC’s when tested under below ambient temperatures. Based on the outcomes of this research, a few papers have been published in peer-reviewed technical journals and it is envisaged that the novel sub-ambient instrumentation will be used for the design, charaterisation and optimization of novel engineered surfaces for various environmental applications.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:566099 |
| Date | January 2012 |
| Creators | Bell, Gerard Anthony |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.bham.ac.uk//id/eprint/3906/ |
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