A novel process in which turbine blade moulds are manufactured by rapid prototyping has been developed. Fine control over the raw materials and their processing is required. The non- Newtonian rheological behaviour of the ceramic slurries can be modified through changes in the dispersant levels. A link between dispersant concentration, particle-particle interactions and firing performance has been suggested. Alumina agglomerates that remain through mixing were identified and shown to affect the viscosity of the resin by as much as 30% leading to poor process robustness. X-ray tomography was used to identify and visualise highly orientated defect structure in the ceramic linked to the layered build and the residual stress distribution developed by the Gaussian profile of the laser. It was shown that changes to the laser settings would affect the structure of defects but did not allow for defect removal. The flexural strength of the ceramic produced was found to be by highly dependent on sample orientation and varied between 14 and 52 MPa. Methods to improve the defect structure were explored, including changes in UV cure technology, changes in process settings, removal of agglomerates from the alumina and improved firing schedules. Both a reduction in defects and improved surface finish were identified. It is apparent that moulds suitable for casting applications can be processed using this novel technique.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:655763 |
| Date | January 2010 |
| Creators | Welch, Stewart T. |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.bham.ac.uk//id/eprint/774/ |
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