The purpose of this study is to investigate the process of hot embossing on alumina based ceramics as a cost-efficient procedure for manufacturing microfluidic testing components. Alumina ceramics were used as an exploratory phase for the final objective of the project, manufacturing of Berea sandstone based ceramic samples. These testing components are vital to the growth of various fields ranging from the retrieval of oil and natural gas to studying the water purification process of aquifers. Previous research has shown potential in using hot embossing on Alumina based ceramics; however, complications with extrusion and micro-structure quality were observed. For this reason, the research performed aimed to produce Berea Sandstone based components by first improving upon the embossing quality of alumina ceramics.
The thesis first investigates changes in the extrusion ratio and the subsequent effects observed on the quality of extrudate. Next, improving the quality of embossed microstructures is examined. This is done by varying the MFI as well as changing the embossing speed and temperature. Finally, a preliminary study into the effectiveness of Berea sandstone based ceramics is reported.
The improved ram extruder demonstrated improved surface quality in post-extrusion samples which can be attributed to a greater extrusion ratio and enhanced temperature uniformity, as well as a changing the extruder stock material to stainless steel. Alumina samples extruded from the new extruder had an average surface roughness of; this was compared to reported for the previous design.
Comparisons of optical scan data showed that a lower MFI provided sharper edges along the testing section; however, demolding from the embossing plate was a challenge often rendering samples unusable. The higher MFI was very easy to demold from the embossing plate and the resolution of the imprinted microstructures improved; therefore, the higher MFI was chosen and other embossing parameters were examined: embossing temperature and speed. It was concluded that low viscosity and slow embossing speeds provide higher quality embossed samples.
After a thorough inspection of several embossing parameters on microstructure quality, introductory study into substituting Berea sandstone for alumina was conducted. The analysis showed a loss in microstructure resolution when compared to alumina ceramics due to an increase in the average particle size of the sandstone powder. During sintering, a properly densified sample was not obtained and SEM results indicated a loss of iron oxide on the periphery of the sample. However, this initial step in manufacturing sandstone samples provides invaluable insight into the future of the project
Robbins, J. F. (2017). Optimization of the Hot Embossing Parameters and Sintering Characterization for Alumina/Berea Sandstone Ceramics. Retrieved from https://repository.lsu.edu/mechanical_engineering_pubs/2