# Processing of fluoro alumino-silicate glass-ceramics by Field Assisted Sintering Technology and honeycomb extrusion technique

Ramakrishnan, Praveen (2016). Processing of fluoro alumino-silicate glass-ceramics by Field Assisted Sintering Technology and honeycomb extrusion technique. University of Birmingham. Ph.D.

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## Abstract

Field Assisted Sintering Technique (FAST) was used for the crystallisation of ionomer glasses and the production of the relevant glass ceramics. Extrusion was also used as an alternative processing method to produce honeycomb glass ceramics derived from similar glass compositions. Apatite-mullite glass ceramics derived from the general glass composition 4.5SiO$$_2$$-3A1$$_2$$O$$_3$$- 1.5P$$_2$$O$$_5$$-(5-x)CaO-xCaF$$_2$$ can be produced by a lost wax method. However, Field Assisted Sintering Technique and Honeycomb Extrusion Technique are never used before and this present work presents the first data on the use of both of the above mentioned techniques. Calcium (Ca), Strontium (Sr) and Magnisium (Mg) containing glass powder compositions were produced and processed by FAST and Extrusion technique. X-ray diffraction of the materials produced by FAST showed the formation of a fluorapatite, mulite and a minor A1PO$$_4$$ phase for the calcium glass. Sr-fluorapatite and Sr-aluminium silicate were formed in Sr glass and mullite and wagnerite were formed in Mg glasses. All the crystal phases formed were in good agreement with previous conventional crystallization studies. The FAST sintered glass ceramic properties were improved when compared with conventional sintering. In extrusion technique, the rheological properties were studied using Benow/Bridgwater model for paste parameters. Honeycomb extrusion pressure drop was also studied using a model developed by Blackburn and Bohm. In this study, we used waste glass to model the binder rehology of glass powder and modelled binder rheology in the apatite mullite glass. The measured paste parameters were in good agreement when compared with the experimental results. The produced honeycomb structure was sintered conventionally using a furnace. Microstructural studies and X-ray diffraction were carried out. The results of this studies show a well-defined porous structure and formation of crystal phases similar to the phases observed during conventional sintering.

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
Supervisor(s):
Supervisor(s)EmailORCID
Stamboulis, ArtemisUNSPECIFIEDUNSPECIFIED
Blackburn, StuartUNSPECIFIEDUNSPECIFIED
Licence:
College/Faculty: Colleges (2008 onwards) > College of Engineering & Physical Sciences
School or Department: School of Metallurgy and Materials
Funders: Other
Other Funders: British Council, India
Subjects: T Technology > TN Mining engineering. Metallurgy
T Technology > TP Chemical technology
URI: http://etheses.bham.ac.uk/id/eprint/6579

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