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Characterisation of plasma arc technology processed waste products

Mao, Jishen (2012)
M.Res. thesis, University of Birmingham.

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Plasma arc technology is a novel method that widely applied in industry for the hazardous waste vitrification. After the plasma arc process, the wastes are transformed into inert and glassy materials ready for storage or other applications.
The aim of this project is to characterise a plasma arc processed waste product. Two types of samples were characterised in this study, Sample A is sodium-free and Sample B is sodium-contained. The microstructure of the samples was characterised using XRD, SEM and TEM; mechanical properties of the samples were measured including Vickers hardness and compressive strength; dissolution of the samples in alkaline solution was measured to test the chemical stability. XRD results show that both of the samples are amorphous, which is confirmed by the TEM electron diffraction study. The sodium-free sample contains areas in green color and areas in white color, while the sodium-contained sample is all in green. SEM results show that the green area in sodium-free sample has homogenous structure and the white area has a dendrite-like structure. The bright part in the dendrite-like structure contains more Al, Si, Ce but less Mg than the dark part. A black fiber-like structure can be found in the sodium-contained sample. The fiber-like structure contains more O, Mg, Al but less Si than the rest of the sample. A detail study of electron diffraction in TEM was performed by transforming the electron diffraction patterns into reduced density function G(r) (RDF). The results show that the nearest-neighbor distance in sodium-contained sample is larger than the sodium-free sample.
Mechanical property measurements show that the sodium-free sample has higher Vickers hardness and compressive strength values than the sodium-contained sample. The sodium-free sample also has a higher dissolution rate than the sodium-contained sample as indicated in the chemical stability study.

Type of Work:M.Res. thesis.
Supervisor(s):Chiu, Yu-Lung
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:Department of Metallurgy and Materials
Subjects:TN Mining engineering. Metallurgy
TP Chemical technology
TS Manufactures
Institution:University of Birmingham
ID Code:3631
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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