No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

A novel continuous casting process used to form a highly filled, thermoplastic paste into a net shape ceramic body has been investigated, a method termed thermal paste processing (TPP). TPP uses a long cylindrical die cooled below the solidification temperature of the continuous phase, so that the extrudate merges from the die as a solid rod. Thermal processes were investigated using standard and novel power compensated DSC techniques, yielding both enthalpic response and thermal transport properties. The rheological behaviour was characterised over 9 decades of apparent shear rate, for temperatures from the melt to mushy range. Steady and dynamic shear responses were probed with controlled stress and controlled strain rotational rheometers, using smooth or serrated parallel disks, concentric cylinders, or vane-type geometries. Capillary rheometry using the multi-pass technique was also performed. The rheological characterisation revealed a mismatch between expected and measured onset temperatures when using a parallel disk rheometer; this led to the measurement and simulation of the sample’s and rheometer’s temperature fields. These results were incorporated into the description of the paste’s rheological response to temperature. The thermal and rheological parameters yielded by the above characterisations were incorporated into a 2-D axisymmetric model of the TPP die system using the finite element method (FEM). The numerical code performance was compared against three suitable benchmark problems reported in the literature. The results from one case concerning the melting of gallium in a square cavity revealed a possible cause of circulation cell instability observed in many numerical results, but not respond experimentally. Predictions from the numerical simulations were compared with equivalent experimental data from an instrumented TPP die system. The formulation variations demonstrate poor to good agreement with experimental data.

Over three quarters of the world's flat glass is produced by the float method, in which molten glass is solidified on large baths of liquid tin. Sulphur is a major contaminant in these baths, causing a defect known as top speck. This dissertation describes the design, construction and evaluation of a sensor based upon a solid electrolyte, intended for use in the detection of this sulphur. Three solid electrolytes were produced: strontium and sodium β-alumina by direct methods, and silver β-alumina by ion exchange. The effects of material composition and sintering cycle on density were investigated, and conductivities, atomic structures and microstructures were characterised and shown to agree with published data. A number of cell designs were constructed to investigate the electrolytes' responses to different partial pressures of sulphur and oxygen, which were produced using mixtures of the metals copper, iron and molybdenum with their respective sulphides and oxides. A non-equilibrium electrolyte response was observed, caused by slow interaction between the electrolyte and the metals. A mixture of molten tin and solid tin sulphide was investigated using a silver-referenced, silver β-alumina cell, and reproducible emfs corresponding to thermodynamic expectations were observed. A non-unity value was determined for the activity of a proposed silver sulphide auxiliary layer at the surface of the β-alumina and shown to be in agreement with a theoretically-calculated value. Experiments were carried out using this cell in molten tin baths of varying sulphur content. Results were generally consistent with the previously-determined values of silver sulphide activity; however, at low sulphur values this activity was not constant and decreased to zero. The minimum level of sulphur which could be detected by this technique was calculated and tested both in laboratory molten tin and in industrial trials.

No description available.

No description available.