See Coversheet for system requirements. The aim of the research is to integrate computer technologies and environmentally - sensitive materials and processes into the practice of the ceramic designer-maker, in order to assess the impact of new technologies on practice. A critical contextual review (including analysis of visual material) revealed a developing interest in environmental issues and computer technologies in designer-maker practice. A shift away from a philosophy which historically has been anti-industrial, towards a wider spectrum of craft production was noted. This diversity was shown in the types of production and the scale of manufacture - from ‘one-offs’ to industrial manufacture. New technologies were acknowledged by critics, commentators and practitioners as facilitating this development, although concerns about the potentially detrimental affect that computer technology could have on craft skills was voiced. A link between a pragmatic philosophy of ‘craft’ practice and new approaches to computer systems design highlighted a perception of the validity of ‘craft’ as a contemporary skill. The lack of established methodologies for practice-based ceramic design research has led to the development of a naturalistic approach within this work which is both holistic and emergent. By necessity this methodology places the design researcher at the centre of the inquiry, and uses practice as the main research vehicle. Selected research outcomes were peer reviewed through two significant international touring exhibitions: ‘Hot Off the Press: Ceramics and Print’ and ‘Objects of Our Time’. Initial investigations concentrated on the development of environmentally-sensitive lustre glazes [lead and cadmium free] incorporating an innovative ‘safe’ reduction firing system. Subsequently, ceramic surface designs and three dimensional forms were developed through the integration of: computer assisted design work (CAD); computer assisted manufacture (CAM); colours and glazes; and environmentally-sensitive screen printing, and existing making methods. The outcome was new aesthetic qualities and an extension of practical capabilities. A critical framework for the analysis of research outcomes was developed in order to make explicit and transferable some of the tacit knowledge embodied in research investigations. The analysis was developed through the use of a computer database system from which an electronic document was developed, allowing the integration of a large amount of visual material into the thesis. The research demonstrated that the integration of new technologies into the holistic and emergent practice of the ceramic designer-maker was appropriate. Many advantages of computer technologies for the ceramic practitioner are identified as transferable to the wider field of designer-maker practice and embody the potential to enhance future developments in this field.

Copper ions are widely reported to have pro-angiogenic properties and can be incorporated into bone substitute bioceramics as bio-instructive cues to stimulate infiltration of blood vessels into the material after implantation. By this, the viability of bone forming cells within the scaffold (which decreases rapidly with increasing depth from the surface) could be enhanced, and the healing process (resorption and replacement of the scaffold with new, natural bone) hastened. Pure-phase copper-doped hydroxyapatite (CuHA) materials with x = 0 - 1 in the nominal formula Ca10(PO4)6CuxOy(H)z were prepared by solid state synthesis at 1100 °C. Attempted preparation of compositions with y = 0.1 and 0.5 in the nominal formula Ca10−yCuy(PO4)6(OH)2 by an aqueous precipitation method led to formation of biphasic products containing considerable amounts of β-tricalcium phosphate. Dissolution tests in TRIS buffer, cell culture medium and citric acid buffer indicated that copper ions are released from CuHA materials at concentrations that increase with copper content in the materials and soaking time, and are in a physiologically-relevant range. This offers the potential to tune copper ion release by controlling the copper content of CuHA materials. In vitro in cultures of human osteoblast-like cells and human mesenchymal stem cells (hMSCs), copper ions released from CuHA downregulated ALP expression in both cell types and (particularly for hMSCs) upregulated VEGF expression. In vivo, the prepared copper-containing materials had pro-angiogenic and possible inflammatory effects in the chick embryo yolk sac membrane and chorioallantoic membrane angiogenesis assays. Copper ions released from beads grafted into the developing chick limb affected the integrity of developing blood vessels in the graft vicinity, causing haemorrhaging. The results suggest that the coupling of angiogenesis and osteogenesis, perhaps through the hypoxia and NO pathways, are important for copper's biological effects, and with further investigation and careful control of dose and timing these effects may be better understood and controlled.

No description available.

This Thesis describes a study of the compaction and the sintering of ceramic powders within the context of their "near net shape forming" into dense bodies. The operation of near net shape forming is the manufacture of ceramic parts with a required external dimensional tolerance combined with a defect free internal microstructure. The current study considers these requirements by focusing upon the fundamental facets of near net shape forming operations. The effects of the processing and material parameters on the compaction behaviour of agglomerated alumina powders have been investigated experimentally. It has been shown that the green compacts, formed from the agglomerated alumina powders by the uniaxial die pressing technique, possess certain density distribution patterns due to the frictional forces during the compaction process, and these density distributions depend primarily upon the properties of the agglomerates and the lubrication state of the die wall. The density distributions in the green compacts have been determined experimentally using the coloured layer technique and predicted using a first order model. Due to the inhomogeneous density distributions in the green compacts, the shrinkage of the compacts was not homogeneous. As a result, the shapes of the sintered compacts were not geometrically linear scaled replicas of the green compacts and the shape distortions in the sintered compacts have been characterised. It has been shown that there is a relationship between the extent of the shape distortions and the density distributions in the green compacts; that is, the more inhomogeneous green compacts the more is the shape distortions in the resulting sintered compacts. Sintering and grain growth equations, modified from established relationships, have been used for the sintering simulations in order to predict both the progression of the density and grain size of the sintered compacts. In order to predict the overall shape of the sintered compacts, a first order model has been developed by combining the predicted density distributions in the green compacts and the predicted density of the sintered compacts. The extent of the shape distortions have been reduced by optimising the properties of the agglomerates and the state of the die wall lubrication condition.

No description available.

This research examines established and emerging practical methods and theoretical ideas in contemporary drawing in relation to studio glass. The Studio Glass Movement, encompassing both applied and fine art practice, originated in the 1950’s and, despite rapid advancements in the subject, glass is still considered an emergent material when compared to most other studio processes. For this reason existing and long established practices in drawing, developed in relation to other materials, may not be as effective in realising or exploring those qualities which are particular to glass, whether aesthetic, technical or philosophical. Parallel to this are rapid changes happening within the field of contemporary drawing as a subject in its own right, which influence the wider context in which studio glass engages. In this research the use of empirical methods provide working examples of how drawing and glass can be integrated, through the production of a body of new work supported by theoretical and contextual findings. The investigation is practice orientated, incorporating both practice led and practice based methodologies. The practice led theoretical research proposes a new drawing taxonomy in which dimension, notation, physiology and improvisation are understood as key components in the theory and practice of drawing. This is examined here in relation to glass as both a subject of drawing and as a material process. Identification and reference to contemporary issues in drawing come from a variety of sources, for example through the Drawing Research Network, contact with specialist drawing research hubs including Wimbledon School of Art and Loughborough University, specific exhibitions and attendance at related events and conferences . The practice based aspect uses facilities at the Glass Department, University of Sunderland and a drawing studio in Newcastle upon Tyne. The main area of exploration is concerned with the use of drawing integrated within kiln cast glass as differentiated from established practices such as engraving and stained glass which use drawing as a surface application to an existing glass body.

Ca(1-x)Nd2x/3TiO3 and MgTiO3-Ca0.61Nd0.26TiO3 composite ceramics were prepared by the mixed oxide route and characterised in terms of their structure, microstructure and properties. Ceramics sintered at 1450-1500oC achieved better than 95% of the theoretical density. X-Ray diffraction (XRD) revealed that Ca(1-x)Nd2x/3TiO3 ceramics were single phase for all compositions. For x ≤ 0.39 the structure was Pbnm with lattice parameters of a = b = √2ac and c = 2ac and a tilt system of a-a-c+. Compositions with x ≥ 0.48 could be better described by a C2/m structure with lattice parameters of a = b = c = 2ac. Scanning electron microscopy (SEM) revealed that the ceramics had grain sizes in the 5-70 μm range with abnormal grain growth for Nd3+ rich compositions. Images revealed that the twin domains in CaTiO3 were needle shaped and on addition of Nd3+ the domain morphology becomes more complex. The needle domain morphology returns for Ca0.43Nd0.38TiO3. High resolution electron microscopy (HAADF-STEM and electron diffraction) was used to probe cation-vacancy ordering (CVO) in the lattice. It was found that there was no CVO for x < 0.48 whilst at x = 0.48 there was evidence of a transition to a short range CVO. A transition to long range ordering is almost complete for the Ca0.1Nd0.6TiO3. The structural characteristics of Ca(1-x)Nd2x/3TiO3 ceramics as a function of temperature were investigated using in-situ XRD and Raman spectroscopy. All compositions were found to have the same structure across the entire temperature range. The Raman spectroscopy as a function of temperature indicated a possible transition with similar characteristics to a Curie temperature in a ferroelectric ceramic. The transition temperature was dependent on the cation ordering with the ceramics with greatest degree of disorder having the lowest transition temperature. The microwave dielectric properties of the samples were measured by a cavity resonance method in the 2-4GHz range. The relative permittivity (εr) was found to decrease from 180 for CaTiO3 to approximately 80 for Ca0.1Nd0.6TiO3 with an exponential dependence between the composition and the property. The temperature coefficient of resonant frequency (τf) ranged from +770ppmK-1 for CaTiO3 to +200ppmK-1 for Ca0.1Nd0.6TiO3. The Q x f for CaTiO3 was found to be 6000GHz and this increased to a maximum of 13000GHz for Ca0.7Nd0.2TiO3. After the Ca0.7Nd0.2TiO3 composition, the Q x f decreased to approximately 1100GHz for Ca0.1Nd0.6TiO3. The εr and τf were found to be mainly dependent on the composition of the ceramics whilst the Q x f value was more complex being dependent on the width of the twin domains in the grains. CaTiO3 samples fabricated by spark plasma sintering at 1150oC and above achieved better than 95% of the theoretical density. XRD revealed only a single phase with an orthorhombic Pbnm structure at room temperature and a tilt system of a-a-c+. SEM confirmed that the samples were single phase with grain size between 500nm-5μm. Transmission electron microscopy (TEM) of specimens sintered at 1150oC showed evidence of both (011) and (112) type domains. The τf of the ceramics was shown to be dependent on the volume of the unit cell, in agreement with the Bosman-Havinga equations. The ceramic sintered at 1150oC showed improvement in the Q x f value compared to samples prepared by conventional sintering. The structure, microstructure and properties of composite ceramics based on the MgTiO3-Ca0.61Nd0.26TiO3 system were investigated. Optimum properties were achieved at a composition of 0.8MgTiO3-0.2Ca0.61Nd0.26TiO3 with τf = -0.1ppmK-1, Q x f of 39000GHz and εr of 25.4. XRD revealed the presence of 3 phases including Ca0.61Nd0.26TiO3, MgTiO3 and MgTi2O5. The grain size of the ceramics was typically 5μm. The Q x f value was sensitive to the cooling rate and these changes could be related to changes in the vibrational properties of the lattice through changes in the lattice parameters.

The system kaolinite - carbon black consisting of cheap precursors has been investigated, in terms of its potential to form A1₂ O₃ - SiC composites. The carbothermal reduction process of mullite and silica was studied, in detail, in the range 1275° to 1810° C and over different periods, both under sintering as well as hot-pressing conditions. It was established that the reduction of mullite and silica starts around 1450° C, where the rate of reaction is very slow. Until about 1800° C during the reduction of mullite, SiO₂ gets preferentially reduced, thus forming a composite ceramic consisting of SiC and A1₂ O₃ phases. The kinetics of the formation of SiC + A1₂ O₃ were followed in the range 1590° - 1660° C and it was noted that under hot-pressing conditions they follow a contracting cylinder model. The rate of reaction increased with the increase in temperature and followed a parabolic path with time because of the geometry of the hot-pressed specimens at each temperature. This indicated that the gas diffusion in and out of the system along the edges of the cylindrical specimens is the rate controlling step. The activation energy of the reduction process was calculated to be 922 KJ/mole. The application of pressure prior to the carbothermal reduction process seemed to be not favourable for the formation of SiC and A1₂ O₃, however, when applied after the beginning of soaking period, this greatly improved the densities and formation of SiC and A1₂ O₃. The microstructure of the samples was analysed using SEM and TEM. It was found that the grain size of the composite ceramic was of the order of 0.2μm. SiC was present mainly in the form of fine platelets. Finally, the isothermal compaction behaviour of the system was studied under a constant pressure in the temperature range 1200° C - 1800° C, during which the formation and carbothermal reduction of mullite and silica took place. A mathematical model based on the least squares fitting was used to fit the compaction curves. Due to the complex nature of the compaction data an empirical approach was used to interpret the data and a viscoelastic model was developed. It was found that the interactive-double-Kelvin unit having two elastic and two viscous components explained the type of compaction behaviour observed in the kaolinite + C system. One of the viscous components (η₁) and one of the elastic components (M₁) were found to be temperature sensitive. It is concluded that starting from the cheap precursors (kaolinite and carbon black) a particulate composite of A1₂ O₃,-SiC can be produced by hot-pressing technique. SiC-whisker formation is not encountered in this system. The very fine grain size of the paniculate composite, resulting in a small flaw size, should provide the composite ceramic with good mechanical properties. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

M.Tech. / This project aimed to develop the Potpaz ceramic water filter into an improved filter design optimally suited to South African rural conditions, to provide potable water rather than contaminated water to households. Communities that do not have access to in-house treated water often end up with a contaminated water supply, as the water to be consumed is usually sourced from communal water collection points and stored in containers. There is evidence that the water consumed at point-of-use in rural areas is not always of a potable quality due to possible contamination between collection and consumption. The existing Potpaz home water treatment device has been scientifically proven to return contaminated water to a potable state. A limited number have been imported to South Africa for use in a project that studied the effect of household point-of-use treatment on the health of the consumer. It was not at all certain whether the households would use these devices effectively because this filter was not part of their everyday water system. Part of investigating whether or not they would effectively use this filter was the inclusion of industrial design within the filter assessment section of a larger research project conducted in the Vhembe region to understand the requirements of the user. Industrial design concerns itself with the requirements of the user, as well as knowledge regarding product design, development and manufacturing. Households that took part in the point-of-use project used the Potpaz home water treatment device for more than two months and were approached to provide feedback regarding its use. From the feedback, it became evident that there were aspects of the Potpaz design that needed modification towards an improved water filter more suited for its intended use in rural households. An Action Researchinfluenced methodology and User Centred Design approach informed the collection of original data and feedback on areas of improvement. This, together with visits to local shops and community potters, provided sufficient background to understand the needs and preferences of the intended rural users regarding the use of the device. This informed the design process and increased the chances of developing a readily accepted, more suitable product to the intended users and the domestic environment in which they live. To achieve this, this project focused on the following aspects regarding Potpaz filters: placement, use and design aspects of usability and ergonomics. Development of the improved filter design culminated in rapid prototyping of a scale model and the fabrication of a full-size working model allowing for physical interface to evaluate the success of the design solution.

Calcium phosphates and recently also magnesium phosphates, are used for medical applications, due to their biocompatibility and bioactivity. These properites makes spherical particles of calcium and magnesium phosphate suitable for carrier materials for drug delivery applications. By creating porous and/or hollow particles itis possible to load the particles with a drug and control therelease of the active substance. In this work, an ion-induced method for the synthesis of spherical calcium and magnesium phosphates was developed. A simple precipitation reaction was used, where substituting magnesium ions could replace the function of templates, such as surfactants or micelles, to induce the formation of spheres of a certain size and morphology. Experimental results showed that magnesium had an inhibitory effect on the nucleation and crystal growth of calcium phosphates. By using substituting ions as a structural regulator, it was possible to alter the size, morphology and phase composition of the spheres. At low magnesium concentrations, the spheres had a smooth surface andwere between 200 nanometer to 1 micrometer in diameter and composed of hydroxyapatite and/or magnesium-substituted beta-TCP. At higher magnesium concentrations, the spheres were about 10-50 micrometer with a rough, flaky surface. Results also proved that calcium ionshave the same effect on the crystallisation and self-assembly of magnesium phosphates. Apart from the magnesium concentration, reaction temperature proved to have a high influence on the sphereformation, whereas Ca/P ratio and reaction times above three hours did not affect the sphere formation to the same extent.