The oxidation behaviour of Fe3A1 intermetallic alloys with and without reactive element (RE) and Ti-46.7A1-1.9W-0.5Si alloy over the temperature ranges of 900 to 1100°C and 750 to 950°C respectively were studied for up to 240h. The isothermal and cyclic oxidation behaviour of Fe3A1 intermetallic materials was studied in static air. The Al203 adherence of (Y and/or Hf)-doped Fe3A1 alloys was examined using newly developed — by the researcher — cyclic oxidation rig built in AMRI's laboratory. However the oxidation of Ti-46.7A1-1.9W-0.5Si alloy was studied in air and under Ar-02 atmospheres of three oxygen partial pressures; P02 = (0.05, 0.2 and 0.8) x 105 Pa. Isothermal sulphidation/oxidation work of coated — with specially designed single and multi- layer coatings — and uncoated Ti-46.7A1-1.9W-0.5Si alloy was performed in relatively high partial pressure of sulphur (pS2 = 6.8 x 10-1 Pa) and low partial pressure of oxygen (p02 = 1.2 x 10-15 Pa) at 850° C for up to 240h. Characterisation of the specimens was conducted using SEM, EDX, and XRD techniques. Higher oxidation rates of Ti-46.7A1-1.9W-0.5Si alloy were observed in air than in Ar-20%02 at all temperatures. The scale formed in air consisted of Ti02/Al203/Ti02/TiN/TiAl2/substrate, whilst the scale developed in Ar-20%02 atmosphere was comprised of Ti02/Al203/Ti02/Al203/Ti3A1/substrate. The oxidation rates of Ti-46.7A1-1.9W¬0.5Si alloy increased with decreasing the oxygen partial pressure in Ar-02 atmospheres at the entire range of temperatures. The employment of single A1TiN and CrN single layer coatings improved the sulphidation/oxidation behaviour of Ti-46.7A1-1.9W-0.5Si alloy at 850°C for up to 240h in H2/H20/H2S gas mixture. However, the use of NbN and CrN diffusion barrier coatings significantly enhanced its corrosion resistance. The scale on uncoated Ti-46.7A1-.9W-0.5Si alloy in sulphidising/oxidising atmosphere consisted of Ti02/Al203/TiS+W/TiA13/TiAl2/substrate. The reactive element (RE) — Y and/or Hf — addition especially Y significantly improved the oxide adherence of Fe3A1 over the specified range of temperature and exposure time (or cycles). However, higher oxidation rate of Fe3A1 alloys doped with Y was obtained under both isothermal and cyclic oxidation. Although the scale thickness of Hf-doped alloy was always higher than that of Y-doped alloys, the oxidation rate constant of the later is found in some cases to be less than that of the first by one order of magnitude. However, the scale on the Hf-doped alloy is relatively adherent to the substrate if compared with the scale of undoped Fe3A1 alloy even at the areas where oxide pegs were observed on Fe3A1-Hf alloy. Generally, no conclusion could be taken from the kinetic data of Fe3A1 alloys regarding the reactive element effect (REE) due to the intergranular attack on the Y-containing alloys. Improving the interface properties by RE addition led to a better control of the outward diffusion of aluminium and eliminated the detrimental effect of sulphur (possibly present in the Fe3A1 alloys). However, the presence of the RE in the alloy led to the formation of coherent scales. At 1100°C and after prolonged exposure, the scale of RE- doped alloys was not able to remain in contact with the substrate especially under thermal cycling conditions. The external scale severely cracked especially at places where oxide ridges were formed. The Y-containing Fe3A1 alloys were capable of producing another thin and adherent scale underneath the cracked external scale.

Polyurethane (PU) foam has unique characteristics making it suitable for many applications such as: aeronautics, automotive, building construction, marine, and many house-hold applications. PU’s biodegradability, biocompatibility, lightweight, and durability make it suitable for several medical applications. The porous structure of PU foams enables them to be used for lightweight components and for medical applications where the permeability allows nutrients to reach cell growth areas. The foam components are currently mainly manufactured by material removal i.e. subtractive machining or a casting/moulding processes. Additive Manufacturing (AM) processes (3D printing), build components in 2D layers and have been utilised to manufacture a range of products for many applications including: jewelry, footwear, industrial design, architecture, engineering and construction, etc. The additive processes have the ability to generate internal hollow structures or scaffolds. The nature of parts produced by AM technologies makes it fit for lightweight products such as aerospace parts, medical scaffolds, etc., in metals and polymers, however the technology has not been used to produce objects using PU as its material, due to the foaming nature of the material when its two base materials (polyol and Diisocyanate) encounter with each other. This research has undertaken a critical review of PU foaming processes, medical applications, and characteristics of AM technology processes. The effect of resins mixing ratios, temperature, and foaming direction on the physical and mechanical properties of PU foam have been investigated and used as a base to establish a platform for further development. The research has evaluated the suitability of Additive manufactured PU foam structures for further application such as medical scaffolds by comparing the foams produced using traditional method and have developed an AM production method (In-flight mixing system) for the material (PU). Based on the evaluations, a new technique has been pro-posed and tested which is able to generate PU 3D structures. Foam produced by the designed system has average pore size of 689μm which will allow the following: the flow of fluid such as blood, diffusion of waste products out of the scaffold, and cell infiltration and can therefore be suggested for the production of medi-cal scaffolds.

For many applications, including power generation, aerospace and the automobile industry, high temperature wear provides serious difficulties where two or more surfaces are able to move relative to one another. It is increasingly the case that with for example, aerospace applications, demands for ever more powerful and efficient engines that thus operate at higher temperatures, conventional lubrication is no longer sufficient to prevent direct contact between metallic surfaces and consequent accelerated wear. One phenomenon that has been observed to reduce metallic contact and thus high temperature wear and friction is the formation of what are termed ‘glazes’, essentially layers of compacted oxide wear debris that becomes sintered together to form a low friction wear resistant oxide surface. This thesis studies the nature of the wear encountered with four different combinations of Superalloys, slid together using a ‘block-on-cylinder’ configuration developed for accelerated simulation testing of car engine ‘valve-on-valve-seat’ wear. Predominantly, Nimonic 80A and Incoloy MA956 were used as sample materials and Stellite 6 and Incoloy 800HT were used as counterface materials.

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Theoretical and Experimental results of research on the Direct Torque Control (DTC) of the Brushless Doubly Fed Reluctance Machine (BDFRM) are presented in this thesis. The main motivation for this work has been found in the relative simplicity of the DTC strategy and attractive properties of the BDFRM drive, foremost its cost-effectiveness associated with the use of a partially rated power electronics, and reliability of brushless structure of the machine itself. It is hoped that the project outcomes will be extremely helpful to the further study of the machine in light of its application in wind power generation and/or large pump systems. The thesis is essentially divided into three main parts. The first part is the theory development, which involves the analysis of the fundamental principles of DTC and BDFRM operation. The second part presents the comprehensive simulation studies of the developed control scheme for the machine in both sensor and sensorless modes. The computer studies have been performed to examine the performance of the controller based on a linear (ideal) machine model. The parameters used for this model have been obtained by off-line testing of a small Axially Laminated BDFRM prototype at Northumbria University, UK. The third part of the thesis contains a comprehensive set of experimental results that have successfully verified the control algorithm for the machine. Based on the Simulink® program, a Digital Signal Processor (DSP) control board from dSPACE® has been used to control a conventional IGBT inverter bridge.

Bandsawing is a preferred method used by steel stockholders and steel users in industry for cutting-off to size in the primary and secondary processes. The state-of- the-art features in current industrial bandsaw machines have transformed this method for cutting-off stock to size into a hi-tech operation capable of storage and handling. This method is particularly suitable for use in engineering factories involved in fast, highly automated mass-production techniques, providing the user with continuous batches of cut-to-length materials. Bandsaw machines have now superseded power hacksaws and circular saws in cutting rate and lower kerf loss due to better computer- controlled saw machines and improved blade designs (bi-metal HSS, carbide tipped). Although, there have been some new developments in bandsaw blades (tooth geometry, band material etc.) there are continuous new demands made on the bandsaw blades by materials engineers, challenged with introducing new materials to satisfy the needs of the design engineers, e.g. aerospace industry. There is therefore a need to improve the bandsaw blade. In order to do this we need to have an understanding of the mechanics of the cutting process associated with bandsawing and the various parameters affecting cutting forces, specific cutting energy, metal removal rates etc. One of the primary problems in evaluating metal bandsaws and developing newer variants, including new saw tooth materials, their heat treatment, or special tooth forms and quality, has been the use of costly and time consuming sawing tests. Furthermore, there are no simple ways of quantitatively evaluating the performance and life of these bands during sawing. Traditional method used by machine operators to assess the performance of blades only give global data, which is difficult to apply to individual teeth. Therefore there is a need to develop "time compression" test methods for evaluating the performance of bandsaw blades to replace full bandsaw blade testing. The work presented in this thesis is on the development of a single tooth testing method to simulate the intermittent cutting action of a bandsaw blade. Cutting tests have been performed to assess the testing method by comparing single tooth test results to full bandsaw blade test results. The test method developed is capable of producing scientific data for bandsawing associated with forces, metal removal rate and specific cutting energy when cutting a variety of workpiece materials at different speeds and feeds. Thus, it can be used as a substitute to full bandsaw blade testing. The cutting data for the workpiece materials tested using the single tooth test method was obtained in 25% of the full bandsaw blade evaluation time. This represents a significant saving in time and cost, which should prove useful to design engineers when designing and testing new prototype bandsaw blades for the future needs of the steel and manufacturing industry involved in metal cutting.

The work develops the application of evolutionary algorithms in the domain of automotive heat exchanger design. The principal employed is that of computer regulated changes to a physical model which attempts optimisation using methods analogous to biological evolution. It shows that the use of airside fins with differing louvre angles can enhance the performance of automotive heat exchangers by a useful margm. This has been achieved with a wind tunnel model that allows automatic configuration of the louvre angles, and novel instrumentation allowing heat transfer performance to be assessed in terms of shear and drag forces acting on the louvres. During the investigation an important coupling between the behaviour of adjacent louvres was discovered, manifested as a loss in useful shear force at around ±12° relative angle. The work as a whole shows that specific louvre angle selections and quantitative estimates of the potential performance gains could be made with the following improvements to the physical model and search algorithms. The number of louvre rows should be doubled (to 16) to better represent typical matrices and the instrumented louvres should be centrally positioned in the air stream. Improved data filtering is required for reliable operation and the specific figure of merit has been shown to be an important factor in the optimisation process. A parallel area of application for the optimisation strategies was the solution of the Wilson plot problem. This represents a novel approach to the analysis of heat exchanger experimental test data where an alternative curve fitting and visualisation format allows more accurate models to be established. By these methods functions defining heat transfer coefficients for both sides of a heat exchanger may be determined that give a fit to experimental data to within less than 1. 5% on measured overall heat transfer coefficient.

Environmental impact reduction (EIR) in Product Development processes, can involve numerous elements and activities. In relation to business objectives, the strategic review and integration of environmental impact reduction should be considered a best practice development opportunity and a contribution towards longer term sustainability. It should be recognised that environmental impact reduction requirements are often complex and challenging for businesses to implement, especially for those companies lacking the knowledge and internal resources to address these activities. This has been found to be the case particularly with Small and Medium Enterprises (SMEs) where flexibility towards new approaches can be strategically more problematic, due to the limitations of available capital and resource. After a combination of literature review, industrial collaboration and data collection from within the manufacturing logistics systems of packaging for SME products, an opportunity was identified to develop a contemporary framework to integrate key critical environmental impact reductive activities, within adjoining New Product Development (NPD) activity. Engaging key activities of environmental impact reduction seamlessly into standardised NPD though a visual mapping process, can promote changes in current behaviour towards best practice development opportunities concerning environmental impact reduction. The contribution to new knowledge from this programme of research has been the development of an investigative framework for visually mapping the product development processes which provides manufacturing SMEs with an approach to capturing „visual snapshots‟ of their current engagement within environmental impact reductive activities. This visual mapping process addresses a range of company sizes and organisational behaviours to provide specific feedback and inform best practices for more sustainable NPD.