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The thesis deals with a research programme in which the cutting performance of a new generation of ceramic cutting tool material is evaluated using the turning process. In part one, the performance of commercial Kyon 2000 sialon ceramic inserts is studied when machining a hardened alloy steel under a wide range of cutting conditions. The aim is to formulate a pattern of machining behaviour in which tool wear is related to a theoretical interpretation of the temperatures and stresses generated by the chip-tool interaction. The work involves a correlation of wear measurement and metallographic examination of the wear area with the measurable cutting data. Four main tool failure modes are recognised: (a) flank and crater wear (b) grooving wear (c) deformation wear and (d) brittle failure Results indicate catastrophic edge breakdown under certain conditions. Accordingly in part two, the edge geometry is modified to give a double rake tool; a negative/positive combination. The results are reported for a range of workpiece materials under orthogonal cutting conditions. Significant improvements in the cutting performance are achieved. The improvements are explained by a study of process parameters; cutting forces, chip thickness ratio, chip contact length, temperature distribution, stress distribution and chip formation. In part three, improvements in tool performance are shown to arise when the edge chamfer on a single rake tool is modified. Under optimum edge chamfer conditions a substantial increase in tool life is obtained compared with the commercial cutting geometry.

Adhesive bonding of aluminium is widely used in the aerospace industry. High initial bood strengths can be obtained, but bond failure occurs atter prolonged exposure to humid enviroments. The thesis contains details ot a test procedure which has been designed and developed for the assessment of different alloys, pretreatments, and adhesives, which will give adhesively bonded aluminium joints of high strength coupled with long term durability. The test involves assembly of lap shear specimens in a precision jig using 250 ballotini spacers in the adhesive to control the bond line thickness. The test is modified by drilling three accurately located holes through the bonded area after assembly of the joint and curing of the adhesive. Further important features at the test, such as fillet control, are detailed. The test was assessed, modified and developed to give a reliable and reproducible method which would discriminate amongst different bonding systems after exposure to humid test environments. This is the first test to have achieved the discrimination necessary for short term assessment of bond systems where long term durability is required. Even better discrimination has been obtained by applying stress in a stress humidity test. Having established accurate, reliable and discriminating test methods they were used to study the durability of structural epoxy adhesive bonds to aluminium as a function of alloy, pretreatment, adhesive and environment. It was established that the long term durability or adhesively bonded aluminium was directly related to the infulence of water migrating within the adhesive. Pretreatments differed in their ability to prevent hydration of the aluminium oxide by the water absorbed within the adhesive.

The last few years have witnessed an unprecedented increase in the price of energy available to industry in the United Kingdom and worldwide. The steel industry, as a major consumer of energy delivered in U.K. (8% of national total and nearly 25% of industrial total) and whose energy costs currently form some 28% of the total manufacturing cost, is very much aware of the need to conserve energy. Because of the complexities of steelmaking processes it is imperative that a full understanding of each process and its interlinking role in an integrated steelworks is understood. An analysis of energy distribution shows that as much as 70% of heat input is dissipated to the environment in a variety of forms. Of these, waste gases offer the best potential for energy conservation. The study identifies areas for and discusses novel methods of energy conservation in each process. Application of these schemes in BSC works is developed and their economic incentives highlighted. A major part of this thesis describes design, development and testing of a novel ceramic rotary regenerator for heat recovery from high temperature waste gases, where no such system is available. The regenerator is a compact, efficient heat exchanger. Application of such a system to a reheating furnace provides a fuel saving of up to 40%. A mathematical model developed is verified on the pilot plant. The results obtained confirm the success of the concept and material selection and outlines the work needed to develop an industrial unit. Last, but not least, the key position of an energy manager in an energy conservation programme is identified and a new Energy Management Model for the BSC is developed.