Browsing by Author "Irwin, M."
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Item Open Access An experimental characterization of thermophysical properties of a porous ceramic shell used in the investment casting process(Springer, 2020-02-12) Jones, Christopher A.; Jolly, Mark R.; Jarfors, A. E. W.; Irwin, M.This study presents the results of an investigation that characterises the thermophysical properties of an investment casting mould, comprising of a Zirconium dioxide/Cobalt aluminate prime slurry and a fused Silica/fibre reinforced backup slurry. Growing prevalence of successful computer simulations within the foundry industry enables defects that emerge during the casting process to become increasingly predictable, providing cost-effective alternatives to trial castings. The viability of these simulations as predictors is heavily dependent upon the facilitation of accurate material property data, as attained through this investigation. Differential scanning calorimetry (DSC) and laser flash analysis (LFA) were utilized to determine the specific heat capacity and thermal diffusivity, respectively. These values, in combination with the material density and linear coefficient of thermal expansion, have been used to determine the thermal conductivity of the mould. With the aim of verifying these parameters, initial studies in Flow-3D® simulation software have been performed to determine the constraints needed to reduce variability in simulation parameters. Due to the diversity of casting moulds used throughout the industry, ensuring the material database is kept as comprehensively populated as possible is a crucial undertaking.Item Open Access A verification of thermophysical properties of a porous ceramic investment casting mould using commercial computational fluid dynamics software(IOP Publishing, 2020-06-12) Jones, Christopher A.; Jolly, Mark R.; Jarfors, A. E. W.; Irwin, M.; Svenningsson, R.; Steggo, J.; Eriksson, J.Defects in cast metals remain a common problem in many areas of the foundry industry, particularly in the investment casting of large area, thin-walled components for aerospace applications. During previous research, the thermophysical properties, density and porosity of a fibre reinforced ceramic investment casting mould were determined using several experimental techniques. Without verification, these experimental results remain nothing more than educated guesswork. The purpose of this study is to verify previous results and to more fully characterise the ceramic mould material with complementary measurements. A commercially available computational fluid dynamic (CFD) simulation package, Flow-3D®, was used in conjunction with a full-scale Ni-superalloy (IN718) casting to assess the accuracy of these results. By placing thermocouples strategically across the mould thickness, temperature profiles were determined and compared directly to predicted profiles extracted from the simulation by a custom-written Python script