The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
L O Gullman - One of the best experts on this subject based on the ideXlab platform.
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microstructure control and extrudability of al mg si alloys microalloyed with manganese
Materials Science and Technology, 1994Co-Authors: Stanislaw Zajac, Bevis Hutchinson, A Johansson, L O GullmanAbstract:AbstractThe hot deformation of AA 6063 and AA 6005 Al alloys has been related to chemical composition and the microstructural evolution occurring during the various heat treatment procedures before extrusion. It was shown that a small addition of Mn significantly accelerates the homogenising process (transformation of the brittle platelike β-AlFeSi phase to the more rounded α-AlFeSi phase) which results in superior hot formability and ductility. The mechanical behaviour of Al–Mg–Si alloys during hot deformation can be explained in terms of a model of dislocations climbing around particles. Large β phase particles increase initial work hardening rate and flow stress and impair hot ductility. The hot ductility of the material investigated via tensile testing was found to correlate with the density of particles covering grain boundaries. It was also shown that grain refinement in the billet leads to more uniform distribution of intermetallic constituents, which accelerates the homogenising process and improv...
Juliane Floury - One of the best experts on this subject based on the ideXlab platform.
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analysis of a new type of high pressure homogeniser a study of the flow pattern
Chemical Engineering Science, 2004Co-Authors: Juliane Floury, Jack Legrand, Jerome Bellettre, Anne DesrumauxAbstract:High-pressure homogenisation is a key unit operation used to disrupt fat globules or cells containing intracellular bioproducts (AIChE J. 43(4) (1997) 1100). Modelling and optimisation of a small homogenising unit are often restrained by a lack of information on the flow conditions within the homogeniser valve. A numerical investigation of the flow within such a new homogenising valve, capable to reach pressure as high as (Stansted Fluid Power Ltd, UK) is presented. Results are obtained using the finite-volume technique and a RNG k–e turbulence model with low Reynolds number near wall treatment conditions. An experimental measurement of the size of the valve gap is presented in order to validate mathematical relations that give valve gap sizes versus homogenising pressure. The modelling results give detailed information on the mechanical stresses and the high shear rates in small disruption valves, and also reveal other phenomena that could not be easily determined experimentally.
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Effect of high pressure homogenisation on methylcellulose as food emulsifier
Journal of Food Engineering, 2003Co-Authors: Juliane Floury, Anne Desrumaux, Monique A.v. Axelos, Jack LegrandAbstract:A new high pressure homogeniser going up to 350 MPa was used to produce fine emulsions stabilised by methylcellulose for food applications. The objective of this study was to evaluate the effect of homogenising pressure on emulsifying and stabilising properties of methylcellulose, a food macromolecule extensively used as stabiliser in emulsions. Oil droplet size distributions of the emulsions were measured by laser-light scattering; rheological properties were characterised with a coaxial cylinder rheometer; and stability was evaluated by heating of the emulsions. Influence of homogenising pressure on interfacial properties (adsorption kinetics, interfacial tension and rheological behaviour) of the polymer was also studied at different pressure treatments. The results showed significant modifications in the structure and the texture of emulsions with increasing homogenising pressure. Homogenised methylcellulose solutions showed weaker thickening and stabilising properties compared to the one of the native methylcellulose.
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Effect of high-pressure homogenization on droplet size distributions and rheological properties of model oil-in-water emulsions
Innovative Food Science & Emerging Technologies, 2000Co-Authors: Juliane Floury, Anne Desrumaux, Jérémie LardièresAbstract:Abstract A new ultra high-pressure homogenizer (STANSTED, UK) going up to 350 MPa, was used to realize very fine oil-in-water emulsions. The effect of Homogenizing pressure (from 20 to 300 MPa) was studied on model emulsions stabilized by whey proteins. Oil droplet size distributions were measured by laser-light scattering. Rheological properties were characterized with a coaxial cylinder rheometer. The results showed significant modifications in the structure and the texture of emulsions with increasing pressure. Ultra high-pressure Homogenizing conditions brought about the high oil content emulsions (>40% w.w.b) from shear-thinning behaviors (at 20 MPa) to Newtonian behaviors (at 300 MPa). Droplet size was reduced with increasing pressure. However, the flow curves could not be fully explained by the droplet size distributions.
Zhihuai Mao - One of the best experts on this subject based on the ideXlab platform.
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effect of high pressure homogenization on the structure and thermal properties of maize starch
Journal of Food Engineering, 2008Co-Authors: Aolei Wang, Yu Lung Chiu, Xiao Dong Che, Liju Wang, Zhihuai MaoAbstract:Abstract Maize starch–water suspensions (1.0%) were subjected to single-pass high-pressure homogenization treatment at 60 MPa, 100 MPa, and 140 MPa. The structure and thermal properties of the high-pressure homogenized starches were investigated using DSC, X-ray diffraction technique, laser scattering, and microscope, with native maize starch (suspended in water, but not homogenized) as a control sample. DSC analysis showed a decrease in gelatinization temperatures ( T o , T p ) and gelatinization enthalpy (Δ H gel ) with increasing Homogenizing pressure. No noticeable effect of high-pressure homogenization on the retrogradation of maize starch was observed. Laser scattering measurements of particle size demonstrated an increase in the granule size at a Homogenizing pressure of 140 MPa. This was attributed to the gelatinization and aggregation of the starch granules. X-ray diffraction patterns showed that there was an evident loss of crystallinity after homogenization at 140 MPa. Microscopy studies showed that the maize starch was partly gelatinized after high-pressure homogenization, and the gelatinized granules were prone to aggregate with each other, resulting in an increase of granule size.
Liju Wang - One of the best experts on this subject based on the ideXlab platform.
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effect of high pressure homogenization on microstructure and rheological properties of alkali treated high amylose maize starch
Journal of Food Engineering, 2012Co-Authors: Ao Wang, Liju Wang, Yanhong Liu, Enu AdhikariAbstract:Abstract The effect of high-pressure homogenization (HPH) on the microstructure, rheological properties, paste clarity, as well as gel retrogradation behavior of alkali-gelatinized high-amylose maize starch (HMS) was investigated. The alkali-treated HMS pastes were subjected to HPH at Homogenizing pressures of 25, 50, 75, 100, and 125 MPa. After HPH treatment, the uniformity in the microstructure of HMS pastes was greatly increased. At Homogenizing pressures greater than 100 MPa, starch ghost particles were found to completely disappear. The apparent viscosity of the HMS pastes was found to decrease significantly due to the application of HPH. The paste clarity of the HMS pastes increased when HPH treatment was applied. After storing at 4 °C for 7 days, HMS pastes homogenized at 50 and 100 MPa displayed weaker viscoelastic behavior than their corresponding unhomogenized pastes. This indicated that HPH treatment is capable of inhibiting starch retrogradation in gels.
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effect of high pressure homogenization on the structure and thermal properties of maize starch
Journal of Food Engineering, 2008Co-Authors: Aolei Wang, Yu Lung Chiu, Xiao Dong Che, Liju Wang, Zhihuai MaoAbstract:Abstract Maize starch–water suspensions (1.0%) were subjected to single-pass high-pressure homogenization treatment at 60 MPa, 100 MPa, and 140 MPa. The structure and thermal properties of the high-pressure homogenized starches were investigated using DSC, X-ray diffraction technique, laser scattering, and microscope, with native maize starch (suspended in water, but not homogenized) as a control sample. DSC analysis showed a decrease in gelatinization temperatures ( T o , T p ) and gelatinization enthalpy (Δ H gel ) with increasing Homogenizing pressure. No noticeable effect of high-pressure homogenization on the retrogradation of maize starch was observed. Laser scattering measurements of particle size demonstrated an increase in the granule size at a Homogenizing pressure of 140 MPa. This was attributed to the gelatinization and aggregation of the starch granules. X-ray diffraction patterns showed that there was an evident loss of crystallinity after homogenization at 140 MPa. Microscopy studies showed that the maize starch was partly gelatinized after high-pressure homogenization, and the gelatinized granules were prone to aggregate with each other, resulting in an increase of granule size.
Jeffrey A. Hawk - One of the best experts on this subject based on the ideXlab platform.
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Homogenizing Advanced Alloys: Thermodynamic and Kinetic Simulations Followed by Experimental Results
Journal of Materials Engineering and Performance, 2017Co-Authors: Paul D. Jablonski, Jeffrey A. HawkAbstract:Segregation of solute elements occurs in nearly all metal alloys during solidification. The resultant elemental partitioning can severely degrade as-cast material properties and lead to difficulties during post-processing (e.g., hot shorts and incipient melting). Many cast articles are subjected to a homogenization heat treatment in order to minimize segregation and improve their performance. Traditionally, homogenization heat treatments are based upon past practice or time-consuming trial and error experiments. Through the use of thermodynamic and kinetic modeling software, NETL has designed a systematic method to optimize homogenization heat treatments. Use of the method allows engineers and researchers to homogenize casting chemistries to levels appropriate for a given application. The method also allows for the adjustment of heat treatment schedules to fit limitations on in-house equipment (capability, reliability, etc.) while maintaining clear numeric targets for segregation reduction. In this approach, the Scheil module within Thermo-Calc is used to predict the as-cast segregation present within an alloy, and then diffusion controlled transformations is used to model homogenization kinetics as a function of time and temperature. Examples of computationally designed heat treatments and verification of their effects on segregation and properties of real castings are presented.