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Alejandro Várez - One of the best experts on this subject based on the ideXlab platform.

  • production of alumina parts by powder injection molding with a binder system based on high density polyethylene
    Journal of The European Ceramic Society, 2008
    Co-Authors: P Thomasvielma, Alon Cervera, Belén Levenfeld, Alejandro Várez
    Abstract:

    Abstract In this experimental work, injection molding of alumina parts was performed with a developed binder system based on high density polyethylene (HDPE), paraffin wax (PW) and stearic acid. Firstly, the optimum binder composition was determined by torque measurements and rheology. Alumina feedstocks with powder loadings between 50 and 60% in volume were prepared with the developed binder system. A suitable formulation for powder injection molding was chosen based on torque measurements, rheological Behaviour and homogeneity of feedstocks. All the feedstocks studied exhibited a pseudoplastic Behaviour with Flow Behaviour Index n

  • production of alumina parts by powder injection molding with a binder system based on high density polyethylene
    Journal of The European Ceramic Society, 2008
    Co-Authors: P Thomasvielma, Belén Levenfeld, Alberto Cervera, Alejandro Várez
    Abstract:

    Abstract In this experimental work, injection molding of alumina parts was performed with a developed binder system based on high density polyethylene (HDPE), paraffin wax (PW) and stearic acid. Firstly, the optimum binder composition was determined by torque measurements and rheology. Alumina feedstocks with powder loadings between 50 and 60% in volume were prepared with the developed binder system. A suitable formulation for powder injection molding was chosen based on torque measurements, rheological Behaviour and homogeneity of feedstocks. All the feedstocks studied exhibited a pseudoplastic Behaviour with Flow Behaviour Index n

Janis E. Swan - One of the best experts on this subject based on the ideXlab platform.

  • analysis of rheological Behaviour of titanium feedstocks formulated with a water soluble binder system for powder injection moulding
    Powder Technology, 2015
    Co-Authors: G. Thavanayagam, Kim L. Pickering, Janis E. Swan
    Abstract:

    Abstract Binder selection and formulation are critical in powder injection moulding. Binders play a key role in controlling the rheological properties of a feedstock and influence whether the resulting feedstock can be successfully injection moulded, debound and sintered without defects. A four-step process was used to mix hydride-dehydride titanium alloy (processed) powder (Ti–6Al–4V) with a polyethylene glycol (PEG) based water soluble binder system. The rheological properties, including Flow Behaviour Index, Flow activation energy, fluidity and melt Flow Index of the homogeneous feedstock, were determined with a capillary rheometer. All feedstock formulations exhibited shear thinning Flow Behaviour. The optimum feedstock consisting of 60 vol.% powder content, 32 vol.% PEG, 6 vol.% polyvinyl butyryl and 2 vol.% stearic acid was suitable for titanium injection moulding.

  • analysis of rheological Behaviour of titanium feedstocks formulated with a water soluble binder system for powder injection moulding
    Powder Technology, 2015
    Co-Authors: G. Thavanayagam, Kim L. Pickering, Janis E. Swan
    Abstract:

    Abstract Binder selection and formulation are critical in powder injection moulding. Binders play a key role in controlling the rheological properties of a feedstock and influence whether the resulting feedstock can be successfully injection moulded, debound and sintered without defects. A four-step process was used to mix hydride-dehydride titanium alloy (processed) powder (Ti–6Al–4V) with a polyethylene glycol (PEG) based water soluble binder system. The rheological properties, including Flow Behaviour Index, Flow activation energy, fluidity and melt Flow Index of the homogeneous feedstock, were determined with a capillary rheometer. All feedstock formulations exhibited shear thinning Flow Behaviour. The optimum feedstock consisting of 60 vol.% powder content, 32 vol.% PEG, 6 vol.% polyvinyl butyryl and 2 vol.% stearic acid was suitable for titanium injection moulding.

P Thomasvielma - One of the best experts on this subject based on the ideXlab platform.

  • production of alumina parts by powder injection molding with a binder system based on high density polyethylene
    Journal of The European Ceramic Society, 2008
    Co-Authors: P Thomasvielma, Alon Cervera, Belén Levenfeld, Alejandro Várez
    Abstract:

    Abstract In this experimental work, injection molding of alumina parts was performed with a developed binder system based on high density polyethylene (HDPE), paraffin wax (PW) and stearic acid. Firstly, the optimum binder composition was determined by torque measurements and rheology. Alumina feedstocks with powder loadings between 50 and 60% in volume were prepared with the developed binder system. A suitable formulation for powder injection molding was chosen based on torque measurements, rheological Behaviour and homogeneity of feedstocks. All the feedstocks studied exhibited a pseudoplastic Behaviour with Flow Behaviour Index n

  • production of alumina parts by powder injection molding with a binder system based on high density polyethylene
    Journal of The European Ceramic Society, 2008
    Co-Authors: P Thomasvielma, Belén Levenfeld, Alberto Cervera, Alejandro Várez
    Abstract:

    Abstract In this experimental work, injection molding of alumina parts was performed with a developed binder system based on high density polyethylene (HDPE), paraffin wax (PW) and stearic acid. Firstly, the optimum binder composition was determined by torque measurements and rheology. Alumina feedstocks with powder loadings between 50 and 60% in volume were prepared with the developed binder system. A suitable formulation for powder injection molding was chosen based on torque measurements, rheological Behaviour and homogeneity of feedstocks. All the feedstocks studied exhibited a pseudoplastic Behaviour with Flow Behaviour Index n

G. Thavanayagam - One of the best experts on this subject based on the ideXlab platform.

  • analysis of rheological Behaviour of titanium feedstocks formulated with a water soluble binder system for powder injection moulding
    Powder Technology, 2015
    Co-Authors: G. Thavanayagam, Kim L. Pickering, Janis E. Swan
    Abstract:

    Abstract Binder selection and formulation are critical in powder injection moulding. Binders play a key role in controlling the rheological properties of a feedstock and influence whether the resulting feedstock can be successfully injection moulded, debound and sintered without defects. A four-step process was used to mix hydride-dehydride titanium alloy (processed) powder (Ti–6Al–4V) with a polyethylene glycol (PEG) based water soluble binder system. The rheological properties, including Flow Behaviour Index, Flow activation energy, fluidity and melt Flow Index of the homogeneous feedstock, were determined with a capillary rheometer. All feedstock formulations exhibited shear thinning Flow Behaviour. The optimum feedstock consisting of 60 vol.% powder content, 32 vol.% PEG, 6 vol.% polyvinyl butyryl and 2 vol.% stearic acid was suitable for titanium injection moulding.

  • analysis of rheological Behaviour of titanium feedstocks formulated with a water soluble binder system for powder injection moulding
    Powder Technology, 2015
    Co-Authors: G. Thavanayagam, Kim L. Pickering, Janis E. Swan
    Abstract:

    Abstract Binder selection and formulation are critical in powder injection moulding. Binders play a key role in controlling the rheological properties of a feedstock and influence whether the resulting feedstock can be successfully injection moulded, debound and sintered without defects. A four-step process was used to mix hydride-dehydride titanium alloy (processed) powder (Ti–6Al–4V) with a polyethylene glycol (PEG) based water soluble binder system. The rheological properties, including Flow Behaviour Index, Flow activation energy, fluidity and melt Flow Index of the homogeneous feedstock, were determined with a capillary rheometer. All feedstock formulations exhibited shear thinning Flow Behaviour. The optimum feedstock consisting of 60 vol.% powder content, 32 vol.% PEG, 6 vol.% polyvinyl butyryl and 2 vol.% stearic acid was suitable for titanium injection moulding.

R.p. Chhabra - One of the best experts on this subject based on the ideXlab platform.

  • hindered settling in non newtonian power law liquids
    Canadian Journal of Chemical Engineering, 2009
    Co-Authors: R.p. Chhabra, A. Unnikrishnan, V Unnikrishnan R Nair
    Abstract:

    New experimental results on the hindered settling of model glass bead suspensions in non-Newtonian suspending media are reported. The data presented encompass the following ranges of variables: 7.38 × 10−4 ≤ Re1∞ ≤ 2; 0.0083 ≤ d/D ≤ 0.0703; 0.13 ≤ C ≤ 0.43 and 1 ≥ n ≥ 0.8. In these ranges of conditions, the dependence of the hindered settling velocity on concentration is adequately represented by the corresponding Newtonian expressions available in the literature. The influence of the power law Flow Behaviour Index is completely embodied in the modified definition of the Reynolds number used for power law liquids. On presente de nouveaux resultats experimentaux sur la precipitation cachee des suspensions de billes de verre dans des modeles pour des milieux en suspension non newtoniens. Les donnees presentees comprennent les gammes de variables suivantes: 7,38 × 10−4 ≤Re1∞ ≤ 2; 0,0003 ≤ d/D ≤ 0,0703; 0,13 ≤ C ≤ 0,43 et 1 ≥ n ≥ 0,8. Dans ces gammes de conditions, la dependance de la vitesse de precipitation cachee par rapport a la concentration est adequate-ment representee par les expressions newtoniennes correspondantes contenues dans la litterature scientifique. L'influence de l'indice de loi de puissance est entierement exprimee dans la definition modifiee du nombre de Reynolds utilisee pour les liquides obeissant au modele de la loi de puissance.

  • effect of blockage on heat transfer from a cylinder to power law liquids
    Chemical Engineering Science, 2007
    Co-Authors: Ram P Bharti, R.p. Chhabra, V Eswaran
    Abstract:

    Abstract The influence of planar confining walls on the steady forced convection heat transfer from a cylinder to power-law fluids has been investigated numerically by solving the field equations using FLUENT (version 6.2). Extensive results highlighting the effects of the Reynolds number ( 1 ⩽ Re ⩽ 40 ) , power-law Index ( 0.2 ⩽ n ⩽ 1.8 ) , Prandtl number ( 1 ⩽ Pr ⩽ 100 ) and the blockage ratio ( β = 4 and 1.6) on the average Nusselt number have been presented. For a fixed value of the blockage ratio, the heat transfer is enhanced with the increasing degree of shear-thinning Behaviour of the fluid, while an opposite trend was observed in shear-thickening fluids. Due to the modifications of the Flow and temperature fields close to the cylinder, the closely placed walls (i.e., decreasing value of the blockage ratio) further enhance the rate of heat transfer as the fluid Behaviour changes from Newtonian to shear-thickening fluids ( n > 1 ) , the opposite influence is seen with the decreasing value of the Flow Behaviour Index ( n ) in shear-thinning ( n 1 ) fluids. Finally, the functional dependence of the present numerical results on the relevant dimensionless parameters has been presented in the form of closure relationships for their easy use in a new application.

  • non isothermal Flow of a power law fluid past a rectangular obstacle of aspect ratio 1 2 in a channel drag and heat transfer
    International Journal of Engineering Science, 2005
    Co-Authors: S Nitin, R.p. Chhabra
    Abstract:

    Abstract A two-dimensional numerical study has been carried out to investigate the drag and Nusselt number characteristics under forced convection conditions between a streaming power law liquid and a rectangle (with its longer side aligned with the direction of Flow) placed symmetrically between two solid walls. In particular, the values of the individual and total drag coefficients, and of the Nusselt number are obtained as functions of the Flow Behaviour Index (1.4 ⩾ n ⩾ 0.5), of Reynolds number (5 ⩽ Re ⩽ 40) and of the Peclet number (5 ⩽ Pe ⩽ 400) for a fixed value of the blockage ratio (1/8). Within these ranges of kinematic and rheological conditions, the drag and Nusselt number show only fair to moderate deviation from the corresponding Newtonian values at the same values of the Reynolds and Peclet numbers. Qualitatively speaking, the shear-thinning Behaviour (n   1) causes both the drag and heat transfer to drop below the corresponding Newtonian values. The power-law fluid Behaviour does not seem to alter the streamline, isovorticity and isotherm plots in a significant manner, except for the fact that the shear-thinning Behaviour not only delays the formation of a visible wake but the resulting wake is also somewhat shorter than that in a Newtonian fluid. The shear thickening, on the other hand, has exactly the opposite influence on wake formation.

  • power law fluid Flow past a square cylinder momentum and heat transfer characteristics
    Chemical Engineering Science, 2003
    Co-Authors: B Paliwal, R.p. Chhabra, Atul Sharma, V Eswaran
    Abstract:

    The momentum and forced convection heat transfer characteristics for an incompressible and steady free stream Flow of power law liquids past a square cylinder have been investigated numerically. The momentum and energy equations have been solved by using a finite difference based numerical solution procedure for a range of rheological and kinematic conditions as follows: power law Index, n: 0.5 to 1.4 thereby covering both shear-thinning and shear-thickening Behaviour, Reynolds number (based on cylinder size), Re: 5 to 40 and Peclet number, Pe: 5 to 400. However, all computations have been performed for one blockage ratio L/H=115. Furthermore, the influence of the type of thermal boundary condition, i.e., the constant heat flux and the constant temperature at the surface of the cylinder, has also been studied. Overall, when the drag coefficient and Nusselt number are normalized using the corresponding Newtonian values, these ratios show only marginal additional dependence on the Flow Behaviour Index. The shear-thinning not only reduces the size of the wake region but it also delays the wake formation and shear-thickening Behaviour shows the opposite effect.