The manufacture of spherical salt beads and their use as dissolvable templates for the production of cellular solids via a powder metallurgy route

Jinnapat, A.; Kennedy, Andrew R.

doi:10.1016/j.jallcom.2010.03.132

Cited by 45 publications

(28 citation statements)

References 15 publications

(21 reference statements)

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“…Sodium chloride (NaCl or salt) powder with 99.5% purity was processed into near-spherical beads (with an aspect ratio of 1.14±0.02) using a method outlined in [25,26]. Beads with diameters between 1.0 and 1.4 mm were selected by sieving.…”

Section: Methodsmentioning

confidence: 99%

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Porous poly-ether ether ketone (PEEK) manufactured by a novel powder route using near-spherical salt bead porogens: Characterisation and mechanical properties

Siddiq

Kennedy

2015

Materials Science and Engineering: C

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Porous PEEK structures with approximately 85% open porosity have been made using PEEK-OPTIMA® powder and a particulate leaching technique using porous, near-spherical, sodium chloride beads. A novel manufacturing approach is presented and compared with a traditional dry mixing method. Irrespective of the method used, the use of near-spherical beads with a fairly narrow size range results in uniform pore structures. However the integration, by tapping, of fine PEEK into a pre-existing network salt beads, followed by compaction and "sintering", produces porous structures with excellent repeatability and homogeneity of density; more uniform pore and strut sizes; an improved and predictable level of connectivity via the formation of "windows" between the cells; faster salt removal rates and lower levels of residual salt. Although tapped samples show a compressive yield stress > 1 MPa and stiffness > 30 MPa for samples with 84% porosity, the presence of windows in the cell walls means that tapped structures show lower strengths and lower stiffnesses than equivalent structures made by mixing.

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Section: Methodsmentioning

confidence: 99%

“…PEEK and NaCl beads were also combined using a tapping-based process previously applied to metal powders [25]. In this process, 4.2 g of salt beads were poured into the cavity of a 22 mm diameter die (with the bottom punch in place) and packing was enhanced by brief tapping using the same Autotap machine as described earlier.…”

Section: Methodsmentioning

confidence: 99%

Porous poly-ether ether ketone (PEEK) manufactured by a novel powder route using near-spherical salt bead porogens: Characterisation and mechanical properties

Siddiq

Kennedy

2015

Materials Science and Engineering: C

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“…Details of the materials and methods used to make the beads are given in [10,11,19]. Castings were made by pouring salt beads (with different volumetric fractions of large and small beads, mixed using a turbula mixer) into a 35mm diameter flanged stainless steel mould with a porous base.…”

Section: Materials and Methods: Preparation Of Porous Samplesmentioning

confidence: 99%

Discrete element modelling of the packing of spheres and its application to the structure of porous metals made by infiltration of packed beds of NaCl beads

Langston

Kennedy

2014

Powder Technology

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Discrete element modelling of the packing of spheres and its application to the structure of porous metals made by infiltration of packed beds of NaCl beads. Powder Technology, Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/34443/7/DEM%20porous%20metals%20-%20Powder %20Technology.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the Creative Commons Attribution Non-commercial No Derivatives licence and may be reused according to the conditions of the licence. For more details see: http://creativecommons.org/licenses/by-nc-nd/2.5/ A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. AbstractA numerical model, using the discrete element method, has been developed to quantify specific parameters that are pertinent to the packing behaviour of relatively large, spherical NaCl beads and mixtures of beads of different sizes. These parameters have been compared with porosity and connectivity measurements made on porous aluminium castings made by molten metal infiltration into packed beds of such beads, after removal of the NaCl by dissolution. DEM has been found to accurately predict the packing fraction for salt beads with both monosized and binary size distributions and from this the pore fractions in castings made by infiltration into packed beds of beads could be predicted. Through simple development of the condition for contacting of neighbouring beads, the number of windows linking neighbouring pores, and their size, could also be predicted across a wide range of small bead additions. The model also enables an insight into the mixing quality and changes in connectivity introduced through the addition of small beads. This work presents significant progress towards the delivery of a 2 simulation-based approach to designing preform architectures in order to tailor the resulting porous structures to best suit specific applications. KeywordsDiscrete element method; particle packing; coordination number; porous metals; IntroductionPorous metals exhibit important characteristics which enable them to perform well in heat transfer applications. The high thermal conductivity of solid ligaments, the large surface area to volume ratios and their tortuous flow paths, which generate turbulence and high level-mixing in the cooling fluid, offer the potential for devices made from porous metals (for example high power electronic devices [1,2], heat shields, regenerators for thermal engines and thermal energy storage devices incorporating phase change materials [3]) to be compact, efficient and light weight.Experimental measurement and modelling [4][5][6][7] have sho...

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“…These are more stable during infiltration, easily leached and as a result a highly porous metal structure can be created (see Figure 6b). In some methods, sieved salt particles are added to a rubber mold, where they are evenly distributed under vibration and then cold isostatically pressed (5 MPa up to 60 MPa [31] ) to produce a porous compact. Another method of preform fabrication is to pour moistened NaCl grains into a core box, then dehumidify and harden at 200 C to develop stable necks between the salt grains after 1-3 h. [3] Figure 4.…”

Section: Preform Infiltrationmentioning

confidence: 99%

Current Status and Recent Developments in Porous Magnesium Fabrication

et al. 2017

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A significant number of studies have been dedicated to the fabrication and properties of metallic foams. The most recent research is focused on metals with low weight and good mechanical properties, such as titanium, aluminum, and magnesium. Whereas the first two are already fairly well studied and already find application in industry, magnesium currently remains at the research stage. The present review covers the studies conducted on fabrication techniques, surface modifications, and properties of porous structures made of magnesium and its alloys.

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The manufacture of spherical salt beads and their use as dissolvable templates for the production of cellular solids via a powder metallurgy route

Cited by 45 publications

References 15 publications

Porous poly-ether ether ketone (PEEK) manufactured by a novel powder route using near-spherical salt bead porogens: Characterisation and mechanical properties

Porous poly-ether ether ketone (PEEK) manufactured by a novel powder route using near-spherical salt bead porogens: Characterisation and mechanical properties

Discrete element modelling of the packing of spheres and its application to the structure of porous metals made by infiltration of packed beds of NaCl beads

Current Status and Recent Developments in Porous Magnesium Fabrication

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