Influence of cassava starch content and sintering temperature on the alumina consolidation technique

Almeida, F.A.; Botelho, Edson Cocchieri; Melo, Francisco Cristóvão Lourenço de; Campos, Tiago Moreira Bastos; Thim, Gilmar Patrocínio

doi:10.1016/j.jeurceramsoc.2008.10.006

Cited by 45 publications

(26 citation statements)

References 35 publications

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“…As a consequence for any of the sintering temperatures tested, total porosity of sintered specimens (e S ) increases linearly when starch content rises, since it is calculated on the basis of bulk density and average real density of the sintered composition (3.22±0.02 g•cm -3 ) (Figure 4). A similar tendency was also obtained by other authors using different starch contents and membrane's preparation methods [9,10,42,45].…”

Section: Microstructure Assessment Of Sintered Membranessupporting

confidence: 88%

Influence of starch content on the properties of low-cost microfiltration ceramic membranes

Lorente-Ayza

Sánchez

Sanz

et al. 2015

Ceramics International

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The use of starch as pore former is frequent in the fabrication of porous ceramic membranes, since starches are cheap, innocuous and environmentally friendly. A study has been conducted to evaluate the influence of potato starch content (0-30 wt %) and sintering temperature (1100 and 1400ºC) on low-cost ceramic microfiltration membranes. The raw materials were a mixture of kaolin, alumina and starch, from which membrane specimens were shaped by uniaxial dry pressing.The results indicated that the percentage of potato starch did affect the properties of the membrane. Thus, an increase of starch content provoked a reduction of bulk density (an increase of porosity) a rise of water permeability and a substantial modification (coarsening) of the pore size distribution. This effect deals with the role as pore former of starch, which burns out when fired. More interestingly, it was experimentally observed that the effect of starch was particularly effective for starch percentages higher than 10 wt% once a connected coarse pore network is developed. On the other hand, an increase in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2 sintering temperature from 1100 to 1400ºC also influenced membranes' characteristics but the effect was much less significant than that of starch content. *Manuscript Click here to view linked ReferencesA percolation analysis based on the Effective Medium Approximation (EMA) contact model allowed to conclude that the critical porosity calculated corresponds to a starch content of 10.2 wt%, which agrees quite well with the estimation from experimental results. Finally, tortuosity was calculated with a simple model derived from Hagen-Poiseuille equation. The obtained data showed that tortuosity factor decreased as the starch content or sintering temperature increased. These findings are consistent with SEM analysis and pore size determination.

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Section: Microstructure Assessment Of Sintered Membranessupporting

confidence: 88%

Influence of starch content on the properties of low-cost microfiltration ceramic membranes

Lorente-Ayza

Sánchez

Sanz

et al. 2015

Ceramics International

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“…These effects are a consequence of the sintering process, which takes place in the presence of the liquid phase provided by the alkaline and alkaline-earth oxide content in the starting raw materials. In addition, as extensively reported in the literature, the addition of starch substantially increases the porosity and shift pore size distribution of the sintered membranes to coarser pore size due to the burnout of the starch during the firing process, regardless of the forming process (pressing or extrusion) [20], [28], [41]- [45]. Finally, it was also observed that increasing the amount of clay in the composition (P2 and E2 against P1 and E1, respectively) drastically decreased the pore size (curves shift to the left) as a consequence of the higher amount of colloidal particles provided by the clay.…”

Section: Membrane Physical Characterizationsupporting

confidence: 60%

“…As explained below, the different microstructures obtained by pressing or extruding ceramics could explain this fact [34], [35]. However, this difference tended to decrease (the pore size distribution curves of the P3 and E3 bodies almost coincide) when starch was added to the initial compositions, as a consequence of the drastic change in microstructure developed by the starch burnout [20], [28], [41]- [44]. With regard to open porosity, no significant differences associated with the shaping process were found.…”

Section: Membrane Physical Characterizationmentioning

confidence: 99%

Comparison of extruded and pressed low cost ceramic supports for microfiltration membranes

Lorente-Ayza

Mestre

Menéndez

et al. 2015

Journal of the European Ceramic Society

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A comparison has been made between ceramic microfiltration membranes of the same composition obtained by pressing and by extrusion in terms of microstructure and properties.The extruded membranes displayed lower porosity and smaller pore size than pressed membranes. The higher the clay content in the starting composition, the clearer this tendency became. In contrast, the difference tended to disappear when starch was added to the initial composition. The mechanical strength values followed a decreasing exponential variation with porosity, which was influenced by the starting composition and the shaping method.Water permeability reflected the strong effect of the mean pore size. The membranes synthesised from the composition with the higher clay content showed the lowest permeability, while those obtained from the composition including starch showed the highest value. A model derived from the Hagen-Poiseuille equation enabled the tortuosity values to be calculated.

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“…coming from different origins: cereal, root, tuber, etc.) can be used [9][10][11][12] . Starch has two functions in this process; primary is added to the ceramic composition as a fugitive additive.…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies revealed that by adjusting the thermal treatment significant variation in pore structure such as pore volume fraction, shape and size of resulting pores, can be achieved [10][11][12][13][14] . Some of these stages are common with conventional dry processing methods which use fugitive inclusions as pore forming agents.…”

Section: Introductionmentioning

confidence: 99%

Influence of starch type on characteristics of porous 3Y-ZrO2 prepared from a direct consolidation casting method

Garrido¹,

Albano²,

Gênova

et al. 2011

Mat. Res.

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Starch consolidation casting has been successfully used to produce porous ceramics with complex shapes at a relatively low producing cost. In this work, porous 3Y-ZrO 2 ceramics were produced using two types of starch (corn and potato). Concentrated (50-52 vol. (%)) aqueous suspensions of the different 3Y-ZrO 2 -starch mixtures (i.e. starch to zirconia weight ratios between 0.20 and 0.52) were thermally consolidated and the effect of the type and amount of added starch on properties of resultant dried product was examined. After starch granules burnout, the effect of sintering temperature varying between 1000 and 1500 °C on the porosity evolution, interconnection and morphology of pores and microstructure of final ceramic was followed by water absorption measurements, Hg porosimetry and scanning electron microscopy SEM. Typical microstructure of the ceramic sintered at 1500 °C consisted of large nearly spherical pores (created by starch) uniformly distributed in a dense ZrO 2 matrix. As the content of starch in the dried product (expressed as volume fraction) X st is increased from 0.23 to 0.65, porosity of the ceramic sintered at 1500 °C increased from 38 to 52 vol. (%) for corn starch, while it achieved 50 to 54 vol. (%) for potato starch; thus, lower X st of potato starch developed a porous zirconia with higher porosity. In this case, the pore structure contained pores having sizes above 50 μm and resulted completely interconnected while for those prepared using corn starch the pore interconnection occurred for X st above 0.50.

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Influence of cassava starch content and sintering temperature on the alumina consolidation technique

Cited by 45 publications

References 35 publications

Influence of starch content on the properties of low-cost microfiltration ceramic membranes

Influence of starch content on the properties of low-cost microfiltration ceramic membranes

Comparison of extruded and pressed low cost ceramic supports for microfiltration membranes

Influence of starch type on characteristics of porous 3Y-ZrO2 prepared from a direct consolidation casting method

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