Rheology of powder suspensions is a key factor in many processing routes, and better understanding of the parameters that control the rheology improves technical progress by reducing the empirical factors in the formulation of powder slurries. The strict requirements for the production of transparent polycrystalline alumina demand a fundamental understanding of powder handling and processing steps. The use of dopants (Mg, Y, La) has proven useful, but produces noticeable effects on suspension rheology and influences the choice of the processing route. With the prospect of spray granulation of such slurries, the rheological behaviour of doped alumina suspensions was investigated from a fundamental approach taking into account slurry and particle characteristics, and computing the interparticle potentials. This information was then used in a yield stress model which successfully predicted the rheological behaviour of the doped alumina slurries. A strategy for improved slurry formulation is presented.
BowenP, CarryC, LuxembourgD, HofmannH: ‘Colloidal processing and sintering of nanosized transition aluminas’, Powder Technol., 2005, 157, (1–3), 100–107.
2.
LangeFF: ‘Colloidal processing of powder for reliable ceramics’, Curr. Opin. Solid State Mater. Sci., 1998, 3, (5), 496–500.
3.
LangeFF, YuBC: ‘Shape forming alumina slurries via colloidal isopressing’, J. Eur. Ceram. Soc., 2010, 30, (14), 2795–2803.
4.
NovakS, DakskoblerA, RibitschV: ‘The effect of water on the behaviour of alumina-paraffin suspensions for low-pressure injection moulding (LPIM)’, J. Eur. Ceram. Soc., 2000, 20, (12), 2175–2181.
FlattRJ, BowenP: ‘Yodel: a yield stress model for suspensions’, J. Am. Ceram. Soc., 2006, 89, (4), 1244–1256.
11.
ThieleES, SetterN: ‘Lead zirconate titanate particle dispersion in thick-film ink formulations’, J. Am. Ceram. Soc., 2000, 83, (6), 1407–1412.
12.
AschauerU, Burgos-MontesO, MorenoR, BowenP: ‘Hamaker 2: a toolkit for the calculation of particle interactions and suspension stability and its application to mullite synthesis by colloidal methods’, J. Dispers. Sci. Technol., 2011, 32, (4), 470–479.
13.
HofmannH, JuilleratF, BowenP: ‘Formation and drying of colloidal crystals using nanosized silica particles’, Langmuir, 2006, 22, (5), 2249–2257.
14.
RingTA: ‘Fundamentals of ceramic powder processing and synthesis’; 1996, San Diego, CA, Academic Press Inc.
15.
DakskoblerA, KosmacT: ‘Rheological properties of re-melted paraffin-wax suspensions used for LPIM’, J. Eur. Ceram. Soc., 2009, 29, (10), 1831–1836.
16.
FlattRJ, BowenP: ‘Yield stress of multimodal powder suspensions: an extension of the YODEL (yield stress mODEL)’, J. Am. Ceram. Soc., 2007, 90, (4), 1038–1044.
17.
RousselN, LemaitreA, FlattRJ, CoussotP: ‘Steady state flow of cement suspensions: a micromechanical state of the art’, Cem. Concr. Res., 2010, 40, (1), 77–84.
18.
HoustYF, BowenP, PercheF, KauppiA, BorgetP, GalmicheL, MeinsJFLe, LafumaF, FlattRJ, SchoberI, BanfillPFG, SwiftDS, MyrvoldBO, PetersenBG, ReknesK: ‘Design and function of novel superplasticizers for more durable high performance concrete (superplast project)’, Cem. Concr. Res., 2008, 38, (10), 1197–1209.
19.
StuerM, ZhaoZ, AschauerU, BowenP: ‘Transparent polycrystalline alumina using spark plasma sintering: effect of Mg, Y and La doping’, J. Eur. Ceram. Soc., 2010, 30, (6), 1335–1343.
20.
ApetzR, BruggenMPBvan: ‘Transparent alumina: a light-scattering model’, J. Am. Ceram. Soc., 2003, 86, (3), 480–486.
21.
KrellA, BlankP, MaHW, HutzlerT, NebelungM: ‘Processing of high-density submicrometer Al2O3 for new applications’, J. Am. Ceram. Soc., 2003, 86, (4), 546–553.
22.
KrellA, BlankP, MaHW, HutzlerT, BruggenMPBvan, ApetzR: ‘Transparent sintered corundum with high hardness and strength’, J. Am. Ceram. Soc., 2003, 86, (1), 12–18.
23.
KrellA, KlimkeJ: ‘Effects of the homogeneity of particle coordination on solid-state sintering of transparent alumina’, J. Am. Ceram. Soc., 2006, 89, (6), 1985–1992.
24.
LyckfeldtO, KackD, RundgrenK: ‘Pressing and sintering developments of freeze granulated Si3N4 materials’, Ceram. Eng. Sci. Proc., 2003, 24, (4), 331–336.
25.
LyckfeldtO, RundgrenK, SjostedtM: ‘Freeze granulation for the processing of silicon nitride ceramics’, Key Eng. Mater., 2004, 264–268, 281–284.
26.
MendelsonMI: ‘Average grain size in polycrystalline ceramics’, J. Am. Ceram. Soc., 1969, 52, (8), 443–446.
27.
PecharromanC, Mata-OsoroG, DiazLA, TorrecillasR, MoyaJS: ‘On the transparency of nanostructured alumina: Rayleigh–Gans model for anisotropic spheres’, Opt. Express, 2009, 17, (8), 6899–6912.
28.
StuerM, ZhaoZ, BowenP: ‘Freeze granulation: powder processing for transparent alumina applications’, Submitted to J. Eur. Ceram. Soc., Special topic on transparent ceramics, 2012.
EvansHWDF: ‘The colloidal domain: where physics, chemistry, biology, and technology meet’, 672; 1999, New York, Wiley-VCH.
31.
Bernard-GrangerG, BenameurN, GuizardC, NygrenM: ‘Influence of graphite contamination on the optical properties of transparent spinel obtained by spark plasma sintering’, Scr. Mater., 2009, 60, (3), 164–167.
32.
BergstromL, KjeldsenAM, FlattRJ: ‘Relating the molecular structure of comb-type superplasticizers to the compression rheology of MgO suspensions’, Cem. Concr. Res., 2006, 36, (7), 1231–1239.
