Effects of heteroflocculation of powders on mechanical properties of zirconia alumina composites

Konsztowicz, Krzysztof J.; Langlois, Richard N.

doi:10.1007/bf00357875

Cited by 16 publications

(10 citation statements)

References 25 publications

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“…It is well known that non‐adsorbing and strongly adsorbing nanoparticle species can alter colloidal stability via entropic depletion interactions 8–11 or heteroflocculation, 12–16 respectively. The term “depletion” describes the exclusion of these smaller species from the gap region between colloidal particles that arises when the colloid separation distance becomes less than the characteristic nanoparticle size.…”

Section: Introductionmentioning

confidence: 99%

Phase Behavior, 3‐D Structure, and Rheology of Colloidal Microsphere–Nanoparticle Suspensions

Rhodes

Lewis

2006

Journal of the American Ceramic Society

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A new route for tailoring the behavior of colloidal suspensions through nanoparticle additions is reviewed. Specifically, the interparticle interactions, phase behavior, 3-D structure, and rheological properties of microsphere-nanoparticle mixtures that possess both high charge and size asymmetry are described. Negligibly charged microspheres, which flocculate when suspended alone, undergo a remarkable stabilizing transition upon the addition of highly charged nanoparticles. The formation of a dynamic nanoparticle halo around each colloid induces an effective repulsion between the microspheres that promotes their stability. With increasing nanoparticle concentration, the colloids again undergo flocculation because of the emergence of an effective microsphere attraction, whose magnitude exhibits a quadratic dependence on nanoparticle volume fraction. The broader impact of these observations on colloidal stabilization and assembly of advanced ceramics is highlighted.

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Section: Introductionmentioning

confidence: 99%

Phase Behavior, 3‐D Structure, and Rheology of Colloidal Microsphere–Nanoparticle Suspensions

Rhodes

Lewis

2006

Journal of the American Ceramic Society

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“…When the microsphere−nanoparticle interactions are strongly attractive, heteroflocculation ensues due to nanoparticle bridging . This aggregation mechanism is relevant for many technological applications including the assembly of core−shell composite particles, ceramics, pigments, coatings, and even pharmaceutical materials …”

Section: Introductionmentioning

confidence: 99%

Phase Behavior and 3D Structure of Strongly Attractive Microsphere−Nanoparticle Mixtures

et al. 2005

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We investigate the phase behavior and 3D structure of strongly attractive mixtures of silica microspheres and polystyrene nanoparticles. These binary mixtures are electrostatically tuned to promote a repulsion between like-charged (microsphere-microsphere and nanoparticle-nanoparticle) species and a strong attraction between oppositely charged (microsphere-nanoparticle) species. Using confocal fluorescence scanning microscopy, we directly observe the 3D structure of colloidal phases assembled from these mixtures as a function of varying composition. In the absence of nanoparticle additions, the charged-stabilized microspheres assemble into a polycrystalline array upon sedimentation. With increasing nanoparticle volume fraction, nanoparticle bridges form between microspheres, inducing their flocculation. At even higher nanoparticle volume fractions, the microspheres become well coated with nanoparticles, leading to their charge reversal and subsequent restabilization. We demonstrate how this fluid-gel-fluid transition can be utilized to control the morphology of the colloidal phases formed under gravity-driven sedimentation.

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“…In ZTA with 8-15 vol% zirconia the favorable properties of alumina can be maintained since ZTA is nearly as hard and as thermally conductive as pure alumina. The zirconia may introduce extra toughening [8][9][10] and lead to a smaller (submicrometer) grain size in the ceramics. The enhanced toughness of the alumina phase may be caused by a latent possibility of martensitic phase transformation of the zirconia phase, but toughening due to crack-deflection is also possible, especially because of the small grain sizes used in the present study.…”

Section: Introductionmentioning

confidence: 99%

“…A homogeneous distribution of small zirconia particles also acts as an impediment for alumina grain growth during sintering. 9,11 He et al 3 studied dry-sliding wear of ZTA, among others. The authors showed that the value of the mild-to-severe weartransition load depends on the following:…”

Section: Introductionmentioning

confidence: 99%

“…[12][13][14] Trabelsi et al 10 stated that the addition of zirconia to alumina results in a material with a lower wear resistance due to the decrease in hardness. Most investigators conclude, however, 3,9 that an optimum amount of zirconia of 10-12 vol% exists, which provides enough improvement in toughness and decreased grain size to compensate for the lower hardness. Kamiya et al 15 performed collision tests (erosive wear) on alumina and ZTA ceramics with Al 2 O 3 or SiC particles and showed that ZTA had the lowest wear rate.…”

Section: Introductionmentioning

confidence: 99%

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Processing of Homogeneous Zirconia‐Toughened Alumina Ceramics with High Dry‐Sliding Wear Resistance

Kerkwijk

Winnubst

Mulder

et al. 1999

Journal of the American Ceramic Society

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The preparation of dense homogeneous zirconia-toughened alumina (ZTA) with high dry-sliding wear resistance is described. These ZTA ceramics are obtained by sintering green compacts, made by colloidal filtration of well-defined ZrO 2 -Al 2 O 3 particle suspensions, for 2 h at 1400°C. The optimum solid and stabilizer concentrations for the filtration process were determined. The sintered ZTA microstructure consists of a homogeneous distribution of zirconia grains in an alumina matrix with grain sizes of 0.2 and 0.5 µm, respectively. In pin-on-disk tribological measurements at relatively high initial contact pressures (1130 MPa) and sliding speeds (0.5 m/s) a very low specific wear rate (about 5 × 10 −8 mm 3 /(Nؒm)) and a coefficient of friction of 0.45-0.55 were found. It is shown that, in this case, wear is dominated by abrasion and polishing.

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Effects of heteroflocculation of powders on mechanical properties of zirconia alumina composites

Cited by 16 publications

References 25 publications

Phase Behavior, 3‐D Structure, and Rheology of Colloidal Microsphere–Nanoparticle Suspensions

Phase Behavior, 3‐D Structure, and Rheology of Colloidal Microsphere–Nanoparticle Suspensions

Phase Behavior and 3D Structure of Strongly Attractive Microsphere−Nanoparticle Mixtures

Processing of Homogeneous Zirconia‐Toughened Alumina Ceramics with High Dry‐Sliding Wear Resistance

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