Electron Microscopy of Modified Aluminum Alkoxide Microstructures on Freeze–Drying

Srivastava, Anuj; Menon, Ashok; Bellare, Jayesh

doi:10.1006/jcis.1997.4946

Cited by 1 publication

(1 citation statement)

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“…Cryo-SEM is an analytical technique which is widely used by biologists or chemists [1][2][3][4] , or by the food industry [5][6][7][8] , to observe hydrated samples without destroying their initial structure in the presence of water. In materials science, it has already allowed investigating suspensions with particles such as silica or latex [9][10][11] , the hydration state advancement of cement 12 , or the structure of gels 13 . The knowledge of the dispersion state of suspension is indeed a key parameter for many ceramic processing routes such as slip coagulation casting, fabrication of homogeneous coatings or spray drying.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Dispersion State of Alumina Suspensions: Contribution of Cryo-Field-Emission Gun Scanning Electron Microscopy Characterizations

Lasalle

Guizard

Deville

et al. 2010

Journal of the American Ceramic Society

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We illustrate in this paper the interest of cryo-field-emission gun scanning electron microscopy (cryo-FEGSEM) to investigate the stability of alumina suspensions. The stability is investigated through viscosity, zeta potential, total organic carbon measurements, and cryo-FEGSEM observations. We focus on two examples: the effect of the quantity of ammonium polyacrylate as dispersant and the effect of its chain length on alumina particles dispersion with a solid content of 32 vol%. In the first example for some suspensions, we measure values of viscosity or zeta potential too similar to discriminate the best state of dispersion. To overcome this problem, we directly observe the suspensions with cryo-FEGSEM. We take advantage of the recent developments of the technique, which provide now extremely high cooling rates and ensure that the freezing step does not induce observations artifacts related to the formation of ice. This technique provides an accurate vision of particles dispersion, agglomeration in ceramic suspensions, and it is possible to visualize the excess of dispersant. In the second example, the longer dispersant appears to be the more effective to obtain the best state of dispersion. Through both examples, we demonstrate that to have the best interpretation of results, it is useful to combine direct observations by cryo-FEGSEM and the usual properties measurements.

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