Mechanical properties of individual MgAl2O4 agglomerates and their effects on densification

The presence of agglomerates during nanopowder sintering can be problematic and can limit achievable final densities. Typically, the practical solution is to use high pressures to overcome agglomerate breakdown strengths to reach higher packing fractions. The strength of agglomerates is often diffic...

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Bibliographic Details
Published inActa materialia Vol. 69; pp. 187 - 195
Main Authors Rufner, Jorgen F., Castro, Ricardo H.R., Holland, Troy B., van Benthem, Klaus
Format Journal Article
LanguageEnglish
Published Kidlington Elsevier Ltd 01.05.2014
Elsevier
Subjects
Agglomerates
Applied sciences
Correlation
Densification
Exact sciences and technology
In situ TEM
Mathematical models
Mechanical properties
Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology
Metals. Metallurgy
MgAl2O4 spinel
Nanoindentation
Nanoparticle agglomerates
Nanostructure
Porous ceramics
Process parameters
Strength
MgAl2O4 spinel
Nanoparticle agglomerates
Porous ceramics
In situ TEM
Nanoindentation
MgAl
Densification
Nanoparticle
In situ
Mechanical properties
Indentation
O
spinel
Transmission electron microscopy
Ceramic materials
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Summary:The presence of agglomerates during nanopowder sintering can be problematic and can limit achievable final densities. Typically, the practical solution is to use high pressures to overcome agglomerate breakdown strengths to reach higher packing fractions. The strength of agglomerates is often difficult to determine and makes processing parameters challenging to optimize. In this work, we used in situ transmission electron microscopy nanoindentation experiments to assess the mechanical properties of individual MgAl2O4 agglomerates under constant indenter head displacement rates. Electron microscopy revealed highly porous agglomerates with pores on both the micron and nanometric length scales. Individual agglomerate strength, at fracture, was calculated from compression tests with deformation behavior correlating well with previously reported modeling results. Macroscopic powder properties were also investigated using green-pressed pellets consolidated at pressures up to 910MPa. The unexpectedly high strength is indicative of the role agglomerates play in MgAl2O4 nanopowder densification.
Bibliography:ObjectType-Article-1
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ISSN:1359-6454
1873-2453
DOI:10.1016/j.actamat.2014.01.051