ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 82 (1999), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The thermodynamic equilibrium between a thin liquid phase and adjoining grains of a co-existing solid phase is treated, using a diffuse interface formulation applied to a multilayer of liquid and solid phases. The analysis leads to spatial variation in composition, which minimizes the overall free energy. The overall energy includes a gradient-energy contribution. For a fixed overall composition, the equilibrium concentration profile is dependent on the thicknesses of the two phases, relative to the interface width (a characteristic-length scale in the analysis). When the thickness of the liquid phase approaches the characteristic length, its composition can deviate markedly from the bulk liquid-phase composition. In the absence of any stabilizing interactions, such as repulsive structural and electrostatic forces, the analysis indicates that there is a driving force for thinning of the film and a minimum thickness exists at which it becomes favorable for the film to dissolve. Therefore, the observations of equilibrium film thicknesses in certain ceramics imply that, in those materials, additional stabilizing forces must exist between the grains.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 83 (2000), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A model experiment is presented to investigate the relationship between the humidity-dependent liquid distribution and the macroscopic stress in a partially wet powder compact. Therefore, films of monosized spherical particles were cast on silicon substrates. Using environmental SEM the geometry of the liquid necks trapped between particles was imaged as a function of relative humidity. Simultaneously the macroscopic stress in the substrate adhered particle film was measured by capacitive deflection measurement. The experimentally found humidity dependence of the liquid neck size and the macroscopic film stress are compared with model predictions. The circle–circle approximation is used to predict the size of the liquid necks between touching particles as a function of the capillary pressure. Using the modified Kelvin relation between capillary pressure and relative humidity, we consider the effect of an additional solute which may be present in the capillary liquid. The results of the stress measurement are compared with the model predictions for a film of touching particles in hexagonal symmetry. The contribution of the capillary interaction to the adhesion force between neighboring particles is calculated using the integrated Laplace equation. The resulting film stress can be approximated relating this capillary force to an effective cross section per particle. The experimentally found humidity dependence of the liquid neck size is in good agreement with the model predictions for finite solute concentration. The film stress corresponds to the model predictions only for large relative humidities and shows an unexpected increase at small values. As is shown with an atomic force microscope, the real structure of the particle–particle contact area changes during the wet/dry cycle. A solution/reprecipitation process causes surface heterogeneities and solid bridging between the particles. It is claimed that the existence of a finite contact zone between the particles gives rise to the unexpected increase of the stress at small relative humidities.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...