ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
  • 11
    Electronic Resource
    Electronic Resource
    Measuring Permeability of Rigid Materials by a Beam-Bending Method: I, Theory (2000)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 83 (2000), S. 0 
    Details
    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: When a saturated porous material is deformed, pressure gradients are created in the liquid, and the liquid flows within the pores to equilibrate the pressure. This phenomenon can be exploited to measure permeability: A rod of saturated porous material is instantaneously bent by a fixed amount, and the force required to sustain the deflection is measured as a function of time. The force decreases as the liquid flows through the pore network, and the rate of decrease depends on the permeability. This technique has been applied successfully to determine the permeability of gels, as well as their viscoelastic properties; in this paper the method is extended to ceramic materials, such as porous glass and cement paste. The theory has been modified to take account of the compressibility of the solid and liquid phases (whereas, those factors are negligible for gels). Analyses are presented for constant deflection, constant rate of deflection, and sinusoidal oscillation, where the solid phase is either purely elastic or viscoelastic, and the beam is either cylindrical or square. Experimental tests on Vycor® glass and cement paste will be presented in companion papers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.2000.tb01540.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Coarsening in a Viscous Matrix (1998)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 81 (1998), S. 0 
    Details
    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: When a viscous material is three-dimensionally constrained (as when a gel or slurry of glass is infiltrated into the interstices of a particle packing), heat treatment leads to coarsening of the pore-size distribution, rather than densification. The smaller pores generate greater capillary pressure; therefore, they shrink and force the large pores to expand. In this article, the kinetics of coarsening are analyzed, and sample calculations are performed for a body with a lognormal distribution of pore sizes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1998.tb02294.x
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Silicate Consolidants for Stone (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 391 (Oct. 2008), p. 1-25 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Consolidants are sols or solutions that are used to restore the strength of weathered stone.The liquids are drawn into the pores of stone by capillary suction, then they harden by gelationand/or drying. In this chapter, we discuss the requirements that such a material must fulfill, anddemonstrate the effectiveness of consolidants based on alkoxysilanes and alkylalkoxysilanes
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/57/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.391.1.pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Sintering of Sol-Gel Films (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 353-363 
    Details
    ISSN: 1573-4846
    Keywords: sintering ; stress ; constraint ; crystallization ; nucleation ; film ; substrate ; rapid thermal annealing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The sintering of films differs from that of bulk gels in several ways. The initial state of a film is generally denser and less crosslinked than a bulk gel made from the same sol, and these factors enhance the densification rate of the film. The substrate constrains the shrinkage of the film, leading to high stresses that retard densification and can influence phase changes. The substrate is a site for heterogeneous nucleation, and crystallization makes densification more difficult, so the competition between sintering and crystallization is particularly important for films. Fast heating favors densification over crystallization, so rapid thermal annealing usually produces denser films. The high surface to volume ratio of a thin film makes it susceptible to degradation by reaction with the substrate and the atmosphere, so choosing compatible materials and avoiding over-firing is essential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026459607116
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Interaction of Formic Acid with the Silica Gel Network (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 165-171 
    Details
    ISSN: 1573-4846
    Keywords: aging ; syneresis ; shrinkage ; formic acid ; viscoelasticity ; permeability ; pore size ; modulus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Silica gels can be made by direct reaction of formic acid with tetraethyl orthosilicate. We have characterized wet gels of this type using a beam-bending technique that yields the elastic modulus, Poisson's ratio, viscoelastic relaxation function, and permeability. When the experiment is performed in ethyl formate, the silica network behaves in an elastic fashion; the permeability is low (〈1 nm2), indicating a pore radius of 〈4.3 nm. The capillary pressure generated in such small pores is estimated to be sufficient to cause collapse of the pores during drying, which would account for the observed ultramicropores in this type of gel. When the pore liquid contains formic acid, viscoelastic relaxation is relatively rapid. Studies of cyclosiloxane compounds indicate that formic acid can attack only the strained siloxane bonds of the network, which would account for the relaxation behavior. Aging in formic acid causes rapid initial shrinkage, because formic acid accelerates condensation of silanols, which drives syneresis; the modulus increases and the permeability decreases monotonically, so there is no indication of coarsening during aging in formic acid, even at 70°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026464918986
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Interaction of formic acid with the silica gel network (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 165-171 
    Details
    ISSN: 1573-4846
    Keywords: aging ; syneresis ; shrinkage ; formic acid ; viscoelasticity ; permeability ; pore size ; modulus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Silica gels can be made by direct reaction of formic acid with tetraethyl orthosilicate. We have characterized wet gels of this type using a beam-bending technique that yields the elastic modulus, Poisson’s ratio, viscoelastic relaxation function, and permeability. When the experiment is performed in ethyl formate, the silica network behaves in an elastic fashion; the permeability is low (〈1 nm2), indicating a pore radius of 〈4.3 nm. The capillary pressure generated in such small pores is estimated to be sufficient to cause collapse of the pores during drying, which would account for the observed ultramicropores in this type of gel. When the pore liquid contains formic acid, viscoelastic relaxation is relatively rapid. Studies of cyclosiloxane compounds indicate that formic acid can attack only the strained siloxane bonds of the network, which would account for the relaxation behavior. Aging in formic acid causes rapid initial shrinkage, because formic acid accelerates condensation of silanols, which drives syneresis; the modulus increases and the permeability decreases monotonically, so there is no indication of coarsening during aging in formic acid, even at 70°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02436835
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Sintering of sol-gel films (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 353-363 
    Details
    ISSN: 1573-4846
    Keywords: sintering ; stress ; constraint ; crystallization ; nucleation ; film ; substrate ; rapid thermal annealing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The sintering of films differs from that of bulk gels in several ways. The initial state of a film is generally denser and less crosslinked than a bulk gel made from the same sol, and these factors enhance the densification rate of the film. The substrate constrains the shrinkage of the film, leading to high stresses that retard densification and can influence phase changes. The substrate is a site for heterogeneous nucleation, and crystallization makes densification more difficult, so the competition between sintering and crystallization is particularly important for films. Fast heating favors densification over crystallization, so rapid thermal annealing usually produces denser films. The high surface to volume ratio of a thin film makes it susceptible to degradation by reaction with the substrate and the atmosphere, so choosing compatible materials and avoiding over-firing is essential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02436865
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Sol-Gel Synthesis of Potassium Titanyl Phosphate: Solution Chemistry and Gelation (1997)
    Springer
    Journal of sol gel science and technology 9 (1997), S. 183-199 
    Details
    ISSN: 1573-4846
    Keywords: KTP ; sol-gel ; non-linear optics ; solution chemistry ; mixed metal oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The solution chemistry and aggregation mechanisms involved in sol-gel synthesis of potassium titanyl phosphate (KTP) are studied in detail. The chemistry of the metal precursors are shown to be critical for the formation of the desired KTP phase. The precursor solution as well as some preparation intermediates were studied by several spectroscopic methods to determine the structure of the organometallic species present in these solutions. The structural evolution taking place in the solution after hydrolysis was studied using photon correlation spectroscopy and small angle X-ray scattering techniques. The influence on the gelation of several preparation parameters such as, the precursors chemistry, the mixing order of the metal alkoxides, the solvent/KTP ratio and the water/KTP molar ratio was also examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026421415654
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Sol-gel synthesis of potassium titanyl phosphate: Solution chemistry and gelation (1997)
    Springer
    Journal of sol gel science and technology 9 (1997), S. 183-199 
    Details
    ISSN: 1573-4846
    Keywords: KTP ; sol-gel ; nonlinear optics ; solution chemistry ; mixed metal oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The solution chemistry and aggregation mechanisms involved in sol-gel synthesis of potassium titanyl phosphate (KTP) are studied in detail. The chemistry of the metal precursors are shown to be critical for the formation of the desired KTP phase. The precursor solution as well as some preparation intermediates were studied by several spectroscopic methods to determine the structure of the organometallic species present in these solutions. The structural evolution taking place in the solution after hydrolysis was studied using photon correlation spectroscopy and small angle X-ray scattering techniques. The influence on the gelation of several preparation parameters such as, the precursors chemistry, the mixing order of the metal alkoxides, the solvent/KTP ratio and the water/KTP molar ratio was also examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02439398
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Sintering Aerogels (1998)
    Springer
    Journal of sol gel science and technology 13 (1998), S. 937-943 
    Details
    ISSN: 1573-4846
    Keywords: sintering ; aerogel ; pore size distribution ; viscosity ; characterization (of aerogels)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Studies of the densification kinetics and structural evolution of non-crystalline aerogels during sintering are examined in light of theory. In most respects, the theory of viscous sintering is capable of quantitatively accounting for the experimentally observed behavior, as long as the initial pore size distribution is known. Unfortunately, it is difficult to obtain adequate structural information; in particular, measurements using nitrogen desorption and thermoporometry often erroneously indicate the presence of macroporosity. Some authors have claimed that large pores contract more quickly than small pores during sintering; under certain circumstances this is predicted by the theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008687610326
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...