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Combining Hard with Soft Materials in Nanoscale Under High-Pressure High-Temperature ConditionsNano-composites with a primary nanocrystalline ceramic matrix and a secondary nanocrystalline material (metal or semiconductor) were synthesized by infiltration of an appropriate liquid into ceramic compacts under pressures of up to 8 GPa and temperatures of up to 2000 K. The purpose of our work is to obtain nanocomposites which constitute homoger?ous mixtures of two phases, both forming nano- grains of about 10 nm in size. The high pressure is used to bring the porosity of the compacted powders down to the nano-scale and force a given liquid into the nano-sized pores. The advantage of the infiltration technique is that, in a single, continuous process, we start with a nanocrystalline powder, compress it to form the matrix of the composite, and crystallize and/or synthesize a second nanomaterial in the matrix pores. The key limitation of this technology is, that the pores in the matrix need to stay open during the entire process of infiltration. Thus the initial powder should form a rigid skeleton, otherwise the so-called self-stop process can limit cr block a further flow of the liquid phase and hinder the process of the composite formation. Therefore powders of only very hard ceramic materials like diamond, Sic, or Alz03, which can withstand a substantial external load without undesired deformation, can be used as the primary phase. With this technique, using diamond and S i c ceramic powders infiltrated by liquid metals (AI, Zn, Sn, Ag, Au) and semiconductors (Si, Ge, GaAs, CdTe), we obtained nano-composites with the grain size in the range of 10 - 30 nm. Our work addresses the key problem in manufacturing bulk nanocrystalline materials, i.e. preservation of nano-scale during the fabrication process. In this paper we discuss basic technical and methodological problems associated with nano-infiltration based on the results obtained for Zn-Sic composites.
Document ID
20040082324
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Palosz, B.
(Polish Academy of Sciences Warsaw, Poland)
Gierlotka, S.
(Polish Academy of Sciences Warsaw, Poland)
Swiderska-Sroda, A.
(Polish Academy of Sciences Warsaw, Poland)
Fietkiewicz, K.
(Polish Academy of Sciences Warsaw, Poland)
Kalisz, G.
(Polish Academy of Sciences Warsaw, Poland)
Grzanka, E.
(Polish Academy of Sciences Warsaw, Poland)
Stel'makh, S.
(Polish Academy of Sciences Warsaw, Poland)
Palosz, W.
(BAE Systems Huntsville, AL, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2004
Subject Category
Composite Materials
Meeting Information
Meeting: NATO Advanced Research Workshop: Innovative Superhard Materials and Sustainable Coatings
Location: Kiev
Country: Ukraine
Start Date: May 12, 2004
End Date: May 15, 2004
Funding Number(s)
CONTRACT_GRANT: NAS8-02096
Distribution Limits
Public
Copyright
Other

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