Material design
Designed Approach
Multi-functional nanomaterials initiated from
designed complex precursors, which are thermally processed to form an intermediate glass.
The glass composition and reaction conditions are fine-tuned to control size, shape, crystallinity and morphology of the final materials.
Fe3C is the material that better represent the versatility of our procedure
Less mithological and more real is the nature of the Damascus steel, whose superior hardness was found to be atrributed to the efficient reinforcing on iron metal by Fe3C nanoroads. The presence of iron carbide seems to be due to the impure starting material used (meteorite) and could explain why, although many efforts from the european blacksmith, they were never able to obtain tools with the same hardness.
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A.A. Levin, D. C. Meyer, M. Reibold, W. Kochmann, N. Pätzke, and P. Paufler, “Microstructure of a genuine Damascus sabre,” Cryst. Res. Technol., vol. 40, no. 9, pp. 905–916, Sep. 2005.
Carburization: heat treatment process in which iron or steel absorbs carbon while the metal is heated
Ancient materials: The combination of iron and carbon was discovered even before pure iron and what ancient population called iron was in reality iron in carbon.
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It seems also an anatolian population called calibi developed as first the art of the carbothermal reduction of iron minerals and the carburization of iron, somehow starting the iron age.
In this way, accordingly with the legend, calibi forged the Julius Cesar sword, which then became the famous Exalibur sword, where the King Artu legend starts from.
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A clear target for nanoscientists is to develop materials with improved performances and reduced impact: minor energy consumption, less toxicity, less waste volume, etc).
Mater artium necessitas…
The Urea-Glass-Route
Upon further increase of the temperature, nucleation and growth of the nanoparticles occur, while the organic matrix simultaneously decomposes providing the N or C necessary to form the final MN or MC, and releasing the excess of N/C, mainly as NOx/COx.
Formally produced by involving dangerous reactants coupled with needed high temperatures (up to 2000°C), these conditions were not enough appealing for a large scale production and unsuitable for nanoparticles synthesis. Our research work successfully aimed at designing novel pathways for the synthesis of metallic ceramics in order to expand their coverage in applied science. Ref Giordano C. , Erpen C., Yao W. T., Antonietti M., “Synthesis of Mo and W Carbide and Nitride Nanoparticles via a Simple "Urea Glass" Route” Nano Letters, 8, (12), 4659, 2008
The Urea-Glass-Route concept
A new synthetic strategies were set up to control nanoparticles’ growth at high temperature, without using any template.
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The idea was to start from a precursor network stable at temperatures high enough to control the particles growth after their nucleation, but still unstable enough to decompose (and leave) before the end of the reaction. In this way, nanoparticles can nucleate and growth in a controlled fashion.
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This ideal starting material can be prepared using urea as stabilizing agent.
