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Ultra-high crystallinity millimeter long multiwall carbon nanotubes fabricated by mechanothermal method

Manafi S. A., Rahimipour M. R., Soltanmoradi A.

Materials Science Poland

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2012

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Vol. 30, No. 3

226--230

EN

In this work, multi-walled carbon nanotubes (MWCNTs) with ultra-high crystalline structure have been prepared by mechanothermal (MT) method. The novel super nanostructure is introduced for the first time as an extraordinary fullerene-carbon based material which, due to its special electronic and mechanical properties, can be used to construct unique building blocks for nanoengineering. Initially, high ultra-active graphite powder has been obtained by mechanical activation under Ar atmosphere. Finally, the mechanically activated product is heat-treated at 1350 °C for 3-4 h under an Ar gas flow. However, the crystallite size and crystallinity degree of the MWCNTs increased with the increase in annealing temperature.

2

A model for abnormal grain growth in nano-crystalline materials based on Zener drag force

Razavi-Tousi S. S., Yazdani-Rad R., Manafi S. A.

Archives of Metallurgy and Materials

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2012

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Vol. 57, iss. 1

79-85

EN

Abnormal grain growth of a matrix in which normal grain growth has stagnated due to the presence of fine incoherent ceramic particles is studied. A balance between driving and retarding forces is used as the criteria for estimating the steady state. Random and non-random approaches are applied for coarse and nano-grained structure respectively.

PL

Badano nieprawidłowy wzrost ziaren w materiale, w którym prawidłowy wzrost ziaren został zahamowany z powodu obecności drobnych cząsteczek ceramicznych. Równowaga pomiędzy siłami pędną i opóżniającą zostały przyjęte jako kryterium oszacowania stanu równowagi. Zastosowano przypadkowe i nieprzypadkowe podejście odpowiednio do struktury grubo i drobnoziarnistej.

3

Effect of heat-treatment on grain growth of nanocrystalline tricalcium phosphate powder synthesized via the precipitation method

Mobasherpour I., Salahi E., Manafi S. A., Darvishi Kamachali R.

Materials Science Poland

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2011

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Vol. 29, No. 3

203--208

EN

Nanocrystalline tricalcium phosphate powder was synthesized via the solution- precipitation method followed by heat treatment in order to achieve phase evolution, which was then studied by XRD and TEM techniques. The crystallites sizes were estimated by the Scherrer method and results were confirmed by TEM micrographs. The experimental observations showed that nanocrystalline tricalcium phosphate can be successfully prepared from raw materials by the precipitation technique. This technique is a competitive method for nanocrystalline tricalcium phosphate synthesis compared to other techniques. Moreover, a simple kinetic growth investigation was performed on the nanocrystalline growth process during heat treatment. Results have shown growth rate to increase exponentially with temperature and the growth rate constants to increase with time. The average activation energies of tricalcium phosphate grain growth obtained by this method were 84.78 and 134.38 KJ/mol.