For centuries, researchers have been trying to achieve precise control and tailor
materials properties. Several approaches, i.e., thermo-activation, electro-activation, and
photo-activation, have been widely utilized. As an alternate and fundamentally different
approach, mechano-activation is still relatively less-known. In particular, understanding
the roles of mechano-activated electronic and molecular structures is yet to be achieved.
This research contributes the fundamental understanding in mechanisms of
mechano-activation and its effects on materials properties. Experimental investigation
and theoretical analysis were involved in the present research. A methodology was
developed to introduce the mechnao-activation and to study its subsequent effects. There
are three major areas of investigation involved. First, the means to introduce mechanoactivation,
such as energetic particle collision or a bending deformation (tensile force);
Second, in-situ and ex-situ characterization using AFM, FTIR, UV-Vis, and XPS etc.
techniques; Third, theoretical analysis through modified Lennard-Jones potentials in
order to explain the behavior of materials under mechano-activation.
In the present research, experiments on a Diamond-Like Carbon (DLC) film, a
Polyvinylidene Fluoride (PVDF) film, and the Silver-Crown Ether nanochains (Ag-NCs)
were carried out. For DLC, the collision-induced transformation between hybridization
states of carbon was confirmed, which also dominated the friction behavior of the film.
For PVDF, results show that the applied tensile force induced the transformation of [alpha], [beta],
and [upsilon] crystalline phase. In addition, the transformation observed was time and direction
dependent. For Ag-NCs, a new approach based on the mechanism of mechano-activation
was developed for nanochain structure synthesis. Molecular dynamics simulation and
experimental results revealed that the formation of Ag-NCs is a synergetic physicalchemical
procedure. Experimental results from DLC and PVDF were further used to
validate the proposed potential, which brought new insight into the activation process.
The current research achieves a precise control on engineering materials properties. The
force-activated materials have wide applications in many areas, such as functional
coating, sensing, and catalysis.
In this study selected experiments have demonstrated the effects of mechanoactivation
in different material systems (ceramic, polymer, metallic nano structure) and at
different length scales. For the first time, a modified potential was proposed to explain
the observed mechano-activation phenomena from the energy point of view. It was
validated by experimental results of DLC and PVDF. The current research brings new
understanding in mechano-activation and opens potential for its applications in tailoring
materials properties.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2009-12-7472 |
| Date | 2009 December 1900 |
| Creators | Wang, Ke |
| Contributors | Liang, Hong, Teizer, Winfried |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | application/pdf |
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