Microstructural characterisation of complex materials using advanced Scanning Electron Microscope (SEM) techniques

The aim of this project is the characterisation of micro-structurally complex materials such as soft solids/liquids, biological materials, composite materials and polymeric and metallic materials. This characterisation is essential in many diverse areas of engineering research. Some of our current projects which need this capability include:1) Derivation of predictive models for deformation and fracture of adhesives, composites, metals, foods, etc. 2) Development of porous load-bearing constructs to replace lost bone segments following trauma,3) Studies of crack formation in hard deposits in order to identify the pressure and shear that cleaning liquids in Cleaning-In-Place methods must generate, and4) Determining which is the optimal consolidation material for integrity of lacquers in various objects of art.The micro-structural characterisation mentioned above will be performed using advanced Scanning Electron Microscope (SEM) modules. The SEM has become an indispensable tool in virtually all fields of research. In an SEM, a beam of electrons is focussed and scanned across the specimen under investigation. The signal from the detected scattered and emitted electrons is used to form a magnified image with dramatically better resolution and depth of view than an optical microscope. In order to study soft solids and liquids under the SEM, it is necessary to use the cryo-SEM technique where the sample is rapidly cooled and transferred to the cold stage of a preparation chamber which is mounted onto the SEM. This procedure is necessary with all soft and other hydrated materials which are sensitive to the vacuum condition and/or the high electron beam energy of an SEM. Another technique that will be used to investigate the micromechanisms during deformation and fracture in complex materials involves the use of a Microtest SEM module. This module essentially allows a mechanical test to be performed within the chamber of an SEM and therefore enables investigation of micro-structural changes as a function of the externally applied load. Lastly, a Heating stage SEM module will also be used in our studies to raise the temperature while the sample is inside the chamber of the SEM and hence observe changes in microstructure as a function of temperature.