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The paper addresses the ‘Determining the influence of preparation and measurement conditions on bonding strength using CAT-Technology’ and the follow points are discussed in more detail: Motivation, CAT – Technology, Influence of bonding area on bonding strength, Influence of storing & measurement temperatures and Influence of substrate thickness and coating support.
Characterization of multiphase metal matrix composites by means of CT and neutron diffraction
(2016)
The present study examines the relationship between the microstructure of multiphase MMC and their damage mechanisms. The matrix AlSi12CuMgNi was combined with 15% vol. Al2O3 (short fibres) and with 7% vol. Al2O3 + 15% vol. SiC (short fibres and whiskers, respectively). The experimental approach encompasses 3D microstructure characterization by means of computed tomography of samples (a) as-received, (b) after heat treatment, and (c) after compression tests at room temperature. The volume fraction of different phases, their distribution, their orientation and the presence of defects and damage are studied.
Influence of addition of SiC whiskers on mechanical properties of composite was investigated. Phase-specific load partition analysis for samples with fibre plane parallel to load was perform by using neutron diffraction measurements during in-situ compression. It shows damage in the Si phase, while Al2O3 short fibres carry load without damage until failure. The computed tomography observations confirm the load partition analysis.
Characterization of the mechanical properties of interphases is essential when designing multicomponent materials such as fiber-reinforced matrices, protective coatings or multi-layered structures for integrated circuits. It can provide vital information about the durability of the finished product as a composite because failure is often initiated in the interfacial region induced by internal or external stress during fabrication or service. Nanoindentation is a powerful tool for investigating mechanical properties on the micro/nano scale. However, there are some challenges associated with conducting nanoindentation near interface regions. One main challenge is that the small thickness of the interphase region (typically 1-2µm) makes it difficult to apply several adjacent indents without overlap. Another issue is that the indentations are usually restricted by local reinforcement, and it becomes difficult to isolate the change in mechanical properties due solely to interphase formation. In this study we try to gauge the feasibility of nanoindentation for characterizing epoxy/Cu interphases. We develop a sample preparation method and optimize nanoindentation parameters in an attempt to avoid the restrictions mentioned above. Atomic force microscopy (AFM) and finite element analysis are employed as reference techniques to evaluate the effectiveness of our technique. We show the influence of preparation method and nanoindentaion parameters on measurements of interphase properties and how they relate the mentioned challenges.
Atomic force microscopy based Infrared spectroscopy (AFM-IR) is a quickly evolving technique that provides chemical analysis and compositional mapping with spatial resolution far below conventional optical diffraction limits. This is possible since the detection method is based on a very sharp AFM tip which starts to oscillate when the sample starts to thermally expand (the changed is caused by the absorption of IR wavelength) where the thermal expansion is related to the IR absorption. This presentation briefly described the application of that new technique from polymer characterization and utilization of AFM-IR in material research, up to life science applications.
An extraction of silica from natural sands of Bancar has been conducted by means of alkali fusion route using NaOH and mechanical alloying using planetary ball milling. The PANI/SiO2 Composite system has been coated in steel surfaces using spraying method. This study was designed to obtain PANI/SiO2 as an anti-corrosion coating material. The filler materials in the composite System consist of micro- and nano-SiO2. The structure of synthesized SiO2 be characterized using XRD and TEM. Corrosion of PANI/SiO2 composite has been tested using immersion method in synthetic geothermal atmosphere (Nord Deutsche Becken/NDB solution). The surface morphology after corrosion was observed by using SEM/EDX. XRD-Patterns and TEM show that the size of produced SiO2 is micro and nano. The size and composition of filler have influenced to surface degradation in geothermal atmosphere significantly. The addition of nano-SiO2 in the PANI matrix influenced corrosion resistance better than micro-SiO2 filler qualitatively. The nano-SiO2 has a high potential as an anti-corrosion material in geothermal atmosphere. The product of corrosion is mainly Fe2O3 and the corrosion process is identified as a pitting corrosion.
Fundamental understanding of crack healing in glassy crystalline materials is very important for many applications, especially for sealing solid oxide fuel cells (SOFC) since cracks caused by sealing or thermal cycling still remain a substantial bottleneck in developing durable SOFC.
Previous studies on soda lime silicate glass [Sin14] showed that crack healing is driven by viscous flow and that healing progress is proportional to time t and inverse viscosity η. This finding would allow to present healing data of a given glass for different temperatures in a master curve healing progress versus t/η. Such master curves would be a helpful tool in understanding crack healing kinetics.
Against this background, crack healing in non-crystallizing sodium calcium silicate (NCS) and sodium borosilicate glasses (NBS) have been studied. Moreover, to evaluate the influence of micros structure in crystallized glass on crack healing process, glass matrix composites (GMC) where prepared out of NCS and zirconia as inert ceramic filler material mimicking a partially crystalline micro structure. Cracks were generated by Vickers indention and healed isothermally at different temperatures. Crack healing progress was monitored by optical and electron microscopy. Results show that the above mentioned proportionality actually applies for the studied glasses for which such a master curve could be obtained. In comparison to a non-crystallized glass, the effective viscosity of GMC is increased by rigid filler content. This effect substantially retards crack broadening during later healing stages, which often ends up in large pores. On the other hand, local viscous crack healing is still possible in larger glassy regions. This behavior seems to be very interesting for crack healing optimized sealants.