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Delft, Netherlands

Sha W.,Queens University of Belfast | Wu X.,Material innovation institute | Sarililah W.,Queens University of Belfast
Materials Science and Engineering B: Solid-State Materials for Advanced Technology | Year: 2010

This paper follows previous X-ray diffraction work on crystallisation and phase transformation of electroless nickel-phosphorus deposits, concentrating on microstructural changes. Amorphous or nanocrystalline coatings, depending on their phosphorus content, were heat treated at temperatures between 100 and 500 °C for 1 h. Changes in microstructure after the heat treatment were examined using high-resolution field emission scanning electron microscope. Crystallisation and grain growth effects are observed, as well as some inherent defect structures in the coatings and their changes. These are compared with the previous X-ray diffraction work and in general, good agreement is observed. The complementary strength and weakness of the different characterisation techniques are discussed. © 2009 Elsevier B.V. All rights reserved. Source

Lafont U.,Material innovation institute | Lafont U.,Technical University of Delft | Moreno-Belle C.,Technical University of Delft | Van Zeijl H.,Technical University of Delft | Van Der Zwaag S.,Technical University of Delft
8th Asian-Australasian Conference on Composite Materials 2012, ACCM 2012 - Composites: Enabling Tomorrow's Industry Today | Year: 2012

Thermally conductive composite with a thermally triggered self-healing response were produced dispersing BN or Graphite particles into 2 type of polysulfide based thermoset matrix. The composites produced exhibit recovery of both cohesion and adhesion properties upon healing. Using a mild healing temperature (65 °C), the materials show full recovery of their initial adhesive strength during several healing cycles. In contrast the composites behave differently regarding the cohesion recovery: 100 to 20% recovery is achieved depending on the filler type, filler loading and the type of matrix. The thermal conductivity of the produced materials increase with the amount of filler. Valuesof 1 and 2 W/mK can be achieved for the BN and graphite based composite, respectively. The results presented in this work clearly show that multifunctional thermal interface materials with different functionality and self-healing response can be realised. Copyright © (2012) Asian-Australasian Association for Composite Materials (AACM). Source

Alderliesten R.C.,Technical University of Delft | Schijve J.,Technical University of Delft | Krkoska M.,Material innovation institute
Fatigue of Materials II: Advances and Emergences in Understanding, Held During Materials Science and Technology 2012, MS and T 2012 | Year: 2013

Special load histories are adopted to obtain information about the behavior of the moving crack tip during the increasing and decreasing part of a load cycle. It is associated with the crack opening and closure of the crack tip. Secondly, modern SEM techniques are applied for observations on the morphology of the fractures surfaces of a fatigue crack. Information about the cross section profiles of striations are obtained. Corresponding locations of the upper and the lower fracture surface are also explored in view of the crack extension mechanism. Most experiments are carried out on sheet specimens of aluminum alloys 2024-T3, but 7050-T7451 specimens are also tested in view of a different ductility of the two alloys. Source

Van Soestbergen M.,Material innovation institute | Van Soestbergen M.,TU Eindhoven | Baukh V.,TU Eindhoven | Erich S.J.F.,TU Eindhoven | And 4 more authors.
Progress in Organic Coatings | Year: 2014

Carcinogenic chromates are phased out as corrosion inhibitors in organic coatings, and are replaced by benign alternatives. Cerium-based compounds are excellent corrosion inhibitors in an aqueous environment. However, whether they are effective as corrosion inhibitor in an organic coating also depends on their interaction with the coating matrix, which should result in a sufficient release of inhibitors over a desired period of time. In this work we report on the leaching of cerium dibutylphosphate, Ce(dbp)3, from an epoxy coating system as a first step toward a fundamental understanding of the leaching behavior. To this end, coating systems containing various levels of inhibitor loading, ranging from 1 up to 50 wt%, were fabricated. These coatings were characterized using Fourier transform spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). Leaching experiments were performed by exposing the coating films to water, while the concentration of dissolved Ce(dbp)3 in this water was monitored in situ using ultraviolet-visible (UV-vis) spectroscopy. The leaching of inhibitors showed a clear dependence on the initial inhibitor loading of the coating system. For highly loaded coatings (>25 wt%) all inhibitors leach out, whereas for a low loading level (<10 wt%) no leaching was observed. The difference between the high and low loading levels might be the formation of a porous network in the highly loaded coatings due to the dissolution of large Ce(dbp)3 clusters. Using Magnetic Resonance Imaging (MRI) we visualized the penetration of a water front into this porous network during the leaching experiments. This water-filled porous network provides an excellent pathway for transport of Ce(dbp)3. For low levels of inhibitor loadings such a network is absent, and the transport of Ce(dbp)3 is blocked. The samples containing moderate levels of inhibitor loading showed an increasing amount of leaching for decreasing values of pH. We believe that this pH dependence is the result of the concurrent leaching of significant amounts of Bisphenol-based coatings residues at low pH since the removal of these residues will also result in an increased porosity of the coating. © 2014 Elsevier B.V. Source

Lafont U.,Material innovation institute | Lafont U.,Technical University of Delft | Van Zeijl H.,Technical University of Delft | Van Der Zwaag S.,Technical University of Delft
ACS Applied Materials and Interfaces | Year: 2012

Synthetic systems with intrinsic self-repairing or self-healing abilities have emerged during the past decade. In this work, the influence of the cross-linker and chain rigidity on the healing ability of thermoset rubbers containing disulfide bonds have been investigated. The produced materials exhibit adhesive and cohesive self-healing properties. The recovery of these two functionalities upon the thermally triggered healing events has shown to be highly dependent on the network cross-link density and chain rigidity. As a result, depending on the rubber thermoset intrinsic physical properties, the thermal mending leading to full cohesive recovery can be achieved in 20-300 min at a modest healing temperature of 65 °C. The adhesive strength ranges from 0.2 to 0.5 MPa and is fully recovered even after multiple failure events. © 2012 American Chemical Society. Source

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