Biography:

Mattheus (Theo) F. A. Goosen has played key roles in the development of new start up academic institutions. For the past nine years he has held the position of founding Associate Vice President for Research & Graduate Studies at Alfaisal University a private start-up non-profit institution in Riyadh, Saudi Arabia (www.alfaisal.edu). The doctoral degree of Dr Goosen is in chemical & biomedical engineering from the University of Toronto (1981) Canada. Theo has more than 180 publications to his credit including over 133 refereed journal papers, 45 conference papers, 10 edited books and 10 patents.  His h index is over 47 and he has well over 8000 citations on Google Scholar. On Scopus he has 133 publications with over 4000 citations. Dr Goosen’s research interests are in the areas of renewable energy, desalination, sustainable development, membrane separations, spray coating technology and biomaterials.

Abstract:

Statement of the Problem: Nanoindentation of WC-12Co thermal spray coatings has been used to evaluate the elastic modulus and hardness of coating on the polished surface of the coatings. While there has been much progress overall, limited research has been reported on the deposition and evaluation of WC-cermet coatings. The aim of this study was to evaluate the microstructural and nanohardness characteristics of tungsten carbide-cobalt (WC-Co) cermet coatings deposited by liquid suspension spraying. Methodology: Commercially available WC-Co coating powder was milled and water based suspension was produced as feedstock for the thermal spray coating process. Microstructural evaluations of WC-Co cermet coatings included XRD (X-Ray Diffraction) and SEM (Scanning Electron Microscopy). Post spraying nanomechanical evaluations were conducted using a Berkovich nanoindenter.  Findings: Results indicated relatively higher modulus but lower hardness of suspension coatings. The load displacement curves during nanoindentation were characteristic of the complex coating microstructure showing signs of microcracking and pile-up. The load displacement (P-h) curves along with the SEM images of indents for S-HVOF (suspension high velocity oxyfuel) coating illustrated evidence of sink-in and pile-up of material around the indent contact residual impression during the nano-indentation process. There was some indication of microcracking during indentation as well.

Conclusions: A comparison of S-HVOF and conventional HVOF coatings points toward phase transformations occurring in the suspension spraying which led to nanocrystalline or amorphous phases. The elastic modulus of S-HVOF coatings was on average higher than the conventional HVOF coating. The load displacement curves show features which are consistent with the complex coating microstructure with evidence of micro-cracking and pile-up.

Biography:

Research Experience (some events): Dec 1999 – Aug 2016 Research Director, Czestochowa University of Technology, Institute of Computer Sciences Czestochowa, Poland. Oct 1994 – Sep 2002.Professor in Full, Jagiellonian University, Institute of Physics, Cracow, Poland. Visiting Scientist -  Integrability of quantum systems, Universiteit Utrecht, Institute for Theoretical Physics Utrecht, Netherlands. Jul 1988 – Sep 1988 Visiting Scientist - Dynamical critical phenomena Universiteit Utrecht, Institute for Theoretical Physics. Apr 1988 – Apr 1988 Visiting Professor - Phase transitions and critical phenomena - lectures for PhD students, The Rockefeller University, New York City, United States Laboratory of Mathematical Physics. Feb 1988 – Oct 1994, Professor (Associate),   Head of Soft Condensed Matter Department, Jagiellonian University, Institute of Physics, Kraków, Poland.

Abstract:

Certain features of certain materials are self-similar. This phenomenon is recognizable by scaling of measurement data corresponding to the considered self-similar feature. To perform scaling we apply notion of homogenous function in general sense. For two independent variables such a function reads P(f,B)=B^β F(f/B^α), where P is a considered magnitude, α and β are scaling exponents, F(∙) is an arbitrary continuous function, where α, β and F(∙) have to be determined by the measurement data. Definition of P(f,B)  enables us to transform all  characteristics P(f,B) to the one universal function of the one variable: P(f,B)/ B^β =F(f/B^α ). This effect is so called the data collapse and can be applied for comparison of measurement data measured in different laboratories, which enable us to estimate quality of each laboratory series. Another application of the data collapse is compression of large experimental data. If the considered data are produced by a self-similar system then one can store them in a form of continuous curve. The data collapse enables us to introduce an absolute dimensionless characteristic:

1), where P and f are dimensionless P and f, respectively. This characteristic divides { P, f } space into the two independent subspaces of materials’ characteristics.

Finally, the scaling supplemented by pseudo-equation of states plays basic role in creation of algorithms for designing of modern materials.

 The presented results base on experimental data of Soft Magnetic Materials and Soft Magnetic Composites. Where, P(f,B) is density of power loss, f is frequency of the field’s modulation and B is maximum of magnetic induction. One can apply this simple mathematics to any self-similar object. However, ultimately one must say that the degree of success achieved when applying the scaling depends on the property of the data. The data must obey the scaling.

Biography:

Dr. Ohmura is a professor of Osaka University.  His main field of research is intelligent laser processing systems, especially theoretical analysis and computer simulation to gain deeper understanding of the complicated physical phenomena in laser material processing, influence of laser optics, and nonlinear optical phenomena.

Abstract:

When laser beam with a high energy density is irradiated onto a material, the energy of the beam is converted into thermal energy by absorption, and the temperature rises locally.  Thermal diffusion occurs due to a steep temperature gradient.  However, as the thermal diffusion time and the thermal diffusion length are very short, a phase change such as fusion, evaporation, sublimation, occurs instantly because energy is added locally in a very short time.  The thermal stress caused by this temperature gradient is large and as a result, hard and brittle materials that are difficult to process by mechanical processing can be processed by non-contact processing.  Two examples of laser assist break of hard and brittle materials are introduced here.  (1) Stealth dicing of the silicon wafer:  A permeable nanosecond pulse laser is focused into the interior of a silicon wafer and scanned in the horizontal direction, causing a belt-shaped modified layer to be formed in the wafer (Fig. 1).  Applying tensile stress perpendicularly to this modified-layer separates the silicon wafer very easily into individual chips.  This method is called “stealth dicing (SD)”.  In order to establish a more highly reliable dicing technology and investigate the optimum processing conditions, the formation mechanism of the internal modified layer was studied (Figs. 2 and 3).  (2) Laser scribing of glass:  Glass sheet is used for flat panel displays, and laser scribing is being used as the separation process.  We conducted thermal stress analysis and crack propagation analysis in order to clarify the processing phenomena and control factor.

Biography:

Ki-Soo Lim is a full professor of physics department at Chungbuk National University in South Korea. He has been working on laser spectroscopy of rare-earth ion doped crystals, glasses, glass-ceramics, and semiconductors. He also studied 3-D bit or holographic data storage in glass, photopolymers and photovoltaic materials. Recent interests and achievements include precipitation and optical properties of glass-ceramics containing fluoride nanocrystals, and micro-nanostructure fabrication on the surface of dielectric materials and polymers by femtosecond laser. He received his B.S. and M.S. degree in Physics at Seoul National University in 1977 and 1980 respectively. He then did his PhD in physics at University of Connecticut, USA, and worked at University of Georgia as a research associate. He joined Chungbuk National University in 1990 after working at Korea Standard Research Institute. 

Abstract:

We report the self-formed nanogratings on the surfaces of semiconductors (ZnO and GaN) and dielectric materials (fused silica, borate glass, LiTaO₃, LiVO₃, sapphire) prepared by scanning focused femtosecond laser pulses at 800 nm with a repetition rate of 1 kHz. Laser fluence range for nanograting self-formation is very narrow. We find a series of periodic-structure orientation is perpendicular to the linear laser polarization. The period of grating structures on the dielectric surface depends on laser power and scan speed, and increases in the range of 200∼300 nm with scan speed and laser pulse energy. In contrast, GaN shows about 600 nm period in the same power range as the dielectric materials. Its period decreases to 450 nm when the laser power is reduced ten times. It also has much lower laser ablation threshold than dielectrics and ZnO, indicating characteristics of metal-like nanogratings due to its high plasma density, large thermal conductivity, and multiphoton absorption coefficients at 800nm. Emission from nanograting area of sapphire indicates the existence of oxygen vacancies. Figure 1 shows the nanograting structure formed by scanning femtosecond laser pulses at 40 μm/s speed of on the surfaces of LiVO₃ and ZnO with 0.13 and 0.09 mW power respectively.

For applications, surface nanostructures can be used to improve out-coupling of light in LED. Material absorption can be also significantly enhanced due to surface nano-structures produced by fs-laser pulse processing, applicable to sensing and solar cells.

Biography:

Lahcène Ouahab received his PhD thesis from the University of Rennes1 in 1985. He was “Maître de conférences” at the University of Constantine (Algeria) and then associate Professor at the University of Rennes1 (1988) before getting a permanent position in CNRS as “chargé de recherche” in 1989. He is presently a CNRS director of research and leads the molecular materials research group. He was director of the  “Laboratoire de Chimie du Solide et Inorganique Moléculaire UMR6511-CNRS Université de Rennes1” 2004-2006. He was awarded the 1998 prize of the Coordination Chemistry Division, the 2011 Claude Berthault Prize of the “Académie des Sciences” and the 2012 “Grand Prix Pierre Süe” of the French Chemical Society. His fields of research include molecular materials, in particular, multifunctional materials, charge transfer complexes, radical ion salts, organic-inorganic hybrids, polymeric coordination complexes and polyoxometallates

Abstract:

Lanthanide-based complexes have greatly contributed to the development of molecular magnetism in the last decade and more particularly in the branch of single molecule magnets (SMMs). The main reasons are their large magnetic moments associated to their intrinsic large magnetic anisotropy. The splitting of the multiplet ground state of a single-ion in a given environment is responsible of the trapping of the magnetic moment in one direction in SMMs. However, the analyses of the crystal field effects on the magnetic anisotropy are not so common. A better understanding of the magneto-structural correlations in lanthanide-based complexes should provide tools to improve their potentialities. In this presentation we will focus on the specific magnetic properties of TTF-based lanthanide mononuclear and polynuclear complexes. We will show how optimize the SMM behavior playing on i) the modulation of the supramolecular effects via chemical modifications of the TTF ligand, ii) simple molecular engineering modifying the electronic distribution and symmetry of the coordination polyhedron, iii) magnetic dilutions (solution and doping) and iv) isotopic enrichment of the dysprosium.

Biography:

Haruhiko Morito has his expertise in material science and engineering. The main objective of his research is to develop an emerging material which has a new function and new physical properties. In particular, he has developed new functional ceramics containing alkali metals. He has also developed a new crystal growth process based on the binary phase diagram of sodium and silicon. He has synthesized the various silicon-based materials by the sodium flux method.

Abstract:

Introduction: Si clathrate compounds have been widely studied due to their unique open-framework structures of Si polyhedrons. Two types of Si clathrates encapsulating Na atoms have been known: type I (Na₈Si₄₆) and type II (Na_xSi₁₃₆, 0 < x ≤ 24). These Na-Si clathrates have been generally synthesized by thermal decomposition of a Na-Si binary compound, Na₄Si₄, at 673–823 K under high-vacuum conditions (<10⁻² Pa), and the obtained samples were in the form of powder with a particle size in the micrometer range. The purpose of this study is the crystal growth of the type I and type II Na-Si clathrates by using a Na-Sn flux. Experimental: The starting material of a mixture of Na, Na₄Si₄, and Na₁₅Sn₄ was prepared by heating Na, Si, and Sn (molar ratio, Na/Si/Sn = 6:2:1) at 1173 K in Ar atmosphere. The mixture was heated at 673–873 K for 6–24 h in the container with a temperature gradient. After heating, air-sensitive compounds in the samples, such as Na-Sn compounds, were reacted with ethanol, and the water-soluble reactants were removed by washing with water. Sn present in the products or formed by the ethanol treatment was removed by dissolution in a dilute nitric acid aqueous solution. Results: The single crystals of type I clathrate were crystallized due to the evaporation of Na from the Na-Sn-Si solution at 673–773 K. Most of the single crystals had sizes of several hundred micrometers to 1 mm, and the maximum size reached to about 3 mm. Heating the starting mixture at 823–873 K resulted in the crystal growth of the type II clathrate. The single crystals having {111} habit planes grew up to about 2 mm in size as shown in Fig. 1.

Biography:

Isaac Adebiyi is a lecturer in the Department of Metallurgical Engineering, Vaal University of Technology, Vandebijlpark, South Africa. He holds a doctoral degree in Metallurgical engineering with specialization in new materials development. His research interests include surface modification of engineering materials (Laser Materials Processing, Cold Spray Coating, High Velocity Oxy Fuel Coating etc.), Additive Manufacturing, Computational Fluid Dynamics Modelling and Simulation, Tribology and Wear Mitigation, Process Optimization, Alloy Design and Physical Metallurgy of Alloys, Microstructure and Phase Evolution Studies, Multifunctional Coatings Development, and Development of Smart and Advanced Materials. He received an award for Innovation and excellence in the use of stainless steel by the Southern African Stainless Steel Development Association. He has authored many publications and has chaired plenary section and moderated international conference.

Abstract:

Statement of the Problem: A more ubiquitous application of Ti-6Al-4V in the aerospace industry has been hindered by its poor set of surface properties. The cold spray coating (CSC) process is suitable for improvements in the surface properties but the process is very complex, and highly dependent and sensitive to small changes in its many process parameters. Moreover, the CSC is also very selective of the choice of powder materials. The choice is not only based on application requirements but also on plastic deformability of the powder. Methodology & Theoretical Orientation: This investigation presents a mathematical identification of the optimum process parameters by using a constitutive equation to solve the continuity, momentum and the energy equations governing the flow of fluid through the low-pressure cold spray nozzle. A CFD analysis is performed to determine the input temperature that will yield the calculated velocity by using the meshing tool of Solidworks to analyze the distribution of velocity, temperature, and pressure in the cold spray nozzle and predict their exit values. The optimum parameters were used to deposit a SiC-based cermet on Ti-6Al-4V. The microstructure and phase evolution in the coatings were studied; porosity was measured using ImageJ analysis software; the hardness was measured using Vickers hardness tester; adhesion test was performed according to ASTM C633-1; and the dry sliding wear behaviour was studied in a ball-on-disc configuration using a load of 25 N at a frequency of 5 Hz. Findings: Results show that the initial phases in the feedstock powder were retained in the coatings. No detrimental phase transformation, decomposition and/or decarburization of the SiC. There was peak shift between the phases in the feedstock powder and that of the coatings. This is traced to impact-induced micro-straining, amorphization and grain refinement. A good adhesion strength, and improvements in hardness and wear resistance were obtained in the coated samples although with a higher coefficient of friction which is traceable to higher strength and lack of micro films in the coating. Conclusion & Significance: The improved surface properties of the coating will lengthen the lifespan of the expensive Ti-6Al-4V alloy, leading to significant cost savings for the aerospace industry.

Biography:

Tengyuan is currently a Ph.D. Candidate of Mechanical & Materials Engineering in Western University, London, Ontario. His research explores printed flexible and stretchable electronics. Based on his research, he co-founded Nectro Inc. in 2015 with the goal of developing novel nano-materials and bringing them to people’s life. Tengyuan was awarded the Vanier Canada Graduate Scholarship in 2015 and won the Doctoral Excellence Research Award in 2016. Now, he looks to combine cutting-edge nanotechnology and advanced chemical/material science to find a robust, low-cost solution for manufacturing high-performance, high-resolution flexible and stretchable electronics.

Abstract:

The accelerating arrival of the Internet of Things (IoT) era creates huge demand for low-cost, high-performance paper electronics. However, fabricating highly conductive circuit on low-cost cellulose paper is challenging due to its high roughness and resolution loss caused by capillary effect.

To address these challenges, we propose a scalable, cost-effective method to fabricate high-performance electronics on regular cellulose paper. Taking advantage of the unique porous structure of cellulose paper, we activate the three-dimensional electroless deposition of copper for fast generation of the hybrid copper-fiber highly conductive structure. Currently, the sheet resistance of most PE product is 50 mΩ/sq. With the technology mentioned above, 5 mΩ/sq (10 times better) can be easily achieved with low cost and high resolution (100 microns feature size). Thanks to its unique copper-fiber hybrid structure, both the physical and electrical properties are greatly enhanced for wider variety of applications. To demonstrate its promising application, a functional battery-free energy harvesting device and a high-performance planar antenna for RFID were fabricated and tested using the proposed method.