Day 2 :
Damietta University, Egypt
Time : 09:30-10:10
Ahmad Tahan is a chairman of ready-made garment technology in faculty of Applied arts at Damietta University. He is Director of Clothing Industries & Accessories Manufacturing at El CIAM CO. Egypt, and Technical Consultant knitting Machine for CENTHON Limited, England.
Clothing functions to protect children from hazardous substances in their environment. For thermal equilibrium of children in their environment, it is convenient for the parameters related to the ambiance (air and temperatures, air velocity and humidity) by which is concerning children (activity and clothing) to compensate their effects. In temperate climates this is possible, whereas in hot or cold climates constraints on lifestyle necessarily exist. The predominant heat path is through blood perfusion from core to skin, and through convection from skin to the environment. One of the important variables in vapor transport investigation is that it has not investigated physiologically by the skin vapor pressure or human microclimate pressure. It was found that most of textile fabrics have superior properties in moisture wicking ability, diffusely and evaporation ability. The physical properties of the fabric’s material and construction (structure and design) as well as the physical activities of the children body have been considered associated with the thermal properties of the fabrics. The four parameters of heat transfer such conduction, convection, radiation and vapor transfer diffusely through the garment have been considered. The fabric materials and construction comfort have been investigated by two compromised types of fabrics as such cotton and cotton blended polyester. The fabric investigated at three different phases as such dry moist and wet showed a very interested behavior. The present research showed that the pressure difference between the skin pressure through the micro climate and the pressure of the ambient condition at wet phase has reached up to 5 times the dry condition. In this aspect, a mathematical model has been developed to describe the dynamic heat and moisture transport behavior. Not only that but also it has shown regardless of type of fibers either synthetic or nature, comfortability depend upon thermal effective resistance volume as a large factor influenced wearing regardless to the ability of fibers to absorb water. However it is also based on the pressure difference between the human micro climate and ambient condition.
The Institute of Materials Research of Slovak Academy of Sciences, Slovakia
Time : 10:10-10:50
Pavol Hvizdos has been working in the Structural Ceramics Department of IMR SAS, Kosice, Slovakia, since 1988. In 1996 he has received his PhD degree in Material Sciences from Technical University, Kosice, Slovakia. From 2000 to 2008 he has worked as a Marie Curie Fellow in Queen Mary University of London, UK and as a Ramon y Cajal Fellow at Polytechnic University of Catalonia, Barcelona, Spain. Currently he is a Senior Scientist in IMR SAS Kosice. His scientific expertise includes microstructure and fracture properties of composite structural ceramics, recently his interests have been focused on nano-indentation and tribology of composite materials and cermets.
Three principal types of materials were developed and investigated: SiC-TiNbC, SiC-CNT a SiC-graphene. They were compacted using standard hot pressing (HP), spark plasma sintering (SPS), and rapid hot pressing (RHP). Their microstructure, chemical and phase composition were studied in detail, the results showed successful microstructure design and confirmed desired composition. In all cases a reference material, a single phase SiC, prepared by the same ways, was used for comparison. As the base, series of three optimized SiC-TiNbC (with 30, 40 and 50 wt.% of TiNbC) composites were developed. Increase in electrical conductivity by four orders was achieved without compromising the mechanical and tribological properties. Technological tests showed possibilities to machine these materials by electric discharge technique as well as other non-conventional methods. The materials with carbon based nano-fillers included SiC-graphene and SiC-CNT (carbon nanotubes). Methods of their preparation were optimized, mainly to achieve a good distribution of the carbon nano-phases. In SiC-graphene (graphene nano-platelets and reduced graphene oxide up to 5 wt.%) the rapid hot press (RHP) technique was successfully developed and tested and materials with graphene nano-platelets and reduced graphene oxide were produced. Both types reached satisfactory parameters with respect to their microstructure and basic mechanical properties. Their electrical conductivity increased by four orders which clearly shows their potential. In SiC-CNT (with up to 10 wt.% CNT) a new technique of in situ CNT preparation by CCVD was developed. This enabled to solve the problem with distributing of CNTs and in this way to increase the electrical conductivity by about three orders of magnitude.
- Ceramics and Composite Materials | Nanotechnology in Materials Science | Polymer Science and Engineering
Ahmad Elsyed Tahan
Damietta University, Egypt
The Institute of Materials Research of Slovak Academy of Sciences, Slovakia
University of Limoges, France
Title: Spark plasma sintering of boron carbide ceramics: Densification mechanisms and thermomechanical properties
Time : 11:05-11:25
Guy Antou is the Assistant Professor since 2005 at SPCTS Laboratory, University of Limoges, mainly dealing with the experimental characterization, the modeling and the numerical simulation of the thermo-mechanical behavior (in particular viscoplastic) of ceramic materials during their elaboration by pressure-assisted sintering or in service (creep). His has 29 publications in international journals, 4 invited conferences, 55 oral communications, 3 grants, etc. to his credit.
Boron carbide is a promising ceramic in the armor field and in nuclear reactors due to its low weight, its high hardness and its high capacity to absorb neutrons. The poor sinterability inherent to the covalent character of the B-C bonding makes the complete densification of boron carbide powder difficult to obtain by conventional sintering technique (i.e. pressure-less sintering). In this work, fully-dense boron carbide ceramics exhibiting fine microstructure (i.e. sub-micrometric grain size) are elaborated using the spark plasma sintering (SPS) without any sintering additive. The SPS densification mechanisms are investigated through the determination of the associated densification parameters (i.e. stress exponent around 3.6 and apparent activation energy of 101±20 kJ.mol-1). These values are correlated with structural observations conducted by transmission electron microcopy. It is shown that the induced deformation mechanism corresponds to a power law creep regime controlled by dislocation motion and potentially associated with a twinning phenomenon at high temperature. In addition, the effect of the impurity content decrease by a suitable heat-treatment of the starting commercial powder is studied on the mechanical properties at room temperature (i.e. Vickers hardness and fracture toughness) and high temperature (up to 1600 °C) by bending tests (i.e. elastic modulus, flexural strength). These properties are correlated with (micro) structural characteristics of both materials. It is shown that heat treatment of the powder decreases the contents of free carbon (exhibiting an onion-like structure) and of secondary oxide phases (silicon and boron-rich) at grain boundaries. It leads to a slight decrease of the hardness, fracture toughness and bending modulus and an increase of the flexural strength. In addition, no brittle-to-plastic transition is noticed up to 1600 °C.
Meijo University, Japan
Time : 11:25-11:45
Mineo Hiramatsu is a Full Professor of Department of Electrical and Electronic Engineering and the Director of Nanocarbon Research Center, Meijo University, Japan. He also serves as the Director of Research Institute, Meijo University. He has served as the Director of The Japan Society of Applied Physics. His main fields of research are plasma diagnostics and plasma processing for the synthesis of thin films and nanostructured materials. He has authored more than 100 scientific papers and patents on plasma processes for materials science.
Graphene-based nanocarbons include fullerene, carbon nanotube (CNT) and graphene sheet itself; nowadays they have a wide range of possible applications. Plasma enhanced-chemical vapor deposition (PECVD) can be easily applied to grow diamond, CNT and graphene films. In the case of PECVD, the main reaction mechanisms of deposition are determined by the species produced in the plasma. In the case of deposition of carbon-based materials, the balance between carbon precursors and etching radicals is important. Control of surface reaction is also important. Sometimes, pretreatment of substrate or selection of substrate is required for the nucleation. In short, for the synthesis and structure control of carbon nanostructures, we should consider the control of multiple radicals playing different roles such as carbon precursors and H atoms. In addition, control of surface reaction for the nucleation should be considered. For instance, ion flux onto substrate is unnecessary for plane graphene formation, but necessary for vertical grapheme nucleation on Si substrate. Moreover, pretreatment of substrate or selection of substrate would be crucial for synthesizing CNTs and graphene, catalyst nanoparticles for CNT growth and metal substrates (Ni and Cu) for plane graphene formation are these examples. We have investigated the synthesis of CNWs and planar few-layer graphene using PECVD with controlling the ion flux incident on the substrate and surface pretreatment with metal nanoparticles. For the growth of CNWs, ion bombardment on the substrate surface would play an important role in nucleation by creating active sites for neutral radical bonding, resulting in the formation of vertical graphene. On one hand, by reducing the ion flux incident on Ni or Cu substrate, planar graphene can be formed. We focus on the structure control of CNWs during the growth processes to be used as platform of the electrochemical and bio applications.
Iran University of Science & Technology, Iran
Title: Different roles of carbonate additives on hexagonal boron nitride microstructure prepared from urea and boric acid
Time : 11:45-12:05
Hajar Ghanbari has her expertise in carbonaceous and 2D materials, ceramic composites and laser-assisted synthesis of nanomaterials. She has proposed her explosion model on the laser-assisted synthesis of graphene in organic solvents in 2014. She has joined Iran University of Science and Technology, Faculty of Metallurgy and Materials Engineering, Ceramics Division since September 2016 and established a research group focusing on modern ceramics.
Hexagonal boron nitride (h-BN) is an advanced ceramic material similar in electronic structure to the most versatile of elements, carbon, sharing the same number of electrons between adjacent atoms. This hexagonal phase is the most stable and softest among BN polymorphs. h-BN powders are mostly used as lubricants. Compared to graphite, the h-BN can be utilized in an oxidizing atmosphere up to 900 °C, as well as low temperatures. Good lubricity, corrosion and oxidation resistance in high temperature guaranteed the premium market for this light material. In this paper, we have been successfully synthesized h-BN from a precursor obtained by urea and boric acid, following by nitridation in >1000 °C temperature and leaching step. We studied the effect of nitridation temperature (1000 °C-1200 oC) through the addition of lithium carbonate (Li2Co3), sodium carbonate (Na2Co3) and calcium carbonate (CaCo3) on the powder morphology and microstructure. Synthesized particles are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). In addition, we measured the contact angle of water on the pressed disks prepared at different temperatures and with different additives. Comparing the results showed that the nitridated powder prepared with the Li2Co3 additive in 1200 °C possessed the highest purity and largest grain size. In addition, the results confirm the non-uniform effect of temperature increase while utilizing three different additives.
COMSATS Institute of Information Technology, Pakistan
Time : 12:05-12:25
Tauqir A Sherazi is an Associate Professor and Head of Material Chemistry Group at Department of Chemistry, COMSATS Institute of Information Technology, Pakistan. His expertise is in the development of cost effective and highly efficient polymer electrolyte membrane materials through controlling the chemistry and morphology of the polymers.
Most electrochemical conversion and storage devices, such as fuel cells and redox-flow batteries, rely on the amazing properties of ion conducting polymer membranes. The development of polymer electrolyte membranes (PEMs) combining high ion conductivity and durability is a major challenge for materials chemistry. Nafion® (DuPont) is state of the art membrane due to its good mechanical strength, excellent proton conductivity and stability, but its limitation to low temperature operation, high cost and fuel crossover are major obstacles that renders its usage in commercialization of fuel cell. Various polymers have been synthesized and explored as an alternative membrane material to reduce cost and improved proton conduction to Nafion but most of these showed trade off properties. The membranes showing good conduction may have poor stability or mechanical strength. This fact impedes the technology to achieve commercialization status. In present study, radiochemical pore filled membranes were prepared in which porous polyethylene (PPE) substrate was radio-chemically grafted and filled with styrene/acrylic acid copolymer. Proton Exchange Membranes prepared through radiochemical pore filling process exhibited high ionic conductivity. High conductivity is attributed to the formation of micro level confinement within the membranes for ion transport is reported for the first time. Despite their simple preparation method, consisting single radiochemical grafting and pore-filling step using commercially available porous substrate, involves least amount of chemical. The polymer provides PEMs which exhibited exceptional proton conductivity at good but relatively lower ion-exchange capacity, as well as a high swelling resistance. An unprecedented hydroxide conductivity of 274 mS cm-1 is obtained at an ion-exchange capacity of 2.85 meq g-1 under optimal operating conditions. The exceptional ion conductivity appears related to the intrinsic microporosity of the charged polymer matrix, which facilitates rapid cation transport.
Anadolu University, Turkey
Sadiye Pelin Erden has her expertise on the production of ceramic metal oxide powders by using different methods such as solid state and hydrothermal synthesis. She is working on production of zinc stannate powders via these methods and investigation of the effect of the material characteristic on the chemical stability of zinc stannate in different aqueous environment.
Zinc stannate that has unique properties, including high electron mobility, high electrical conductivity, low visible absorption and excellent optical properties. Recently, its potential applications have been investigated for various applications such as gas sensors, electrode materials for dye sensing solar cell (DSSC) and catalyst for photo-degradation of dyes and pollutants. In order to obtain the maximum performance in such applications, Zn2SnO4 materials should represent a high chemical stability. However, the chemical stability of Zn2SnO4 materials in aqueous environment depending on pH and this has not been well understood in detail yet. Therefore, the research objective of this study was to evaluate the effects of the material characteristics (particle surface area, particle size and form) and pH of the suspension on the chemical stability of Zn2SnO4 in aqueous environment and hence to determine the interaction between the particles and aqueous medium. In this study, zinc stannate particles with different surface area and particle size were synthesized by solid state reaction and hydrothermal methods. After the Zn2SnO4 powders were synthesized, Zn2SnO4 suspensions in aqueous environment were prepared at pH 3 and pH 9 by adding HCl acid and NaOH base solutions to the deionized water, respectively. Supernatants from the suspensions were collected for the following 30 days in 24 hours intervals. Zn+2 and Sn+4 ion concentrations were determined by ICP-OES. The ICP-OES results showed that cations of Zn2SnO4 dissolve more in the acidic side than the basic one. In addition, dissolution rate of the hydrothermally synthesized Zn2SnO4 powder with higher surface area (18.053 m2/g) at pH 3 was much faster than that of the solid state synthesized Zn2SnO4 powder with relatively lower surface area (1.99 m2/g).