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Schwertz M.,French German Research Institute of Saint Louis | Schwertz M.,CNRS Mulhouse Institute of Materials Science | Katz A.,French German Research Institute of Saint Louis | Sorrel E.,French German Research Institute of Saint Louis | And 8 more authors.
Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science | Year: 2015

This paper deals with the development of a novel and predictive finite element method (FEM) model coupling electrical, thermal, and mechanical time-dependent contributions for simulating the behavior of a powdery material submitted to a spark plasma sintering (SPS) treatment by using COMSOL Multiphysics® software. The original approach of this work lies in the use of the modified Cam-Clay model to solve the mechanical phenomenon occurring during a SPS sintering treatment. As the powder properties and behaviors are different from the final sintered material and display a nonlinear dependence as a function of temperature and pressure, the model includes the description of the sample densification. In this way, numerical and experimental results obtained on conductive model material (aluminum) such as temperature, stress distributions, and shrinkage, were directly compared. This FEM model demonstrated the ability to predict the powder behavior during temperature-controlled experiments precisely, as they are typically performed in the SPS technique. This approach exhibits a remarkable level of interest because it takes into account the nature of the material and also the specific characteristics of the powder studied. © 2015 The Minerals, Metals & Materials Society and ASM International Source


Ashraf M.,National Textile University | Champagne P.,University of Lille Nord de France | Champagne P.,Laboratoire des Materiaux Ceramiques et Procedes Associes | Campagne C.,University of Lille Nord de France | And 7 more authors.
Journal of Industrial Textiles | Year: 2014

The conditions to make nanorods functionalized fabric superhydrophobic have been optimized to obtain three kinds of self-cleaning characteristics such as physical, chemical, and biological. Physical self-cleaning is the lotus effect which is characterized by measuring both water contact and sliding angles. Chemical self-cleaning is the degradation of color stains and solutions due to photocatalytic effect of ZnO when exposed to ultraviolet. Biological self-cleaning refers to the antibacterial activity of functionalized fabric which is characterized by using a Gram-negative bacterium (Escherichia coli) and a Gram-positive bacterium (Staphyloccocus aureus) by both qualitative and quantitative methods using NF ISO 20743:2009 transfer method. The chemical and biological self-cleanings are studied on nanorods functionalized fabric before and after hydrophobization. © 2014, © The Author(s) 2014. Source


Ashraf M.,CNRS Textile Engineering Laboratory | Ashraf M.,University of Lille Nord de France | Ashraf M.,Laboratoire des Materiaux Ceramiques et Procedes Associes | Campagne C.,CNRS Textile Engineering Laboratory | And 9 more authors.
Journal of Colloid and Interface Science | Year: 2013

ZnO nanorods were grown on microfibers of Polyethylene terephthalate (PET) fabric by seeding method to develop hierarchical roughness structure. XRD and XPS analysis show the presence of crystalline ZnO and chemical Zn species at the fiber surface at each stage of the process. Five series of samples with different seed concentrations have been realized, and their surface morphology and topography were characterized by AFM and SEM. Increasing seed concentrations lead to samples with superhydrophilic properties. Not only the water contact angle at fabric surface tends to zero but also the water capillary diffusion inside fabric is faster. Nanostructuration affects the structure inside the fabric, and further experiments with decane liquid have been made to get a better understanding of this effect. To study the superhydrophobicity, nanorods treated samples were modified with octadecyltrimethoxysilane (ODS) by two method; solution deposition and vapor deposition. The superhydrophobicity was characterized by measuring the water contact angle and water sliding angle with 5 μl water droplet. The samples modified with ODS by vapor deposition showed higher water contact angles and low water sliding angle than the ones modified with solution method. The lotus effect has been well correlated with the surface morphology of the nanorods structured fibers. The application of the Cassie-Baxter equation is discussed. © 2012 Elsevier Inc. Source

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