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Vol 2 No 1 (2020)

  • High Temperature Compression Tests of A Commercial Isotropic Ultrafine Grain Graphite

    Lisa Centofante, Alberto Monett, Giovanni Meneghetti

    Graphite is often used to design components working at high temperature in a variety of industrial and research environments. It is therefore important to know the mechanical resistance of this material at high temperature. This work reports the compressive strength up to 2000°C of an isotropic ultrafine grain graphite, the POCO EDM-3, which has not been analysed in the literature yet. This graphite is used to design components able to withstand extreme environmental conditions, due to the properties resulting from the uniform and isotropic microstructure of the material. A vacuum compression test equipment was developed, able to work above 2000°C. Both cylindrical and hourglass-shaped specimens were tested and the influence of density was also evaluated. The influence of the materials in contact with the specimen ends was also analysed, but a negligible dependence was observed. The tests demonstrated that the compressive strength increases as the density and the temperature increase: at 2000°C a 22% average increase of the compressive strength over its room-temperature value was noted.

  • The Synergistic Effect of NaHSO4 and NaCl Salts on Corrosion Inhibition Performance of Two Gemini Cationic Surfactant Ionic Liquids

    E. Kowsari, M. Payami, E. Kamali Ardakani, S. Kholghi Eshkalak, M. Ghambarian, R. Amini, B. Ramezanzadeh, A Ehsani, S. Ramakrishna

    In this study, two imidazolium-based ionic liquid surfactants (TSIL and EFAIL) were first synthesized, and then investigated the synergistic effects of NaHSO4 and NaCl salts on corrosion inhibition performance of TSIL and EFAIL inhibitors on low carbon steel samples in 1M HCl solution. For this aim, the electrochemical techniques of potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), surface morphology analyses, and quantum chemical calculations were employed. Results showed that adding salts to acidic solutions containing EFAIL and TSIL increased their inhibition efficiency. Furthermore, addition of NaHSO4 to TSIL-containing solution could further increase the inhibition efficiency compared to other mixtures of the salts and the inhibitors. The DFT results also revealed that the energy gap of TSIL is lower than that of EFAIL, implying that TSIL has more chemical reactivity and less kinetic stability than EFAIL.

  • Kinetic Study of Copper Retention by Kaolin Using a System of Supports Designed in 3D

    A. Macías-García, J.E. Calderón-Rios, M.A. Díaz-Díez, D. Torrejón-Martín, Juan Pablo Carrasco-Amador

    Kaolin is a clay product of the decomposition of feldspatic rocks; it is a hydrated aluminum silicate whose main component is kaolinite; its formula is 2H2O-Al2O3-2SiO2 and it has a wide application in various industries. In this study copper ions removal of aqueous solutions using kaolin, was investigated. Kaolin sample are texturally and chemically characterized and its electrical conductivity was established, and finally diverse kinetic models were tested to the copper ion retention process. Kinetic adsorption and electroadsorption processes of Cu (II) ions on kaolin are practically identical.  The qe values for both adsorption and electroadsorption are of the order of 10.1 mg·g-1 for an equilibration time of 1200 min. This suggests that adsorption procedure is the determining factor. In view of results, we can indicate that kinetic adsorption procedure of Cu (II) ions on kaolin is adjusted to a pseudo second order kinetics. High regression coefficients are reached, greater than those of first order pseudo model, with worths above 0.99. Its explanation comes from the valence forces involved in the adsorption mechanism, due to electrons exchange between Cu (II) ions and the adsorbent. Likewise, correlation between experimental qe values, and the calculated qe, through the kinetic model are good. A more detailed observation through intraparticle diffusion model allows us to distinguish two well defined linear parts, a first one: that would correspond to the transport of ions from the dissolution to the external covering of the absorbent, with a fast ions distribution on the external kaolin covering. And a second part, which symbolize the intraparticular diffusion, as well as Cu (II) union with the kaolin  internal active sites.

  • Application Analysis of Green Building Materials in Civil Engineering Construction

    Xiangyu Xu, Xue Li

    The concept of green construction has been widely applied in current development progress of construction industry. The key application points of this concept is to pay attention to the protection of surrounding environment, to take measures of saving energy and reducing emissions and reduce the consumption rate of energy and to prompt the sustainable development of economy when conducting engineering constructions. Currently, when constructing civil engineering, green building materials is continuously expanding its application area. The emergence of some new materials provides effective support for green construction of civil engineering. Construction enterprises, when applying these materials, must strictly follow the principle of green construction, select right construction raw materials to conduct the engineering so as to improve the total quality of construction. The paper analyzes and discusses the application of green building materials in civil engineering construction.

  • UV-mediated Thiol-ene Polyol Functionalization for Synthesis of Biobased Waterborne Polyurethanes

    Jevgenij Lazko, Loïc Poussard, Jérôme Mariage, Fouad Laoutid, Jean Marie Raquez, Philippe Dubois

    Developing waterborne polyurethane coatings from biobased polyols represents an interesting alternative, allowing at the same time to increase the use of sustainable renewable raw materials and to reduce volatile organic compounds emissions. In this work, biobased Veopur polyol was first functionalized with mercaptopropionic acid (MPA) using solvent-free UV-mediated thiol-ene reaction performed in bulk. Grafted carboxylic moieties were then neutralized by triethylamine (TEA) in order to obtain the required amphiphilic behavior. In the final step, functionalized water dispersible polyol was polymerized with water soluble polyisocyanate to form waterborne polyurethane (WPU). The influence of key-process parameters on grafting efficiency was investigated by iodometric titration, Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H NMR). Particle size measurements and stress-strain tests were carried out to characterize WPU water dispersions and corresponding materials, respectively.