Experimental characterization, machine learning analysis and computational modelling of the high effective inhibition of copper corrosion by 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol in saline environment.

An oxadiazole derivative with functional groups favouring its adsorption on copper surface, namely 5-(4-Pyridyl)-1,3,4-oxadiazole-2-thiol, has been explored as potential inhibitor of copper corrosion in 3.5 wt.% NaCl. Electrochemical evaluation by electrochemical impedance spectroscopy, potentiodynamic polarization and SVET reveals inhibition efficiencies exceeding 99%. Surface microscopy inspection and spectroscopic analysis by Raman, SEM-EDX and XPS highlight the formation of a compact barrier film responsible for long-lasting protection, that is mainly composed of the organic molecules. Machine Learning algorithms used in combination with Raman spectroscopy data were used successfully for the first time in corrosion studies to allow discrimination between corroded and inhibitor-protected metal surfaces. Quantum Chemistry calculations in aqueous solution and Molecular Dynamic studies predict a strong interaction between copper and the thiolate group and an extensive coverage of the metal surface, responsible for the excellent protection against corrosion

Structural, thermal, in vitro degradation and cytocompatibility properties of P2O5-B2O3-CaO-MgO-Na2O-Fe2O3 glasses

Borophosphate glasses with compositions of (48 − x)P2O5-(12 + x)B2O3-14CaO-20MgO-1Na2O-5Fe2O3 (where x = 0, 3, 8 mol%) were prepared via a melt-quenching process. The effects of replacing P2O5 with B2O3 on the structural, thermal, degradation properties and cytocompatibility were investigated. Fourier transform infrared (FTIR) spectroscopy analysis confirmed the existence of BO3 triangular units and BO4 tetrahedral units within all the glasses with an increase of B/P ratio from 0.25 to 0.5. The BO4 units within the glass structure were observed to cause an increase in density (ρ) as well as glass transition (Tg) temperature and to decrease the crystallisation temperature (Tc). A decrease in thermal stability which indicated by process window was also observed in the case of substitution of P2O5 with B2O3. Degradation analysis of the glasses indicated that the dissolution rate increased with the addition of B2O3. The decrease in the thermal stability and chemical durability were attributed to the increase of BO3 units, which could increase crystallisation tendency and be easily hydrolysed by solution. The effect of boron addition on the cytocompatibility of the glasses was analysed using Alamar Blue and alkaline phosphatase (ALP) assays and DNA quantification. MG63 osteosarcoma cells cultured in direct contact with the glass samples surface for 14 days showed better cytocompatibility, compared to the tissue culture plastic (TCP) control group. In summary, the glass formulation with 12 mol% B2O3 presented the best cytocompatibility and thermal stability, thus could be considered for continuous fibre fabrication in future research and downstream activities

Structural, thermal and dissolution properties of MgO- and CaO-containing borophosphate glasses: effect of Fe2O3 addition

This paper investigated manufacture of high-durability phosphate glass fibres for biomedical applications. Five different borophosphate glass formulations in the systems of 45P2O5–5B2O3–5Na2O–(29 − x)CaO–16MgO–(x)Fe2O3 and 45P2O5–5B2O3–5Na2O–24CaO–(21 − x)MgO–(x)Fe2O3 where x = 5, 8 and 11 mol% were produced via melt quenching. The compositions and amorphous nature of the glasses were confirmed by ICP-MS and XRD, respectively. FTIR results indicated depolymerisation of the phosphate chains with a decrease in Q2 units with increasing Fe2O3 content. DSC analyses showed an increase in Tg by ~5 °C with an increment of 3 mol% in Fe2O3 content. The thermal properties were also used to calculate processing window (i.e. Tc,ons—Tg) and another parameter, Kgl, to determine the suitability for fibre drawing directly from melt, which equals (Tc,ons—Tg)/(Tl—Tc,ons). The degradation study conducted in PBS solution at 37 °C showed a decrease of 25–47% in degradation rate with increasing Fe2O3 content. This confirmed that the chemical durability of the glasses had increased, which was suggested to be due to Fe2O3 addition. Furthermore, the density measured via Archimedes method revealed a linear increase with increasing Fe2O3 content

Structural studies of iron doped B₂O₃•0.7PbO•0.3Ag₂O glasses by FT-IR and Raman spectroscopies

Glasses from xFe₂O₃·(100-x)[3B₂O₃·0.7PbO·0.3Ag₂O] system, with 0 ≤ x ≤ 20 mol.%, were prepared and investigated by means of two complementary spectroscopic methods, FT-IR absorption and Raman scattering in order to obtain information concerning the network structure. Both FT-IR and Raman spectroscopic techniques have revealed changes in the local structure of the glasses when the composition is modified. The iron ions modifier role is pointed out by the shape of the recorded spectra, changed with increasing the Fe₂O₃ content. The influence of a gradual addition of the iron oxide on the local structure of silver lead borate based glasses has been studied. The FT-IR data indicate the presence of the BO₃ and BO₄ structural units in the glasses, the network structure being mainly built by: di-, tri-, tetra-, penta- and orthoborate groups. The characteristic bands of the different structural groups evidenced in these glasses were identified and quantitatively analyzed after increasing the Fe₂O₃ content. The Fe₂O₃ content dependence of Ar (A₄/A₃) ratio (where the values A₄ and A₃ reflect the relative amount of tetra-, respectively tri-coordinated boron atoms) was studied. In addition, characteristic vibrational modes of bonds from iron, lead and silver oxides were detected in the FT-IR spectra. Raman data is in accordance with the FT-IR results and complete them. Using Raman scattering, we detected new structural groups as pyro-, ditri- and dipenta-borate groups, indicating changes in the structure of our glasses after Fe₂O₃ additio

Thermophysical properties of modified Ti-bearing blast furnace slags

Our study investigated the influence of P2O5 and B2O3 on the viscosity and crystallization behavior of Ti-bearing blast furnace (Ti-BF) slags for the purpose of Ti extraction. The investigation of the crystallization behaviors were carried out using a single hot thermocouple technique (SHTT) and the viscosity was obtained by rotating cylinder method. For the viscosity, the results showed that P2O5 substantially increased the slag viscosity. P2O5 is a network-forming oxide, which increased the degree of polymerization of slags and accordingly increased the slag viscosity. However, both of slag viscosity and apparent activation energy for viscous flow remarkably decreased with B2O3 addition. As a typical network forming oxide, B2O3 was introduced into the network and existed dominantly as 2-D structure, BO3 triangular, which caused a simpler structure and a decreasing slag viscosity. As for the crystallization behaviors of Ti-BF slags, both P2O5 and B2O3 enhanced the crystallization trend of rod-shape rutile and suppressed the crystallization trend of dendrite CaTiCO3. Therefore the added P2O5 and B2C>3 caused the primary phase change from CaTiCO3 to rutile. Additionally, it was found that the rod-shape rutile showed a 1-D growth, whereas the dendrite CaTi03 showed a 3-D growth style. Copyright ? 2015 by The Minerals, Metals & Materials Society. All rights reserved.EIJanuary703-7092015-Januar