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Arc Interactions with Contaminants
Published in Paul G. Slade, Electrical Contacts, 2017
Gerald J. Witter, Werner Rieder
Witter and Polevoy also conducted surface analysis on the high contact resistance long arc samples they had tested [70]. The work was done using electron spectroscopy for chemical analysis (ESCA), which not only identifies elemental monolayer but also provides information on the valence of the element. This analysis showed that silver, carbon, and oxygen were present on the surface but also the valence state of the carbon and oxygen corresponded to that which matches the compound silver carbonate. From the analysis it was also determined that almost all of the silver on the surface was tied up as this compound.
Using photocatalyzed-peroxonization to disinfect and denature genetic material of bacterial plasmids present in hospital wastewater
Published in Journal of Environmental Science and Health, Part A, 2023
Aline Dal Conti-Lampert, André L. F. Souza, Renan C. Testolin, Gisele Canan-Rochenbach, Marco A. B. Barreiros, Cleder A. Somensi, Gizelle I. Almerindo, Rafael Ariente-Neto, Sergio Y. G. González, Claudemir M. Radetski, Sylvie Cotelle
In the oxidation reactions, silver oxide and silver carbonate (Ag2O and Ag2CO3, Sigma-Aldrich) and titanium dioxide (TiO2, Degussa) were used as nanocatalysts. Hydrogen peroxide (H2O2), sulfuric acid (H2SO4), sodium hydroxide (NaOH), and other reagents were purchased from Dinâmica Química Contemporânea (SP, Brazil).
Ag-containing antibacterial self-healing micro-arc oxidation coatings on Mg–Zn–Sr alloys
Published in Surface Engineering, 2021
Yang Chen, Jinhe Dou, Zengfen Pang, Zhiqiang Zheng, Huijun Yu, Chuanzhong Chen
The surface morphology and element composition of MAO coatings are shown in Figure 2. It can be seen from Figure 2(a) that relatively large micro-pores and micro-cracks formed in MAO coatings, some of the micro-pores were filled with irregular clusters. According to the element composition analysis, the proportion of element O, C, F, Mg and Ti in the irregular clusters was high, indicating that the MAO coatings were mainly composed of oxide or fluoride of magnesium and titanium. Figure 2(b) shows that more micro-pores and micro-cracks appeared on the AgAC-1 MAO coating, but the diameter of pores was smaller and more uniform than AgAC-0 sample. The element composition analysis indicated that AgAC-1 coating contained titanium oxide, magnesium oxide, fluoride or carbonates. Figure 2(c) shows that the surface of AgAC-2 MAO coatings was relatively more flat, only a few micro-pores formed on MAO coatings, and the pores were almost sealed by the clusters of nano-sized particles. The element composition analysis showed that the irregular cluster-like substances were mainly silver oxide and titanium oxide. As shown in Figure 2(d), the addition of 3 g L−1 CH3COOAg in electrolyte caused larger pore diameters in MAO coatings, increased the occurrence of micro-cracks, because of the increasing breakdown current and more intense reactions. The micro-pores were filled with cluster-like substances. The element composition analysis indicated that these substances might be silver oxides or silver carbonate, which demonstrated the self-sealing effects of CH3COOAg additives. In conclusion, the addition of 2 g L−1 CH3COOAg could significantly reduce the size and number of micro-pores in MAO coatings, and minimize the occurrence of micro-cracks via moderate micro-arc oxidation reactions. The silver and titanium oxides in MAO coatings could fill and seal the micro-pores, micro-cracks in MAO coatings due to the absorption of CH3COOAg and K2TiF6 into the discharge channel under high temperature and pressure. When the concentration of CH3COOAg exceeded 2 g L−1, the sealing effect was undermined, the proportion of silver oxide greatly increased, the number of micro-pores and micro-cracks became more. The increase in micro-pores and micro-cracks tended to trigger off external corrosive media entering into the coatings and accelerate the corrosion of the magnesium alloy substrate. Therefore, AgAC-2 MAO coating was considered to have the strongest corrosion resistance. It was worth mentioning that the diameter of all the spherical particles was less than 10 nm. The element composition analysis showed that these particles were magnesium oxide, magnesium fluoride, titanium oxide and silver oxide respectively. Figure 2(c,d) shows that plenty of nano-sized Ag-containing particles existing on the surface of MAO coatings might lead to the apoptosis of bacteria.