[en] This work demonstrates a novel organic conversion coating treatment on an AA2024-T3 substrate. The process is based on simple immersion in aqueous solutions containing an organic molecule, N-Benzoyl-N-phenylhydroxylamine (BPHA), after a hydrothermal oxide has been formed on the alloy surface. Potentiodynamic polarization results indicate that BPHA conversion coating outperforms coatings formed in the same concentration of other corrosion inhibitors, including NaVO₃, Na₂SiO₃, CeCl₃, and benzotriazole. BPHA coating also displays strong and persistent corrosion inhibition under ASTM B117 salt spray exposure conditions and static immersion testing. The cross-section of BPHA-coated substrate is prepared by focus ion beam-scanning (FIB), and analyzed by high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) coupled with energy dispersive spectroscopy (EDS), which show a thick surface film with a three-layer structure. Raman spectroscopy and XPS are used to examine the surface chemistry of BPHA-coated samples, both of which suggest the formation of a BPHA surface film, possibly stabilized by the keto-to-iminol conversion that made the BPHA molecule strongly nucleophilic. The formation of BPHA-metal oxide complex seems to be closely related to the excellent corrosion resistance of BPHA coating.

[en] This study investigates the effect of rake angle on cutting performance during machining of stone-plastic composite material with diamond cutters. To that end, an orthogonal cutting experiment was designed, in which stone-plastic composite material was planed by a polycrystalline diamond (PCD) cutter to produce chips. The features studied include cutting forces, cutting heat, chip formation and cutting quality. The conclusions are as follows: Firstly, increased rake angle causes frictional force and resulting force to decrease, promoting an increase in normal force. Secondly, during planing, cutting heat is primarily distributed in the chips, with less retained in the cutting edge, and the least retained in the machined surface. The temperatures of both cutting edge and chip decline with an increase in rake angle. Thirdly, as rake angle increases, chip morphology changes from segmental to curved and then to particle chips, with chip-breaking lengths first increasing and then decreasing. Finally, an increased rake angle leads a more stable cutting process and improved cutting quality. Therefore, with the precondition of blade strength, a diamond cutter with a larger rake angle can be used to machine stone-plastic composite to improve production quality by forming a smoother machined surface.

[en] Highlights: • Inhibitor-loaded microspheres were fabricated by the electrospray technique. • The microspheres respond to both acidic and alkaline pH conditions. • Inhibitors were released from the microspheres upon a pH change. • A smart coating was prepared by embedding the microspheres into a coating matrix. • The coating enhanced corrosion resistance at anodic and cathodic sites of AA2024-T3. In this study, we describe a smart coating that responds to either an increase or a decrease in pH to assist inhibitor effectiveness. Dual-pH sensitive microspheres containing a corrosion inhibitor were fabricated using a simple, template-free, one-step process. A polyelectrolyte coacervate consisting of polyacrylic acid and polyethylenimine was the shell material of microspheres that enclosed Ce(NO₃)₃ inhibitor using a coaxial electrospray method. The Ce(NO₃)₃-loaded microspheres with a core-shell structure can release Ce(NO₃)₃ at both acidic and alkaline pH. A smart coating consisting of these microspheres embedded in a polyvinyl butyral coating releases Ce(NO₃)₃ to improve the corrosion resistance of AA2024-T3.

[en] This review covers the corrosion interactions between different materials that are relevant to the disposal of high-level nuclear waste, in particular the waste forms and containers. The materials of interest are borosilicate glass, crystalline ceramics, metal alloys, and any corrosion products that might form. The available data show that these interactions depend on the structure, chemistry, thermodynamic history, and proximity of the materials in contact, as well as the environmental attributes, such as temperature, solution chemistry, and radiation. Several key mechanisms that govern these interactions are highlighted. Scientific gaps and open questions are summarized and discussed. (authors)

[en] Highlights: • Metal dissolution kinetics in local pit environments were studied at different temperatures. • A method was introduced to calculate activation energy ($\mathrm{\Delta }{G}_{\mathrm{a}}^{*}$) of pit dissolution. • The order of $\mathrm{\Delta }{G}_{\mathrm{a}}^{*}$ for different alloys follows the same order as their pitting potentials. • Rate of cathodic reaction at the pit surface increases with increasing pit depth and temperature. • Perspective on the prediction of critical pitting temperature using $\mathrm{\Delta }{G}_{\mathrm{a}}^{*}$ was proposed. Metal dissolution kinetics of stainless steels 316L, 304, 430, and pure Fe in local pit environments were studied at temperatures from 20 to 50 °C. A method was introduced to calculate the activation energy of pit dissolution ($\mathrm{\Delta }{G}_{\mathrm{a}}^{*}$) at a fixed pit environment and a given potential. $\mathrm{\Delta }{G}_{\mathrm{a}}^{*}$ of the alloys is in the order: SS316L > SS304 > SS430 > Pure Fe, which follows the same order as their pitting potentials. The cathodic reaction at the pit bottom surface influences the pit dissolution behavior and this effect increases with increasing pit depth and temperature. Additionally, a perspective on the prediction of critical pitting temperature using $\mathrm{\Delta }{G}_{\mathrm{a}}^{*}$ is proposed.

[en] This study investigates the effect of rake angle on cutting performance during machining of stone-plastic composite material with diamond cutters. To that end, an orthogonal cutting experiment was designed, in which stone-plastic composite material was planed by a polycrystalline diamond (PCD) cutter to produce chips. The features studied include cutting forces, cutting heat, chip formation and cutting quality. The conclusions are as follows: Firstly, increased rake angle causes frictional force and resulting force to decrease, promoting an increase in normal force. Secondly, during planing, cutting heat is primarily distributed in the chips, with less retained in the cutting edge, and the least retained in the machined surface. The temperatures of both cutting edge and chip decline with an increase in rake angle. Thirdly, as rake angle increases, chip morphology changes from segmental to curved and then to particle chips, with chip-breaking lengths first increasing and then decreasing. Finally, an increased rake angle leads a more stable cutting process and improved cutting quality. Therefore, with the precondition of blade strength, a diamond cutter with a larger rake angle can be used to machine stone-plastic composite to improve production quality by forming a smoother machined surface.

[en] This study explores the corrosion interactions between model nuclear waste glass materials and corrosion resistant alloys, under accelerated conditions that simulate the near field of a nuclear waste repository. The interactions between the corrosion of stainless steel (SS) 316, alloy G30, or alloy 625, and international simple glass or soda-lime silica glass are systematically studied. The dissimilar materials were exposed in close proximity to each other in different electrolytes at 90 degrees C. After exposure, the glass surface exposed near metals showed different regimes of corrosion, with distinct surface morphologies and chemistries that were likely affected by the local environment created by the localized corrosion of metals. Surface and solution analyses showed that the corrosion rate of glass was enhanced by the presence of metals. Infrared spectroscopy data suggested the local build-up of stresses in the contact area of glass, which may lead to the mechanical instability of the glass alteration layer. On the other hand, the effect of glass on metal corrosion is strongly dependent on the leaching solution. In electrolytes containing abundant aggressive anions such as Cl^-, glass seems to suppress the localized corrosion of SS by the precipitation of a Si-rich surface film that protects the SS substrate from solutions. However, in less aggressive electrolytes, the corrosion rate of SS was increased by the presence of glass corrosion products. Overall, our study showed that the hidden and localized damage on glass in contact with metals may enhance the release rate of glass components compared to typical uniform glass corrosion. (authors)

[en] Titanium dioxide/Nano-graphite (TiO_2/Nano-G) composite was synthesized by a sol-gel method and TiO_2/Nano-G electrode was prepared in hot-press approach. The composite was characterized by X-ray photoelectron spectroscopy (XPS), fourier transform infrared (FT-IR), scanning electrons microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrochemical performance of the TiO_2/Nano-G anode electrode was investigated through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electro-catalytic performance was evaluated by the yield of ·OH radicals, degradation of methyl orange and ceftriaxone sodium. The results demonstrated that TiO_2 nanoparticles were dispersed on the surface and interlamination of the Nano-G uniformly, TiO_2/Nano-G electrode owned higher electro-catalytic oxidation activity and stability than Nano-G electrode. Degradation rate of ceftriaxone sodium within 120 min by TiO_2(40)/Nano-G electrode was 97.7%. And ·OH radicals given by TiO_2/Nano-G electrode was higher than that of Nano-G electrode and DSA (Ti/IrO_2-RuO_2) electrode. The excellent electro-catalytic performance could be ascribed to the admirable conductive property of the Nano-G and more production of ·OH offered by TiO_2(40)/Nano-G electrode.

[en] Graphical abstract: The chemical-coupling Nano-graphite(G)/TiO_2 composite was successfully prepared via a modified sol-gel method and then was fabricated as a photoelectrode by the hot-press approach. Nano-G/TiO_2 photoelectrode displayed high PEC activity and stability, which was attributed to Nano-G as suitable electronic conductors to promote charge collection and charge transport as well as the synergetic effect between PC and EC reactions. - Highlights: • Nano-G/TiO_2 photoelectrode was prepared by the sol-gel and hot-press methods. • Nano-G/TiO_2 photoelectrode exhibited high charges separation performance. • Nano-G/TiO_2 photoelectrode displayed excellent PEC activity. • Contribution of active species for degradation of RhB was investigated. • Enhanced PEC mechanism of Nano-G/TiO_2 photoelectrode was proposed. - Abstract: Nano-graphite(Nano-G)/TiO_2 composite photoelectrode was fabricated via sol-gel reaction, followed by the hot-press approach. The morphology, structure and light absorption capability of composite was characterized by various characterizations. The photoelectrochemical property and photoelectrocatalytic(PEC) activity of photoelectrode were also investigated. Results revealed that anatase TiO_2 nanoparticles with an average diameter of 10 nm were dispersed uniformly on the thickness of 2–3 nm Nano-G, and Ti−O−C bond was formed. The absorption edge of Nano-G/TiO_2 photoelectrode was red-shifted towards low energy region and the enhanced visible light absorption was obtained. The charge transfer resistance of Nano-G/TiO_2 photoelectrode was significantly decreased after the addition of Nano-G. And its transient photoinduced current was 10.5 times the value achieved using TiO_2 electrode. Nano-G/TiO_2 photoelectrode displayed greatly enhanced PEC activity of 99.2% towards the degradation of phenol, which was much higher than the 29.1% and 58.3% degradation seen on TiO_2 and Nano-G electrode, respectively. The highly efficient and stable PEC activity of Nano-G/TiO_2 photoelectrode was attributed to the synergy effect between photocatalysis and electrocatalysis, as well as enhanced light absorption ability and higher separation efficiency of photogenerated charge carriers. Moreover, contribution of series of reactive species to the PEC degradation of Nano-G/TiO_2 photoelectrode was determined.

[en] Highlights: • Three novel 3D metal coordination polymers prepared with new triazol-functionalized rigid ligand have been synthesized and structurally characterized. • Compound 1 exhibits highly selective separation abilities of CO2 and C3H8 over CH4 at room temperature suggesting that 1 has potential application in gas storage and separation. • The magnetic properties of compound 2 have been investigated. - Abstract: By using a triazol-functionalized tricarboxylate, three novel metal coordination polymers, namely, [Zn₂L(OH)]·0.5H₂O (1), [Co₂L(OH)(H₂O)]·5.5H₂O (2), [Cu₂(HL)] (3) L = [5-(3-(4-carboxyphenyl)−5-methyl-4H-1,2,4-triazol-4-yl)isophthalate] were synthesized under hydrothermal reactions. All the compounds were characterized by element analysis, IR spectroscopy, thermogravimetric analysis, power X-ray diffrcation and single-crystal X-ray diffrcation. Structural analysis reveals that compounds 1 and 2 have 3D networks with flu topologies where rigid trizaol-functionalized ligands as 4-connected nodes and Zn₄(COO)₆ or Co₄(COO)₆ clusters serves as 8-connected secondary building units. Compound 3 has 3D network with pcu topology where Cu₄(COO)₄ clusters serve as 6-connected secondary building units. Gas adsorption studies reveal that desolvated compoud 1 exhibits high H₂ absorption capacity at 77 K and highly selective separation abilities of CO₂ and C₃H₈ over CH₄ at room temperature. The results suggest that 1 has potential application in gas storage and separation. In addition, the magnetic properties of compound 2 were also investigated.