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According to the requirements for anode materials of safe and high‐capacity lithium‐ion batteries (LIBs), various Sn/TiO2 and SnO2/TiO2 composite materials have been developed, but no reports have yet combined them by a simple fabrication method. Herein, a novel and simple approach is reported for the fabrication of nanoporous TiO2–TiN/Sn–SnO2 composite films by successive Ti anodization and cathodic hybrid electrodeposition of Sn in a nitric acid‐based aqueous solution containing Sn2+ and/or Sn4+ ions. The conductivity of the anodic TiO2–TiN composite films facilitates the simultaneous electrodeposition of metallic Sn and electrophoretic deposition of SnO2 colloids, both on the surface and inside the nanopores of the film. Notably, the nanoporous structure is preserved, which provides a large surface area. The electrodeposition of Sn–SnO2 nanoparticles on the nanoporous TiO2–TiN film significantly improves the charge transfer and conductivity of the composite film and enhances the discharge capacity to up to 2386.1 µAh cm−2 (approximately sixfold higher than that of the bare matrix film). [ABSTRACT FROM AUTHOR]

Gallium nitride (GaN) films were synthesized on n-type-Si (111) substrates using a low-cost and low-temperature technique of electrochemical deposition. The electrochemical behavior of Ga3+, NH4+, and NO3− ions in the aqueous solutions used as sources of GaN were confirmed by cyclic voltammetry. The scanning electron microscopy images showed that the films deposited at a current density of 3.5 mA cm−2 or greater have plate-like surface morphologies on the Si substrate. The energy-dispersive X-ray spectroscopy results showed that oxygen, gallium, and nitrogen coexist in these plate-like films. In the X-ray diffraction patterns, the sample synthesized at a current density of 3.5 mA cm−2 for 24 h exhibited peaks of gallium oxide and hexagonal-GaN phase. Photoluminescence analysis revealed a peak at 3.2 eV, which corresponds to the band gap energy of GaN, as well as a broad peak at around 2.5 eV at room temperature. [ABSTRACT FROM AUTHOR]

The effects of solution temperature on the initial corrosion characteristics of wrought AZ61 and die-cast AZ91D Mg alloys in 0.1M NaCl were analyzed. Systematic studies indicate that AZ91D exhibits higher corrosion resistance than AZ61 at room temperature. However, at high temperatures of around 55 °C, we observed contradictory corrosion behavior, as demonstrated by cyclic corrosion tests and electrochemical tests including potentiodynamic polarization, potentiostatic polarization, and elecrochemical impedance spectroscopy. As a result, AZ61 rather showed higher corrosion resistance from the point of view of pit initiation during the immersion at 55 °C resulting from the strengthening of surface passivation. These results can be attributed to the microstructure of AZ61 which contains sub-micron scale β-phase particles dispersed effectively within the α-Mg grains whereas AZ91D has many α-Mg that do not containing any β-phases. [ABSTRACT FROM AUTHOR]

Many techniques for the surface modification of titanium and its alloys have been proposed from the viewpoint of improving bioactivity. This paper contains an overview of surface treatment methods, including coating with hydroxyapatite (HAp), an osteoconductive compound. There are two types of coating methods: pyroprocessing and hydroprocessing. In this paper, hydroprocessing for coating on the titanium substrate with HAp, carbonate apatite (CO3-Ap), a CO3-Ap/CaCO3 composite, HAp/collagen, and a HAp/gelatin composite is outlined. Moreover, evaluation by implantation of surface-modi?ed samples in rat tibiae is described. [ABSTRACT FROM AUTHOR]

Various techniques for forming TiO2 coatings on Ti have been investigated for the improvement of the osteoconductivity of Ti implants. However, it is not clear how the oxidizing process a?ects this osteoconductivity. In this study, TiO2 coatings were prepared using the following three processes: anodizing in 0.1 M H3PO4 or 0.1 M NaOH aqueous solution; thermal oxidation at 673 K for 2 h in air; and a two-step process of anodizing followed by thermal oxidation. The oxide coatings were evaluated using SEM, XRD, and XPS. The water contact angle on the TiO2 coatings was measured as a surface property. The osteoconductivity of these samples was evaluated by measuring the contact ratio of formed hard tissue on the implanted samples (defined as the RB-I value) after 14 d implantation in rats' tibias. Anatase was formed by anodizing and rutile by thermal oxidation, but the difference in the TiO2 crystal structure did not in?uence the osteoconductivity. Anodized TiO2 coatings were hydrophilic, but thermally oxidized TiO2 coatings were less hydrophilic than anodized TiO2 coatings because they lacked in surface OH groups. The TiO2 coating process using anodizing without thermal oxidation gave e?ective improvement of the osteoconductivity of Ti samples. [ABSTRACT FROM AUTHOR]

A novel chemical process for producing hydrophobic nano-copper particles with satisfied anti-oxidation property is described here. The resultant particles have been characterized by X-ray diffraction, size distribution analysis and SEM, TEM observation. Well-dispersed nano-copper particles with c.a. 30 nm in diameter were obtained from the water/organic solution containing 0.2M Cu2+ ion, glucose as the first reductant, ascorbic acid as the second reductant. In this process, oleic acid acted as both a phase-transfer agent and a particle protector coordinating their carboxyl end groups on the new generated copper particles surface, the hydrophobic carbon tails of the oleic acids were pointed outwards from the surface of the synthesized particles. This organic film seems to play an important role for prevent the new generated copper particles from oxidation. In addition, this process also adopting two-step reduction method can lead compulsively disconnect nucleation and nucleation growth, and weaken conventional eruptible nucleation. By controlling the first reduction product’s size, this process is more convenient for delaying the nuclei processes and for controlling the ultimate copper particles size. [ABSTRACT FROM AUTHOR]

Mg alloys were anodized in alkaline NaOH solutions with various additives as a non-chromate method. Specimen AZ91 was anodized at a potential that produced a strong surface dissolution reaction and generated a large amount of Mg(OH)2. The effect of sealing after anodizing was investigated, focusing on the effects of sealing time, temperature and solution conditions. The current density decreased with increasing A1(OH)3 concentration in 1 M NaOH solution during anodizing; sparking occurred at potentials above 80 V. The best corrosion resistance with anodizing in 1 M NaOH solution occurred at a potential of 4 V, which caused the strongest active dissolution reaction. The sealing effect improved with increasing time and temperature, and corrosion resistance was proportional to the relative ratio of Mg(OH)2. If the oxygen thickness observed by EDX equaled the film thickness, the film formed at 4 V in 1 M NaOH was 10–15 Μm thickness. The optimum corrosion resistance in sealing at various solutions after anodizing was 1M-NaOH solution. [ABSTRACT FROM AUTHOR]

Impressed current cathodic protection can result in hydrogen embrittlement, which can cause trouble with high-strength steels, particularly at welds. Therefore, the limiting potential for hydrogen embrittlement should be examined in detail as a function of the cathodic protection potential. This study investigated the effects of post-weld heat treatment (PWHT) on marine structural steels from an electrochemical viewpoint. In addition, the slow strain rate test (SSRT) was used to investigate both the electrochemical and mechanical effects of PWHT on impressed current cathodic protection. According to the SSRT, the optimum cathodic protection potential was −770 mV [with a saturated calomel electrode (SCE)]. SEM fractography analysis showed that the fracture morphology at an applied cathodic protection potential of −770–850 mV (SCE) was a dimpled pattern with ductile fractures, while a transgranular pattern was seen at potentials below −875 mV (SCE). Therefore, the cathodic protection potential range should be −770–850 mV (SCE). [ABSTRACT FROM AUTHOR]

Chemical conversion treatment of Mg−Al alloy (AZ91) using colloidal silica as an alternative to chromate conversion was investigated as a function of solution pH, temperature, solution conditions, and treatment time. The solution used for the colloidal silica coating consisted of colloidal silica, titanium sulfate, and cobalt ions to maintain good anti-corrosion and adhesion properties. Adding CoSO4 to the colloidal silica solution enhanced the adhesion force between the silica film and magnesium substrate. The optimum conditions for the chemical conversion treatment solution were pH 2, 90-sec treatment, and 25°C. [ABSTRACT FROM AUTHOR]

Gold dissolves easily in an alkaline thiourea solution with Na2SO3 and Na2S2O8, where the accompanied elements of Au, such as Ag, Cu, Ni and Fe can hardly dissolve. It was considered that electrochemical reduction and catalytic action of SO prevent thiourea from decomposing irreversibly and accelerates dissolution of gold. The S2O as an oxidant can control the potential so that formamidine disulfide may form efficiently. The dissolution of gold is mainly through oxidation of Au by formamidine disulfide and compexation of thiourea with Au+, and not direct oxidation of S2O. Thus, sufficient formamidine disulfide is necessary to accelerate the dissolution of gold. The reason for Ag, Cu hardly being dissoluble is that the black layers of Ag2S and Cu1.92S form on the surface of Ag and Cu. The metal Ni and Fe do not dissolve in the alkaline media due to their sulfide films passivation samely. [ABSTRACT FROM AUTHOR]

Anodic polarization behavior of gold, silver, copper, nickel and iron in potentiostatic condition has been examined in an alkaline aqueous thiourea solution, where gold is hardly dissoluble normally. The addition of Na2SO3 into the solution can accelerate anodic dissolution of gold. The factors affecting selective dissolution of gold in the alkaline thiourea solution by electrolysis have been studied, and the optimum condition was obtained. In 0.1 mol/L thiourea solution of pH 12.5 containing 0.5 mol/L Na2SO3 and 2.5% acetone, at the potential of 0.34 V vs NHE, at the temperature of 323 K, the dissolved mass of gold anode with the exposed area of 1.0 cm2 reached more than 300 mg · dm−3 within 30 min, and other metals such as silver, copper, nickel and iron could hardly dissolve. [ABSTRACT FROM AUTHOR]

Guided bone regeneration (GBR) is an established treatment. However, the mechanisms of GBR are not fully understood. Recently, a GBR membrane was identified that acts as a passive barrier to regenerate bone via activation and migration of macrophages (Mps) and bone marrow stem cells (BMSCs). Atmospheric pressure plasma treatment of the titanium membrane (APP-Ti) activated macrophages. The purpose of this study was to analyze whether macrophages attached to an APP-Ti membrane affected differentiation of BMSCs in a GBR model. Human THP-1 macrophages (hMps) were cultured on non-treated Ti (N-Ti) and APP-Ti membrane. Macrophage polarization was analyzed by RT-PCR and immunocytochemistry. Secreted proteins from hMps on N-Ti and APP-Ti were detected by LC/MS/MS. hBMSCs were co-cultured with hMps on N-Ti or APP-Ti and analyzed by osteogenic differentiation, Alizarin red S staining, and alkaline phosphatase (ALP) activity. N-Ti and APP-Ti membrane were also implanted into bone defects of rat calvaria. hMps on APP-Ti were polarized M2-like macrophages. hMps on N-Ti secreted plasminogen activator inhibitor-1 and syndecan-2, but hMps on APP-Ti did not. hBMSCs co-cultured with hMps on APP-Ti increased cell migration and gene expression of osteogenic markers, but suppressed mineralization, while ALP activity was similar to that of hMps on N-Ti in vitro. The volume of newly formed bone was not significantly different between N-Ti and APP-Ti membrane in vivo. M2 polarized hMps on APP-Ti suppressed osteogenic induction of hBMSCs in vitro. The indirect role of hMps on APP-Ti in newly formed bone was limited. [ABSTRACT FROM AUTHOR]