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Experimental water-to-methyl ethyl ketone partition coefficients have been determined for 34 different organic solutes at ambient room temperature based on gas–liquid chromatographic measurements. ...

The chemical structures of Co oxynitrides – in particular, interactions among N and O atoms bonded to the same cobalt – are of great importance for an array of catalytic and materials applications. X-ray diffraction (XRD), core and valence band X-ray photoelectron spectroscopy (XPS) and plane wave density functional theory (DFT) calculations are used to probe chemical and electronic interactions of nitrogen-rich CoO1−xNx (x > 0.7) films deposited on Si(100) using NH3 or N2 plasma-based sputter deposition or surface nitridation. Total energy calculations indicate that the zinc blende (ZB) structure is energetically favored over the rocksalt (RS) structure for x > ∼0.2, with an energy minimum observed in the ZB structure for x ∼ 0.8–0.9. This is in close agreement with XPS-derived film compositions when corrected for surface oxide/hydroxide layers. XRD data indicate that films deposited on Si(100) at room temperature display either a preferred (220) orientation or no diffraction pattern, and are consistent with either rocksalt (RS) or zinc blende (ZB) structure. Comparison between experimental and calculated X-ray excited valence band densities of states – also similar for all films synthesized herein – demonstrates a close agreement with a ZB, but not an RS structure. Core level XPS spectra exhibit systematic differences between films deposited in NH3 vs N2 plasma environments. Films deposited by N2 plasma magnetron sputtering exhibit greater O content as evidenced by systematic shifts in N 1s binding energies. Excellent agreement with experiment for core level binding energies is obtained for DFT calculations based on the ZB structure, but not for the RS structure. The agreement between theory and experiment demonstrates that these N-rich Co oxynitride films exhibit the ZB structure, and forms the basis of a predictive model for understanding how N and O interactions impact the electronic, magnetic and catalytic properties of these materials.

Electroless functionalization of cerium oxide nanoparticles (NPs) based on the grafting of aryl groups from the reduction of diazonium salts is presented as a useful and facile method for enhancing the properties of the NPs. For this study, 4-methyl-, 4-ethyl-, and 4- n-butyl-benzene diazonium salts were used as model molecules to demonstrate the ability to change the hydrophobic properties of the cerium oxide (CeO

The chemical structures of Co oxynitrides - in particular, interactions among N and O atoms bonded to the same cobalt - are of great importance for an array of catalytic and materials applications. X-ray diffraction (XRD), core and valence band X-ray photoelectron spectroscopy (XPS) and plane wave density functional theory (DFT) calculations are used to probe chemical and electronic interactions of nitrogen-rich CoO

A study on corrosion inhibition mechanism has been performed on rare earth containing WE43 magnesium alloy in 3.5 wt.% NaCl containing 8-hydroxyquinoline (HQ). After an initial increase in corrosion rate due to the formation of sparingly soluble MgQ2 complex, it was found to decrease owing to inhibition effect of the complex. Scanning electrochemical microscopic analysis showed a decrease in corrosion currents and enhanced resistance to pitting corrosion was observed for WE43 samples in the presence of HQ after an exposure of 48 h. With time, the MgQ2 thus generated formed a protective layer on the Mg alloy surface to prevent further corrosion. The corrosion rate of WE43 samples decreased by ~ 50% in HQ containing medium after a constant exposure of 28 days (from ~ 0.22 mg/cm2 day in no HQ to ~ 0.11 mg/cm2 day in HQ). For the WE43 samples in the presence of HQ, formation of MgO and MgQ2 was detected by x-ray photoelectron spectroscopy and x-ray diffraction. Shallower and smaller pits appeared on the magnesium alloy with HQ in the solution as compared to deeper and larger pits on the samples with no HQ in the solution. The significance of metal-complexing organic agent, hydroxyquinoline, in initial acceleration and subsequent prevention of Mg corrosion via protective MgQ2 complex layer formation is demonstrated.

This article provides a second manifestation of a new tradition by which the editors of Comments on Inorganic Chemistry wish to lead by example, whereby we start publishing original research conten...

The deterioration of metals under the influence of corrosion is a costly problem faced by many industries. Therefore, particle-reinforced composite coatings are being developed in different technological fields with high demands for corrosion resistance. This work studies the effects of nanoplatelet reinforcement on the durability, corrosion resistance, and mechanical properties of copper-nickel coatings. A 90 : 10 Cu-Ni alloy was coelectrodeposited with nanoplatelets of montmorillonite (Mt) embedded into the metallic matrix from electrolytic baths containing 0.05, 0.10, and 0.15% Mt. X-ray diffraction of the coatings indicated no disruption of the crystal structure with addition of the nanoplatelets into the alloy. The mechanical properties of the coatings improved with a 17% increase in hardness and an 85% increase in shear adhesion strength with nanoplatelet incorporation. The measured polarization resistance increased from 11.77 kΩ·cm2 for pure Cu-Ni to 33.28 kΩ·cm2 for the Cu-Ni-0.15% Mt coating after soaking in a simulated seawater environment for 30 days. The incorporation of montmorillonite also stabilized the corrosion potential during the immersion study and increased resistance to corrosion.

The effects of higher concentrations (5 and 10%) of an organic modifier, butanol, added to an aqueous electroplating solution for nickel deposition have been studied. Nickel coatings were deposited on steel substrates from a modified all-sulfate bath with 5 and 10% additions of butanol under acidic conditions, while a modified pulse potential was applied. X-ray diffraction of the resulting nickel coatings showed a preferred (220) orientation for the crystal structure. The coatings were nanocrystalline with particle sizes between 16 and 35 nm as calculated from Williamson–Hall analysis. No cracking of the films was observed in the scanning electron microscopy images, even as the percentage of butanol increased, as typically is observed in other aqueous-organic baths. Corrosion resistance of the nickel coatings in a 3.5% sodium chloride solution was best for coatings deposited from plating solutions containing 5 and 10% butanol. E corr was shifted from −0.405 V for the nickel coating from the additive-free bath to −0.234 V for the nickel coating from the 5% butanol solution. EIS results indicated a twofold improvement in charge transfer resistance for nickel coatings deposited when butanol was used in the plating bath. The advantages of using higher percentages of organic modifiers like butanol to enable the use of non-electroactive particles for production of composite coatings are discussed.

Experimental water-to-methyl isobutyl ketone partition coefficients have been determined for 27 different organic solutes based on gas chromatographic measurements. Updated Abraham model correlations were determined for describing solute transfer into methyl isobutyl ketone by combining the measured partition coefficient data determined in the present study with published experimental values taken from chemical and engineering literature. One hundred nineteen compounds were used in determining the revised Abraham model correlations. After calculations, the revised mathematical correlations were found to match the experimental data to within an overall average standard deviation of 0.21 log units.

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has been coupled to direct analyte-probed nanoextraction (DAPNe) through use of nanomanipulation for the analysis of ink chemistry on documents. DAPNe is first used to extract ink from the document and then deposits the sample on the MALDI plate. Through this method, cutting the document for MALDI-MS analysis is avoided. DAPNe extracts ink from documents with minimal to no visible destruction. Specific dyes and binding agents in the extracted ink are monitored with mass spectrometry. Different matrices, 1, 5-diaminonapthalene (DAN), 2, 5-dihydroxybenzoic acid (DHB), and silver nanoparticles, were tested to compare intensity enhancement of the mass spectra signals. The advantages of using MALDI-MS coupled to DAPNe are shown by characterizing Crystal Violet, Basic Yellow 2, Rhodamine B, and polyethylene glycol from red and blue pens, black pen, and a black inkjet printer cartridge.

CoCrMo biomedical alloys were coated with a hydroxyapatite layer to improve biocompatibility and in vitro corrosion performance. A fast electrodeposition process was completed in 5 minutes for the hydroxyapatite coating. Effect of the solution temperature and applied potential on the in vitro corrosion performance of the hydroxyapatite coatings was modeled by response surface methodology (RSM) coupled with central composite design (CCD). A 5-level-2-factor experimental plan designed by CCD was used; the experimental plan contained 13 coating experiments with a temperature range from 283 K to 347 K (10 °C to 74 °C) and potential range from −1.2 to −1.9 V. Corrosion potential (E corr) of the coatings in a simulated body fluid solution was chosen as response for the model. Predicted and experimental values fitted well with an R 2 value of 0.9481. Response surface plots of the impedance and polarization resistance (R P) were investigated. Optimized parameters for electrodeposition of hydroxyapatite were determined by RSM as solution temperature of 305.48 K (32.33 °C) and potential of −1.55 V. Hydroxyapatite coatings fabricated at optimized parameters showed excellent crystal formation and high in vitro corrosion resistance.

CoCrMo bio-metallic alloys were coated with a hydroxyapatite (HA) film by electrodeposition using various electrochemical parameters. Response surface methodology and central composite design were used to optimize deposition parameters such as electrolyte pH, deposition potential, and deposition time. The effects of the coating parameters were evaluated within the limits of solution pH (3.66 to 5.34), deposition potential (-1.13 to -1.97 V), and deposition time (6.36 to 73.64 minutes). A 5-level-3-factor experimental plan was used to determine ideal deposition parameters. Optimum conditions for the deposition parameters of the HA coating with high in vitro corrosion performance were determined as electrolyte pH of 5.00, deposition potential of -1.8 V, and deposition time of 20 minutes.

The hydrophobic and corrosion resistive film of cross-linked poly(hexafluoroisopropyl methacrylate) was successfully prepared by a simple photopolymerization method. The starting materials were a monomer of 1,1,1,3,3,3-hexafluoroisopropyl methacrylate, a photoinitiator of hydroxycyclohexyl phenyl ketone, and a cross-linker of poly (ethyleneglycol diacrylate). A very simple coating technique of drop-casting was used to deposit the fluorinated polymer onto an aluminum alloy substrate (AA 3003). The polymer coating was stable over a 60-day period when exposed to an aqueous solution of 3.5% NaCl as measured by open circuit potential technique. The fluorinated polymer coating had high corrosion protection when measured by potentiodynamic polarization with a reduction of 90% in the corrosion current density for the polymer-coated aluminum alloy over the bare substrate. The corrosion current density decreased to 0.065 μA/cm2 for the aluminum alloy coated with the polymer film compared to 0.708 μA/cm2 for uncoated aluminum alloy. Fourier-transform infrared spectroscopy was used to monitor the polymerization process. The dynamic contact angle technique was used to measure the hydrophobicity for the fluorinated polymer coating and increased from 65° to 100° for the uncoated and coated substrate, respectively. Contact angle measurements before and after treatment with strong acid were carried out to confirm the chemical resistance of the polymer coating. The thermal stability of the fluorinated polymer was measured using thermogravimetric analysis showing thermal stability up to 200 °C.

Metal-organo-ceramic nanocomposite coatings were prepared via electrodeposition as corrosion protection coatings. A diazonium synthesis procedure was used to successfully graft ferrocene onto CeO2 nanoparticles. The modified nanoparticles were characterized by fourier-transform infrared spectroscopy (FTIR), solid-state NMR, electrochemical techniques, atomic absorption spectroscopy (AAS), and thermogravimetric analysis (TGA). A mixture of the grafted nanoparticles and nickel ions was added to an electrolyte plating solution for deposition of a Ni Fc-CeO2 nanocomposite coating onto steel substrate as a corrosion protection layer. The effect of CeO2 and ferrocene-CeO2 nanoparticles on the formation, morphology, composition, and corrosion resistance of the nickel coating was investigated by potentiodynamic polarization, powder x-ray diffraction (XRD), scanning electrochemical microscopy (SEM), inductively coupled plasma mass spectrometry (ICP-MS), and electrochemical impedance spectroscopy (EIS).

Silver nanoparticles were synthesized with clay mineral (montmorillonite)/PVP (polyvinyl pyrrolidone) suspensions using an electrochemical approach. The polymer and exfoliated clay mineral solution protect and prevent aggregation of the silver nanoparticles. The clay mineral component is environmentally friendly and low cost. Unlike other studies, the clay platelets are exfoliated (sheared apart to individual platelets) to expose a much larger surface area and function as supporting material and stabilizer. A prime advantage of this novel approach is that the polymer and layered silicates protected the silver nanoclusters from agglomerating, effectively immobilizing and enhancing contact with the cathode for reduction. An electrochemical approach for nanoparticle synthesis has several advantages; including control and tuning of the experimental parameters, easy set-up, and short synthesis times. Morphology of the silver nanoparticles depended on current density of the electrochemical synthesis. Transmission electron microscopy showed small spherical silver nanoparticles formed at current densities below 1.25 mA/cm2 and silver dendritic formation at current densities greater than 2.5 mA/cm2. Size distribution of nanocomposites in solution measured by dynamic light scattering was 27 nm for the silver nanoparticles. X-ray diffraction was used to measure the crystallite size of the dried powders, which ranged between 10 and 60 nm depending on the experimental parameters. Nanocomposite coatings were also formed on graphite foil electrodes. Dense uniform films of spherical silver nanoparticles were produced at low current densities ( 2.0 mA/cm2).

To improve the biocompatibility of medical implants, a chemical composition of bone-like material (e.g., hydroxyapatite) can be deposited on the surface of various substrates. When hydroxyapatite is deposited on surfaces of orthopedic implants, several parameters must be addressed including the need of rapid bone ingrowth, high mechanical stability, corrosion resistance, biocompatibility, and osseointegration induction. However, the deposition process can fail due to poor adhesion of the hydroxyapatite coating to the metallic substrate. Increasing adhesion by enhancing chemical bonding and minimizing biocoating degradation can be achieved through surface activation and pretreatment techniques. Surface activation can increase the adhesion of the biocoating to implants, providing protection in the biological environment and restricting the leaching of metal ions in vivo. This review covers the main surface activation and pretreatment techniques for substrates such as titanium and its alloys, stainless steel, magnesium alloys, and CoCrMo alloys. Alkaline, acidic, and anodizing techniques and their effects on bioapatite deposition are discussed for each of the substrates. Other chemical treatment and combination techniques are covered when used for certain materials. For titanium, the surface pretreatments improve the thickness of the TiO2 passive layer, improving adhesion and bonding of the hydroxyapatite coating. To reduce corrosion and wear rates on the surface of stainless steel, different surface modifications enhance the bonding between the bioapatite coatings and the substrate. The use of surface modifications also improves the morphology of hydroxyapatite coatings on magnesium surfaces and limits the concentration of magnesium ions released into the body. Surface treatment of CoCrMo alloys also decreased the concentration of harmful ions released in vivo. The literature covered in this review is for pretreated surfaces which then undergo deposition of hydroxyapatite using electrodeposition or other wet deposition techniques and mainly limited to the years 2000-2019.

Cerium oxide/montmorillonite nanocomposite films were synthesized electrochemically from solutions containing 0.5 to 50% Na-montmorillonite. The nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. Nanocomposite films synthesized from montmorillonite concentrations lower than 10% were continuous, uniform, and dense. X-ray diffraction confirmed that the nanocomposite films retain the face-centered cubic structure of cerium oxide while incorporating exfoliated platelets of the montmorillonite into the matrix. In addition, calculations from XRD data showed particle sizes ranging from 4.50 to 6.50 nm for the nanocomposite coatings. Raman and FTIR spectroscopy had peaks present for cerium oxide and the layered silicates in the coatings. Cross-sectional scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed the presence of montmorillonite throughout the cerium oxide matrix.

Forensic DNA samples may include the presence of PCR inhibitors, even after extraction and purification. Studies have demonstrated that metal ions, co-purified at specific concentrations, inhibit DNA amplifications. Metal ions are endogenous to sample types, such as bone, and can be introduced from environmental sources. In order to examine the effect of metal ions as PCR inhibitors during quantitative real-time PCR, 2800 M DNA was treated with 0.0025-18.750 mM concentrations of aluminum, calcium, copper, iron, nickel, and lead. DNA samples, both untreated and metal-treated, were quantified using the Quantifiler(®) Human DNA Quantification Kit. Quantification cycle (Cq) values for the Quantifiler(®) Human DNA and internal PCR control (IPC) assays were measured and the estimated concentrations of human DNA were obtained. Comparisons were conducted between metal-treated and control DNA samples to determine the accuracy of the quantification estimates and to test the efficacy of the IPC inhibition detection. This kit is most resistant to the presence of calcium as compared to all metals tested; the maximum concentration tested does not affect the amplification of the IPC or quantification of the sample. This kit is most sensitive to the presence of aluminum; concentrations greater than 0.0750 mM negatively affected the quantification, although the IPC assay accurately assessed the presence of PCR inhibition. The Quantifiler(®) Human DNA Quantification Kit accurately quantifies human DNA in the presence of 0.5000 mM copper, iron, nickel, and lead; however, the IPC does not indicate the presence of PCR inhibition at this concentration of these metals. Unexpectedly, estimates of DNA quantity in samples treated with 18.750 mM copper yielded values in excess of the actual concentration of DNA in the samples; fluorescence spectroscopy experiments indicated this increase was not a direct interaction between the copper metal and 6-FAM dye used to label the probe that targets human DNA in the Quantifiler(®) kit. Evidence of inhibition was observed for the human-specific assay at a lower metal concentration than detected by the IPC, for all metals examined except calcium. These results strongly suggest that determination of a "true negative" sample should not be based solely on the failure of the IPC to indicate the presence of a PCR inhibitor and indicate that amplification of all samples should be attempted, regardless of the quantification results.

Bio-metallic CoCrMo alloys were coated with hydroxyapatite layers by electrodeposition to improve biocompatibility. Surface morphology was analyzed by scanning electron microscopy. Chemical composition was investigated by FTIR. In vitro corrosion performance was examined by electrochemical impedance spectroscopy and Tafel measurements in a simulated body fluid. Corrosion performance of the coatings deposited at various pH values was investigated using Zview and COMSOL computer modeling programs. Both programs successfully modeled EIS results. Increasing the electrolyte pH improved corrosion performance of the biocompatible coatings. Electrolyte pH influenced corrosion properties, chemical composition, and surface morphology of the coatings.

The crystallization kinetics of magnesium hydroxide in low concentration solutions has been studied using an electrical conductivity method. Using various experimental relationships, several kinetic factors could be determined during the nucleation and growth process. From measurements of ion concentrations at various temperatures, the induction period of nucleation could be determined. As concentration and temperature increase, the crystallization rate increases affecting the nucleation and crystal growth of Mg(OH) 2 . The crystal-solution interfacial surface tension was also calculated and shown to be affected by the magnesium anion source. The results show that a uniform particle size distribution of nuclei is formed during the initial homogeneous nucleation process and the nucleation and crystal growth rates can be represented by a first order reaction equation. Through the study of crystallization kinetics, a control strategy is proposed to synthesize a uniform particle size distribution of magnesium hydroxide.

Zinc-nickel γ-phase alloy coatings were electrochemically deposited from a borate electrolytic bath on stainless steel substrates as protective coatings for corrosive environments. Alkaline conditions were used with a working pH range of 9.3–9.5 resulting in uniform deposits and corrosion protection. Strongly adhering deposits were obtained with smooth and even overall coverage of the substrate. The effect of borate addition was examined in relation to zinc, nickel and zinc-nickel alloy deposition. The presence of borate did not affect the anodic stripping potential of zinc in solution but did result in an anodic shift in the stripping potential of nickel with increasing borate concentration. Borate was adsorbed onto the electrode surface and shifted the onset of hydrogen evolution towards more cathodic potentials as borate concentration was increased. X-ray diffraction and atomic absorption spectroscopy confirmed the presence of the γ-phase alloy with a nickel content range of 8–15%. Pulse potential and direct potential processes were examined as deposition methods. The pulse potential method resulted in smaller grain sizes and uniform coatings as confirmed in scanning electron microscopy. The overall corrosion potential for the zinc-nickel γ-phase coatings was improved as compared to the pure nickel and zinc coatings.

Nickel–molybdenum–montmorillonite (Ni–Mo–MMT) nanocomposite coatings were prepared by electrodeposition from an alkaline citrate bath containing different concentrations of exfoliated montmorillonite. X-ray diffraction results revealed that the embedding of silicate platelets modified the texture of the Ni–Mo matrix and increased the grain size. Nanoindentation measurements showed increasing microhardness and Young's modulus for the nanocomposite coatings deposited from 1.0 g/L solutions of silicate platelets compared to pure Ni–Mo films. The potentiodynamic polarization and electrochemical impedance measurements showed that the Ni–Mo–MMT nanocomposite layers have higher corrosion resistance in 3.5% NaCl compared to pure Ni–Mo. SEM and AFM micrographs showed a slight increase in the particle size and the surface roughness of the electrodeposited film, respectively as a result of incorporation of MMT particles into the Ni–Mo alloy matrix.

Electrodeposition of different metals and alloys is popular for corrosion resistance because of the major problems that persist with corrosion. Two major alloys of Cu-Ni, 70-30 and 90-10, have been evaluated for corrosion protection on a stainless steel substrate. Copper and copper alloys are commonly used in marine environments to resist biofouling of materials by inhibiting microbial growth. The results show that the incorporated montmorillonite in the Cu-Ni matrix at 0.05% (238.1-297.5 kΩ cm2) and 0.1% (138.2-102.9 kΩ cm2) improved the overall corrosion resistance versus the pure alloy film (71.9-68.5 kΩ cm2). These coatings hold promise for the off-shore drilling environment in the oil and gas industry.

A method for the extraction and analysis of ink samples was developed using microscopy with direct analyte probe nanoextraction coupled to nanospray ionization mass spectrometry (DAPNe-NSI-MS) for localized chemical analysis of document inks. Nanomanipulation can be effectively coupled to nanospray ionization mass spectrometry providing picomolar sensitivity, and the capability to analyze ultra-trace amounts of material and reduce the required sample volume to as low as 300 nL. This new and innovative technique does not leave destructive footprints on the surface of a document. To demonstrate the breadth of this technique, analysis of inks from various eras were tested, iron gall ink and modern inks, as well as the capability to detect the oxidative products of polyethylene glycol (PEG), a common binding agent. The experimental results showed that DAPNe-NSI-MS was able to chelate iron(II) and manganese(II) ions of iron gall ink and organic components of modern and carbon-based inks. Regardless of whether the ink composition is modern or ancient, organic or inorganic, this new instrumental approach is able to identify and characterize the ingredients by modifying the extraction solvent, illustrating the potential diversity of the DAPNe technique.

A stable sensor for the determination of gallic acid (GA) and caffeic acid (CA) was fabricated by electrodeposition of Zn-Al-NO3 layered double hydroxide film on a glassy carbon electrode (LDHf/GCE). A sensitive electrochemical method was achieved for the determination of GA and CA in a phosphate buffer solution (pH 3). The differential pulse voltammetry response of the LDHf/GCE to GA has a linear concentration range from 4 µM to 600 µM with a correlation coefficient of 0.9985 and the calculated detection limit of 1.6 µM at a signal-to-noise ratio of 3. The differential pulse voltammetry response of the LDHf/GCE to CA has a linear concentration range from 7 µM to 180 µM with a correlation coefficient of 0.9969 and the calculated detection limit of 2.6 µM at a signal-to-noise ratio of 3. The constructed sensor was applied to the determination of GA in commercial green tea samples.

Pure nickel and nickel-montmorillonite (Ni-MMT) composite coatings were produced using pulse current electrodeposition from Watts' type solution. Experimental results show that the codeposition of MMT particles into the Ni matrix improves the microhardness of the coatings and modifies the [100] texture of pure Ni deposits to a mixed crystal orientation through [100] and [211] axes. Ni-MMT composite coatings show improved corrosion resistance in simulated seawater as compared to pure Ni as revealed from electrochemical polarization and impedance measurements. SEM and AFM micrographs indicate a reduction in the Ni crystallite grain size and increase in the surface roughness of the film as a result of embedding of MMT particles in the Ni matrix. NPRP Grant 4-306-2-111 from the Qatar National Research Fund (a Member of The Qatar Foundation). Scopus

Organic corrosion inhibitors are widely used to decrease the corrosion rates of steels in acidic conditions. In this study, inhibitive performance of three organic disulfide compounds as novel corrosion inhibitors for steel in acidic media have been studied. Generally, it is widely accepted that the inhibition of organic corrosion inhibitors is dependent upon the structure of the organic molecule. The inhibition process proceeds through a passive organic film formation on the metal surface. Compounds with electronegative atoms (N, O, and S) and aromatic ring systems facilitates the film formation on metal substrate, improving corrosion inhibition. Compared with other corrosion inhibitors, aromatic disulfide compounds provide corrosion inhibition through two pathways. First pathway is the chemical adsorption through the π-bonds in aromatic ring which can interact with free 3d orbitals of iron and the second pathway through the chemical adsorption by S atoms in disulfide bonds. Disulfide bond can enhance the corrosion inhibition by forming dπ- dπ bonds through the overlap of 3d electrons in Fe atom and vacant 3d orbitals of S atoms. Addition of polar groups to the disulfide compounds make these compounds more water soluble than the previously reported disulfides. Furthermore these disulfide compounds can be synthesized easily from relatively cheap material which makes these compounds economically feasible. To evaluate the inhibitive effect of the disulfides, steel samples have been subjected to immersion tests in HCl. Different HCl concentrations have been used as the acidic medium for immersion tests because it is the most common acidifying reagent used in the oil and gas industry. Various inhibitor concentrations and immersion times have been used to estimate the inhibitor efficiencies. Potentiodynamic polarization and electrochemical impedance spectroscopy have been utilized to measure the corrosion properties. Scanning electron microscopy, x-ray photoelectron spectroscopy and infrared spectroscopy have been used to study the steel surface before and after the immersion tests. Figure 1

Gas hydrate formation and corrosion can cause serious safety and flow assurance problems in deep water environments. One aspect that has been given less attention is the corrosion behavior of materials in salinity environment where gas hydrate formation and CO2 (sweet) corrosion can simultaneously occur. This type of environment is common in oil and gas deep water environments. The aim of this work is to investigate the corrosion behavior of Ni-Mo alloy coatings in an environment containing salt and dissolved CO2 gas at gas hydrate formation temperature (5 oC). Even though materials exposed to deep water operations can still experience corrosion at gas hydrate temperatures (low temperatures), previous research have done similar studies in room or higher temperatures using other test materials. Ni-Mo coatings were selected as the test material due to its excellent corrosion resistance in aggressive environments and serves as a based material for many oil and gas materials. A specialty designed jacketed glass cell was used to conduct the immersion test. The immersion test solutions were sweet low-salinity (CO2 + 1 wt% salt + 5 oC) and sweet high-salinity (CO2 + ~24 wt% salt + 5 oC) test solutions, respectively. The as-deposited Ni-Mo alloy coating has the highest corrosion resistance of 33.28 kΩ cm2. The corrosion resistance dropped to 14.36 kΩ cm2 and 11.11 kΩ cm2 after 20 hrs of immersion in the sweet low-salinity and sweet high-salinity test solutions, respectively. From grazing incidence XRD, the (111) reflection peak of the Ni-Mo coating was depressed and broaden after immersion in both test solutions due to increase in oxide layer formation on the surface Ni-Mo coating. SEM revealed a cracked surface morphology after immersion in sweet high-salinity test solution and elemental analysis shows the presence of oxygen after immersion in both test solutions, which is an indication of the formation of oxygen containing compounds on the surface of the Ni-Mo coating. The oxygen content increased from 1.70 wt% after immersion in sweet low-salinity test solution to 2.37 wt% after immersion in sweet high-salinity test solution. This work provides a new corrosion design consideration and solution, and will help in designing models and corrosion prediction software used for simulating materials exposed to salinity environment where gas hydrate formation and CO2 corrosion can both occur. Incorporating this consideration into corrosion design of pipeline will improve offshore pipeline performance and serve as a baseline for initial corrosion allowance for materials exposed to this type of environment. Figure 1

Addition of environmentally friendly layered double hydroxide (LDHs) to organic coatings can increase barrier properties within the coatings due to the platelet structure of the LDHs. A new approach combining silane coupling agents to enhance compatibility of the inorganic and organic matrix is used to form improved corrosion resistance coatings. For this work, Zn-Al-LDH are prepared via a co-precipitation method and modified by sodium 12-aminododecanoate through an anion exchange process. The organo-modified layered double hydroxide (LDH) is functionalized using 3-aminopropyltriethoxysilane (APTES) which is then incorporated into the epoxy matrix (EPON 828). The reaction between amine part of the amino dodecanoate as a strong nucleophilic group and epoxy ring part as an electrophilic group improves compatibility of LDHs layers and epoxy molecules in the composite. Differential scanning calorimetry is used to study this exothermic epoxy-amine ring opening reaction to determine the curing temperature of the coatings before and after modified LDH inclusion. The change in LDH structure, effect of incorporation of modified LDHs in the epoxy matrix, grafting of APTES on the LDH surface and elemental analysis are investigated respectively, by x-ray diffraction, thermogravimetric analysis, infrared spectroscopy and energy dispersive x-ray analysis. In the last step of preparation, Epikure 3571 as a curing agent, is added to the LDHs/epoxy system, then the coating is applied on steel substrates. After the thermal curing process, the anti-corrosion performance provided by this coating is assessed by multiple methods including, open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy in 3.5% NaCl aqueous solution. Further, scanning electron microscopy is used to study morphological changes on the coating before and after immersion test and to scan the localized corrosion spots. The results are compared with the coated steel samples with clear epoxy coating and none modified LDH/epoxy. Figure 1

This book chapter reviews the electrodeposition of Cu-Ni incorporated with nano- to microparticles to produce metal matrix composites.

A new promising phosphor material established on Eu3+ doped monoclinic (SrAl2Si2O8)/tetragonal (Sr2Al2SiO7) composite with controllable photoluminescence (PL) has been successfully synthesized using one-pot processing technology. Completely phase-separated SrAl2Si2O8/Sr2Al2SiO7 can be achieved in a single matrix starting from single-source precursors. In this work, a series of composite phosphor samples (including 50 mol%(SrAl2Si2O8)–50 mol%(Sr2Al2SiO7): 2, 6, 10, and 14 mol% Eu) were obtained after thermal treatment at 1300 °C for 36 h. The SrAl2Si2O8/Sr2Al2SiO7:Eu composites yield red (c. 616 nm) and blue (c. 440 nm) emission light when excited by near-UV 380 nm light. The crystal structures were investigated by X-ray diffraction after phase separation, and showed relatively small changes in lattice parameters. X-ray photoelectron spectroscopy and electron paramagnetic resonance for the composites showed red and blue emissions originating from Eu3+ and Eu2+ ions, which served as two different but coexisting activators due to the different crystal structural characteristics in Sr2Al2SiO7 and SrAl2Si2O8, respectively. The energy transfer between Eu3+ and Eu2+ in the same matrix tends to cause the alternating changes in the relative intensity of red and blue emitting lights with varied Eu concentration. As a result, controllable luminescence over the whole visible region can be obtained by doping appropriate rare earth contents or tailoring initial compositions of the precursors.

The drug release rate was studied for an anti-inflammatory drug, ibuprofen, in a modified carrier polymer matrix. Nanohybrids were synthesized of layered double hydroxide functionalized with ibuprofen. The ibuprofen was tethered with the layered double hydroxide and blended into the polymer, Poly l lactic acid (PLLA). Effective weight percentages of 3 and 5% of the nanohybrids were used in the polymer producing nanocomposite films. Corresponding films of 1.2 and 2 wt.% of pure ibuprofen were used in the polymer. The cumulative drug release rate of the nanocomposite films increased from ∼10% to 60%. The mechanism for release changed from diffusion control (stage 1) to a mix diffusion/ion-exchange control (stage 2) for the nanocomposite films. There was an improvement of elastic modulus for the nanocomposite films. These results indicated that nanocomposite films showed a significant improvement over the non-nanocomposite films.

Calcium phosphates were electrochemically deposited on stainless steel, titanium, and copper metal substrates with modified simulated body fluid of pH adjusted from 4 to 10 at 25 - 65 °C while maintaining cathodic potentials at -1.2 to -1.8 V (vs. SCE). The coatings were characterized by powder x-ray diffraction, scanning electron microscopy, and linear polarization corrosion method. X-ray diffraction show depositions in electrolytic solutions of pH below 8 contain hydroxyapatite along with a significant amount of impurities; however at pH 10 the deposit primarily consists of hydroxyapatite with little impurity, ideal for orthopedic implants. As the pH increases the morphology changes as shown with scanning electron microscopy, from an amorphous to a dense crystalline phase. Linear polarization and Tafel plot show surgical stainless steel has the most improvement in anticorrosion when coated with hydroxyapatite.

Zinc-nickel alloys with 8-15% nickel were deposited onto stainless steel for corrosion protection. Alkaline deposition conditions were utilized given that alkaline systems have been found to offer superior substrate coverage which results in better corrosion protection of the metal substrate (stainless steel) compared to acid bath depositions. This method utilizes ammonium hydroxide as the base source with a working pH range of 9-9.5. Sodium acetate was used as the complexing ligand as it was found to stabilize the metal ions in the electrolytic solution. Strongly adhering, quality deposits were obtained with electrodeposition at room temperature. Bath compositions and applied potential had an effect on morphology of the films as seen in scanning electron microscopy. Upon examination by x-ray diffraction and atomic absorption spectroscopy, all deposits were confirmed as γ phase zinc-nickel alloys with a nickel content of 8-15%. The corrosion potential for the γ-phase coatings was improved over the pure zinc coatings.