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1.
This study examines the possibility of using poly(o-toluidine)/CdO (POT-CdO) nanoparticle composite coating for corrosion protection of mild steel in chloride environment. The POT-CdO nanoparticle composite coating was synthesized on mild steel from aqueous tartrate solution containing CdO-nanoparticles (size ~18 nm) by using cyclic voltammetry. These coatings were characterized by cyclic voltammetry, UV–Visible absorption spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction measurements. The corrosion protection aspects of the resulting POT-CdO nanocomposite structure were investigated in aqueous 3% NaCl solution by potentiodynamic polarization technique and electrochemical impedance spectroscopy. The results of these investigations reveal that the POT-CdO nanoparticle composite acts as a protective coating on mild steel and reduces the corrosion rate of mild steel almost by factor of 70.  相似文献   

2.
In this study, the effect of annealing temperature and alumina particles on micro-hardness, corrosion, wear, and friction of Ni-P-Al2O3 composites coating is studied. The electroless nickel composite coating with various alumina particle content is deposited on a mild steel substrate. The corrosion behaviour and tribological behaviour (wear and friction) of the composite coated samples are investigated and compared with Ni-P coated samples. The micro-hardness, wear resistance, and corrosion resistance of the composite coating improved significantly after heat treatment (400 °C) and in the presence of alumina particles. The composite coating deposited with alumina particle concentration of 10 g/L in an electroless bath and heat treated at 400 °C shows excellent results compared to Ni-P, as-deposited Ni-P-Al2O3 coating and coatings heat treated at different annealing temperature (200 °C, 300 °C, and 500 °C). Microstructure changes and composition of the composite coatings due to incorporation of alumina particles and heat treatment are studied with the help of SEM (scanning electron microscopy), EDX (energy dispersive X-ray analysis and XRD (X-ray diffraction analysis).  相似文献   

3.
Poly-3-amino-5-mercapto-1,2,4-triazole/TiO2 (p-AMTA/TiO2) composite was effectively synthesized over the copper surface by cyclic voltammetric technique and used as a protective coating against corrosion. The resulting polymeric composite was characterized using Fourier transform infrared spectroscopy. The presence of TiO2 particles in the polymer matrix was substantiated from X-ray diffraction pattern and energy-dispersive X-ray spectrum. The uniform dispersion of TiO2 particles in the polymeric matrix was confirmed by the scanning electron microscope images. The protective effect of composite coating was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization methods in 3.5 % NaCl medium. Impedance measurements showed that charge transfer resistance (R ct) values increased for polymeric composites which suggested the enhanced corrosion protection of copper. Further, the decrease in corrosion current density (i corr) values and shifting of corrosion potential (Ecorr) toward the cathodic direction confirmed the anticorrosive behavior of the polymeric composite. The reason for the higher protection of polymeric composite may be due to the well-dispersed TiO2 particles in the polymer matrix exhibiting the enhanced barrier properties to protect copper surface from corrosion. The defects in the coatings can be reduced by embedded TiO2 particles in the pores of the polymeric films to enhance the corrosion protection, consequently.  相似文献   

4.
Electroactive conducting polymer composite coatings of polyaniline (PANI) are electrosynthesized on styrene–butadiene rubber (SBR) coated stainless steel electrode by potentiostatic method using aqueous H2SO4 as supporting electrolyte. The protective behaviour of these coatings in different corrosion media (3.5% NaCl and 0.5 M HCl) is investigated using Tafel polarization curves, open circuit potential measurements and electrochemical impedance spectroscopy. The results reveal that SBR/PANI composite coating is much better in corrosion protection than simple PANI coating. The corrosion potential of composite films shifts to more noble values indicating that SBR/PANI composite coating act as an effective corrosion protective layer.  相似文献   

5.
In this paper, graphitic carbon nitride (g-C3N4) was first proposed for the pioneer application of anticorrosion coatings. Original g-C3N4 was facilely treated using HNO3 and the exfoliated g-C3N4 sheets (E-g-C3N4) were fabricated, and then, polyaniline/E-g-C3N4 composites (PANI/E-g-C3N4) as novel anticorrosive media were synthesized by chemical oxidative polymerization and devoted to the corrosion protection of coatings. The E-g-C3N4 sheets and PANI/E-g-C3N4 composites were characterized by X-ray diffraction, Fourier transform infrared, thermogravimetric analysis, and transmission electron microscopy. The anticorrosion properties of the samples prepared were investigated by electrochemical measurements including Tafel plots, electrochemical impedance spectra, and open-circuit potential. Accelerated corrosion tests of iron panels coated by PANI/E-g-C3N4 were performed in 3.5 wt% NaCl solution. Anticorrosive mechanism of PANI/E-g-C3N4 was discussed in detail. PANI/E-g-C3N4-3 fillers possessed superior corrosion inhibition than individual components on iron coatings, which was due to the synergetic effect of anticorrosion between E-g-C3N4 and PANI.  相似文献   

6.
This study considers the feasibility of uptake of cephalexin, an emerging contaminant, from aqueous solutions by using green local montmorillonite (GLM), montmorillonite coated with ZnO (ZnO/GLM) and montmorillonite coated with TiO2 (TiO2/GLM) in the presence of H2O2. Batch adsorption experiments were carried out as a function of pH, initial concentration of the cephalexin, adsorbent dosage, contact time, and temperature. Finally, the adsorbents were characterized by XRD, SEM and FTIR analyses. XRD patterns showed dramatic changes in the adsorbents after loading with the nanoparticles, confirming successful placing of the nanoparticles onto GLM. The GLM mineral surface after nanoparticle loading appears to be fully exposed and more porous with irregular shapes in particles diameters of 1-50 microns. FTIR analyses also confirmed dramatic changes in surface functional groups after modification with these nanoparticles. The results showed that the removal efficiency of cephalexin was better at lower pH values. Totally, the removal efficiency increased with increase in adsorbent dosage and contact time and decreased with concentration and temperature increase. The thermodynamics values of ΔG o and ΔH o revealed that the adsorption process was spontaneous and exothermic. In isotherm study, the maximum adsorption capacities (qm) were obtained to be 7.82, 17.09 and 49.26 mg/g for GLM, ZnO/GLM and TiO2/GLM, respectively. Temkin constant (B T ) showed that adsorption of cephalexin from solution was exothermic for all three adsorbents.  相似文献   

7.
Organic coating approaches for corrosion protection with inherently conducting polymers have become important because of restriction on the use of heavy metals and chromates in coatings due to their environmental problems. The present work is directed towards the synthesis of polyaniline (PANI) and polyaniline–SiO2 composites (PSCs) by chemical oxidation polymerization in the presence of phosphoric acid and evaluation of synthesized PANI and PSCs for protection of mild steel from corrosion in a strong aggressive medium (i.e. 1.0 mol L–1 HCl). A suitable coating with PSC was formed on mild steel using epoxy resin by the powder coating technique. A comparative study of the corrosion protection efficiency of mild steel coated with PANI and PSC in 1.0 mol L–1 HCl solution was evaluated using the Tafel extrapolation, chrono‐amperometry and weight loss methods. The PSC coating showed that a significant reduction in the corrosion current density reflects the better protection of mild steel in an acidic environment. Higher protection efficiency up to 99% was achieved by using PSC‐coated mild steel at 6.0 wt% loading of PSC in epoxy resin. The coating performance and corrosion rate of mild steel were investigated by using immersion of polymer‐coated mild steel in 1.0 mol L–1 HCl for 60 days and indicated that PSC‐coated mild steel showed better performance from corrosion than PANI in an acidic medium.© 2012 Society of Chemical Industry  相似文献   

8.
Bi‐layered composites of polyaniline (PANI) and poly(o‐anisidine) (POA) were investigated for corrosion protection of low carbon steel (LCS). In this work, homopolymers and bi‐layers of PANI and POA were electropolymerized on LCS from an aqueous salicylate solution by using cyclic voltammetry. These coatings were characterized by cyclic voltammetry, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Corrosion tests were carried out in aqueous 3% NaCl solution for LCS coated with PANI, POA, bi‐layered POA/PANI (POA on top of the PANI) or PANI/POA (PANI on top of the POA) composites using open circuit potential (OCP) measurements, potentiodynamic polarization technique, and electrochemical impedance spectroscopy (EIS). The single layer of PANI and POA protected the LCS in 3% NaCl for 8 and 16 h, respectively. The bi‐layered composite coatings provide effective protection to LCS for a longer time than a single layered PANI or POA coating. However, the corrosion protection offered to LCS depends on the deposition order of polymer layers in the composite. The PANI/POA composite provides better protection to LCS against corrosion than POA/PANI coating. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

9.
In this paper, a novel multifunctional superamphiphobic coating for anticorrosion was successfully prepared on aluminum substrate via a simple spraying technique. Al2O3 nanoparticles were chemically grafted onto montmorillonite (MMT) nanosheets via coupling effect of NH2-C3H6-Si(OC2H5)3 (KH-550) and then modified by low surface energy material polydimethylsiloxane (PDMS). The ethylene tetrafluoroethylene (ETFE) composite coating with 25 wt% MMT/Al2O3-PDMS binary nanocomposite exhibited well-designed nano/μ structures and possessed superamphiphobicity with high contact angles towards water (164°), glycerol (158°) and ethylene glycol (155°). This coating demonstrated outstanding self-cleaning ability and strong adhesive ability (Grade 1 according to the GB/T 9286). The superhydrophobicity could be maintained after 8000 times abrasion or annealing treatment for 2 h under 350 °C. The coating still retained high water-repellence after immersion in 1 mol/L HCl (146°), 1 mol/L NaOH (144°) and 3.5 wt% NaCl (151°) solutions for 30 d. It should be noted that this superamphiphobic coating revealed excellent long-term corrosion protection with extremely low corrosion rate (4.3 × 10?3 μm/year) and high protection performance (99.999%) after 30 d immersion in 3.5 wt% NaCl solutions based on electrochemical corrosion measurements. It is believed that such integrated functional coating could pave new way for self-cleaning and anticorrosion applications under corrosive/abrasive environment.  相似文献   

10.
The effect of corrosion protection performance of epoxy coatings containing magnesium (Mg) nanoparticles on carbon steel was analyzed using scanning electrochemical microscopy (SECM) and electrochemical impedance spectroscopy (EIS). Localized measurements such as oxygen consumption and iron dissolution were observed using SECM in 0.1 M NaCl in the epoxy-coated sample. Line profile and topographic image analysis were measured by applying ?0.70 and +0.60 V vs the Ag/AgCl/saturated KCl reference electrode as the tip potential for the cathodic and anodic reactions, respectively. The tip current at ?0.70 V for the epoxy-coated sample with Mg nanoparticles decreased rapidly, which is due to cathodic reduction in dissolved oxygen. The EIS measurements were conducted in 0.1 M NaCl after wet and dry cyclic corrosion test. The increase in the film resistance (R f) and charge transfer resistance (R ct) values was confirmed by the addition of Mg nanoparticles in the epoxy coating. Scanning electron microscope/energy-dispersive X-ray spectroscope analysis showed that Mg was enriched in corrosion products at a scratched area of the coated steel after corrosion testing. Focused ion beam–transmission electron microscope analysis confirmed the presence of the nanoscale oxide layer of Mg in the rust of the steel, which had a beneficial effect on the corrosion resistance of coated steel by forming protective corrosion products in the wet/dry cyclic test.  相似文献   

11.
It is difficult to research on the surface structure of amorphous phase in fly ash during leaching reaction due to crystalline phase and complex structure. In the present work, in order to reveal the effects of leaching reaction on the surface structure of amorphous phase in fly ash, the modelling CaO-Fe2O3-Al2O3-SiO2 glass was prepared by the traditional melting methods. The leaching reaction of CaO-Fe2O3-Al2O3-SiO2 glass with 7.5 M KOH was investigated by spectroscopy, spectrophotometer and wet chemical method. The results show that the content of Q 1, Q 2, Q 3 and Q 4 of glass without corrosion was 4.21, 9.51, 23.03 and 52.55%, respectively, which shows that the network polymerization of glass is compact. The leaching reaction of glass can be described by the following equation: dS/dt = k/(r + S 0). Leaching in KOH for various times induces the content of Q 4 and Q 1 to be decreased, and Q 2 and Q 3 increased, resulted in the depolymerization of network and the surface glass dissolved in alkaline solution to form a gel phase. In stage one of leaching reaction, the rate of iron ion leached from glass surface was slow, which resulted in the small slope of straight-line relationship of leaching curve. In the following stage, the leaching rate of iron ion increased with the prolongation of time.  相似文献   

12.
With a view to minimize the unavoidable large volume changes of tin based Cu6Sn5 alloy anodes, a composite Cu6Sn5/graphite anode has been prepared via. a mechanical alloying process and subsequently coated with disordered carbon through pyrolysis of PVC. Phase pure products with better crystallinity and preferred surface morphology were obtained, as evident from PXRD and SEM respectively. Upon electrochemical charge-discharge, the intermetallic Cu6Sn5 alloy-graphite composite anode was found to exhibit an enhanced initial discharge capacity of 564 mAh g−1 followed by significant capacity fade (>20%) especially after five cycles. On the other hand, carbon coated Cu6Sn5 alloy-graphite composite demonstrated promising electrochemical properties such as steady reversible capacity (∼200 mAh g−1), excellent cycle performance (<5% capacity fade) and high coulombic efficiency (∼98%) via. significant reduction of volume changes. The carbon coating offers buffering and conductive actions on the anode active material and thereby enhances the electrochemical behavior of carbon coated Cu6Sn5 alloy/graphite composite anode material.  相似文献   

13.
Using sol-gel method, poly(vinyl alcohol)/SiO2 hybrid coating materials with an improved gas barrier property could be produced. Phase compatibility between organic PVA segments and inorganic silicate network in the hybrid was evaluated by analyzing FT-IR spectra and investigating the crystallization behavior in terms of X-ray diffraction patterns for the hybrid gels. For the preparation of coating film with barrier property, the biaxially oriented polypropylene (BOPP) substrate was coated with the hybrid sols by a spin coating method. Morphological analysis for the fractured surface of the hybrid gel and the surface of the coated film was performed not only to examine the microstructure of the hybrid, but also to propose evidence for the oxygen permeation behavior through the coated film. It was revealed that an optimum amount of inorganic silicate precursor, TEOS, should be used to obtain high barrier PVA/SiO2 hybrid coating materials with enhanced micro-phase morphology and optical transparency. This homogeneous morphology densified with nano-structured silicate, obtained at optimal conditions, was found to result in a significant increase in the oxygen barrier property of film coated with PVA/SiO2 hybrid by about 50 times relative to the pure BOPP substrate. In addition, the effect of pretreatments of the BOPP substrate surface on the barrier property was also examined.  相似文献   

14.
The inhibiting effect of two organic copolymers namely poly(vinyl caprolactone-co-vinyl pyridine) (PVCVP) and poly(vinyl imidazol-co-vinyl pyridine) (PVIVP) on the corrosion of steel in phosphoric acid was investigated at various temperatures. The study was carried out by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurements. Inhibition efficiency (E %) increased with polymer concentration to attain 85% at 10−4 M for PVIVP. Adsorption of polymers on the steel surface in 2 M H3PO4 followed the Langmuir isotherm model. EIS measurements show that the dissolution of steel occurs under activation control. Polarisation curves indicate that the tested polymers functioned as cathodic inhibitors. E % values obtained from various methods used are in good agreement with each other. The temperature effect on the corrosion behaviour of steel in 2 M H3PO4 in the presence and absence of the inhibitor was studied in the temperature range 298–338 K. The adsorption free energy (ΔG o ads) and the activation parameters (E a, , ΔS o a) for the steel dissolution reaction in the presence of polymer were determined.  相似文献   

15.
A soluble copolymer from aniline and o-toluidine [poly(aniline-co-o-toluidine)] was synthesized by chemical oxidative copolymerization using ammonium persulphate as an oxidant in hydrochloride aqueous medium. The resultant copolymer was characterized by Fourier Transform Infrared (FTIR) spectroscopy and chemically deposited on mild steel specimens using N-methyl-2-pyrrolidone (NMP) as solvent via solution evaporation method. The anticorrosive properties of copolymer coating was investigated in major corrosive environments, such as 0.1 M HCl, 5% NaCl solution, artificial seawater, distilled water and open atmosphere by conducting various corrosion tests which include: immersion test, open circuit potential (OCP) measurements, potentiodynamic polarization measurements and atmospheric exposure test. The corrosion performance of copolymer coating was also compared separately with polyaniline (PANi) and poly(o-toluidine) (POT) homopolymer coatings. The surface morphologies of polymer coatings were evaluated using scanning electron microscopy (SEM). The synthesized copolymer exhibited excellent protection against mild steel corrosion; the protection efficiency being in the range of 78–94% after 30 days of immersion. The corrosion performance of copolymer in 5% NaCl and artificial seawater was comparable, which was only marginally better than in 0.1 M HCl. In general, the performance of copolymer coating was found to be better than that of homopolymer coatings.  相似文献   

16.
In this study, the amino silane coupling agent (KH550)-modified SrAl204: Eu2+, Dy3+ phosphor powder coated with phenolic epoxy resin (EOCN) in the presence of triarylsulfonium hexafluoroantimonate catalyst was prepared using the combination of organic–inorganic composite dip-coating and UV curing coating methods. The results of SEM, TEM, and FTIR showed that the organic coating was a layer of compact membrane with a thickness of 20–50 nm, which can be named silane-modified epoxy monomer generated by the KH550 and the EOCN. Furthermore, it was observed that afterglow and spectrum properties of the coated phosphor powder had good long-afterglow luminescence properties, and revealed two emission peaks at 435 nm and 520 nm under the same excitation wavelength of 360 nm, respectively. More interesting, the emitting color of the coated sample was located in the area of cyan light on CIE1931 chromaticity diagram, which led to a slight blue shift rather than the yellow–green color of the pure SrAl204: Eu2+, Dy3+ phosphor powder.  相似文献   

17.
The effect of the temperature of WO3/ZrO2 support calcination in the range of 700–1000°C on the phase composition, acid, and catalytic properties of Pt/WO3/ZrO2 catalysts is studied. Using ammonia TPD, it is found that calcination in the temperature range of 850–950°C results in the formation of strong acid sites that increase the yield of the target products of the reaction of n-heptane isomerization: high octane di- and trimethylsubstituted isomers. DRIFT is used to determine the role of catalyst calcination in an air flow plays in the formation of charged platinum atoms, which results in higher catalyst activity.  相似文献   

18.
In this study, polymeric hindered amine light stabilizers (HALS)-functionalized silica coated rutile titanium dioxide (TiO2-SiO2) nanoparticles were prepared by encapsulating commercially available TiO2-SiO2 nanoparticles with methyl methacrylate (MMA) and 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (PMPM) copolymers via miniemulsion polymerization. The obtained functional (TiO2-SiO2/P(MMA-co-PMPM)) fillers have been added to polyurethane acrylate (PUA) oligomers to get UV-curable nanocomposite coatings. The functionalization of the TiO2-SiO2 nanoparticles with polymeric HALS has been confirmed by infrared spectra (IR), thermogravimetric (TG), and X-ray photoelectron spectroscopy (XPS) analyses. The scanning electron microscope (SEM) micrographs indicated that homogeneous dispersion of TiO2-SiO2/P(MMA-co-PMPM) composite nanoparticles resulted in improved transparency and mechanical properties of the UV-curable PUA coatings. Rhodamine B (Rh.B) photodegradation measurement confirmed the excellent UV-shielding performance of PUA nanocomposite coatings containing TiO2-SiO2/P(MMA-co-PMPM). The addition of TiO2-SiO2/P(MMA-co-PMPM) composite nanoparticles reduced the UV-curable PUA coatings degradation rate dramatically. The UV-aging resistance of PUA coatings was improved significantly. Over all, the combination of TiO2-SiO2 nanoparticles and polymeric HALS offers an attractive way to fabricate the multi-functional fillers, which can be used to improve the mechanical properties and UV-aging resistance of PUA coatings simultaneously.  相似文献   

19.
The density d at a temperature of 25°C is measured by the hydrostatic weighing method, the Vickers microhardness H V is determined, and the fluctuation free volume fraction f g is calculated for glasses in the SrO-B2O3-SiO2 system with a constant strontium oxide content in the range from 35 to 45 mol %. It is demonstrated that the quantities H V and f g decrease and the density d increases with an increase in the SrO content.  相似文献   

20.
The paper reports on the successful use of the nano crystalline cobalt ferrite doped Nerium oleander leaf waste activated carbon (CoFe2O4/NOAC) synthesized by an urea assisted auto combustion technique to assess accurate kinetics and equilibrium parameters regarding the investigation of adsorption. The specific features of nano composite were investigated by various analytical techniques such as Scanning electron microscope with EDAX, powder X-ray diffraction study, BET surface area analysis, TG and DSC, Vibrating Sample Magnetometer. The BET analysis indicates that CoFe2O4 nano particles embedded in NOAC have increased the pore diameter for better adsorption. TG and DSC show the thermal stability of composite. The VSM study shows the Ferro magnetic behavior of nano composite which revealed that CoFe2O4/NOAC could be separated and retrieved easily by an external magnet after adsorption of AV49. The efficiency of adsorption of AV49 from aqueous solution was investigated through a series of batch experiments by using CoFe2O4/NOAC. The batch adsorption experiments showed the efficient removal on CoFe2O4/NOAC under optimum conditions such as pH 6.5, contact time-55 min and adsorbent dosage-50 mg. Adsorption kinetics—Pseudo first order and second order, Isotherms—Langmuir and Freundlich have been adapted to analyze the adsorption capacity. The results showed that the adsorption followed the pseudo second order kinetics and Langmuir isotherm equation is the best to describe the adsorption process. According to the thermodynamic study, it was very effective at higher temperatures also. The thermodynamic parameters ?Go, ?Ho and ?So were also evaluated for this adsorption.  相似文献   

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