Corrosion Resistance Of Nanocomposite Coatings Research Articles

In vitro assessment of corrosion resistance and biocompatibility of tantalum-niobium oxide surface-functionalized Mg alloy

Magnesium alloys have been considered as temporary biomaterials for orthopedic applications. Despite having great mechanical (bone-like) characteristics and osseointegration, magnesium alloys deteriorate quickly in physiological conditions. Modifying the Mg alloy surface with tantalum-based thin films is an effective process to reduce the rate of corrosion and improve biocompatibility. In the present work, tantalum-niobium oxide nanocomposite thin films were successively deposited on Mg–Al6–Zn1.5-Cu2-Ge0.5 Mg alloys via reactive magnetron sputtering to improve anticorrosion and biocompatibility. Crystallographic structure, surface morphology and chemical compositions were characterized using XRD, TEM, FE-SEM, EDS and XPS. Electrochemical and hydrogen evolution experiments were used to evaluate the resistance to corrosion of the samples. The biocompatibility of the samples was evaluated by cell viability using the osteoblast cell line (MC3T3-E1). Results revealed the existence of the composite thin-film in the crystalline form and the cauliflower-like clustered morphology. Enhancement in the corrosion resistance of nanocomposite coatings was confirmed by a decrease in current density (Icorr) during the polarization studies. The wettability studies revealed the hydrophilic character of the coatings and they are bioactive in simulated body fluid (SBF) after 5 days by the mineralization of calcium phosphate. The hemocompatibility assessment proved that the coatings were blood compatible in nature. MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay on MC3T3-E1 cells showed that tantalum-niobium oxide thin films are biocompatible and can stimulate cellular proliferation and differentiation. Overall, the outcome of these studies provided promising tantalum-niobium oxide composite thin films with unique nanocrystalline surface properties and improved the corrosion resistance and biocompatibility of the Mg alloys for orthopedic applications.

Protection of mild steel with molecular engineered epoxy nanocomposite coatings containing corrosion inhibitor functionalized nanoparticles

Selection of appropriate intelligent coatings to protect metallic objects from corrosion is still challenging especially when filler or dispersing materials are used for reinforcing polymer matrix. A novel siloxane corrosion inhibitor precursor was designed and chemically grafted onto the silica nanoparticles to prepare molecular engineered nanofiller (NPInh). The 1H NMR, 13C NMR, FT-IR, TGA and TEM characterization were applied to confirm the successful preparation of NPInh and the grafting amount of corrosion inhibitor precursor onto silica nanoparticles. The surface morphology, dispersion behavior of functionalized nanofiller, mechanical properties and corrosion resistance of the prepared inhibitor functionalized silica nanoparticles with epoxy composites coated on the mild steel were studied. The experimental results indicated the homogeneous dispersion of nanofiller in the epoxy nanocomposite coatings could be enhanced by silica surface modification using inhibitor precursor, and the NPInh component acted as a crucial role in improving the mechanical properties and corrosion resistance of nanocomposite coatings through the combined contribution of mechanical enhancement of nanoparticles and the shielding effect of corrosion inhibitor component. Combining with the apparently optimized strain durability, impact resistance and adhesion strength, the electrochemical measurements showed that the novel epoxy nanocomposite coatings blended with corrosion inhibitor functionalized nanoparticles (NPInh) were capable of superior corrosion resistance with decreased corrosion current (10−10 A/cm2) and a greatly improved protection efficiency (99.9%) after immersion in 3.5 wt% NaCl solution. Moreover, the salt spray durability characterization elucidated that epoxy nanocomposite coating modified with NPInh achieved higher salt spray resistances up to 1000 h. Therefore, it is anticipated that the molecular engineered nanocomposite coatings could open up a new category in the field of corrosion protection by spontaneously improving the dispersity of nanofiller and the barrier effect of coating.

Comparing the corrosion protection performance of graphene nanosheets and graphene quantum dots as nanofiller in epoxy coatings

Purpose In this research, the effect of graphene nanosheets and graphene quantum dots (GQDs) as carbon-based nanofillers on corrosion protection performance of epoxy coatings is considered. Design/methodology/approach Graphene nanosheets are synthesized via chemical vapor deposition method, and GQDs are synthesized by a simple and gram scale procedure from carbon black. The prepared nanofillers are characterized by X-ray diffraction technique, Fourier transform infrared spectroscopy and transmission electron microscopy. Further, solvent-based epoxy coatings containing 0.1 Wt.% graphene nanosheets and GQDs are prepared, and the corrosion resistance of nanocomposite coatings is considered by electrochemical impedance spectroscopy. Findings The results indicate that both epoxy/graphene nanosheets and epoxy/GQDs samples have significantly higher corrosion resistance than pure epoxy coating. Meanwhile, GQDs can more effectively enhance the corrosion protection performance of epoxy coatings compared to graphene sheets, which can be attributed to the presence of functional groups on GQDs and improving the dispersion quality in polymer matrice. Originality/value In this research, for the first time, the graphene quantum dots (GQDs) prepared by a “top-down” method from carbon black are used as nanofiller in epoxy coatings, and the potential application of graphene nanosheets and GQDs as anti-corrosion nanofiller in epoxy coatings is investigated.

Synthesis and characterization of Ni– $$\hbox {Si}_{3}\hbox {N}_{4}$$ Si 3 N 4 nanocomposite coatings fabricated by pulse electrodeposition

Pure Ni and Ni–silicon nitride $$(\hbox {Si}_{3}\hbox {N}_{4})$$ nanocomposite coatings have been successfully fabricated on copper substrates by a pulse electrodeposition method employing the Watts bath. The obtained coatings were characterized with X-ray diffractometry and scanning electron microscopy. Also, surface hardness and the corrosion behaviour of the coatings were analysed by potentiodynamic polarization and electrochemical impedance spectroscopy in a 3.5% NaCl solution. It was found that incorporation of $$\hbox {Si}_{3}\hbox {N}_{4}$$ particulates has reduced the crystallite size and also changed the growth orientation of the crystallite from (111) to (220) and (200) crystal planes. The co-deposition of $$\hbox {Si}_{3}\hbox {N}_{4}$$ in the Ni matrix led to better properties of these coatings. Accordingly, the hardness value of nanocomposite coatings was about 80–140 Hv higher than that of pure nickel due to dispersion-strengthening and matrix grain refining and increased with the enhancement of incorporating $$\hbox {Si}_{3}\hbox {N}_{4}$$ particle content. The presence of the $$\hbox {Si}_{3}\hbox {N}_{4}$$ particulates slightly decreases the current efficiency. The current efficiency was decreased by increasing current density from 1 to 4 A $$\hbox {dm}^{-2}$$ . Moreover, the corrosion resistance of nanocomposite coatings was significantly higher than the pure Ni deposit. Also, the Ni– $$\hbox {Si}_{3}\hbox {N}_{4}$$ coating produced at a density of 4 A $$\hbox {dm}^{-2}$$ showed the lowest corrosion rate (0.05 mpy).

Investigation of wear and corrosion resistance of nanocomposite coating formed on AZ31B Mg alloy by plasma electrolytic oxidation

Ceramic-WC coatings were prepared on AZ31 B Mg alloy by plasma electrolytic oxidation (PEO) from a phosphate based bath containing suspended tungsten carbide nanoparticles at various process times. Scanning electron microscope results indicated that increase of coating time and incorporation of tungsten carbide into the ceramic coating during the PEO process led to a decrease in the number and diameter of coating pores. Phase analysis showed that the nanocomposite coating was composed of MgO, Mg3(PO4)2 and WC. Tribological properties and corrosion behaviour of uncoated AZ31 B Mg alloy and ceramic coatings were evaluated using a pin-on-disc tribometer and potentiodynamic polarisation technique in 3.5% NaCl solution, respectively. The wear and electrochemical tests showed that wear and corrosion resistance of ceramic-WC nanocomposite coatings were better than ceramic only ones. In addition, wear and corrosion behaviour of coatings improved with increasing the coating time.

Preparation and Characterization of Ni–TiO2 Nanocomposite Coatings Produced by Electrodeposition Technique

In this paper Ni-TiO2 nanocomposite coatings with different sizes of TiO2 nanoparticles were successfully prepared by electrodeposition process from a nickel electrolyte in which the TiO2 nanoparticles were suspended. The influence of relevant deposition parameters on the nanocomposite coating characteristics was discussed. X-ray diffractometer (XRD) has been applied in order to investigate the phase structure of the nanocomposite coatings. The surface morphology of nanocomposite coatings was characterized by a scanning electron microscopy equipped with an energy dispersive spectroscopy (SEM/EDS). The electrodeposited nanocomposite coatings obtained at different deposition parameters were evaluated for their mechanical and corrosive properties. Obtained results show that the size of TiO2 nanoparticles and applied current density during deposition process has a direct effect on mechanical and corrosive properties of nanocomposite coatings. Increasing current density and smaller nanoparticle size has affirmative effect on mechanical properties whereas corrosion resistance of nanocomposite coatings deposited at 3 A.dm-2 current density are higher than the coatings prepared at higher current density values.

SiAlON–epoxy nanocomposite coatings: Corrosion and wear behavior

ABSTRACTIn this study, epoxy powder as a matrix was combined with different contents of silicon–aluminum–oxygen–nitrogen (SiAlON) nanoparticles using a planetary ball mill. Pure epoxy and nanocomposite powders were applied on the surface of plain carbon steel components by the electrostatic spraying method. Curing of the coatings was done in an oven or microwave for the appropriate time. The coating structure and morphology of the SiAlON nanoparticles were studied by scanning electron microscopy and transmission electron microscopy, respectively. The corrosion properties of the coatings were assessed by immersion, Tafel polarization, and electrochemical impedance spectroscopy tests in 3.5% NaCl solution. The results show that addition of 10 wt % SiAlON nanoparticles markedly increases the corrosion resistance of epoxy coatings. Thus, it can be inferred that the corrosion rate of these coatings is 15 to 18 times lower than that of pure epoxy samples and 8 to 11 times lower than coatings with 20 wt % SiAlON. The higher corrosion resistance of nanocomposite coatings can be attributed to the barrier properties of SiAlON nanoparticles. The tribological performance of the coatings was studied with the pin‐on‐disk test. The results of wear testing show that the samples containing 10 wt % SiAlON provide about five times more wear resistance than pure ones and about two times more than coatings with 20 wt % SiAlON. However, the coefficient of friction for nanocomposite coatings is reduced about 50% compared to the pure sample. Also, the curing process in either regime (oven or microwave) has the same effect on the corrosion and wear properties, and the coatings are completely crosslinked. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43855.

Structure, mechanical properties and corrosion resistance of nanocomposite coatings deposited by PVD technology onto the X6CrNiMoTi17-12-2 and X40CrMoV5-1 steel substrates

This article presents the research results on the structure and mechanical properties of nanocomposite coatings deposited by PVD methods on the X6CrNiMoTi17-12-2 austenitic steel and X40CrMoV5-1 hot work tool steel substrates. The tests were carried out on TiAlSiN, CrAlSiN and AlTiCrN coatings. It was found that the structure of the PVD coatings consisted of fine crystallites, while their average size fitted within the range 11–25 nm, depending on the coating type. The coatings demonstrated columnar structure and dense cross-sectional morphology as well as good adhesion to the substrate, the latter not only being the effect of adhesion but also by the transition zone between the coating and the substrate, developed as a result of diffusion and high-energy ion action that caused mixing of the elements in the interface zone. The critical load L C2 lies within the range 27–54 N, depending on the coating and substrate type. The coatings demonstrate a high hardness (~40 GPa) and corrosion resistance.

Influence of embedded particles on microstructure, corrosion resistance and thermal conductivity of CuO/SiO 2 and NiO/SiO 2 nanocomposite coatings

Homogeneous CuO/SiO 2 and NiO/SiO 2 nanocomposite coatings containing CuO and NiO nanoparticles in silica matrix were successfully synthesized by sol–gel process on an aluminum alloy substrate, respectively. The evolution of phase and morphology of both nanocomposites was characterized by XRD, SEM, TEM and FTIR. The effect of incorporating various nanoparticles on the corrosion behavior and the thermal conductivity of nanocomposite coatings was investigated by potentiodynamic polarization curve and comparative exponential method. The thermal conductivity as well as the corrosion resistance of nanocomposite coatings was significantly improved by the introduction of metal oxide particles. In comparison with NiO/SiO 2 nanocomposite coatings, CuO/SiO 2 composite coatings displayed lower protective behavior as well as higher thermal conductivity. Experimental results revealed that those improvements can directly be related to the nanocomposite effect and the nature of added nanoparticles.