Corrosion Resistance Of Films Research Articles

Corrosion Resistance of Aluminum Films Electroplated on Steel from Chloroaluminate Ionic Liquids Containing Toluene as a Co-Solvent

Aluminum is a widely used material for corrosion resistant coatings. From a thermodynamic perspective, it is a very active metal. However, its excellent corrosion resistance stems from the formation of a robust, self-healing ~50 nm thick barrier film of Al2O3, which is formed spontaneously upon exposure to air at ambient temperature. Unfortunately, it is established that aluminum cannot be plated from aqueous solutions under normal conditions because hydrogen is evolved before most Al(III) species are reduced to Al. A number of commercial Al plating processes have been developed. Typically, these processes are based on pyrophoric mixtures of AlCl3 or AlBr3 with LiAlH4 dissolved in suitable organic solvents, such as ethers or mixtures of substituted benzenes.The first report in which a room-temperature haloaluminate ionic liquid was used to plate Al appeared in 1948.1 Although moisture-sensitive themselves, such ionic liquids, particularly those based on mixtures of AlCl3 and quaternary ammonium chloride salts, have many safety and convenience advantages over the currently used commercial Al plating baths. In this work, we report the pulsed-current plating of Al on steel substrates from the Lewis acidic AlCl3-1-ethyl-3-methylimidazolium chloride (EtMeImCl) ionic liquid with and without organic co-solvents. Compared to DC methods, pulsed-current techniques can produce electrodeposited metals with smaller grain size and greater brightness, as well as less internal stress and correspondingly greater corrosion resistance.Some preliminary results for Al films electrodeposited on steel from this ionic liquid are shown in Figs. 1 and 2. The surface morphology and corrosion resistance of these films were interrogated with optical microscopy and electrochemical impedance spectroscopy (EIS) in aqueous NaCl, respectively. Micrographs of typical Al electrodeposits (Fig. 1) indicate that their surface morphologies changed significantly with changes in t on and t off. For example, the grain size of the Al film prepared with t on = 0.25 s is much smaller than that for deposits prepared with t on =1 s. Figure 2 shows complex plane impedance plots resulting from EIS experiments. These plots show at least one time constant. A circuit model for an electrode coated with an inert porous layer2 was fitted to the data in Fig. 2 to extract information about the pore resistance (R p) of the coating. The pore resistance reflects the corrosion resistance of the electrodeposited films. Figure 2 shows that the best results were obtained for t on = 0.25 s and t off = 0.50 s in agreement with the results obtained by microscopy. It was generally found that films with the best corrosion resistance were obtained with smaller values of t on. Optimization of the parameters for the pulse plating of Al will be discussed with respect to the surface structure, grain size, corrosion resistance, and brightness of the deposits. References 1F. H. Hurley, U.S. Pat. 2,446,331 (1948). 2M. E. Orazem and B. Tribollet, Electrochemical Impedance Spectroscopy, (New Jersey: John Wiley and Sons, 2008). Acknowledgement This work was funded by the Strategic Environmental research and Development Program (SERDP) through contract DE-AC05-00OR22725 to Oak Ridge National Laboratory.

Effect of additive Al2 O3 powders on micro-arc oxide coating of magnesium alloy

Abstract In order to understand the effect of additive Al2O3 powders on the film corrosion resistance and the microstructure of the micro-arc oxide (MAO) ceramic film of magnesium alloy, AZ91D die cast magnesium alloy was oxidized with a special micro-arc apparatus. Morphological characteristics and phase constituent of ceramic coatings were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD). And the aluminum (Al) element of before and after the Al2O3 accession were analyzed by energy-dispersive X-ray (EDX). The results showed that after adding Al2O3 powders, pores on ceramic coatings decreased, the loose layer became more compact, the new phase of Al2O3 appeared, and the Al element of the ceramic membrane increased. Ultrasonic waves promoted the content of Al2O3 in the layer. Electrochemical corrosion experiments in 3.5% NaCl solution showed that the corrosion resistance of ceramic coatings after adding Al2O3 powders was improved greatly.

Corrosion control in CO2/H2S-produced water of offshore oil fields

Purpose – In order to solve the corrosion problems in the South China Sea, the purpose of this paper was to study the main influences of corrosion including temperature, H2S content and corrosion inhibitor content in CO2/H2S oil field-produced water. Design/methodology/approach – The corrosion products formed on the steel surface were observed and analyzed using scanning electron microscope (SEM) and X-ray diffraction (XRD). Findings – The results indicate that temperature significantly influences the corrosion rate, which is a maximum at 70°C. The corrosion rate decreases as H2S content increases which is less than 10 mg/L, but then it increases rapidly. The FeCO3/Fe x S y protective film and a corrosion inhibition also were considered. Research limitations/implications – A mixture containing an imidazoline derivate and an organic amine can enhance the corrosion resistance of the corrosion product film. Practical implications – A mixture containing an imidazoline derivate and an organic amine can enhance the corrosion product film corrosion resistance. Social implications – Imidazoline is one kind of environmentally safe agent which can be used in the ocean. Originality/value – The corrosion can be controlled to a satisfactory extent in the presence of a mixture containing an imidazoline derivate and an organic amine.

Study on Anodic Oxidation of 2024 Aluminum Alloys in Sulfuric-Citric Acid

Porous anodic alumina has been obtained through anodic oxidation in a mixed solution of sulfuric and citric acid. We investigated the microstructure and morphology of 2024 aluminum after being anodically oxidized under different voltage and temperature. Hardness and corrosion resistance of anodized aluminum has been also investigated. The results show that after anodization, many nanoholes appeared on the surface layer of the coating. Thickness of the anodized film increased from 2.7μm to 26.3μm with the voltage changing from 10 V to 18 V. Aodized films with the thickness of 18μm could be obtained under the temperature of 47°C. When the oxidation voltage is 12V, the hardness of the oxidation film reached 126HV. Maximum hardness (130 HV) could be achieved when the oxidation temperature was 57°C. After being dealt with in the NaCl solution, the electrochemical corrosion resistance of the anodic film got a sharp increase, and the anodic oxidation voltage had a great impact on the anodized film. When the oxidation voltage was 16V, the corrosion resistance of the film reached the highest value and the corrosion voltage was-0.7V. From the polarization curves, it has been found that the films obtained under the temperature of 37°C possessed more positive corrosion potential (-0.73V) and optimal anticorrosion performance.

Microstructural characterisation of tungsten coatings deposited using plasma sputtering on Si substrates

Nanostructured W thin films synthesized by RF Plasma system have been characterized. These coatings may have appeal for functional applications, e.g. in corrosion resistance and barrier film. The role of the some process parameters, like pressure and sputter gas, has been investigated. We have shown that the microstructure (α and β-W phase) can be tuned as a function of the sputter gas and substrate pretreatment.

蒸気コーティング法によるマグネシウム合金上への耐食性皮膜の作製

Corrosion resistant films were prepared on magnesium alloy AZ31 by steam coating using NaNO3 aqueous solution as steam source. The chemical and corrosive resistant properties of the films were estimated using XRD, FT-IR, SEM, and electrochemical method. XRD patterns revealed that the film was composed of crystal Mg (OH) 2 and Mg–Al system layered double hydroxide (LDH), independent of treatment time. The film grew densely and uniformly with an increase in treatment time. Cross sectional SEM images revealed that the deposition rate was 8 μm/h. FT-IR spectra showed that the Mg–Al LDH had carbonate-ions and nitrate-ions in the interlayer. Potentiodynamic polarization curves of the film treated at 433 K for 7 h indicated that the corrosion current density decreased by more than four orders of magnitude as compared to that of the uncoated one. Immersion test in 5 mass% NaCl aqueous solution at 308 K for 168 h revealed that the chemical composition on the surface of the film treated at 433 K for 7 h changed hardly before and after the immersion test. These results indicates that the film coated AZ31 has a superior corrosive resistance.

Cr Release from Stainless Steels

Cr release from stainless steels in different simulant fluids according to different test conditions is carried out with emphasis on ferritic stainless steels. Effects of Cr content and surface roughness on Cr release are discussed specially with a relation to corrosion resistant and passive film formation. Some primary results are attained: (1) higher Cr content means better corrosion resistance including higher potential and lower corrosion rate and less amount of Cr release from base metal; (2) decreasing surface roughness is in favor of the formation of passive film which can retrain Cr release from base metal effectively; (3) Cr content and surface roughness have synthetical effects on Cr release with a narrow innoxious field referring to surface roughness with decreasing Cr content in stainless steels.

Magnetic properties of corrosion-resistant CoW films

CoW films with different compositions have been prepared by an electrochemical deposition method.

High-Temperature and Anodic Oxidation of Thin NiSi and NiSi2 Films

The high-temperature and anodic oxidation of thin NiSi and NiSi2 films produced by thermal annealing of Ni film on single-crystalline silicon is studied. Both types of oxidation lead to the formation of thin protective SiO2 layers. The high-temperature oxidation of NiSi films begins at 930 K, which is 100 K lower than that of NiSi2 films. When temperature increases, the mass increment of NiSi films becomes greater than that of NiSi2 films. This difference is three times as great at 1273 K, which is due to the difference in structure and stoichiometry. It is shown that the electrochemical corrosion resistance of films increases from Ni to NiSi and to NiSi2.

The corrosion resistance and passive film compositions of 12% Cr and 15% Cr oxide dispersion strengthened steels in nitric acid media

The passive film compositions and corrosion resistance of 12% Cr and 15% Cr oxide dispersion strengthened (ODS) steels in 3M HNO3 to 9M HNO3 was evaluated. The potentiodynamic polarization plots exhibited a shift in corrosion potential, and higher passive current density with increasing HNO3 concentrations. In 12% Cr ODS steel, high corrosion rate was observed in all HNO3 concentrations. However, low corrosion rate observed in 15% Cr ODS steel was attributed to Al2O3 enrichment. The TEM analysis indicated a complex Y2Hf2O7 formation in 15% Cr ODS steel, and this may have a role in suppressing intergranular corrosion attack.

Enhanced antimicrobial properties, cytocompatibility, and corrosion resistance of plasma-modified biodegradable magnesium alloys

Magnesium alloys are potential biodegradable materials and have received increasing attention due to their outstanding biological performance and mechanical properties. However, rapid degradation in the physiological environment and potential toxicity limit clinical applications. Recently, special magnesium–calcium (Mg–Ca) and magnesium–strontium (Mg–Sr) alloys with biocompatible chemical compositions have been reported, but the rapid degradation still does not meet clinical requirements. In order to improve the corrosion resistance, a rough, hydrophobic and ZrO2-containing surface film is fabricated on Mg–Ca and Mg–Sr alloys by dual zirconium and oxygen ion implantation. Weight loss measurements and electrochemical corrosion tests show that the corrosion rate of the Mg–Ca and Mg–Sr alloys is reduced appreciably after surface treatment. A systematic investigation of the in vitro cellular response and antibacterial capability of the modified binary magnesium alloys is performed. The amounts of adherent bacteria on the Zr–O-implanted and Zr-implanted samples diminish remarkably compared to the unimplanted control. In addition, significantly enhanced cell adhesion and proliferation are observed from the Zr–O-implanted sample. The results suggest that dual zirconium and oxygen ion implantation, which effectively enhances the corrosion resistance, in vitro biocompatibility and antimicrobial properties of Mg–Ca and Mg–Sr alloys, provides a simple and practical means to expedite clinical acceptance of biodegradable magnesium alloys.

Deposition and characterization of multi-principal-element (CuSiTiYZr)C coatings

Multi-principal-element (CuSiTiYZr)C coatings were prepared by co-sputtering of pure Cu, Si, Ti, Y and Zr targets in an Ar+CH4 atmosphere, for different CH4/(CH4+Ar) flow rate ratios (0.25; 0.35; 0.50). The films were analyzed for elemental and phase composition, crystalline structure, morphology, mechanical characteristics, corrosion resistance and tribological performance. Ternary (TiZr)C coatings were also examined for comparison.The (CuSiTiYZr)C coatings were found to be amorphous, whatever the CH4/(CH4+Ar) ratio. For all the coatings, an increase in the carbon content led to an improvement of corrosion resistance, mechanical and tribological film characteristics, mainly due to the formation and development of an amorphous free-carbon phase. The (CuSiTiYZr)C coatings exhibited superior corrosion and wear behaviour, when comparing to (TiZr)C reference coatings with similar carbon content. The highest hardness (29.5GPa), the lowest friction coefficient (∼0.15) and the best wear-corrosion resistance were measured for the (CuSiTiYZr)C coating with carbon/metal ratio of about 1.3 (CH4/(CH4+Ar) flow rate=0.50).

Titanium Oxide (TiO2) Coatings on NiTi Shape Memory Substrate Using Electrophoretic Deposition Process

The aim of the present research is to convert bioinert surface of NiTi to bioactive and biocompatible surface. In order to develop a bioactive and corrosion resistant film on NiTi, electrophoretic deposition process was done and TiO2 particles were deposited on the NiTi surface. Suspensions including TiO2 particles were prepared using a mixture of acetone and n-butanol (0%, 30%, 60%, 80% and 100% acetone) without using any dispersant. Sedimentation test was used to characterize the suspensions. SEM investigations on surface morphology of coatings shows deposition within 0% acetone cause to crack-free and dense coating with relatively coarse grains and high corrosion resistance.

Corrosion Resistance of 9% Cr Oxide Dispersion-Strengthened Steel in Different Electrolytic Media

The corrosion resistance and passive film compositions of 9% Cr oxide dispersion-strengthened steel in different acidified and chloride media was evaluated. The results presented below show that with increasing concentrations of 1 M to 11.5 M nitric acid (HNO3), the open-circuit potential reveals a more noble potential, while in chloride-containing media, a less noble potential was observed. The potentiodynamic polarization plots exhibited higher breakdown/transpassive potentials in acidic media with 0.5 M sulfuric acid (H2SO4) and 1 M to 11.5 M HNO3, and there was a shift in the corrosion potential toward the transpassive region as the HNO3 concentration increased from 1 M to 11.5 M. However, no intergranular corrosion attack was observed at the HNO3 concentrations studied. In acidic-chloride media (0.5 M H2SO4 with 0.1 M and 0.5 M sodium chloride [NaCl]) and in chloride only media (0.1 M NaCl and 0.5 M NaCl) poor pitting corrosion resistance was attributable to the microstructural inhomogeneity and inclusions in the steel. The x-ray photoelectron spectroscopy analysis indicated that the passive film has iron(III) oxide (Fe2O3) and chromium(III) oxide (Cr2O3), along with yttrium oxide (Y2O3). The scanning electron microscopy (SEM) examinations showed that the pits on the specimen were hemispherical and formed lace-like patterns. The corrosion properties affected by the dispersed oxide are also discussed in the paper.

Influence of sonication on anticorrosion properties of a sulfursilane film dopped with Ce (IV) on galvannealed steel

Currently, galvannealed carbon steel has been submitted to phosphatizing and/or chromatizing as surface pre-treatments; however, for economic and environmental issues, the viability of using silanes as an alternative pre-treatment has been studied. The aim of this work is to study the effect of sonication of the solvent solution (50/50%, m/m water/ethanol) with 50ppm of Ce (IV) ions on the corrosion behavior of bis-1.2-[triethoxysilylpropyl]tetrasulfide (BTESPT) silane film deposited on galvannealed steel. The sonication influence on reactions has been studied and seems to promote the formation of small molecules starting from large ones, the change of the local pH and temperature, beyond the change of the solution viscosity. The corrosion resistance of the steel coated samples was evaluated by electrochemical impedance spectroscopy (EIS), linear polarization resistance (Rp) and potentiodynamic polarization curves. The molecular vibrational and chemical properties of the films were obtained by infrared (IR) and micro Raman spectroscopies. The physical characterization of sonicated solutions was performed by measuring their kinematic viscosity. The images from scanning electron (SEM) microscope were obtained to characterize the aspect and morphology of the film. The results showed that the sonication led to obtaining more homogeneous, compact and corrosion resistant silane films.

Recent Developments in Functional Thin Films

Thin film technology is a significant focus of academic, governmental, and industrial research efforts. The economic impact of thin film use is significant and is growing at an impressive rate. BCC Research assigned the thin film global market a value of $9.3 billion in 2011; it is anticipated to reach a value of $14.9 billion by 2016. 1 Drivers of thin film research at this time include lowering the processing cost and environmental burden associated with thin film processing. 2 In addition, efforts are underway to develop thin films on flexible substrates for use in medical prostheses and in energy harvesting devices. Functional thin films have other potential biomedical applications, including use in drug delivery. 3 A search using Thomson Reuters’s Web of Knowledge indicates that the number of published items involving functional thin films has steadily increased each year since 1994; more than 1150 papers were published on this topic and nearly 30,000 citations involved this topic in 2012. 4 In this issue of JOM, the development of thin films for biomedical, corrosion resistance, electronic, optical, radiation detection, thermal barrier, and tribological applications is described. In ‘‘Improved Mobility and Transmittance of Room-Temperature Deposited a-IGZO Films with Low-Temperature Post-Fabrication Anneals,’’ T.L. Alford et al. demonstrate radio frequency (RF) sputtering of amorphous indium gallium zinc oxide onto flexible poly ethylene naphthalate substrates. Annealing the film at low temperatures in an oxygen atmosphere and in vacuum is shown to modify the optical and electrical properties of the thin films. In ‘‘Inkjet Printing of Amphotericin B onto Biodegradable Microneedles using Piezoelectric Inkjet Printing,’’ R.D. Boehm et al. demonstrate modification of the surfaces of Gantrez (ISP Investments, Inc., Wilmington, DE) 169 BF microneedles with amphotericin B using piezoelectric inkjet printing. A radial diffusion assay is used to demonstrate the activity of these drug-loaded microneedles against the yeast Candida parapsilosis. In ‘‘Effect of LowTemperature Microwave Processing and Copper Content on the Properties of Ag-Cu Thin Film Alloys,’’ S. Das and T.L. Alford examine the use of microwave annealing for enhancing the structural and electrical properties of silver-copper thin films. Their work indicates that copper oxide encapsulation layers are formed by microwave annealing. In ‘‘Reflectance Spectroscopy of Functional Ag-Cu Thin Films: Correlation of Reflectivity with Cu Content,’’ S. Das and T.L. Alford evaluate the use of magnetron sputtering to co-sputter pure silver and copper targets. The electrical mobility and optical reflectivity properties of silver-copper thin films on silicon substrates are evaluated. In ‘‘Thermo-mechanical

Effects of Heat-treatment on Mechanical Properties and Corrosion Resistance of NbN Films

Abstract The NbN and Nb films are prepared by the technique of radio frequency (RF) magnetron sputtering and heat-treated at 300 °C and 400 °C respectively in the present work. The influences of heat-treatment on the morphology, chemical composition, structure, nanomechanical properties and corrosion resistance of the films are studied. Results show that the particles in the films prepared by the above method are all in nano-size. The polygon shaped particles in the Nb films are very thin and small, while the particles in the NbN films prepared under the same condition are pebble-like, larger, and more compact. The nanomechanical properties and corrosion resistance of both the films are improved apparently after the heat-treatment. The corrosion resistance and mechanical properties of NbN film are always better than those of Nb film. The mechanism about the heat-treatment on the property considering the structural evolution is also discussed in this paper.

Study on the Corrosion Resistance of ZrN Films on the Aluminium Alloys Surface

Aluminum alloy have the active chemical properties,low standard electrode potential, and the surface will be easily forming about 1-3nm oxide film in dry air, therefore aluminum alloy have the poor corrosion resistance.ZrN film deposited by mid frequency reactive magnetron sputtering process on aluminium alloy surface in order to improve the corrosion performance. Study the influences of nitrogen flow rate, sputtering time and temperature to the corrosion performance. The results show that: The corrosion performance of ZrN films will be improved with the nitrogen flow rate increase,but when the nitrogen flow rate was more than 18sccm, ZrN film corrosion resistance will be reduce;The corrosion performance improved with the sputtering time increase,when the time reach 15min, ZrN film corrosion resistance was no longer increase;The corrosion performance improved with the temperature, when the temperature reach 130°C, the corrosion resistance was no longer increase.The best process parameters was: nitrogen flow rate 18sccm, sputtering time 15min, temperature 130°C.

Surface morphology, corrosion resistance and in vitro bioactivity of P containing ZrO2 films formed on Zr by plasma electrolytic oxidation

The present work was aimed at developing the corrosion resistant and bioactive oxide film on zirconium by plasma electrolytic oxidation in phosphate electrolyte. The effect of plasma electrolytic oxidation treatment time on surface morphology and corrosion resistance of the oxide films was further investigated. The phase composition, surface morphology, thickness and elemental composition of the oxide films were analyzed by X-ray diffraction and scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy. The corrosion behavior of substrate and oxide films in simulated body fluid environment was studied by open circuit potential and potentiodynamic polarization tests. The apatite forming ability of the oxide film was evaluated after immersing in simulated body fluid for 14days. X-ray diffraction patterns show that the oxide films predominantly comprised of monoclinic zirconia with a small amount of tetragonal zirconia. With prolonging treatment time, phase transformation of tetragonal to monoclinic zirconia was observed. Scanning electron microscopy results show that for a treatment time of 2–8min, uniform and highly dense oxide films, thickness varying from 3 to 14μm with no obvious pores were formed and the phosphorous content in the films was found to be in the range of 2.8–6.8 at.%. Corrosion test results reveal that all oxide films improved their corrosion resistance especially in terms of pitting potential and showed superior passivity in simulated body fluid environment. Bioactivity test results confirm that plasma electrolytic oxidation treated zirconium was fully covered by apatite layer in simulated body fluid medium. The incorporation of phosphorous in oxide film during coating process significantly enhanced the apatite forming ability of zirconium. In conclusion, among all the plasma electrolytic oxidation coated samples, the 6min coated zirconium with high corrosion resistance and bioactivity is a potential candidate as orthopedic implants.

Influence of Oxidizing Ion Concentration on the Corrosion Resistance of Type 304L Stainless Steel in Nitric Acid Medium

The influence of the oxidizing ions Fe3+ and Cr6+ with two different concentrations on the corrosion resistance of Type 304L (UNS S30403) stainless steel in 3 M and 6 M nitric acid (HNO3) medium has been determined. The corrosion resistance and passive film behavior of Type 304L stainless steel in the presence of oxidizing ions were evaluated using electrochemical potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and x-ray photoelectron spectroscopy (XPS) techniques. The corrosion resistance was observed to decrease with an increase in acid concentration and oxidizing ions. The concentrations of oxidizing ions were found to have a profound effect on the corrosion potential and passive current density when compared to that in nitric acid without oxidizing ions. XPS results revealed a significant reduction of chromium(III) oxide (Cr2O3) on the passive film as the concentration of oxidizing ions in nitric acid increases. An oxide layer thickness of ~13 nm enriched with iron oxide could be estimated for the passivated sample in the nitric acid medium with higher oxidizing ion concentration compared to 1 nm thick oxide film in nitric acid without oxidizing ions. Both XPS and EIS analyses confirmed the detrimental effect of oxidizing species on the passive film leading to increased corrosion with an increase in nitric acid and oxidizing ion concentration. The corrosion results could be correlated with microstructural observations.