Anticorrosion Characteristics Research Articles

Influence of Interlayer on Wear and Corrosion Resistance of DLC Film

Diamond-like carbon (DLC) films have many excellent characteristics such as low friction coefficient, wear resistance, gas barrier property and biocompatibility. These many positive characteristics enable DLC coatings to be applied to a lot of fields from metallic materials to polymer materials for overcoatings. However, usual DLC film has a lot of micro-pores or pinholes, and those defects become problems as DLC film is not able to make the best use of abrasion resistance effectively due to the substrate corrosion. In addition, the DLC films deposited directly on the steel substrates often encountered the problem of poor adhesion. It has been attempted to overcome the negative effect by means of multilayer structure using metal and ceramic layers. In this study, we aim to deposit DLC films satisfied with both antiwear and anticorrosion characteristics. This time, we attempted to improve those properties by enhancing adhesion strength between DLC film and substrate. Interlayers used were a Si modified DLC (Si-C:H) interlayer deposited by using Si(CH3)4 gas and a Cr interlayer deposited with magnetron sputtering method. These interlayered DLC films were deposited on austenite stainless steel substrates. DLC films with Si-C:H and/or Cr interlayer were deposited by a pulse plasma CVD method using C2H2 gas. Three kinds of coatings: (1) substrate/Si-C:H/DLC, (2) substrate/Cr/DLC and (3) substrate/Cr/Si-C:H/DLC had been done. As fundamental tests, Raman spectroscopy, nano indentation, X-ray reflectometer analysis and rutherford back scattering spectrometry/elastic recoil detection analysis were carried out to reveal both mechanical and anticorrosion characteristics. Then, ball-on-disk tests and electrochemical measurements also had been running. These results lead us to conclusion that the effects of the DLC coating had been confirmed and an optimal structure to improve both tribological property and anticorrosion property was substrate/Si-C:H/DLC. Moreover, in the case of emphasizing tribological property, substrate/Cr/Si-C:H/DLC structure was recommended.

Study on the Preparation and the Construction Technology of Anti-Static and Anti-Corrosion Self-Leveling Floor Coating

Multifunctional epoxy self-leveling floor coating with excellent anti-static and anti-corrosion characteristics is prepared by modified epoxy resin and curing agent which have excellent chemical resistance characteristics. Conductive materials are adding into the formula. The coating structure and the matching construction technology are designed for the anti-static and anti-corrosion self-leveling floor coating application.

Electrochemical Characteristics of the Hydroxyapatite Coatings Prepared by Mg Sacrificial Anode

Abstract The hydroxyapatite (HA) coating, one of the most important biomaterials, was prepared on Ti6Al4V alloy by Mg sacrificial anode to improve the anticorrosion electrochemical characteristics. Energy dispersive X-ray analysis (EDX), electron probe microanalyzer (EPMA), Fourier transform infrared spectra (FTIR) and X-ray diffraction (XRD) were used to analyze the HA coating. The results show that the HA coating is composed of needle-like hydroxyapatite crystals with the Ca/P ratio of 1.4063. After the immersion test of 30 d, the crystals become larger in Hank's solution, from needle-like to sheet-like in Ringer's solution and column-like in Tyrode's solution. The tests of open circuit potential, polarizing curves and EIS method in Hank's solution, Ringer's solution, Tyrode's solution and human blood show that the Ti6Al4V alloy with HA coating has better electrochemical characters than Ti6Al4V alloy.

Preparation of Fe/Cr doped SiO2 thin film on 304 stainless steel substrate originated from corrosion

A Fe/Cr doped SiO2 thin film which can improve the anticorrosion characteristic of materials was prepared on SUS304 stainless steel substrates by a modified hydrothermal method which constitutes two parts of preparation process. The corrosion of stainless steel stimulated by aqueous Lithium bromide solution and the dissolution of silica from Na–Ca glass simultaneously. And then a Fe/Cr doped SiO2 thin film is coated onto the substrate. The Fe/Cr doped SiO2 film was characterised by scanning electronic micrographs, X-ray diffraction, X-ray photoelectron spectroscopy and Electron probe X-ray microanalyser. Results showed that the corrosion products MX+, M(OH)x+ (M: metal) and the silica reticular are combined to form a Fe/Cr doped SiO2 thin film. Furthermore, a chemical bond formed between silicon reticular and metal ions to improve the compactness and the adhesive property of the film. The anticorrosion characteristics of the film were measured by the methods of weight loss and electrochemical potentiodynamic polarisation, indicating that the Fe/Cr doped SiO2 thin film can improve the anticorrosion performance of stainless steels effectively.

Aliphatic polyurethane–montmorillonite nanocomposite coatings: Preparation, characterization, and anticorrosive properties

AbstractPolyurethane (PU)–clay nanocomposite coatings were prepared by a sonication method. The stability and morphology of these coatings was characterized by turbidometry, X‐ray diffraction, and transmission electron microscopy. The anticorrosive properties of these coatings were investigated by salt‐spray and electrochemical impedance spectroscopy methods. According to the results, dispersed nanoclay layers in the matrix of the nanocomposite coating compositions led to superior anticorrosive characteristics compared to those of pure PU coatings. The best results were obtained with coatings containing about 5 wt % clay. The resistance of the coating containing 5% clay was about 9.002 GΩ after 225 days of immersion in a 3.5 wt % NaCl solution, whereas it was only 97 kΩ for the pure PU coating. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

ChemInform Abstract: Deposition of Multifunctional Titania Ceramic Films by Aerosol Routes.

Aerosol coating processes were developed to deposit titania ceramic films onto steel and silica substrates. In situ light-scattering measurements were used to understand the deposition mechanisms in different system configurations. The conditions that were necessary to obtain uniform, nonporous, and well-adhered titania films on steel substrates were established. The as-coated films had excellent anticorrosion characteristics at room temperature, as established by the standard salt-fog test. Film crystallinity and morphology were examined using X-ray diffractometry and scanning electron microscopy; these analysis methods revealed an oriented, nanocrystalline anatase phase. Film composition was established, as a function of film thickness, using Auger electron spectroscopy and was confirmed to be stoichiometric (Ti:O = 1:2). The optical band gap and optical phonons of the deposited films were probed using spectrophotometry and Raman scattering, respectively; these analysis methods revealed a blue shift of the gap, relative to bulk anatase, and a localization of carriers in the nanometer-sized crystallites.

Microstructural and Electrochemical Characterization of Ni/Ti<sub>2</sub>N Composite Coating for Sintered NdFeB Permanent Magnets

Sintered NdFeB magnets have complex microstructure that makes them susceptible to corrosion in humid or moist environments. The paper presents the anticorrosion characteristics of a novel Ni/Ti2N composite coating applied through electrodeposition and cathodic arc physical vapour deposition (CAPVD) to sintered NdFeB permanent magnets. The performance of composite coating was evaluated in simulated marine environment with the help of dc polarization techniques. The rate of coating degradation was also determined by employing ac electrochemical impedance spectroscopy (EIS). The coating morphology and surface chemistry were studied with scanning electron microscope (SEM). X-ray diffraction (XRD) was used for identification of component phases in the coating-substrate system. The results showed that the composite coating provided an adequately improved corrosion protection to the sintered NdFeB magnets in the simulated marine environment compared to the earlier reported ceramic and metallic coatings. The composite coating did not damage the magnetic properties of coating-substrate system that remained at par with the ceramic and nickel coating having copper interlayer.

Biocompatibility of Poly(Acrylic Acid) Thin Coatings Electro-synthesized onto TiAlV-based Implants

The protection of metal orthopedic implants against corrosion is a crucial medical problem. It was found that electrochemical polymerization of thin, passive poly(acrylic acid) (PAA) films on titanium and TiAlV substrates provides good anti-corrosion properties. In this work, an investigation of anti-corrosion features was carried out to clarify the hypothesis of the presence of an electrostatic contribution to the performance of a PAA coating. Ion release tests were performed at three different pHs; the pH dependence of the polymer swelling was examined by quartz crystal microbalance with dissipation monitoring, to establish the role of this phenomenon on the polymer barrier properties. The potential application of these PAA thin films as biocompatible protective coatings for metal implants and compatibility towards MG-63 human osteoblast-like cells was assessed.

Multiscale Molecular Modeling and Experimental Validation of Polyaniline‐CNTs Composite Coatings for Corrosion Protecting

AbstractToday's demand for materials with specific properties is rapidly overtaking available technology, especially in the understanding of why many materials have the properties they do. The morphology of polymer–carbon nanotubes (CNTs) material and how this influences the further features of the material is one such property. In this work, a computational method based on molecular mechanics (MM) and dynamics (MD) and dissipative particle dynamics (DPD) techniques, to design and predict specific morphologies and mechanical properties of polyaniline (PANI)‐CNTs and PANI‐poly (m‐aminobenzene sulfonic acid) (PABS) functionalized CNTs composite materials is presented. Furthermore, experiments were carried out to assess the anticorrosive features of the composite materials. Computational bulk models of PANI‐CNTs and PANI‐PABS‐CNTs were implemented with different compositions at atomistic‐ and mesoscale and composite coatings were grown in situ onto carbon steel electrodes (OL 48‐50). PANI‐PABS‐CNTs computational models and films were investigated concerning mechanical properties, materials morphology using computational tools, and experimentally, by means of scanning electron microscopy and corrosion protecting ability by potentiodynamic tests. The results clearly confirmed that the PABS‐CNTs are properly dispersed in composite coatings and have beneficial effect on mechanical integrity, and anticorrosion protecting ability is significantly higher than those characteristics for pure PANI. Copyright © 2010 John Wiley & Sons, Ltd.

Anticorrosion characteristics of a Zn-primer coating in a ballast tank under various chloride concentrations

At an open-circuit potential, the anodic polarization curves had very similar values, and no significant differences were observed among the conditions. In the cathodic polarization curves, total residual chloride (TRC) reacted with the Zn-primer coating and created a film that had anticorrosion properties. Therefore, the anticorrosion property improved. With an increase in applied potential in the potentiostatic experiment, the observed surface corrosion occurred due to the dissolution reaction. From Tafel analysis, the corrosion current density had the highest value in natural seawater and the lowest value in the 2 ppm solution. Generally, metals corrode faster with increasing TRC concentration, but with the formation of Zn(OH)2, which has anticorrosion properties, the corrosion resistance of a Zn-primer-coated specimen in seawater can be improved.

S0401-1-1 DLC成膜したステンレス鋼の耐摩耗性及び耐腐食性評価([S0401-1]表面改質および薄膜コーティング(1))

DLC (Diamond-like carbon) film shows low friction coefficient against various materials and has high wear-resistance. However, usual DLC film has micro-pores or pinholes, and those defects become problems that DLC film is not able to make the best use of abrasion resistance effectively due to the corrosion of the substrate. In this study, we aim to deposit DLC films satisfied with both antiwear and anticorrosion characteristics. This time, we focused on the interlayer. We use Si modified DLC (Si-DLC) interlayer deposited by using Si(CH_3)_4 gas and Cr interlayer. As a fundamental test, the adhesion strength between DLC film and a steel substrate was investigated by a scratch test. Then, with measuring the pitting potential as well as the tribological properties, the effects of the DLC coating had been confirmed. A ball-on-disk (BoD) test and an electrochemical measurement lead us to conclusion that an optimal structure to improve both tribological property and anticorrosion property was substrate/Cr/Si-C:H/DLC.

Multilayer ceramic coating for impeding corrosion of sintered NdFeB magnets

Sintered NdFeB magnets have complex microstructure that makes them susceptible to corrosion in active environments. The current paper evaluated the anticorrosion characteristics of multilayer titanium nitride ceramic coating applied through cathodic arc physical vapour deposition (CAPVD) for protection of sintered NdFeB permanent magnets. The performance of ceramic coating was compared to the electrodeposited nickel coating having a copper interlayer. Electrochemical impedance spectroscopy (EIS) and cyclic polarization in simulated marine environment were employed to determine the rates of coatings degradation and passivation behaviour respectively. The coating morphologies and surface chemistry were studied with scanning electron microscope (SEM). X-ray diffraction (XRD) was used for identification of component phases in the coatings and the substrate. The results showed that the polarization resistance of ceramic coating increased with the exposure time. The rate of degradation of R p for the ceramic coating had an extraordinary negative slope followed by a stable duration, before declining towards the coating failure. In comparison the nickel coating with copper interlayer degraded sharply. The vapour deposited ceramic coating was found to have permeable defects that tended to “re-passivate” during exposure providing prolonged corrosion protection to the NdFeB substrate. The magnetic properties were unaffected and remained at par with the nickel coating having copper interlayer.

A Study of Surface Treatment on LY12 Aluminum Alloy by γ-APS

The work aims to investigate the anti-corrosion behavior of silane treated LY12 aluminum alloy (AA LY12) and optimize the process conditions of silane treatment. The silane films were prepared on AA LY12 from γ-aminopropyltriethoxysilane (γ-APS) hydrolized in ethanol/water mixture by dip coating method. The optimum process parameters were obtained from the orthogonal designs in terms of silane solution concentration, ethanol/water ratio, dipping time, curing temperature and curing time. Prior and after silane treatment, the surface of AA LY12 was characterized by contact angle measurements and scan electron microscopy (SEM). The potentiodynamic polarization tests and electrochemical impedance spectroscopy measurements (EIS) were employed to study the anti-corrosion characteristics of silane films on AA LY12. The impedance plots were fitted with the different equivalent circuits. Furthermore, the influence of the above process parameters of silane treatment on film formation and anti-corrosion performance was explored. The results indicate that the γ-APS treated AA LY12 significantly improved the corrosion resistance, compared to the untreated one.

The corrosion-electrochemical behavior of the PT-7M titanium alloy after oxynitriding

The corrosion-electrochemical behavior of the PT-7M titanium alloy after oxynitriding in a 0.9% aqueous solution of sodium chloride is investigated. Oxynitriding is performed by modifying the oxygen of the nitride layer formed upon thermal-diffusion saturation in the atmosphere of molecular nitrogen. It is established that the protective properties of the alloy are determined by the quantitative ratio of the oxynidride and oxide phases in the modified surface layer. It is shown that, as the content of the oxynitride phase in the composition of the surface layer increases and the oxygen component in its composition decreases, the anticorrosion characteristics of the alloy surface are improved.

Corrosion and optimum corrosion protection potential of friction stir welded 5083-O Al alloy for leisure ship

Electrochemical tests were undertaken to determine the optimum conditions in seawater for corrosion protection of friction stir-welded 5083-O Al alloy. Polarization trend observations show that the limiting potential that avoids the effects of hydrogen embrittlement is −1.6 V, corresponding to the crossover point between concentration polarization and activation polarization. However, the optimum protection potential is between −1.5 and −0.7 V since the current density at these values is low in the potentiostatic tests. When a galvanic cell is formed in the seawater, the welds exhibit electrochemically stable trends. Welded parts in galvanic tests with various area ratios are stable and have excellent anticorrosion characteristics.

Corrosion characteristics in concrete environment of hot dip galvanised steel and Zn alloy hot dip coated steel

The modern civilisation is based on steel reinforced concrete structures. Thus, the deterioration of concrete presents a threat to the infrastructure of our society and it is caused mainly by the corrosion of steel rebars. Such deterioration requires huge expenditure to maintain and recover the concrete structures. And the cracking and spilling of concrete may lead to accidents resulting in injury or death. From the viewpoint of both economics and safety, the anticorrosion characteristics of rebars should be enhanced. Hot dip galvanised rebars have been used for this purpose in Euro-American countries, while they have not been used in Japan. For the latter, high anticorrosion epoxy coated rebars have dominated the market. But due to the high cost of these, the application of less expensive hot dip galvanised steels should be investigated. The authors investigated the anticorrosion characteristics in concrete of hot dip galvanised steel and Zn alloy hot dip coated steel in this study. The electrochemical behaviours of specimens in the simulated concrete solutions were analysed by cyclic voltammetry, optical microscopy and X-ray diffraction analysis, and the corrosion characteristics of those specimens and the potential of this application were discussed.

231 耐摩耗性および耐食性を有するDLC膜の開発(コーティング・溶射・薄膜プロセス)

231 耐摩耗性および耐食性を有するDLC膜の開発(コーティング・溶射・薄膜プロセス)

Location of delamination in laminated composite plates by pulsed laser holography

The location of delamination in composite laminates based on their vibration characteristics is presented in this paper. Composite materials are widely used as structural materials for aerospace engineering, because of its excellent mechanical properties such as light weight, high stiffness and anti-corrosion characteristics. This paper uses pulsed electronic speckle pattern interferometry (Pulsed-ESPI) to perform non-destructive evaluation of carbon fiber reinforced plastic (CFRP) laminate plates containing various sizes of artificial defects located at the centre of the specimen, based on vibration characteristic using double-pulsed Ruby laser with a pulse duration of 30 ns. The pulsed separation can be adjusted in between 2 and 800 μs. The main advantage of this technique over conventional ESPI is the ability to carry out measurements even under harsh environmental conditions. From the results, it seems to be effective for the detection of defects in various kinds of composite materials. In this paper, the basic principles of the technique are described briefly.

High temperature oxidation and corrosion in marine environments of thermal spray deposited coatings

Flame spraying is a widely used technique for depositing a great variety of materials in order to enforce the mechanical or the anticorrosion characteristics of the substrate. Its high rate application is due to the rapidity of the process, its effectiveness and its low cost. In this work, flame-sprayed Al coatings are deposited on low carbon steels in order to enhance their anticorrosion performance. The main adhesion mechanism of the coating is mechanical anchorage, which can provide the necessary protection to steel used in several industrial and constructive applications. To evaluate the corrosion resistance of the coating, the as-coated samples are subjected in a salt spray chamber and in elevated temperature environments. The examination and characterization of the corroded samples is done by scanning electron microscopy and X-ray diffraction analysis. The as-formed coatings are extremely rough and have a lamellic homogeneous morphology. It is also found that Al coatings provide better protection in marine atmospheres, while at elevated temperatures a thick oxide layer is formed, which can delaminate after long oxidation periods due to its low adherence to the underlying coating, thus eliminating the substrate protection.

Using EIS to analyse samples of Al–Mg alloy AA5083 treated by thermal activation in cerium salt baths

This paper describes a study undertaken of the morphological and anticorrosive characteristics of surface layers formed on the Al–Mg alloy AA5083 from solutions of Ce(III), by means of various heat treatments while immersed in baths of cerium salts. SEM/EDS studies have demonstrated the existence of a heterogeneous layer formed by a film of aluminium oxide/hydroxide on the matrix and a series of dispersed islands of cerium deposited on the cathodic intermetallics. With the object of evaluating the degree of protection provided by the layers formed and of characterising the particular contribution of the electrochemical response of the system in NaCl, the results obtained by means of EIS are presented and discussed.