Cathodic Disbondment Resistance Research Articles

One pot synthesis of amino silane grafted cerium phosphate (AS@CePO4) as an effective anticorrosion nanopigment for epoxy coating

This work proposed a facile method to synthesize an effective anticorrosion nanopigment based on amino silane grafted cerium phosphate for epoxy coated steel system. CePO4 nanoparticles were synthesized from Ce(NO3)3 and Na3PO4 precursors, then surface-grafted with a coupling agent N-2-(aminoethyl)-3-aminopropyl trimethoxysilane (denoted as AS) via a one-pot reaction to obtain the AS@CePO4 nanopigment. The effectiveness of this nanopigment on corrosion protection, dry/wet adhesion strength, and cathodic disbondment resistance was thoroughly evaluated on an epoxy-coated steel system. The composition and morphology of pigments as well as epoxy containing pigments were characterized by Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) methods. The adhesion strength, cathodic disbondment resistance and corrosion protection performance characteristics of the coatings were evaluated by pull-off test, cathodic disbondment test, electrochemical and salt spray tests, respectively. The synergic effect from stronger bonding of AS coupling agent and excellent inhibitory ability of CePO4 led to strengthened adhesion strength, better corrosion protection performance, and higher cathodic disbondment resistance of epoxy coated steel system.

Anti-Corrosion Effects of Aluminum Bronze Film Coatings and Cathodic Disbondment Resistance of Coating Films

Anti-Corrosion Effects of Aluminum Bronze Film Coatings and Cathodic Disbondment Resistance of Coating Films

Corrosion behavior of zirconium-pretreated/epoxy-coated mild steel: New approach for determination of cathodic disbondment resistance by electrochemical impedance spectroscopy

The protective performance of zirconium-pretreated epoxy films with and without zinc sulfate additive in 3.5 wt% NaCl solution was investigated. A new parameter with a reasonable relation based on EIS tests for the scratched samples was introduced to determine the amount of corrosive electrolyte diffusing into the coating/substrate interface, and it was attributed to cathodic disbondment resistance. It was revealed that coating segregation was reduced via surface pretreating by zirconium with additives.

Explorations of the adhesion and anti-corrosion properties of the epoxy coating on the carbon steel surface modified by Eu2O3 nanostructured film

In the present study, the epoxy coating adhesion and adsorption on the carbon steel surface treated by a high free energy nano-porous film based on europium (Eu) oxide were estimated using different analyses. Furthermore, the Eu2O3 film impact on the steel@Eu-oxide/epoxy anti-corrosion properties, performance, and cathodic disbondment resistance was investigated. By atomic force microscopy (AFM) analysis, the steel@Eu-oxide roughness, and through the FE-SEM method, the deposited film homogeneity/uniformity degrees were examined. The uniform coverage of the steel surface by a nanostructured Eu-oxide film led to the free energy (γs) improvement up to 30%. The EIS outcomes indicated a significant increase (about 57%) in the scratched coating corrosion resistance against saline attack in the case of the Eu-treated sample. The cathodic delamination test results displayed about 58% improvement of the epoxy resistance against cathodic disbondment. The simulation outcomes strongly affirmed the strengthened coating dry/wet adsorption on the europium oxide adsorbents compared with iron oxides.

Corrosion Resistance and Cathodic Disbondment of Epoxy Coating Applied on Zinc Phosphate Conversion Coating Containing Different Amounts of Cobalt Ions

In this study, the influence of phosphate surface pretreatment containing a cobalt ion additive on the anti-corrosion features of epoxy coating was investigated. Phosphate conversion coating (PCC) specimens were prepared. Then the epoxy coating was electrostatically sprayed on the phosphated substrate. The surface morphology and the composition of a zinc phosphate conversion coating with a cobalt ion additive were studied by scanning electron microscopy and X-ray diffraction, respectively. Also, the corrosion protection properties of specimens were studied by the polarization potentiodynamic test in 3.5% NaCl solution. Protective performance of double-layer coatings was studied using electrochemical impedance spectroscopy during 30 days in the mentioned solution. In addition, the impact of phosphate chemical treatment on increasing the adhesion strength of the powder coating was studied using the pull-off adhesion test and cathodic disbodnment test in the same solution. As a result, it was found that the corrosion resistance of PCC containing a cobalt additive enhanced significantly and that the PCC containing 3 g/L Co is less porous than other coatings. Also, the protection properties, adhesion strength, and cathodic disbondment resistance of the double-layer coatings with phosphate pretreatment containing 3 g/L Co increased significantly.

Enhancement of the active/passive anti-corrosion properties of epoxy coating via inclusion of histamine/zinc modified/reduced graphene oxide nanosheets

Abstract This research introduces a green/novel route for preparation of an epoxy system with bi-functional active/passive anti-corrosion properties via inclusion of modified/reduced graphene nanoparticles. For the first time, the reduced nanosheet (RGO) with the barrier-inhibitive activities was prepared using bioactive reductant based on histamine. Also, zinc cations were loaded onto RGO sheets by two sequence based (RGO-Hist-Zn-I nanosheet) and in-situ based (RGO-Hist-Zn-II nanosheet) approaches. Characterization of the synthesized RGOs using X-ray photoelectron spectroscopy, field emission-scanning electron microscopy, transmittance electron microscopy, ultraviolet-visible and inductively coupled plasma techniques approved the precision of graphene oxide reduction via histamine and zinc cation's chemical adsorption. The performance of the RGO nanosheets was investigated by electrochemical impedance spectroscopy, potentiodynamic polarization, salt spray, pull off adhesion, cathodic disbondment (CD) and energy dispersive X-ray spectroscopy analyses. The results clarified that the epoxy coating reinforced with RGO-Hist-Zn-I provided the best anti-corrosion performance (log |Z|10 mHz = 9.73 Ω cm2 after 60 days immersion in NaCl solution), self-healing property (liberation of histamine and zinc cations from the nanocomposite bulk to the scratch region after 8 h immersion), adhesion to steel surface (lowest adhesion loss, i.e. 14.2% after 38 days of immersion and CD resistance (ca. 4.7 mm).

The role of neodymium based thin film on the epoxy/steel interfacial adhesion and corrosion protection promotion

The main aim of this study is to investigate the impact of the steel substrate Nd-based chemical modification on the corrosion protection performance, cathodic delamination and adhesion properties of epoxy coating. The morphology, chemical composition, topography and chemistry of the treated samples were studied by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and contact angle measurement. The treated samples and also the epoxy coated samples corrosion resistance was examined through electrochemical impedance spectroscopy (EIS). The impact of mild steel surface modification on the epoxy coating protection efficiency, adhesion strength and cathodic disbondment (CD) resistance was surveyed by salt spray, Pull-off and CD tests. Results showed the deposition of Nd oxide/hydroxide, a surface with lower surface free energy and higher roughness compared to the untreated sample. Chemical treatment by Nd-based film remarkably improved the epoxy coating corrosion protection properties, increased the adhesion strength through chemical and hydrogen bonds, and led to an excellent CD resistance.

Influence of functionalized multi-layer graphene on adhesion improvement and corrosion resistance performance of zinc-rich epoxy primer

ABSTRACTThe influence of functionalised multi-layer graphene (FMLG) on anti-corrosion behaviour of zinc-rich primer (ZRP) was investigated. Electrochemical impedance spectroscopy, salt spray, cathodic delamination, pull-off adhesion tests and scanning electron microscopy analysis were evaluated. Samples were prepared using 0.25, 0.5, 0.75 and 1 wt-% of FMLG substituted by the same amount of zinc particles in epoxy containing 75 wt-% of zinc dust. Results revealed that sacrificial and barrier performances of ZRP were improved in the presence of FMLG. In addition, the adhesion and cathodic disbondment resistance showed significant improvement. The best results were obtained for ZRP containing 0.75 wt-% of FMLG.

Development of nanocomposite coatings with improved mechanical, thermal, and corrosion protection properties

In this study, new composite coatings are fabricated and investigated for their applications as the metal coating. The studied coatings consist of two-layered composites with various nanoparticulates as fillers in a polymeric matrix (styrene acrylic). The first layer bonded to the steel plate uses a combination of zinc particles, multi-walled carbon nanotubes, and graphene nanoplatelets. For the second layer, hexagonal boron nitride with high electrical insulation properties is added to the matrix. The morphology of the nanoparticulates is conducted using a scanning electron microscope. The coefficient of thermal expansion, cathodic disbondment resistance, gas penetration, and scratch resistance of the coatings are evaluated. The corroded area on the cathodic disbondment test specimens reduced down up to 90% for the composite with zinc (20 wt%), multi-walled carbon nanotubes (2 wt%), and graphene nanoplatelets (2 wt%), compared to a specimen coated with a pure polymer. It is seen that the presence of nanoparticulates decreased gas permeation and thermal expansion of the matrix by 75% and 65%, respectively. The addition of nanoparticulates also enhanced scratch resistance of the coating composites.

Corrosion and cathodic disbondment resistance of epoxy coating on zinc phosphate conversion coating containing Ni 2+ and Co 2+

Abstract In this study, surface morphology, composition and anti-corrosion properties of zinc phosphate conversion coating with nickel and cobalt additives were investigated. In the second step, the phosphated coating was used as the pretreatment for the epoxy coating. The results showed that the corrosion resistance of phosphated coating containing additives has been increased significantly. The phosphated coating containing mixture of additives formed on the surface, has lower porosity and higher compaction than other samples. Also by adding a mixture of additives to the composition of the phosphated coating, adhesion strength and resistance to the cathodic disbondment of organic coatings were increased.

Electrochemical impedance spectroscopy as a tool to measure cathodic disbondment on coated steel surfaces: Capabilities and limitations

The disbondment of protective organic coatings under excessive cathodic protection potentials is a widely reported coating failure mechanism. Traditional methods of evaluating cathodic disbondment are based on ex situ visual inspection of coated metal surfaces after being exposed to standard cathodic disbondment testing conditions for a long period of time. Although electrochemical impedance spectroscopy (EIS) has been employed as an effective means of evaluating various anti-corrosion properties of organic coatings; its application for assessing the cathodic disbondment resistance of coatings has not been sufficiently exploited. This paper reports an experimental study aimed at developing EIS into a tool for in situ measurement and monitoring of cathodic disbondment of coatings. A clear correlation between EIS parameters and the disbonded coating areas has been confirmed upon short term exposure of epoxy-coated steel electrodes to cathodic disbondment conditions; however the degree of this correlation was found to decrease with the extension of exposure duration. This observation suggests that EIS loses its sensitivity with the propagation of coating disbondment, and that in order to achieve quantitative determination of the coating cathodic disbondment localized EIS measurements are required to measure the parameters related to local disbonded areas.

Fusion bonded epoxy mainline and field joint coatings performance from the X100 field trial – A case study

Operating and distribution companies are potentially interested in the use of high and ultra-high strength steels for the transportation of high pressure gas. The ultra-high strength X100 grade steel was commercially developed as a potential option to meet this. However, there has been limited industry wide use of X100 to date.BP carried out a 2 year field trial to demonstrate the operational capacity and integrity of a large diameter (48 inch/1219 mm) high pressure pipeline constructed from X100 grade steel. The 800 m pipeline was buried in a clay backfill and exposed to wet ground conditions associated with the North of England. Flow pressure cycling was carried out, using water, to simulate 40 years of operational service.A 200 m section of the pipeline was exposed to three different potential (cathodic protection) zones for the duration of the trial: zero potential, intermediate potential (−850 to −950 mV) and high potential (−1200 to −1300 mV). This section also had damage and defects induced which are typically associated with bad installation and commissioning.An area of potential concern is the degradation of the mechanical properties (strain ageing) due to the external coating application temperature. Thus, a low coating application temperature is deemed desirable.The mainline and field joint coatings employed for the trial were fusion bonded epoxy (FBE). Both of these have been used in other BP projects, with a good track record. They were applied at a lower application temperature of 220 °C, compared to the more typical 230–240 °C. The lower application temperature was within the manufacturers approved application and curing temperature range. The lower temperature was used to assess the ultimate performance properties of the mainline and field joint FBE coatings.Mainline and field joint coating samples were taken from the three different potential zones and extensive testing and characterisation carried out. This paper presents and discusses the results of the testing.It was found that the different potential zones had negligible effect on the properties of the mainline and field joint coatings. The post-field trial properties of the mainline coatings were unaltered (i.e. same as pre-field trial) despite burial for over 2 years.Although the mechanical properties (flexibility and impact resistance) of the field joint coatings were acceptable, the coatings' water soak and cathodic disbondment resistance were far inferior to those of the mainline coating. This can be related to the comparably lower adhesion, and directly attributed to the adhesion promoting chromate pre-treatment used for mainline coatings, but not so for field joints. This is stipulated by environmental legislation. This is an area which needs to be addressed prior to X100 being used in any future project.

Filled reactive ethylene terpolymer primers for cathodic disbondment mitigation

AbstractA reactive ethylene terpolymer (RET) with inorganic fillers of clay, talc, and zinc was examined for its cathodic disbondment (CD) performance and as a potential coating primer material for pipeline applications. The filler type and volume fraction influenced the mechanical, thermal, adhesion, and CD resistance of the coatings. The tensile modulus and strength of the RETs increased at higher loadings of selected fillers. The dry adhesive strength of the clay‐filled RET maintained the same level of adhesion up to approximately 23 vol %, whereas the talc‐ and zinc‐filled RETs showed decreases in adhesive performance. CD resistance was significantly improved with 18–23 vol % clay, whereas the overall disbondment area was reduced approximately 82% from pure RET. However, the post‐cathodic‐disbondment adhesive strength for the clay‐filled RET decreased as a result of the degradation of the primer/topcoat interface caused by moisture absorption. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Cathodic disbondment resistance with reactive ethylene terpolymer blends

Adhesion to metallic substrates can be improved through the addition of polar functional groups, which bond with surface groups on the metal substrate. Additionally, polar interactions have been shown to increase adhesive strength even in wet environments (such as in the case for cathodic protection). A polymer blend is proposed as a coating material to provide adequate protection against the diffusion of moisture and air to the metallic surface along with superior adhesion even in the presence of wet and corrosive environments to resist cathodic disbondment. A reactive ethylene terpolymer (RET) of ethylene/ n-butyl acrylate/glycidyl methacrylate (E/nBA/GMA) was compounded with HDPE to develop a potential coating material. The HDPE component offers high chemical and moisture resistance to permeation, while the RET component provides the material with high polarity and reactivity, which enhances adhesion to the substrates to be coated. The introduction of the reactive ethylene terpolymer decreases the magnitude of cathodic disbondment area of polyethylene coatings. After applying a cathodic potential to the coating substrate, the adhesive strength was observed to remain the same for silane-pretreated steel dollies. Without silane pretreatment, post-CD adhesive loss resembles that of the open circuit “wet” condition. EDAX data in conjunction with oxygen and water vapor transmission rates suggest an initial stage of disbondment where interfacial oxide is dissolved resulting in the delamination of coating around the initial defect. This initial disbondment zone acts like a moving crack tip creating larger areas of disbondment where interfacial bonds are degraded by the ingress of moisture and ions along the interface.

Characterization of high performance composite coating for the northern pipeline application

High performance composite coating (HPCC) provides a potential, excellent coating alternative for integrity maintenance of pipelines in the northern area. In this work, the physical, chemical and mechanical properties of HPCC were investigated to determine the microstructure, water permeability, cathodic disbondment resistance, electrochemical impedance, adhesion and impact resistance of the coating. It is shown that the addition of polyethylene layer significantly improves the compactness of the coating and enhances its resistance to water and chemical penetration, resulting in a small water vapor transmission rate and permeance. There is a quite small cathodic disbondment of HPCC under the standard test. The impedance characteristic measured on HPCC-coated steel shows a capillary behavior, indicating an effective protection over the underlying steel from corrosion. The adhesion of HPCC to the substrate ranks top one according to both ASTM and CSA standards. The impact energy of HPCC is 9.7 J at 22 °C, and about 10.2 J around 0 °C.