Epoxy-coated Steel Research Articles

Influence of phosphate ion on the morphology, adhesion strength, and corrosion performance of zirconium-based surface treatment

In this study, the effect of phosphate ion (PO4 3−) was investigated on the different properties of a zirconium-based nanoceramic conversion layer. At the first step, the phosphate ion concentration was optimized using the DC polarization technique. In the next step, the surface morphological aspect of the bare and treated mild steel was evaluated utilizing field emission scanning electron microscopy technique. The results indicate formation of a composite conversion coating on the mild steel surface. Practical adhesion strength between treated mild steels and an epoxy resin was studied by pull-off adhesion test. Finally, the effect of phosphate ion on the corrosion properties of epoxy-coated mild steel was evaluated utilizing electrochemical impedance spectroscopy. It was revealed that the phosphate ion could increase both the adhesion strength and anticorrosion properties of the epoxy-coated substrate.

Evaluation of corrosion resistance of coated steel strips embedded in mortar under chloride exposure

Purpose – The purpose of this paper was mainly to select one of the three types of coatings for protection of steel used as reinforcement in composite pipes (thin steel shell covered by cement-mortar) subjected to chloride exposure. To achieve this target, an attempt was made to develop a simple methodology for evaluating the performance of corrosion protection measures in terms of chloride threshold level (CTL) and corrosion initiation time (TI). Design/methodology/approach – Bare, epoxy, red oxide and zinc primer-coated steel strips were embedded in cement mortar with sand/cement and water/cement ratios of 2 and 0.5 (by mass), respectively, to prepare the specimens which were exposed to chloride solution having a high concentration of 10 per cent NaCl. For determining the amounts of the water-soluble chloride diffused inside the specimens, powdered samples of mortar were collected from two different depths from the exposed surface of specimens on completion of each of the four different exposure times. The corrosion current densities were determined at two different stages. A step-by-step procedure for calculating CTL and TI using the measured chloride contents and corrosion current densities was established with the help of relevant information available in the literature. Findings – Based on the comparison of the values of CTL and TI calculated for bare steel and steel with all three types of coatings, utilizing the experimental data and the proposed calculation procedure, the epoxy-coated steel was found to have the best performance. Originality/value – This research has resulted into development of a simple methodology for evaluation of the performance of protective measures against corrosion of steel embedded in mortar or concrete exposed to chloride-bearing environment.

Damage resistance and anticorrosion properties of nanosilica-filled epoxy-resin composite coatings

Abstract Silica nanoparticles surface-capped with diglycidyl ether of bisphenol A were dispersed in a solution of epoxy resin, hardener and acetone. The resultant suspension was then coated onto the surface of duplex stainless steel of type DSS 2205 and cured with temperature, generating a 50 μm thick silica/epoxy coating. Epoxy coating without nanosilica was also prepared as a reference in the same manner. Mechanical properties of these coatings were compared and characterized using the Vickers hardness test. Three-point bending test was performed in combination with acoustic emission to analyze the damage initiation and development in the coating. The effects of incorporating the silica particles on the surface characteristics and the corrosion resistance of the epoxy-coated steel were investigated with contact-angle and surface energy as well as by potentiodynamic polarization and electrochemical impedance spectroscopy in a 3.5 wt.% NaCl solution. Results indicate, that silica particles significantly improved the microstructure of the coating matrix, which was reflected in an increased damage resistance, reduced degree of delamination, increased surface roughness and induced hydrophobicity. The silica/epoxy coating was proven to serve as a successful barrier in a chloride-ion-rich environment with an enhanced anticorrosive performance, which was confirmed by the reduced corrosion rate.

Filiform Corrosion of Polyvinyl Butyral- and Bisphenol A-Based Epoxy-Coated Steel After Standard Laboratory Exposures

Filiform corrosion (FFC) has been shown to occur during field exposure of scribed organic-coated steel. In this paper, the FFC filament morphologies formed under polyvinyl butyral (PVB) and bisphen...

The study on the influence of surface cleanness and water soluble salt on corrosion protection of epoxy resin coated carbon steel

The corrosion resistance of epoxy-coated carbon steel was evaluated. The carbon steel surface was subjected to different treatment methods such as steel grit blasting and power tool treatment as well as contamination of water soluble salt. To study the effect of the surface treatments and contamination, the topology of the treated surface was observed by confocal microscopy and a pull-off adhesion test was conducted. The corrosion resistance of the epoxy-coated carbon steel was further examined by electrochemical impedance spectroscopy (EIS) combined with immersion test of 3.5 wt% of NaCl solution. Consequently, the surface contamination by sodium chloride with 16 mg/m2, 48 mg/m2 and 96 mg/m2 didn`t affect the adhesion strength for current epoxy coated carbon steel and blister and rust were not observed on the surface of epoxy coating contaminated by various concentration of sodium chloride after 20 weeks of immersion in 3.5 wt% NaCl aqueous solutions. In addition, the results of EIS test showed that the epoxy-coated carbon steel treated with steel grit blasting and power tool showed similar corrosion protection performance and surface cleanness such as Sa 3 and Sa 2.5 didn`t affect the corrosion protectiveness of epoxy coated carbon steel.

The Large Turbine Impeller Cavitation Technology of Integrated Prevention and Control Lancang River Basin

There is a large widespread cavitation turbine components. By using HVOF Stellite alloy coating technology, brushing epoxy technology, epoxy-coated steel wire technology, brazed carbide block technology, repeated welding technology integrated control over the water turbine components cavitation,effectively prevent the turbine parts water cavitation in running condition, improve the reliability of hydroelectric equipment..

Performance of Glass Fiber-Reinforced Polymer-Doweled Jointed Plain Concrete Pavement under Static and Cyclic Loadings

Glass fiber-reinforced polymer (GFRP) dowel bars are a non-corrodible and maintenance-free alternative that will potentially reduce the life-cycle cost of jointed plain-concrete pavement (JPCP), especially in harsh environmental conditions. This paper investigates the performance of GFRP dowels in JPCP under static and cyclic loads. In addition, it compares their behavior with that of commonly used epoxy-coated steel dowels. GFRP and epoxy-coated steel dowels were employed in fabricating a total of six JPCP prototypes (slab-joint). The test prototypes measured 2440 mm long x 610 mm wide x 254 mm deep (96 x 24 x 10 in.). The slabs were cast with a butted joint; each test prototype contained two dowel bars. The test parameters included: 1) dowel-bar type (GFRP and epoxy-coated steel); 2) dowel-bar diameter (34.9 and 38.1 mm [1.38 and 1.50 in.] for GFRP; 28.6 mm [1.13 in.] for epoxy-coated steel); and 3) loading scheme (static and cyclic). The test results revealed that both 34.9 and 38.1 mm (1.38 and 1.50 in.) GFRP dowels showed crack patterns and failure modes similar to those of the epoxy-coated steel dowels. The 34.9 and 38.1 mm (1.38 and 1.50 in.) GFRP dowels and 28.6 mm (1.13 in.) epoxy-coated steel dowels were not affected by 1,000,000 cycles between 10 and 50 kN (2.25 and 11.24 kip). In addition, both the 34.9 and 38.1 mm (1.38 and 1.50 in.) GFRP dowels showed higher joint effectiveness than that of the 28.6 mm (1.13 in.) epoxy-coated steel dowels. This paper also discusses the results of a field application in which the GFRP dowels were implemented in a new concrete-pavement highway in Mirabel, QC, Canada.

Mechanical and anticorrosion properties of nanosilica-filled epoxy-resin composite coatings

Homogeneous, 50-μm-thick, epoxy coatings and composite epoxy coatings containing 2wt% of 130-nm silica particles were successfully synthetized on austenitic stainless steel of the type AISI 316L. The surface morphology and mechanical properties of these coatings were compared and characterized using a profilometer, defining the average surface roughness and the Vickers hardness, respectively. The effects of incorporating the silica particles on the surface characteristics and the corrosion resistance of the epoxy-coated steel were additionally investigated with contact-angle measurements as well as by potentiodynamic polarization and electrochemical impedance spectroscopy in a 3.5wt% NaCl solution. The silica particles were found to significantly improve the microstructure of the coating matrix, which was reflected in an increased hardness, increased surface roughness and induced hydrophobicity. Finally, the silica/epoxy coating was proven to serve as a successful barrier in a chloride-ion-rich environment with an enhanced anticorrosive performance, which was confirmed by the reduced corrosion rate and the increased coating resistance due to zigzagging of the diffusion path available to the ionic species.

Evaluation of performance and design of GFRP dowels in jointed plain concrete pavement – part 1: experimental investigation

Dowel bars are provided at the transverse joints of the jointed plain concrete pavement to allow for expansion and contraction of the pavement due to moisture and temperature changes. This paper presents experimental and analytical investigations for the deflection response of glass fibre-reinforced polymer (GFRP) dowels for different joint widths and concrete grades. The results were compared with those obtained from investigations into the conventional epoxy-coated steel dowel bars of similar rigidity. The experimental results showed that the 38 mm (1.5 in.) GFRP dowels perform better in terms of joint face deflection compared with 25 mm (1 in.) epoxy-coated steel dowel bars. In addition, these results showed that the deflection of the GFRP dowel was significantly affected by changing the concrete compressive strength and the joint widths.

Effect of Surface Pretreatment on the Corrosion Resistance of Epoxy-Coated Carbon Steel

The corrosion resistance of epoxy-coated carbon steel was evaluated. The carbon steel surface was subjected to different treatment methods such as steel grit blasting with different size, steel shot ball blasting and power tool treatment. To study the effect of the treatments, the topology of the treated surface was observed by optical 3D microscopy and a pull-off adhesion test was conducted. The corrosion resistance of the epoxy-coated carbon steel was further examined by electrochemical impedance spectroscopy (EIS) combined with hygrothermal cyclic testing. The results of EIS indicated that the epoxy-coated carbon steel treated with steel grit blasting showed an improved corrosion resistance compared to untreated epoxy-coated surfaces or surfaces subjected to shot ball blasting and power tool treatments.

Influence of Si nanoparticles on the electrochemical behavior of organic coatings on carbon steel in chloride environment

Scanning electrochemical microscopy (SECM) is an excellent technique to detect electrochemical processes with high spatial resolution. In this work, the effect of silicon (Si) nanoparticles on the corrosion protection performance of epoxy-coated steel was examined by electrochemical impedance spectroscopy (EIS) and SECM analysis. The EIS was performed in continuous immersion in 0.1 M NaCl(aq) solution. The addition of Si nanoparticles increased the coating film resistance (R f) and the charge transfer resistance (R ct) of coated steel. SECM mapping and line scan analysis was performed in order to estimate the coating performance with Si nanoparticles in 0.1 M NaCl(aq) solution. SECM results indicated that the tip current at −0.70 V was decreased by the addition of Si nanoparticles in epoxy film. These results suggested that the dissolved oxygen (DO) was consumed by anodic dissolution of Si nanoparticles. Surface analysis showed that the Si was enriched at the scratched region of the coated steel after a corrosion test. From these results, Si was dissolved as Si n+ and transferred to the scratched area, and then consumed the DO in the solution. Thus, the anodic dissolution of Fe at the scratched area was suppressed by the Si nanoparticles, which implies the sacrificial effect of Si from the coating against the steel corrosion. Hence, it was concluded that the Si nanoparticles had a beneficial effect on enhancing the corrosion resistance of the coated steel.

Life-Cycle Cost Analysis of Alternative Reinforcement Materials for Bridge Superstructures Considering Cost and Maintenance Uncertainties

A life-cycle cost analysis (LCCA) was conducted on prestressed concrete bridge superstructures using carbon fiber reinforced polymer (CFRP) bars and strands. Traditional reinforcement materials of uncoated steel with cathodic protection and epoxy-coated steel were also considered for comparison. A series of deterministic LCCAs were first conducted to identify a range of expected cost outcomes for different bridge spans and traffic volumes. Then, a probabilistic LCCA was conducted on selected structures that included activity timing and cost random variables. It was found that although more expensive initially, the use of CFRP reinforcement has the potential to achieve significant reductions in life-cycle cost, having a 95% probability to be the least expensive alternative beginning at year 23–77 after initial construction, depending on the bridge case considered. In terms of life-cycle cost, the most effective use of CFRP reinforcement was found to be for an AASHTO beam bridge in a high traffic volume area.

EIS evaluation of protective performance and surface characterization of epoxy coating with aluminum nanoparticles after wet and dry corrosion test

The effect of addition of aluminum (Al) nanoparticles to epoxy coating on the ability to protect the carbon steel was studied by electrochemical impedance spectroscopy and focused ion beam-transmission electron microscopy. The EIS was conducted in 0.1 M NaCl solution after wet/dry cyclic corrosion test. The addition of Al nanoparticles increased the film resistance (R f) and the charge transfer resistance (R ct) of epoxy-coated steel. The surface analysis showed that uniform and fine Al–Fe complex oxide layers were formed acting as barrier layers that enhanced the corrosion protection of the epoxy-coated steel. It has been concluded that the Al nanoparticles had a beneficial role in improving the corrosion resistance of the epoxy-coated steel.

A Comparative Toxicity Assessment of Materials Used in Aquatic Construction

Comparative toxicity testing was performed on selected materials that may be used in aquatic construction projects. The tests were conducted on the following materials: (1) untreated wood species (hemlock [Tsuga ssp], Western red cedar (Thuja plicata), red oak [Quercus rubra], Douglas fir [Pseudotsuga menziesii], red pine [Pinus resinosa], and tamarack [Larix ssp]); (2) plastic wood; (3) Ecothermo wood hemlock stakes treated with preservatives (e.g., chromated copper arsenate [CCA], creosote, alkaline copper quaternary [ACQ], zinc naphthenate, copper naphthenate, and Lifetime Wood Treatment); (4) epoxy-coated steel; (5) hot-rolled steel; (6) zinc-coated steel; and (7) concrete. Those materials were used in acute lethality tests with rainbow trout, Daphnia magna, Vibrio fischeri and threespine stickleback. The results indicated the following general ranking of the materials (from the lowest to highest LC(50) values); ACQ > creosote > zinc naphthenate > copper naphthenate > CCA (treated at 22.4 kg/m(3)) > concrete > red pine > western red cedar > red oak > zinc-coated steel > epoxy-coated steel > CCA (6.4 kg/m(3)). Furthermore, the toxicity results indicated that plastic wood, certain untreated wood species (hemlock, tamarack, Douglas fir, and red oak), hot-rolled steel, Ecothermo wood, and wood treated with Lifetime Wood Treatment were generally nontoxic to the test species.

エポキシ樹脂塗装鉄筋・ステンレス鉄筋

エポキシ樹脂塗装鉄筋・ステンレス鉄筋

Effects of residual white rust of inorganic zinc silicate primer on corrosion protection of epoxy-coated carbon steel

Inorganic zinc silicate primer is widely used in shipbuilding as a preconstruction primer (or shop primer) on steel plates; however, white rust of zinc is formed on inorganic-zinc-silicate-coated steel surfaces exposed to outdoor conditions such as rain and humidity. In this study, effects of residual white rust of inorganic zinc silicate primer on corrosion protection of epoxy-coated carbon steel were examined by water ballast simulation and condensation chamber tests. Pull-off adhesion, blistering, and cathodic disbondment tests were also performed for the same purpose. Test results clearly indicated that the residual white rust did not affect the corrosion protection when the steel surface was treated with light to heavy sweep blasting.

Effect of nanoparticles on the anticorrosion and mechanical properties of epoxy coating

Homogeneous epoxy coatings containing nanoparticles of SiO 2, Zn, Fe 2O 3 and halloysite clay were successfully synthesized on steel substrates by room-temperature curing of a fully mixed epoxy slurry diluted by acetone. The surface morphology and mechanical properties of these coatings were characterized by scanning electron microscopy and atomic force microscopy, respectively. The effect of incorporating various nanoparticles on the corrosion resistance of epoxy-coated steel was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. The electrochemical monitoring of the coated steel over 28 days of immersion in both 0.3 wt.% and 3 wt.% NaCl solutions suggested the beneficial role of nanoparticles in significantly improving the corrosion resistance of the coated steel, with the Fe 2O 3 and halloysite clay nanoparticles being the best. The SiO 2 nanoparticles were found to significantly improve the microstructure of the coating matrix and thus enhanced both the anticorrosive performance and Young's modulus of the epoxy coating. In addition to enhancing the coating barrier performance, at least another mechanism was at work to account for the role of the nanoparticles in improving the anticorrosive performance of these epoxy coatings.

The role of a zinc phosphate pigment in the corrosion of scratched epoxy-coated steel

The roles of a zinc phosphate pigment in the corrosion of scratched epoxy-coated steel were studied by means of electrochemical impedance spectroscopy, electrochemical noise measurement and scanning electrochemical microscopy. The experimental results of electrochemical noise measurement and electrochemical impedance spectroscopy revealed that zinc phosphate exhibited inhibition effect on the corrosion of the scratched epoxy-coated steel. The scanning electrochemical microscopy results implied that the scratched surface under zinc phosphate coating was re-healed by an insulating film. The mechanism of the inhibition effect of a zinc phosphate pigment was analyzed based upon the combined stochastic theory and shot noise theory using the Weibull distribution and Gumbel distribution function.

Integrated Monitoring System for Carbon Composite Strands in Cable-Stayed Bridge, Penobscot Narrows, Maine

An integrated monitoring system for carbon fiber composite cable (CFCC) strands recently implemented in the Penobscot Narrows Bridge in Maine is presented. This cable-stayed bridge features a cradle-stay system in the pylons that provides a continuous cable stay between the main span bridge deck anchorage and the back span bridge deck anchorage. The cradle-stay system allowed for replacing epoxy-coated steel strands with CFCC strands. The monitoring system installed in the bridge is composed of a set of sensors and devices that provide complementary structural information: (a) load cells supported on steel anchorage chairs, (b) linear voltage differential transformers (LVDTs) mounted on the steel anchorage chairs, (c) fiber-optic strain (FOS) sensors embedded in composite sleeves, and (d) temperature sensors. The monitoring system was designed to detect variations over time in individual carbon fiber strand force and strains at the anchorage locations and to correlate the measurements with ambient temperature. Laboratory tests were conducted to proof-load the steel anchorage chairs and to calibrate the LVDTs and embedded FOS strain measurement systems. The baseline response of the CFCC strands that was based on load cell, FOS sensors, and LVDTs measurements after the strand stressing operation is presented. The CFCC strands experienced changes in tensile force between +3% and −5% over the first 4 months in service, which were consistent with ambient temperature fluctuations. The FOS measured strand strains and the LVDT deflections of the anchored chair exhibited trends consistent with the variations in CFCC strand force.

Carbon Fiber-Reinforced Polymer Strand Application on Cable-Stayed Bridge, Penobscot Narrows, Maine

Maine's first cable-stayed bridge opened to traffic on December 30, 2006. Designed as an emergency replacement for the Waldo–Hancock Bridge, the new bridge uses an innovative cradle system to carry the stays from the bridge deck through the pylon and back to the bridge deck. Each strand is anchored independently; thus, strands may be removed, inspected, and replaced while the bridge carries traffic. This advantage, coupled with Maine Department of Transportation concerns for the premature loss of the Waldo–Hancock Bridge due to corrosion, created interest in an opportunity to install and monitor representative carbon fiber-reinforced polymer (CFRP) strands in the cable stays of this bridge. CFRP strands were installed for the purposes of assessing their performance in a service condition and evaluating them for use on future bridges. Three representative stays in the bridge were designed to include two reference strands each, which may be removed and not replaced without change to the bridge's structural integrity. Six epoxy-coated steel strands were removed and successfully replaced with CFRP strands in June 2007. Data are being collected from the monitoring equipment installed on all of the strands (both traditional steel and CFRP strands) in the bridge to evaluate CFRP strand performance for future bridge cable stay and post-tensioning installations. The bridge location ensures that the test strands will be evaluated under a wide range of temperatures and variety of wind loads.