Salt Spray Corrosion Test Research Articles

Hot-dip galvanizing process and coating corrosion behavior of fe-mn-al-c steel

The temperature of the zinc bath and the immersion duration are critical factors that significantly impact the surface quality and adhesion of batch hot-dip galvanizing coatings. This study focuses on the influence of different zinc bath temperatures (460, 490, and 520 °C) and immersion duration (1, 3, 5, and 10 min) on the hot-dip galvanized coatings of Fe-Mn-Al-C lightweight steel, which were characterized using scanning electron microscopy and energy dispersive X-ray analysis. The results demonstrate that with the increasing zinc bath temperature and immersion duration, the coating thickness and bond strength initially increase and then decrease. The inhibition layer in the coating gradually fractures and thickens with the rising temperature, leading to changes in the alloy phases within the coating. The optimal batch hot-dip galvanizing condition for the experimental steel is immersing at 490 °C for 3 min. Furthermore, we conducted a neutral salt spray corrosion test on the specimens under the optimal batch hot-dip galvanizing condition to study their corrosion behavior and mechanism and evaluate the impact of batch hot-dip galvanizing on the corrosion resistance of Fe-Mn-Al-C steel.

Study on mechanical properties of locally corroded square steel tube short column

To investigate the axial compressive properties and failure modes of 18 locally corroded square steel tube short columns, salt spray corrosion tests were conducted. The findings indicate that local corrosion in the horizontal direction significantly impacts the ultimate bearing capacity of the specimens, with all failures occurring in the corroded areas. However, the influence of the corrosion area on the ultimate bearing capacity and ductility of the specimens is not evident. A local corrosion model for square steel tube short columns was developed using the finite element method. The ultimate bearing capacity determined through finite element simulation closely aligns with experimental results, validating the reliability of the simulation approach. Moreover, a comparison is made between the prediction models of the BP neural network and the GA-BP neural network, with the prediction effectiveness of each model evaluated using the leave-one-out method. The verification results indicate that the GA-BP neural network model demonstrates superior predictive performance, with an average error of 3.14%.

The Effect of Artificial Ageing on the Changes in Selected Properties of Organic Coated Sheets.

This contribution presents the results of research focused on changes in selected properties of organic-coated steel sheets in a corrosive environment of salt mist. The aim of this study was to characterise coated sheets and to analyse the influence of elevated temperature on changes in their selected properties. The methodology and experiments were chosen to simulate the accelerated ageing and to evaluate the surface of organic-coated steel sheets. During the research, the effect of artificial ageing due to increased temperature on changes in mechanical properties of coated sheets was monitored, which were determined by tensile testing according to STN EN 10002-1. The fracture surface of the test samples was analysed using a SEM. The following observations were made for the evaluation of coating by cross-cut tests according to EN ISO 2409. Corrosion tests were carried out by conducting salt spray corrosion tests according to EN ISO 9227. The test specimens were artificially sectioned using a laser beam. The results of the research experiments confirmed the assumption that the utilisation of the laser beam was convenient for the creation cross-cut test of the material. After the ageing test, only small significant changes in the basic mechanical properties of the tested materials were observed. It is necessary to take into account that there were changes in the appearance of the coating. The cross-cut test confirmed the results that the plastic-coated sheets could be utilised in salt corrosion environments.

Controllable size of graphite nanosheets and functionalized SiO2 microspheres with excellent anti-corrosive/wear function for superhydrophobic coating

The application of superhydrophobic coatings is limited by their complex fabrication process, expensive modification, and lack of durability. This study addresses these issues by proposing a simple and economical method for fabricating strong superhydrophobic coatings by scraping off the fluorinated suspension. This coating comprises epoxy resin (EP), graphene nanosheets, and modified silicon oxide on the Q235 steel substrate. The contact angle and sliding angle of we prepare the coating coating are 152.3° and <10° respectively, exhibiting excellent super-hydrophobicity. After being immersed in 3.5 % sodium chloride solution for 1440 minutes, the coating shows a resistance of 1.14×106 Ω cm2, which is two orders of magnitude higher than that of the coating immersed for 30 minutes (1.08×104 Ω cm2), indicating its excellent corrosion resistance. A 30-day salt spray corrosion test also confirms the good corrosion resistance of the coating. When the coating is polished 100 times under a load pressure of 500 g on 1000-mesh sandpaper, the contact angle is only reduced by 7 times, indicating its good abrasion resistance. In addition, the coating also has good weather resistance and self-repairing ability against ultraviolet radiation. This simple and environmentally friendly manufacturing method has great potential for large-scale practical applications in many fields.

An effective utilization of raw fly ash obtained from thermal power plants using thermal spray technique to improve corrosion resistance for marine applications

Marine-grade steel structures in offshore environments often corrode due to the aggressive environmental conditions. Many ceramic materials can cater to this demand. However, as per economic and ecological concerns, fly ash (FA), an industrial waste, can be another strong contender to control corrosion. Therefore, the present study developed composite coatings of fly ash with additives ((50-48) wt.% Al2O3; 0–2 wt% carbon nanotube (CNT)) onto marine-grade steel using a plasma spray technique to improve its corrosion resistance. The microstructure of 1 wt% CNT-reinforced alumina-FA (1CAF) coating was denser than 2 wt% CNT-reinforced alumina-FA (2CAF) coating due to the uniform dispersion of CNT and, thereby, uniform remelting of coating at localized sites. Consequently, the microhardness and adhesion strength of the 1CAF coating were improved by ∼14.66 % and ∼15.96 %, respectively. Further, Rietveld's analysis of coatings showed that quartz, being the primary phase for corrosion control, was 19.23 ± 0.87 %, 16.33 ± 1.04 % and 14.60 ± 1.87 % for alumina-FA (AF), 1CAF, and 2CAF, respectively. The electrochemical impedance spectroscopy and the salt spray corrosion tests showed that 1CAF coating corrosion resistance was improved by ∼11.2 % compared to AF coating, even with a lower quartz phase (∼15.08 %) due to the densification of coating. This densification was due to the remelting by CNT to seal pores in the coating. Furthermore, for the same reason, an increase in coating resistance and charge transfer resistance of 1CAF coating by ∼80.9 % and ∼19.93 %, respectively, were seen in the equivalent circuit analysis, showing great promise in controlling interfacial corrosion. Further post-treatments like plasma or laser treatments can seal the coatings further to improve corrosion resistance. Therefore, such coatings are expected to withstand harsh, corrosive environments and are well-suited for marine applications.

Research and development of corrosion monitoring sensor for bridge cable using electrical resistance probes technique

A cable corrosion monitoring sensor with a temperature compensation probe has been designed and manufactured to monitor the corrosion of high-strength steel wires in the transition zone between the cable body and the anchorage. The influence of temperature and tensile force on the resistance of steel wires was thoroughly investigated. Reliability tests were conducted on the temperature compensation probe, along with salt spray corrosion tests on the corrosion sensor. The research results demonstrated that, compared to the temperature sensor, temperature compensation probe can better reflect the actual temperature of the corrosion sensor and provide effective temperature compensation for the corrosion sensor. Moreover, the developed corrosion sensor can effectively reflect the mass loss rate of the corrosion probe. The sensor is capable of detecting a corrosion level as low as 0.02 % of the complete steel wire mass, which corresponds to an average corrosion depth of 0.412 μm.

In-situ crosslinking reaction of graphene oxide & waterborne epoxy resin to construct continuous phase anticorrosive coating

The mechanism of using graphene oxide as a two-dimensional filler to increase the path length of the corrosive medium to the metal surface is limited to improving the corrosion resistance of the coating. This study propose novel dispersion and in-situ crosslinking reaction mechanism for constructing water-based heavy-duty anticorrosive coatings by using graphene oxide (GO) and waterborne epoxy resin (WEP). The results showed that GO can be uniformly dispersed directly into WEP without complex functional modifications. Oxygen-containing functional groups on moleculars structure of GO&WEP co-polymerized with diethylenetriamine (DETA) forming a continuous phase film which improved the density of the coating. Characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal conductivity measurement instrument, pencil hardness tester, adhesion tester, salt spray corrosion test chamber, and electrochemical impedance spectroscopy (EIS) were used to evaluate coating structure and performance properties. The results showed that graphene characteristics enhanced physical properties and anti-corrosion performance of composite coatings. The construction mechanism of the coating is different from that of the current GO modified and dispersed in the coating as a two-dimensional filler to extend the path length of the corrosive medium to the metal surface. The coatings prepared by adding the optimum mass ratio of 0.1–0.2 % GO to WEP have the best physical properties and anti-corrosion properties. When the GO content is 0.2 wt%, the thermal conductivity increases by 86.0 %. After added 0.025 wt% GO, the coating hardness is increased by two grades directly from 2B to HB. With the addition of GO concentration increased to 0.05 wt%, the adhesion is increased from 2 to level 1.When the GO content exceeds 0.05 %, the coating will not bulge off after 4 months of salt water immersion experiment.

Fatigue Behavior and Fracture Surface Analysis of Corroded High-Strength Bridge Cable Wires.

Bridge cable wires suffer from alternating stress and environmental erosion, leading to premature failure prior to its design life. This paper investigates the fatigue and mechanical behaviors of corroded bridge cable wires with a zinc-aluminum (Zn-Al) alloy coating. Based on the salt spray corrosion test and microstructure analysis, the anti-corrosion resistance and corrosion appearance characteristics of the Zn-Al alloy coating and galvanized coating were investigated. The Zn-Al alloy coating was superior in resistance to corrosion fatigue for the improvement in toughness and the generation of anti-corrosion Zn-Al and Fe-Zn-Al phases. Equations of the accelerated corrosion depth of the steel wires had been regressed to roughly estimate the corrosion life of the Zn-Al alloy coating, which can reach 29.1 years with a thickness of 70 μm. The fatigue and mechanical properties of the bare wires after the salt spray test were further studied based on tensile tests and fatigue tests. The fatigue properties of the bridge cable wire would decrease with the corrosion degree due to the deterioration and embrittlement of materials, where ductility characterized by the elongation rate was the most affected. Fracture surfaces of the wires were captured and analyzed based on a method for recognizing graphical contours. Insufficient fatigue life may occur in the steel wires after corrosion and increase with the degree of corrosion. The pit depth logarithmically weakened the fatigue life of steel wires for the weakening of fatigue toughness and the bearing area. The flat fracture was more common with a single fatigue source, while multiple fatigue sources led to step-like fractures for the generation of multiple dispersed crack propagation regions. Corrosion fatigue was more sensitive to the existence of fatigue sources than the reduction. Multiple initiation sources significantly reduced the fatigue life due to the cracking facilitation of the joint effect of multiple pits. The electrochemical reactions of corrosion can lead to material embrittlement and a reducing effect on the fracture toughness of the steel wires.

Design and application research of portable reversible thermochromic patches in grid power supply systems

This study aims to develop a novel portable reversible thermochromic patch and evaluate its potential applications in temperature monitoring and indication. The film is based on the concept of electronic charge transfer thermochromic coatings, enabling accurate detection of high temperatures. Experimental results demonstrate that when the temperature of the monitored device’s circuit reaches 70 °C or above, the color of the film changes from deep blue to colorless, indicating potential overheating in the power grid. Using salt spray corrosion testing and cycle performance testing, we validate the film’s excellent corrosion resistance in harsh natural environments and its provision of reliable color indication. The film possesses portability and ease of attachment to various electrical devices and circuits requiring temperature sensing. By connecting the color information of the film to a computer system, we can achieve digital temperature monitoring, providing potential applications in future smart grid development.

Investigation on tribological characteristics of Al 7075 coated with aluminium chromium nitride (AlCrN) by magnetron sputtering

Structural components used in aerospace, automotive, and civil applications should have an increased shelf life. Fretting wear occurring in aluminum alloys decreases the reliability of the components. This study presents the investigations of tribological characteristics of Al7075, coated with Aluminium Chromium Nitride (AlCrN) by Physical Vapor Deposition (PVD) magnetron sputtering technique. Although Al7075 possesses a high strength-to-weight ratio, it has inadequate resistance against fretting wear. The experimental findings of the wear test (Pin on Disc) reveals that AlCrN coating on Al7075 increases the wear resistance and exhibits a low coefficient of friction. A thin film coating of AlCrN given on Al7075 enhances its tribological and corrosion properties. The existence of AlCrN coating composition on the substrate is confirmed by the results of Energy Dispersive Spectroscopy (EDX). Crystal structural phase analyzed using X-ray diffraction (XRD) shows Face Centered Cubic (FCC) structure for coated Al7075 samples. The pin-on-disc test results show that the wear rate has reduced for coated samples. A salt spray corrosion test is executed to evaluate the corrosion rate for 24 h. When comparing coated samples to uncoated samples, it is found that the corrosion rate is lower for coated samples. The average hardness value of the coated Al7075 sample is higher than the uncoated ones. The surface roughness of the coated sample is observed to be less than that of uncoated Al7075 samples.

Excellent corrosion resistance and good wear resistance of amorphous AlTiO coating prepared by arc ion plating

An amorphous AlTiO coating was prepared using arc ion plating. Its wear resistance and corrosion resistance were compared with those of AlTiN coating. The results indicated that the amorphous AlTiO coating had a dense structure, with H/E ratio and friction coefficient of 0.06 and 0.70, respectively, which were approaching to the values for the AlTiN coating. The friction and wear tests demonstrated that both AlTiN coating and AlTiO coating had good wear resistance. Electrochemical experiments demonstrated that the AlTiO coating exhibited excellent corrosion resistance, with a corrosion current density (Icorr) only 1.97% of that of the AlTiN coating. After neutral salt spray corrosion test with a duration of 500 h, the AlTiN coating was completely corroded, while only two corrosion spots were observed on the AlTiO coating.

MICROSTRUCTURE AND EROSION CORROSION PROPERTY OF CRNI ALLOYED COATING ON CARBON STEEL

In this study, CrNi alloyed coating was deposited on Q235 low carbon steel by arc-added glow plasma depositing technique in order to increase the corrosion resistance property. It was found that the CrNi alloyed coating was composed of face-centered cubic Cr0.7Ni2.9Fe0.36 phase. The EDS results indicated that 7.3 [Formula: see text] m coatings were prepared which was bonded metallurgically with the substrate. The salt spray corrosion test result showed that the corrosion product film of coating was dense while the corrosion film of carbon steel was multilayered in morphology. The corrosion product film of CrNi coating reduced the corrosion rate. However, the corrosion product of Q235 with loose multi-layer structure increased corrosion process. The erosion corrosion properties of carbon steel and coating were tested in NaCl solution with different flowing speed through electrochemical test methods. The erosion corrosion results showed that the corrosion rate of carbon steel was increased in flowing NaCl solution. The corrosion product of CrNi coating could protect inner material in NaCl solution at flowing speed of 2 m⋅s[Formula: see text] to 6 m⋅s[Formula: see text].

Effect of methane and acetylene pre-gases on the corrosion resistance of DLC coatings

Diamond-like carbon (DLC) coatings were applied to 304 stainless steel specimens using two different pre-gases: methane and acetylene.Compared to DLC prepared with acetylene pre-gas(DLC-C2H2). DLC prepared with methane pre-gas(DLC-CH4) has a denser coating body and a smoother surface.The DLC-C2H2 film shows crack defects on the surface, and the DLC-CH4 film has a lower sp2/sp3 ratio than DLC-C2H2. DLC-CH4 has better electrochemical characteristics and salt spray corrosion testing results than DLC-C2H2 films in NaCl solution. DLC-CH4 has a high charge transfer resistance of 9.54 × 103 Ω/cm2. Compared to DLC-C2H2, DLC-CH4 coatings form a more complete, continuous, smooth surface and a minor porosity in the coating body, inhibiting localized corrosion processes. The DLC-CH4 coatings have less sp2 phase, which results in lower electrical conductivity and limited electron transport at the coating surface. DLC-CH4 shows more excellent corrosion resistance.

A method for preparing alloy coating on the aluminum alloy substrate via laser cladding technology to prevent the galvanic corrosion of TC4/5083 couple

The Cu-Ni-Cr alloy coating was prepared on 5083 aluminum alloy substrate using laser cladding technology. The microstructure of the coating and its galvanic corrosion resistance in contact with TC4 alloy were studied. The results indicate that the Cu-Ni-Cr alloy coating primarily consists of Al-rich dendrite phase and Cu-rich matrix phase. The shear strength of the Cu-Ni-Cr alloy coating is 154.68 MPa, which is greater than that of the aluminum alloy substrate. The galvanic current density of the TC4/Cu-Ni-Cr couple is 0.05 μA·cm−2. The neutral salt spray corrosion test results demonstrate that the Cu-Ni-Cr alloy coating exhibits excellent resistance to galvanic corrosion. The coating can attenuate the galvanic corrosion effect when it is in contact with the TC4 titanium alloy, offering new solutions to address the galvanic corrosion challenges between titanium alloy and aluminum alloy in marine environments.

Fracture prediction of corroded ZG300-500H cast steel with micromechanical fracture model

The effects of corrosion on the fracture prediction of steel are investigated. The power function for cast steel ZG300-500H in the acetic acid salt spray corrosion environment is fitted to illustrate the acceleration of the acetic acid salt spray corrosion test, and the statistical characteristics of the pit depth and pit diameter-depth ratio are analyzed. The material parameters of micromechanical fracture model under monotonic load are calibrated by tensile test and finite element analysis on smooth-notch tensile specimens. The VGM model and SMCS model can also be applied to predict the fracture of corroded ZG300-500H cast steel based on the random distribution model of corrosion pits. The finding is that the crack of the non-corroded single-notch specimens always initiates from the centre of the critical cross section. Corroded specimen cracks initiate from the severe corrosion areas. Once a crack is initiated, it always extends along the thickness and forms a visible crack. The subsequent crack propagation along the width direction can be simulated accurately.

Mechanical properties and corrosion behavior of similar/dissimilar resistance spot welded automotive aluminum alloys

AbstractRecently, usage of high strength aluminum alloys in automotive applications increase. The reasons for that increase are the light‐weight, high strength, good formability, weldability and corrosion resistance of the aluminum alloys to improve fuel economy as well as decreasing carbon dioxide emission. Automotive hybrid structures are commonly manufactured using dissimilar AA5000‐AA6000 joints to improve mechanical requirements and corrosion resistance of the parts. In this study, AA5754 H111‐AA6063 T4 materials were joined both similarly and dissimilarly by resistance spot welding method. Within the study, a mid‐frequency direct current technology was used instead of conventional alternative current technology. The welded zone was investigated by micro hardness measurements and microstructural characterization. Tensile‐shear and cross‐tension tests were performed. The welded zone of all welded specimens was subjected to salt spray corrosion test. A nugget pull‐out fracture mode was observed on the fracture surface of the all welded joints after tensile‐shear and cross‐tension tests. The lowest hardness values were measured from the weld metals for all welded joints. Porosity and inclusion were observed in the weld nugget with minor cracks in heat affected zone by optical microscope investigations.

Properties of Padding Welds Made of CuAl2 Multiwire and CuAl7 Wire in TIG Process.

This paper presents the influence of the Hot Isostatic Pressing (HIP) process on the structure, mechanical properties and corrosion resistance of padding welds made using the TIG method from aluminium bronzes-CuAl7 and CuAl2 (a composite bundled wire). The tested CuAl7 material was a commercial welding wire, while the CuAl2 composite was an experimental one (a prototype of the material produced in multiwire technology). The wire contains a bundle of component materials-in this case, copper in the form of a tube and aluminium in the form of rods. The padding welds were manufactured for both the CuAl7 wire and the CuAl2 multiwire. The prepared samples were subjected to the Hot Isostatic Pressing (HIP) process, chemical composition tests were performed, and then the samples were subjected to observations using light microscopy, Vickers hardness testing, electrical conductivity tests, and apparent density determination using Archimedes' Principle. Tribological tests (the 'pin on disc' method) and neutral salt spray corrosion tests were conducted. The padding weld made of CuAl2 multifiber material subjected to the HIP process is characterized by an improvement in density of 0.01 g/cm3; a homogenization of the hardness results across the sample was also observed. The average hardness of the sample after the HIP process decreased by about 15HV, however, the standard deviation also decreased by about 8HV. The electrical conductivity of the CuAl2 welded sample increased from 16.35 MS/m to 17.49 MS/m for the CuAl2 sample after the HIP process. As a result of this process, a visible increase in electrical conductivity was observed in the case of the wall made of the CuAl2 multiwire-an increase of 1.14 MS/m.

Depth profiles of akaganéite, goethite and maghemite on A1010, HPS and weathering steel panels after wet-dry corrosion tests

ABSTRACT The panels of high chromium steel (A1010), high-performance steel (HPS 70W) and weathering steel (WS) were exposed to accelerated salt-spray corrosion test for 1 week and to less aggressive test for additional 13 weeks. After the tests, the corrosion products formed were extracted layer after layer and examined as a function of their depth with Mössbauer transmission spectroscopy. In the case of A1010 steel, the amounts of goethite (α-FeOOH) and akaganéite (β-FeOOH) were almost equal along the depth of the corroded layer up to ∼20 μm. The rust layers on HPS and WS panels were much thicker, respectively up to ∼0.6 mm and ∼1 mm, poorly adherent and contained mostly akaganéite near the metal–rust interface, α-FeOOH increasingly further away, and – after long exposure – also up to 20% Fe as maghemite (γ-Fe2O3). Formation of β-FeOOH near the interface was promoted by chloride concentrated by spray-dry cycles. The microstructure and depth profiles of identified species, and especially the role of β-FeOOH, are discussed.

MICROSTRUCTURAL AND CORROSION ANALYSIS OF CROWN PINION WITH VARIOUS COMPOSITIONS OF HIGH CARBON STEEL AND SILICON CARBIDE MATERIALS

The pinion and crown are key components in an automobile’s transmission system. The surface characteristics of high-carbon steel have a major effect on differential gear action. As a result, gear damages and increased downtime for repairs are experienced over time. To address this issue, manufacturers have started using alternative materials such as aluminium alloys and composites to improve the durability and efficiency of the transmission system. Engineers can now adjust the design of crown and pinion gears for best performance thanks to developments in computer-aided design and simulation tools. This has led to the development of more compact and lightweight transmission systems that offer better fuel efficiency and acceleration. However, these innovations come at a cost, as they require specialized manufacturing processes and materials that can be expensive. Nevertheless, the benefits of improved transmission systems are clear, as they can significantly enhance the driving experience while reducing maintenance costs over time. As technology continues to evolve, we can expect further improvements in material design that will further enhance crown pinion performance and reliability. To overcome these failures and increase the material’s life, high-carbon steel is preferred. In this study, high-carbon steel composites with various material proportions (100% to 0%, 99% to 1%, and 97.5% to 2.5% of high-carbon steel, and silicon carbide, respectively) are experimentally investigated and evaluated for better structural strength and surface behavior of the crown pinion. The crown pinion is thoroughly analyzed using salt spray corrosion testing and X-ray diffraction analysis. According to the results, the proportion of 97.5% high carbon steel with 2.5% silicon carbide has better surface properties than the other proportions, and it is also recommended to make the crown pinion for future uses.

Salt spray corrosion behavior and electrochemical performance of laser cladded Ni60–Ti3AlC2 composite coatings in 3.5% NaCl solution

Ni60–4%Ti3AlC2, –8%Ti3AlC2 and –12%Ti3AlC2 composite coatings were prepared on S355 steel by laser cladding, and the effects of Ti3AlC2 mass fraction on the corrosion behavior electrochemical performance of obtained coatings were analyzed using a salt spray corrosion test chamber and electrochemical workstation. The results show that the Ni60–Ti3AlC2 composite coatings are composed of Ti3AlC2, TixAly, Al4C3, Al3Ti and TiC phases, and their grains are refined with the increase of Ti3AlC2 mass fraction. The Ni60–12%Ti3AlC2 composite coating has the best salt spray corrosion resistance among the three kinds of coatings, which is attributed to the formations of α–Al2O3 and TiO2 oxide films The differences of diffusion rates between the Al and the Ti change the pH value near the anode and cathode of Ni60–Ti3AlC2 composite coatings, which is conducive to the formation of double–layer dense passive films to protect the composite coatings from further corrosion.