Search Results (18)

Wire beam electrode techniques and classical electrochemical techniques were used to investigate the effect of the area ratio of each part of the welded joint on the galvanic corrosion behavior. The results showed that the order of the corrosion current density of the different regions in the simulated X80 steel welded joint was as follows: coarse-grained heat-affected zone > fine-grained heat-affected zone > intercritical heat-affected zone > base metal > weld metal. As the area ratio of weld metal increased, the galvanic potential shifted positively, the maximum anode galvanic current density increased and the main anode galvanic effect increased. On the other hand, as the area ratio of the base metal and the heat-affected zone decreased, the coupled potential shifted negatively and the maximum anode galvanic current density decreased. The galvanic corrosion intensity of the simulated X80 steel welded joint increased as the area ratio of the weld metal decreased and increased as the area ratio of the heat-affected zone and base metal increased. To enhance corrosion resistance, it is advisable to choose a shape with a larger groove to increase the WM area in the welded joint. Additionally, selecting a welding method with lower heat input and a higher energy density can help reduce the HAZ area in the welded joint. Full article

The cathodic protection provided by epoxy coating/epoxy zinc-rich coatings on defective areas under atmospheric and immersion conditions was studied via a Q235 wire beam electrode (WBE), scanning electron microscopy, X-ray diffraction, and surface morphology analysis. The results showed that the cathodic protection processes under the two test conditions displayed significant differences. The effective protection time of the defective area under the atmospheric condition was 1.7 times that under the immersion condition. Compared with the immersion condition, zinc particles in zinc-rich coatings under the atmospheric condition exhibited higher cathodic protection efficiency. The possible activation mechanism of zinc particles under the two conditions was elucidated. Full article

Marked changes in temperature, pH, dissolved oxygen (DO) content, and nutrient content typically occur in marine thermoclines, which are key factors that affect the corrosion of metals. Offshore platforms require marine metals to be exposed to deep-sea environments and thus increase their penetration into the marine thermocline. This study investigates the galvanic corrosion of E690 steel in a marine thermocline using a simulated marine thermocline (SMT). Specifically, the corrosion of E690 steel was analyzed using the wire beam electrode (WBE) technique, linear polarization (LP), corrosion morphology, and weight loss measurement. Results indicated that the SMT had a stable multilayer structure, and the variations in temperature, DO, pH, and nutrient concentration in the SMT were similar to those in the natural marine thermocline. There were two forms of E690 steel corrosion in the SMT: galvanic corrosion and seawater corrosion. The corrosion rate of seawater corrosion was influenced by the DO concentration. Galvanic corrosion occurred after the intrusion of E690 steel into the marine thermocline. The driver of galvanic corrosion was the difference values for E_corrs of E690 steel at various depths of the marine thermocline. The E_corr of E690 steel was influenced by the temperature, pH, and DO of the seawater, in the following order: DO >> T > pH. The continuous reduction in E_corr with depth contributed to large-scale galvanic corrosion, and the oscillation variation in E_corr with depth was the reason for small-scale galvanic corrosion. The primary anodic regions of galvanic corrosion were located in the area with the fastest temperature variation in the thermocline, and the position of the anodic regions rose with time. The anodic regions gradually expanded with time. The proportion of galvanic corrosion in the average corrosion rate could increase up to approximately 80% in the stable anodic region. There were many hemispherical corrosion pits on the surface of the single electrodes that were at the depths of 75 cm, 105 cm, and 135 cm. These single electrodes comprised a long-term, sustainable anodic region of galvanic corrosion. Full article

This work demonstrates an approach towards the understanding of multi-scale and open-circuit localised electrochemical processes of AA2024-T3 in the presence and absence of an environmentally friendly rare-earth inhibitor; cerium diphenyl phosphate (Ce(dpp)₃). At high temporal resolution, a wire bean electrode (WBE) made from 100 identical AA2024-T3 wires revealed sudden increases in galvanic anodic and cathodic activities immediately after dosing of 50 and 100 ppm of the inhibitor and an overall suppression of macro-scale activities by increasing the inhibitor concentration to 200 ppm, suggesting it as a fast-screening tool for inhibitors and measuring inhibition efficiency. At high spatial resolutions, scanning probe electrochemical techniques confirmed local activation of corroding microstructures on individual AA2024-T3 wires similarly by dosing the inhibitor up to 100 ppm. In agreement with WBE findings, the effective shutdown of both anodic and cathodic activities occurred after increasing the inhibitor concentration to 200 ppm confirming the optimal concentration of the Ce(dpp)₃ and the mixed mode inhibition mechanism of this selected inhibitor on AA2024-T3. Full article

The effect of cathodic polarization on the corrosion behavior of alkyd-resin-coated carbon steel with an artificial coating defect was researched using a wire beam electrode (WBE) and electrochemical impedance spectroscopy (EIS) in both static and flowing simulated solutions. The microscopic morphology and chemical structure of the organic coating were characterized by scanning electron microscopy (SEM) and infrared spectroscopy (FT-IR) to reveal the degradation mechanisms of organic coatings under different polarization potentials. The study found that the failure process of the alkyd coating could be accelerated by cathodic polarization. After 312 h of immersion, the impedance under −1100 mV was one order of magnitude lower than that under the open-circuit potential (OCP). The coating delamination became serious with the negative shifting of polarization potential, and the delamination area ratio under −1100 mV in both static and flowing seawater rose to 23% and 14%, respectively. Interestingly, the flowing condition of the immersion solution that combined with cathodic polarization exhibited a synergistic effect, which could accelerate (in the earlier stage) and then alleviate the delamination of the coating. Furthermore, the results showed that both the diffusion of the corrosion particles and the anodic dissolution reaction of the metal could be significantly affected by cathodic polarization and the flowing condition of the solution, which provides a possible approach to gain insight into the delamination of organic coating. Full article

This paper clarifies the effects of the fluid parameters of flow velocity, impact angle and sand impact frequency on the erosion-enhanced corrosion of 90/10 copper–nickel alloy by combining computational fluid dynamics (CFD) simulation, wire beam electrode (WBE) technology and electrochemical measurements. The results show that under the conditions without sand particles, erosion-enhanced corrosion is dominated by the impact angle and the flow velocity at lower (<0.860 m/s) and higher (2.370~5.644 m/s) flow velocities, respectively, while both the two fluid parameters have noticeable effects on erosion-enhanced corrosion at intermediate flow velocities (0.860~2.370 m/s). In contrast, adding sand particles corresponding to the sand impact frequency can further increase the corrosion current density without changing the effects of the flow velocity and impact angle. It demonstrates that all three fluid parameters show great effects on the erosion-enhanced corrosion of 90/10 copper–nickel alloy under conditions with sand particles. Full article

The degradation effect of mold on the coating in a hot and humid environment is one of the important factors that cause layer failure. Combined with the wire beam electrode (WBE) and the traditional surface analysis technique, the local biodegradation of the coatings and the corrosion behaviors of metal substrates can be characterized accurately by a WBE. Herein, a WBE was used to study the degradation impact of Talaromyces funiculosus (T. funiculosus) isolated from a tropical rainforest environment on the corrosion of polyurethane (PU) coating. After immersion for 14 days, the local current density distribution of the WBE surface can reach ~10⁻³ A/cm² in the fungal liquid mediums but maintains ~10⁻⁷ A/cm² in sterile liquid mediums. The |Z|_0.01Hz value of the high current densities area (#85 electrode) was 1.06 × 10⁹ Ω cm² in a fungal liquid medium after 14 days of immersion. After being attacked by T. funiculosus, the degradation of the PU was more severe, and there were wrinkles, cracks, blisters, and even micro-holes distributed randomly on the surface of electrodes. This resulted from the self-corrosion caused by the T. funiculosus degradation of the coating; the corrosion caused by the electric coupling effect of the coating was introduced. Energy dispersive spectroscopy (EDS) and Raman spectra results showed that the corrosion products were flakey and globular, which consisted of γ-FeOOH, γ-Fe₂O₃, and α-FeOOH. Full article

A partial pre-rusted wire beam electrode (WBE) was designed to study the influence of the rust layer on rebar corrosion in the carbonated simulated concrete pore solution (SCPS). The results show that the passive film generated on the pre-rusted steel area is more fragile than that formed on the fine polished steel area in carbonaceous media. Nevertheless, the pitting corrosion resulting from the presence of chloride ions still tends to occur on the fine polished steel surface due to the local acidification process being hindered by the rust layer. The rust layer could play a more important role than the passive film in inhibiting the initiation of chloride-induced corrosion on rebar. The expansion path of the corrosion product would be blocked by the rust layer, leading to the pit propagating in the fine polished region. Furthermore, the growth of pitting corrosion is greatly accelerated due to the catalytic cathodic reaction of the rust layer. Full article

A robotic system for the automatic wire pulling of coreless motor winding is designed, including the design of an opening-closing control system and a micro-gripper’s tip structure with a double-armed elastic-beam structure for the support part and an enveloping clamping structure for the tip part. The micro-gripper captures the electrode wire from the root, encircles the wire after the envelope region is closed, and the thin and flexible electrode wire is pulled to the top of the electrode pad by the movement of the micro-gripper and released. The mechanical index of the micro-gripper is simulated to obtain the optimal structural parameters. The experimental results show that the electrode wire’s maximum bearing force is about 0.3 N. Under this reaction force, the deformation of the tip-envelope region of the micro-gripper is about 27.5 μm, which is sufficient for electrode wire pulling micro-manipulation. By comparison with the steel micro-gripper, the silicon micro-gripper has more advantages in shape integrity, machinability and mechanical properties. Full article

Using pulse power technology to break concrete structures can reduce environmental pollution, save energy, and increase safety and reliability. The whole process of concrete beam subjected to shock wave generated by pulse power discharge was simulated and analyzed. An experiment of breaking reinforced concrete beams by metal wire explosion in liquid was carried out. And the main parameters are pulse power discharge voltage, copper wires section size, concrete beam material strength, drilling parameters, etc. The results show that with the increase of discharge voltage and the total area of copper wire cross section between electrodes, the breaking effect of concrete beam is obviously improved. The breaking effect of the beam is slightly improved when the concrete strength is reduced. The breaking effect of concrete beams with 40 mm aperture is better than that of concrete beams with 50 mm aperture. As the distance between adjacent boreholes decreases, the fractures are easier to connect. According to the test results, the formulas for calculating the crack width of concrete beams were proposed, which takes the output voltage, the number of copper wires between electrodes, the hole spacing, the strength of concrete and other key parameters as independent variables. The calculated results agree well with the test results. Full article

The corrosion behavior of L360 pipeline steel coated with or without elemental sulfur (S8) in CO₂–Cl⁻ medium at different pH was studied. An autoclave was used to simulate the working conditions for forming the corrosion scale, and an electrochemical workstation with a three-electrode cell was used to analyze the electrochemical characterization of the corrosion scale. A wire beam electrode was used to determine the potential and current distribution, and scanning electron microscopy and X-ray diffraction were used to characterize the morphology and composition of the corrosion scale. The results showed that the deposition of S8 on the surface of the electrodes caused serious localized corrosion, especially under acidic conditions. The morphology and localized corrosion intensity index further proved that the deposition of S8 significantly promoted corrosion, especially pitting corrosion. Finally, a novel corrosion mechanism of L360 pipeline steel coated with S8 in a CO₂-Cl⁻ environment under acidic conditions was proposed, and we then modeled the theoretical mechanisms that explained the experimental results. Full article

Interest in the use of organic electronic devices in radiation sensing applications has grown in recent years. The numerous device configurations (e.g., diodes, thin film transistors) and potential for improved tissue equivalence compared to their silicon-based analogues make them attractive candidates for various radiation dosimetry measurements. In this work, a variation of the organic thin film transistor (OTFT) is studied, in which a polymer electret is added. An OTFT electret design can be used in either a wired or wireless configuration for in vivo dosimetry with the possibility of real-time detection. The linearity, reproducibility, and dependence on energy of these devices were measured through exposure to 100 kVp photons from an orthovoltage treatment unit (Xstrahl 300) and 6 MV photons from a Varian TrueBeam medical linear accelerator. Prior to irradiation, all transistors were programmed with a −80 V bias applied to the Gate electrode (V_g) for 3 s. In the wireless configuration, after each delivered dose, the transfer characteristic was scanned to readout the amount of erased charges by monitoring the drain current change. When the programmed charge was sufficiently depleted by radiation, transistors were reprogrammed for repeated use. The real-time readout in a wired configuration was performed by measuring the drain current with V_g = −15 V; V_d = −15 V. The 6 MV photon beam was turned on and off at different dose rates of 600, 400, 300, 200, and 60 cGy/min to quantify the sensitivity of the device to changes in dose rate. The wireless transistors showed a linear increase in current with increasing dose. The sensitivities for different energies were 60 ± 5 nA/Gy at 6 MV at a dose rate of 600 cGy/min and 80 ± 10 nA/Gy at 100 kVp at a dose rate of 200 cGy/min. The sensitivity of detectors tested in a wired configuration at V_d = −15 V; V_g = −15 V was 8.1 nA/s at a dose rate of 600 cGy/min. The principle of pentacene OTFTs with polymer electret as radiation detectors was demonstrated. Devices had excellent linearity, reproducibility, and were able to be reprogrammed for multiple uses as wireless detectors. The wired transistors demonstrated an effective response as real-time detectors. Full article

Although WEDM is one of the most precise finishing technologies, deviations from the required geometric shapes and surface roughness occur in the production of parts with rotary surfaces. Even though these shortcomings have only a minimal impact on planar cuts, the production of circular profiles is a different problem. One of the factors causing this poor quality is the vibration of the wire electrode. With appropriate vibration adjustment, it would be possible to achieve significant improvements of the eroded area quality, both in terms of geometric accuracy and in terms of surface roughness. This would significantly increase quality, enabling WEDM technology to compete with other technologies in terms of economic efficiency. Therefore, the proposed solution aims to provide a partial adjustment to the wire tool electrode vibrations, based on their sensing by the means of acoustic emissions or a laser beam, with subsequent dynamic adjustment of the actual technological parameter values. This way, the given solution will increase the production accuracy of circular holes, increase productivity, and ultimately provide an overall increase in the economic efficiency of the WEDM process. The article also presents the scheme of a control algorithm for monitoring and subsequent adjustments of the vibrations of the wire tool electrode during the electroerosion process in order to minimize geometric deviations of circularity, cylindricity and roughness of the machined surface. Full article

Corrosion in the interface zone is a complicated local corrosion phenomenon. The conventional single-electrode method finds it difficult to obtain the kinetic information of corrosion occurrence and development process. In this paper, metal corrosion was studied by Wire Beam Electrode (WBE) technology on the interfaces of sea mud/seawater and seawater/atmosphere. The study found that the metal corrosion in the interface is a process of coupling a dual corrosion cell into a single corrosion cell. Initially, a corrosion cell is formed with the seawater/atmosphere interface acting as the cathode and the upper part of the metal in the seawater area as the anode. This is due to the oxygen concentration cell caused by the waterline effect. The cathode area is always enriched near the seawater/atmosphere interface. The lower part of the metal in the seawater area and the metal in the sea mud area are the anode and the cathode, respectively, of another corrosion cell. Along with the immersion time, the anodic area of the first corrosion cell gradually extends to the lower part of the metal in the seawater zone and finally the sea mud zone, resulting in the disappearance of the second corrosion cell. In the single corrosion cell stage, the seawater/atmosphere interface is the cathode area; the seawater area and the sea mud area are the anode areas, and the electrode adjacent to the cathode area becomes the anode area with the largest current density. During the whole experiment, the sea mud zone is a process of polarity transition from the cathode zone to the anode zone, and finally forms the anode zone of the whole electrode together with the anode zone in the sea zone. Full article

Water-line corrosion is a highly concentrated type of localized corrosion. The conventional single electrode method is limited in its ability to obtain the kinetic information of the corrosion occurrence and development processes. Herein, the coating deterioration and underlying metal corrosion processes in water-line area were studied by a small wire beam electrode to monitor the current density distribution. The distance between each electrode was very small (interval: 0.3 mm), thus facilitating it to approach the practical metal component with a continuous surface. The results showed that cathodic and anodic sites tended to be weak points of the coating at the initial stage. With the continuous degradation of the coating, the cathodic zone tended to occur in the above the anodic zone due to the effect of differential aeration cells (DACs). Subsequently, the cathodic zone expanded to the waterline and the polarity reversed to the anodic zone, causing the coating to peel and blister continuously from the bottom up. When the cathodic zone extended to the gas phase area above the water line, this area became the strongest cathodic zone under the action of the thin liquid film, thus significantly accelerating the corrosion of the base metal at the bottom. The present study aims to achieve an in-depth understanding of coating deterioration and underlying metal corrosion processes in the water-line area, providing a new means of directly visualizing the role of DACs played in water line corrosion. Full article