This work presents a study on the use of cathodic protection as a measure against corrosion in pipelines.The cathodic protection,compliant with the API 5L standard,is implemented here by applying an impressed current,...This work presents a study on the use of cathodic protection as a measure against corrosion in pipelines.The cathodic protection,compliant with the API 5L standard,is implemented here by applying an impressed current,while carefully considering several essential variables,such as soil characteristics,the type and color of the pipeline material,as well as the placement and size of the anode.Therefore,it is crucial to optimize the location and values of anodic overflows or ground resistances to ensure a uniform distribution of potential across the entire structure.In this method,impressed current protection uses an auxiliary anode and an external direct current source to induce a current through the electrolyte and the pipeline,thus countering the resistance of the steel.This approach is advantageous as it allows for the adjustment of electrical characteristics,particularly current levels,to meet specific needs.The factors essential to the effectiveness of cathodic protection systems,which optimize the distribution of protection potential across the structure,largely depend on the precise management of ground resistances during anodic discharge,particularly the attenuation coefficient(α).These factors were studied,and the results obtained were presented and discussed based on their influence.展开更多
Metal-organic framework[MOF,i.e.,NH_(2)-MIL-53(Al)]modified TiO_(2)(NMT)composite photoanodes were successfully prepared by hydrothermal synthesis and were used for the photoelectrochemical cathodic protection(PECCP)o...Metal-organic framework[MOF,i.e.,NH_(2)-MIL-53(Al)]modified TiO_(2)(NMT)composite photoanodes were successfully prepared by hydrothermal synthesis and were used for the photoelectrochemical cathodic protection(PECCP)of nickel-plated magnesium alloy(Mg/Ni).Results showed that the synthesis tem-perature significantly impacted the morphology and PECCP performance of the NMT photoanodes.The NMT@150 photoanode prepared at a reaction temperature of 150℃exhibited the best PECCP perfor-mance and produced a current density of 1980μA cm^(-2)under visible light irradiation,which was 19.8 times higher than that of a single TiO_(2)photoanode.The composite photoanode could polarize the open circuit potential of the coupled Mg/Ni electrode to-876 mV and remain relatively stable within 35 h.XPS and EPR tests showed that a Z-scheme heterojunction was formed between the NH_(2)-MIL-53(Al)and TiO_(2)nanotubes,allowing the photogenerated electrons to accumulate mainly on the conduction band of NH_(2)-MIL-53(Al).The heterojunction greatly promoted the separation and transfer of photogenerated electron-hole in the NMT composite photoanode,significantly enhancing the PECCP performance for Mg/Ni.展开更多
A new type of photoelectrochemical cathodic protection technology(a combination of seawater corrosion and biological fouling resistance)is being actively researched to alleviate the serious corrosion of marine metal m...A new type of photoelectrochemical cathodic protection technology(a combination of seawater corrosion and biological fouling resistance)is being actively researched to alleviate the serious corrosion of marine metal materials.At present,there is almost no research on anti-corrosion and anti-fouling dual functional materials.In this paper,Cu_(2)ZnSnS_(4)is attached to the surface of TiO,nanotubes through a one-step hydrothermal method for modification.The results indicate that when the hydrothermal reaction time is 24 h,Cu_(2)ZnSnS_(4)/TiO_(2)nanocomposite material exhibits excellent performance in coupling with the protected 304 SS,with its open circuit potential shifts negatively to-1.04 V.This material improves the separation efficiency of photogenerated electrons and effectively improves the photochemical cathodic protection of 304 stainless steel.The high removal rate of Staphylococcus aureus(up to 93%)of the as-prepared samples also proved that it has the effect of the anti-biological fouling.展开更多
The low photoelectric conversion efficiency of photoelectrode is an important factor that limits the application in photoelectrochemical cathodic protection(PECCP)field for marine anti-corrosion of metallic structures...The low photoelectric conversion efficiency of photoelectrode is an important factor that limits the application in photoelectrochemical cathodic protection(PECCP)field for marine anti-corrosion of metallic structures.In this work,a photoelectrode of TiO_(2)/CdZnS/ZnS triple-phase heterojunction was fabricated by loading the narrow-band CdZnS associated with the broad-band ZnS via hydrothermal and continuous ion layer adsorption methods,respectively.The composite of CdZnS enhances the photoelectric conversion ability of TiO_(2),while the ZnS composite can prevent the CdZnS from photo-corrosion and suppress the spillover of the photogenerated electrons.The three-phase heterostructure effectively improves the PECCP performance on 316 L stainless steel(SS)under simulated solar irradiation,especially in 3.5 wt%NaCl solution without the sacrificial agent.In addition,the prepared TiO_(2)/CdZnS/ZnS photoelectrode also performs anti-biofouling effect evidenced by the high removal efficiency of Pseudomonas aeruginosa(P.aeruginosa),which can be attributed to the oxidizability of photogenerated holes.The TiO_(2)/CdZnS/ZnS triple-phase heterojunction with desirable performance is a promising semiconductor material for the applications of PECCP and anti-biofouling.展开更多
Metallic pipeline corrosion poses a significant challenge in the petrochemical industry. In this study, the design and control of a stand-alone photovoltaic (PV)-powered cathodic protection (CP) system based on the im...Metallic pipeline corrosion poses a significant challenge in the petrochemical industry. In this study, the design and control of a stand-alone photovoltaic (PV)-powered cathodic protection (CP) system based on the impressed current method were investigated. The proposed CP system was applied to a 250 km long steel-buried pipeline in the Sharm El-Sheikh region of Egypt. The system design involved the numerical modeling of the anode bed for the impressed current CP (ICCP) system and the sizing of the DC power source, including the PV array and battery bank. The system was designed and controlled to deliver a constant and continuous anode current to protect the underground pipeline from corrosion during daylight and nighttime. A maximum power point tracking (MPPT) algorithm based on the fractional open-circuit voltage (FOCV) technique was implemented to maximize power extraction from the PV array. Additionally, a proportional-integral (PI) controller was optimized and employed to achieve MPPT, while another PI controller managed the anode current of the CP system. Safe charging and discharging of the system’s battery are ensured via an ON-OFF controller. The parameters of the PI controllers were optimized using the particle swarm optimization (PSO) technique. Simulation results demonstrated that the proposed CP system achieved the required protection objectives successfully.展开更多
Al-Zn-Mg alloys with different Zn/Mg mass ratios were evaluated as sacrificial anodes for cathodic protection of carbon steel in 3.5 wt.%Na Cl solution.The anodes were fabricated from pure Al,Zn and Mg metals using ca...Al-Zn-Mg alloys with different Zn/Mg mass ratios were evaluated as sacrificial anodes for cathodic protection of carbon steel in 3.5 wt.%Na Cl solution.The anodes were fabricated from pure Al,Zn and Mg metals using casting technique.Optical microscopy,SEM-EDS,XRD and electrochemical techniques were used.The results indicated that with decreasing Zn/Mg mass ratio,the grain size ofα(Al)and the particle size of the precipitates decreased while the volume fraction of the precipitates increased.The anode with Zn/Mg mass ratio>4.0 exhibited the lowest corrosion rate,while the anode with Zn/Mg mass ratio<0.62 gave the highest corrosion rate and provided the highest cathodic protection efficiency for carbon steel(AISI 1018).Furthermore,the results showed that the anode with Zn/Mg mass ratio<0.62 exhibited a porous corrosion product compared to the other anodes.展开更多
Photoelectrochemical(PEC) cathodic protection is considered as an environment friendly method for metals anticorrosion. In this technology, a n-type semiconductor photoanode provides the photogenerated electrons for m...Photoelectrochemical(PEC) cathodic protection is considered as an environment friendly method for metals anticorrosion. In this technology, a n-type semiconductor photoanode provides the photogenerated electrons for metal to achieve cathodic protection. Comparing with traditional PEC photoanode for water splitting, it requires the photoanode providing a suitable cathodic potential for the metal, instead of pursuit ultimate photon to electric conversion efficiency, thus it is a more possible PEC technology for engineering application. To date, great efforts have been devoted to developing novel n-type semiconductors and advanced modification method to improve the performance on PEC cathodic protection metals. Herein, recent progresses in this field are summarized. We highlight the fabrication process of PEC cathodic protection thin film, various nanostructure controlling, doping, compositing methods and their operation mechanism. Finally, the current challenges and future potential works on improving the PEC cathodic protection performance are discussed.展开更多
In this work,TiO_(2)nanotube arrays(NTAs)sensitized with MoS_(2)microspheres(MoS_(2)/TiO_(2)nanocomposites)were prepared on a flat Ti substrate via two-step anodization and hydrothermal method sequentially.TiO_(2)NTAs...In this work,TiO_(2)nanotube arrays(NTAs)sensitized with MoS_(2)microspheres(MoS_(2)/TiO_(2)nanocomposites)were prepared on a flat Ti substrate via two-step anodization and hydrothermal method sequentially.TiO_(2)NTAs were composed of many orderly nanotubes,whose large specific surface area was favorable for light absorption and MoS_(2)microsphere adhesion.The MoS_(2)microsphere as a narrow band gap semiconductor extended the TiO_(2)NTAs’absorption band edge to the visible region.The 2D structure of MoS_(2)microspheres and the construction of heterojunction electronic field at the interface of MoS_(2)microspheres and TiO_(2)NTAs promoted the separation of photoinduced carriers.The MoS_(2)/TiO_(2)nanocomposites could provide higher photoelectrochemical cathodic protection for 304 stainless steel(304 SS)under visible light than pristine TiO_(2)NTAs.展开更多
Platforms I and II are steel structures located in offshore areas southeast of the Zhujiang (Pearl) River Delta, the northern South China Sea,. in about 110 in water depth. The jackets, with aluminum sacrificial anode...Platforms I and II are steel structures located in offshore areas southeast of the Zhujiang (Pearl) River Delta, the northern South China Sea,. in about 110 in water depth. The jackets, with aluminum sacrificial anodes for cathodic protection (CP) of the immersed zone, were launched in March 1995. In May 096 a CP survey showed that, after almost one year of service, a low polarization level had been achieved and some extended unprotected zones existed; mainly in the deepest part of the Platform II. Further to this, a joint activity was decided in order to assess the need of a possible retrofitting of the CP systems. The results of the activity carried out are dealt with, including technical and economical comparisons amongst several retrofitting options, both with sacrificial anodes and with impressed current systems. The adopted solution is illustrated and data are reported on the level of protection presently achieved.展开更多
Fracture behaviour of low-alloy steels AIST4340,HY100,Welten60,AISIA537 and A131 in artificial seawater under static,cyclic loading and at cathodic protection potential has been investigated by using the techniques of...Fracture behaviour of low-alloy steels AIST4340,HY100,Welten60,AISIA537 and A131 in artificial seawater under static,cyclic loading and at cathodic protection potential has been investigated by using the techniques of fracture mechanics, electrochemistry and electronfractography.The results reveal that at hydrogen evolution potentials(cathodic pro- tection potential)the critical yield strength required for the occurrance of SCC decreases from 985 at corrosion potential(E_c)to 872 MPa.The effect of cathodic protection on crack propagation of corrosion fatigue(CF)is not simple,it is closely related to the yield strength of steels and their SCC behaviour.For the steels with high yield strength,cathodic protection promotes(da/dN)_Ⅱ evidently,and reduces △K_(th) value.The(da/dN)-△K curves dis- play a plateau at the third stage of CF for steels with medium or low yield strength.It is men- tioned that the cathodic protection potential for oceaneering constructures should be control- led at top level of the protective range.It seems reasonable that the strength of steel for oceaneeing use might be increased by 200 or 300 MPa.展开更多
A novel three-dimensional hierarchical WO_(3)photoelectrode was prepared by solvothermal method,and ZnO was deposited on its surface by electrochemical method.The WO_(3)/ZnWO_(4)/ZnO multiphaseheterojunction photoelec...A novel three-dimensional hierarchical WO_(3)photoelectrode was prepared by solvothermal method,and ZnO was deposited on its surface by electrochemical method.The WO_(3)/ZnWO_(4)/ZnO multiphaseheterojunction photoelectrode was prepared by further annealing treatment to explore the photoinduced cathodic protection(CP)performance.Compared with WO_(3)and ZnO,the photoinduced CP and electron storage capacity performance of WO_(3)/ZnWO_(4)/ZnO is significantly improved in 3.5%NaCl solution without adding any hole scavenger.The electron storage capacity of the WO_(3)/ZnWO_(4)/ZnO heterojunction makes it possible to continuously protect metallic materials in the dark after switching off the light,which can realize long-term and effective photoinduced CP.展开更多
Semiconductor quantum dots with high quantum yield and photovoltaic conversion efficiency have ushered in a brilliant moment for constructing internal electric field heterojunctions for photogenerated cathodic protect...Semiconductor quantum dots with high quantum yield and photovoltaic conversion efficiency have ushered in a brilliant moment for constructing internal electric field heterojunctions for photogenerated cathodic protection applications.In this paper,TiO_(2)nanotubes grown vertically on the surface of titanium substrates were modified via a combination of conventional electrochemical oxidation and a one-step solvothermal pathway to sensitize with CuInS_(2)quantum dots.Compared with pure TiO_(2)photoelectrodes,the modification improves sunlight absorption efficiency and provides photoelectron cathodic protection to the 304 stainless steel(304 SS).Through 9 h solvothermal reaction,the CuInS_(2)/TiO_(2)coupled with protected 304 SS exhibited an excellent property when the simulated sunlight irradiation.Its mixed open circuit potential is negatively shifted to-0.99 V,at the mean time with a stable photocurrent density(118μA cm^(-2)).The results indicate that CuInS_(2)and TiO_(2)established a p-n heterojunction with wellmatched energy level,which can effectively facilitate the carrier separation and retain the strong redox capbility of photo-induced electrons and holes.展开更多
The environmental conditions around the first offshore HZ 21- 1 steel wellhead platform in the South China Sea are characterized by deep water, frequent typhoons, rough waves, high water temperature, severely corrosiv...The environmental conditions around the first offshore HZ 21- 1 steel wellhead platform in the South China Sea are characterized by deep water, frequent typhoons, rough waves, high water temperature, severely corrosive seawater, and thick fouling organism attachments. The design and effectiveness of galvanic anode protection system are presented, and several methods are described, which are the calculation method of the protective current density considering the variation of water depth, the method of determining protection parameters considering various factors, the arrangement of anodes based on potential distribution and current requirements at different water depths, and the method of anode installation. Finally the effect of the accuracy of selected cathodic protection parameters on the economic benefits of offshore projects is also discussed..展开更多
The behavior of a new type of secondary anode material made of carbon fiber reinforced cement used for cathodic protection of steel in concrete was studied. The mechanical, electrical and electrochemical properties of...The behavior of a new type of secondary anode material made of carbon fiber reinforced cement used for cathodic protection of steel in concrete was studied. The mechanical, electrical and electrochemical properties of this conductive mortar were investigated. Results indicate that the addition of carbon fiber enhances the strength and ductility of the mortar, as well as the electrical property. The anodic polarization behavior was tested on specimens immersed in aqueous solutions of saturated Ca（OH）2 in the presence or absence of 3% NaCl. Based on impedance measurements the electrochemical parameters of conductive mortar were calculated. It is shown that the investigated conductive mortar can be used in cathodic protection of reinforced concrete. The study also shows that the optimum fiber content in mortar should be in the range from 0.5 vol% to 0.7 vol%.展开更多
This paper introduces the research status and present situation of application of Pt/Ta composite anode materials for cathodic protection in China. It also introduces the corrosion resistance, bending properties and e...This paper introduces the research status and present situation of application of Pt/Ta composite anode materials for cathodic protection in China. It also introduces the corrosion resistance, bending properties and electrochemical performance in seawater and freshwater of the Pt/Ta composite anode materials for cathodic protection. It points out that compared with other platinum composite anodes, the Pt/Ta composite anode has the advantage of small volume, light weight, big drainage rate, long service life, it possesses superiority to be used in the confluence environment of sea water and fresh water and in the medium condition of resistivity changes at all times.展开更多
The Cu2O/TiO2 p-n heterojunction composite photoelectrodes were prepared by depositing Cu 2 O nanoparticles on the surface of TiO 2 nanotubes via anodic oxidation and constant current deposition.Field emission scannin...The Cu2O/TiO2 p-n heterojunction composite photoelectrodes were prepared by depositing Cu 2 O nanoparticles on the surface of TiO 2 nanotubes via anodic oxidation and constant current deposition.Field emission scanning electron microscopy(SEM)and high-resolution transmission electron microscopy(HRTEM)analyses showed that Cu 2 O nanoparticles not only deposited on the surface of TiO 2 nanotube array,but also on the wall of TiO 2 nanotubes.The Cu 2 O deposition amount could be adjusted by changing the deposition time.The photoelectrochemical cathodic protection(PECCP)performance of the prepared photoelectrodes for 316L stainless steel(SS)was tested under visible light.The constant current deposition time had a signifi cant eff ect on the PECCP performance of Cu 2 O/TiO 2-X photoelectrodes and Cu 2 O/TiO 2-20 had the best PECCP performance for the coupled 316L SS.This was attributed to the appropriate amount and thickness of Cu 2 O to form p-n heterojunctions with TiO 2,in which separation of the photogenerated carriers was accelerated and transfer of the photogenerated electrons to 316L SS for PECCP was facilitated.展开更多
The long and short fatigue crack growth (FCG) behavior of 12CrNi3MoV (S1) and 10CrNi5MoV(S2) steel was investigated at cathodic protection in 3.5 % NaCl solution and artificial seawater. The results indicate that l...The long and short fatigue crack growth (FCG) behavior of 12CrNi3MoV (S1) and 10CrNi5MoV(S2) steel was investigated at cathodic protection in 3.5 % NaCl solution and artificial seawater. The results indicate that long and short FCG show different behavior at cathodic protection. Short FCG is apparently hindered at appropriate cathodic protection potential (-900 mV SCE) and accelerated at over protection potential(-1200 mV SCE). Cathodic protection increases long FCG rate, and the more negative the cathodic protection potential, the greater the long FCG rate. At the same amplitude of stress intensity ( ΔK ), short FCG rate is greater than the long one and their difference becomes less at cathodic protection. The FCG rate in 3.5 % NaCl solution is greater than in artifitial seawater. The FCG rate of S2 steel is bigger then that of S1 steel. The FCG rate of weld bond of S2 steel is lower than that of parent metal and weld beam. In above cases, the anode dissolution, the wedging of corrosion products or deposit and hydrogen embrittlement in long and hort crack tip are also discussed.展开更多
A novel and long-lasting N_(3)BD/TiO_(2) composite photoanode with stable and superior photoelectrochemical and photoelectrochemical cathodic protection(PECCP)performances was achieved by synthesizing and depositing c...A novel and long-lasting N_(3)BD/TiO_(2) composite photoanode with stable and superior photoelectrochemical and photoelectrochemical cathodic protection(PECCP)performances was achieved by synthesizing and depositing covalent organic framework(N_(3)BD)on titanium oxide(TiO_(2))nanotube arrays.The composite's increased visible light absorption capability enhanced the galvanic corrosion protection of nickel-phosphorus alloy-coated magnesium alloy(Mg/Ni)through PECCP technology.The open circuit potential(OCP)drops of the Mg/Ni electrode coupling with the N_(3)BD/TiO_(2) composite were 310 and 630 mV at dark state and under illumination,respectively.They remained relatively stable under intermittent visible light irradiation within 72 h,demonstrating excellent long-term stability.The superior photoelectrochemical and PECCP properties of the N_(3)BD/TiO_(2) are attributed to forming S-scheme heterojunctions,which effectively promote the separation and transfer of photogenerated electron-hole pairs and retain a strong redox capacity.This finding provides new insight into the design and synthesis of COF-modified photoanode with highly efficient and stable photoelectrochemical and PECCP performances.展开更多
Constructing a photoanode with both high dark-state protection performance and high stability remains a top priority for photoelectrochemical cathodic protection technology,especially in a marine environment(dark-stat...Constructing a photoanode with both high dark-state protection performance and high stability remains a top priority for photoelectrochemical cathodic protection technology,especially in a marine environment(dark-state or rainy conditions)without hole scavenging agents.In this work,we developed a class of energy-storage quasi-planar heterojunctions(WO_(3)-Nb_(2)O_(5)-ZnIn_(2)S_(4))with directional paths(low onset potential and well-matched energy band)and embedded morphology.The co-design of embedded and directional paths reduces the carrier transport energy barrier at the composite interface,and increases the interface contact area,thereby achieving highly stable and sensitive dark-state energy storage and photoelectrochemical cathodic protection performance in 3.5 wt.%NaCl solution without hole scavenging agent(Dark-state energy storage efficiency increased by 43%.For carbon steel,the performance retention rate is 99.6%after 500 cycles,the performance retention rate is 89%after 5000 s).展开更多
Photogenerated electrons generated by photoexcitation of semiconductor materials can be transferred to metal materials to provide corrosion protection.Conversely,the accumulation of photogenerated holes accelerates th...Photogenerated electrons generated by photoexcitation of semiconductor materials can be transferred to metal materials to provide corrosion protection.Conversely,the accumulation of photogenerated holes accelerates the recombination of photogenerated carriers.Consequently,the development of efficient strategies for the consumption of photogenerated holes has emerged as a critical challenge in the field of photoelectrochemical cathodic protection technology.In this paper,TiO_(2)/TiOBr heterojunction photoelectrode was firstly prepared by simple hydrothermal method,and NiCo-LDH(layered double hydroxide)was further deposited on TiO_(2)/TiOBr to obtain TiO_(2)/TiOBr/NiCo-LDH photoelectrode.The construction of a heterojunction between TiO_(2)and TiOBr promotes the separation of photogenerated carriers,while the deposition of NiCo-LDH reduces the overpotential for hole oxidation.Hence,the photoinduced potential drop and photoinduced current density of TiO_(2)/TiOBr/NiCo-LDH photoelectrode coupled with 316 L stainless steel in 3.5 wt%NaCl under simulated sunlight irradiation can be up to 303 mV and 25.87μA/cm^(2),respectively.This study provides a new idea for the design and preparation of TiO_(2)-based photoelectrodes with excellent photocathodic protection under visible light.展开更多
文摘This work presents a study on the use of cathodic protection as a measure against corrosion in pipelines.The cathodic protection,compliant with the API 5L standard,is implemented here by applying an impressed current,while carefully considering several essential variables,such as soil characteristics,the type and color of the pipeline material,as well as the placement and size of the anode.Therefore,it is crucial to optimize the location and values of anodic overflows or ground resistances to ensure a uniform distribution of potential across the entire structure.In this method,impressed current protection uses an auxiliary anode and an external direct current source to induce a current through the electrolyte and the pipeline,thus countering the resistance of the steel.This approach is advantageous as it allows for the adjustment of electrical characteristics,particularly current levels,to meet specific needs.The factors essential to the effectiveness of cathodic protection systems,which optimize the distribution of protection potential across the structure,largely depend on the precise management of ground resistances during anodic discharge,particularly the attenuation coefficient(α).These factors were studied,and the results obtained were presented and discussed based on their influence.
基金supported by the National Natural Science Foundation of China(No.52271073)the Central Govern-ment Guided Special Program(No.2021ZYD0049)the Young Elite Scientists Sponsorship Program by CAST(No.2018QNRC001).
文摘Metal-organic framework[MOF,i.e.,NH_(2)-MIL-53(Al)]modified TiO_(2)(NMT)composite photoanodes were successfully prepared by hydrothermal synthesis and were used for the photoelectrochemical cathodic protection(PECCP)of nickel-plated magnesium alloy(Mg/Ni).Results showed that the synthesis tem-perature significantly impacted the morphology and PECCP performance of the NMT photoanodes.The NMT@150 photoanode prepared at a reaction temperature of 150℃exhibited the best PECCP perfor-mance and produced a current density of 1980μA cm^(-2)under visible light irradiation,which was 19.8 times higher than that of a single TiO_(2)photoanode.The composite photoanode could polarize the open circuit potential of the coupled Mg/Ni electrode to-876 mV and remain relatively stable within 35 h.XPS and EPR tests showed that a Z-scheme heterojunction was formed between the NH_(2)-MIL-53(Al)and TiO_(2)nanotubes,allowing the photogenerated electrons to accumulate mainly on the conduction band of NH_(2)-MIL-53(Al).The heterojunction greatly promoted the separation and transfer of photogenerated electron-hole in the NMT composite photoanode,significantly enhancing the PECCP performance for Mg/Ni.
基金Projects(42106051,U2106206)supported by the National Natural Science Foundation of China。
文摘A new type of photoelectrochemical cathodic protection technology(a combination of seawater corrosion and biological fouling resistance)is being actively researched to alleviate the serious corrosion of marine metal materials.At present,there is almost no research on anti-corrosion and anti-fouling dual functional materials.In this paper,Cu_(2)ZnSnS_(4)is attached to the surface of TiO,nanotubes through a one-step hydrothermal method for modification.The results indicate that when the hydrothermal reaction time is 24 h,Cu_(2)ZnSnS_(4)/TiO_(2)nanocomposite material exhibits excellent performance in coupling with the protected 304 SS,with its open circuit potential shifts negatively to-1.04 V.This material improves the separation efficiency of photogenerated electrons and effectively improves the photochemical cathodic protection of 304 stainless steel.The high removal rate of Staphylococcus aureus(up to 93%)of the as-prepared samples also proved that it has the effect of the anti-biological fouling.
基金financially supported by the Natural Science Foundation of Shandong(No.ZR2021MD002)the National Natural Science Foundation of China(Nos.42106051 and U2106206).
文摘The low photoelectric conversion efficiency of photoelectrode is an important factor that limits the application in photoelectrochemical cathodic protection(PECCP)field for marine anti-corrosion of metallic structures.In this work,a photoelectrode of TiO_(2)/CdZnS/ZnS triple-phase heterojunction was fabricated by loading the narrow-band CdZnS associated with the broad-band ZnS via hydrothermal and continuous ion layer adsorption methods,respectively.The composite of CdZnS enhances the photoelectric conversion ability of TiO_(2),while the ZnS composite can prevent the CdZnS from photo-corrosion and suppress the spillover of the photogenerated electrons.The three-phase heterostructure effectively improves the PECCP performance on 316 L stainless steel(SS)under simulated solar irradiation,especially in 3.5 wt%NaCl solution without the sacrificial agent.In addition,the prepared TiO_(2)/CdZnS/ZnS photoelectrode also performs anti-biofouling effect evidenced by the high removal efficiency of Pseudomonas aeruginosa(P.aeruginosa),which can be attributed to the oxidizability of photogenerated holes.The TiO_(2)/CdZnS/ZnS triple-phase heterojunction with desirable performance is a promising semiconductor material for the applications of PECCP and anti-biofouling.
文摘Metallic pipeline corrosion poses a significant challenge in the petrochemical industry. In this study, the design and control of a stand-alone photovoltaic (PV)-powered cathodic protection (CP) system based on the impressed current method were investigated. The proposed CP system was applied to a 250 km long steel-buried pipeline in the Sharm El-Sheikh region of Egypt. The system design involved the numerical modeling of the anode bed for the impressed current CP (ICCP) system and the sizing of the DC power source, including the PV array and battery bank. The system was designed and controlled to deliver a constant and continuous anode current to protect the underground pipeline from corrosion during daylight and nighttime. A maximum power point tracking (MPPT) algorithm based on the fractional open-circuit voltage (FOCV) technique was implemented to maximize power extraction from the PV array. Additionally, a proportional-integral (PI) controller was optimized and employed to achieve MPPT, while another PI controller managed the anode current of the CP system. Safe charging and discharging of the system’s battery are ensured via an ON-OFF controller. The parameters of the PI controllers were optimized using the particle swarm optimization (PSO) technique. Simulation results demonstrated that the proposed CP system achieved the required protection objectives successfully.
文摘Al-Zn-Mg alloys with different Zn/Mg mass ratios were evaluated as sacrificial anodes for cathodic protection of carbon steel in 3.5 wt.%Na Cl solution.The anodes were fabricated from pure Al,Zn and Mg metals using casting technique.Optical microscopy,SEM-EDS,XRD and electrochemical techniques were used.The results indicated that with decreasing Zn/Mg mass ratio,the grain size ofα(Al)and the particle size of the precipitates decreased while the volume fraction of the precipitates increased.The anode with Zn/Mg mass ratio>4.0 exhibited the lowest corrosion rate,while the anode with Zn/Mg mass ratio<0.62 gave the highest corrosion rate and provided the highest cathodic protection efficiency for carbon steel(AISI 1018).Furthermore,the results showed that the anode with Zn/Mg mass ratio<0.62 exhibited a porous corrosion product compared to the other anodes.
基金supported by National Natural Science Foundation of China(Grant no.41506093)
文摘Photoelectrochemical(PEC) cathodic protection is considered as an environment friendly method for metals anticorrosion. In this technology, a n-type semiconductor photoanode provides the photogenerated electrons for metal to achieve cathodic protection. Comparing with traditional PEC photoanode for water splitting, it requires the photoanode providing a suitable cathodic potential for the metal, instead of pursuit ultimate photon to electric conversion efficiency, thus it is a more possible PEC technology for engineering application. To date, great efforts have been devoted to developing novel n-type semiconductors and advanced modification method to improve the performance on PEC cathodic protection metals. Herein, recent progresses in this field are summarized. We highlight the fabrication process of PEC cathodic protection thin film, various nanostructure controlling, doping, compositing methods and their operation mechanism. Finally, the current challenges and future potential works on improving the PEC cathodic protection performance are discussed.
基金financially supported by the National Natural Science Foundation of China(No.41827805)Chinese Academy of Engineering(No.2019-XZ-21)。
文摘In this work,TiO_(2)nanotube arrays(NTAs)sensitized with MoS_(2)microspheres(MoS_(2)/TiO_(2)nanocomposites)were prepared on a flat Ti substrate via two-step anodization and hydrothermal method sequentially.TiO_(2)NTAs were composed of many orderly nanotubes,whose large specific surface area was favorable for light absorption and MoS_(2)microsphere adhesion.The MoS_(2)microsphere as a narrow band gap semiconductor extended the TiO_(2)NTAs’absorption band edge to the visible region.The 2D structure of MoS_(2)microspheres and the construction of heterojunction electronic field at the interface of MoS_(2)microspheres and TiO_(2)NTAs promoted the separation of photoinduced carriers.The MoS_(2)/TiO_(2)nanocomposites could provide higher photoelectrochemical cathodic protection for 304 stainless steel(304 SS)under visible light than pristine TiO_(2)NTAs.
文摘Platforms I and II are steel structures located in offshore areas southeast of the Zhujiang (Pearl) River Delta, the northern South China Sea,. in about 110 in water depth. The jackets, with aluminum sacrificial anodes for cathodic protection (CP) of the immersed zone, were launched in March 1995. In May 096 a CP survey showed that, after almost one year of service, a low polarization level had been achieved and some extended unprotected zones existed; mainly in the deepest part of the Platform II. Further to this, a joint activity was decided in order to assess the need of a possible retrofitting of the CP systems. The results of the activity carried out are dealt with, including technical and economical comparisons amongst several retrofitting options, both with sacrificial anodes and with impressed current systems. The adopted solution is illustrated and data are reported on the level of protection presently achieved.
文摘Fracture behaviour of low-alloy steels AIST4340,HY100,Welten60,AISIA537 and A131 in artificial seawater under static,cyclic loading and at cathodic protection potential has been investigated by using the techniques of fracture mechanics, electrochemistry and electronfractography.The results reveal that at hydrogen evolution potentials(cathodic pro- tection potential)the critical yield strength required for the occurrance of SCC decreases from 985 at corrosion potential(E_c)to 872 MPa.The effect of cathodic protection on crack propagation of corrosion fatigue(CF)is not simple,it is closely related to the yield strength of steels and their SCC behaviour.For the steels with high yield strength,cathodic protection promotes(da/dN)_Ⅱ evidently,and reduces △K_(th) value.The(da/dN)-△K curves dis- play a plateau at the third stage of CF for steels with medium or low yield strength.It is men- tioned that the cathodic protection potential for oceaneering constructures should be control- led at top level of the protective range.It seems reasonable that the strength of steel for oceaneeing use might be increased by 200 or 300 MPa.
基金financially supported by the National Natural Science Foundation of China(No.41976036)the State Key Laboratory for Marine Corrosion and Protection,Luoyang Ship Material Research Institute(LSMRI)(Nos.KF190408 and KF190404)。
文摘A novel three-dimensional hierarchical WO_(3)photoelectrode was prepared by solvothermal method,and ZnO was deposited on its surface by electrochemical method.The WO_(3)/ZnWO_(4)/ZnO multiphaseheterojunction photoelectrode was prepared by further annealing treatment to explore the photoinduced cathodic protection(CP)performance.Compared with WO_(3)and ZnO,the photoinduced CP and electron storage capacity performance of WO_(3)/ZnWO_(4)/ZnO is significantly improved in 3.5%NaCl solution without adding any hole scavenger.The electron storage capacity of the WO_(3)/ZnWO_(4)/ZnO heterojunction makes it possible to continuously protect metallic materials in the dark after switching off the light,which can realize long-term and effective photoinduced CP.
基金supported by the National Natural Science Foundation of China(Nos.42106051,U2106206,U1706225,42006046,2019YFC0312103)。
文摘Semiconductor quantum dots with high quantum yield and photovoltaic conversion efficiency have ushered in a brilliant moment for constructing internal electric field heterojunctions for photogenerated cathodic protection applications.In this paper,TiO_(2)nanotubes grown vertically on the surface of titanium substrates were modified via a combination of conventional electrochemical oxidation and a one-step solvothermal pathway to sensitize with CuInS_(2)quantum dots.Compared with pure TiO_(2)photoelectrodes,the modification improves sunlight absorption efficiency and provides photoelectron cathodic protection to the 304 stainless steel(304 SS).Through 9 h solvothermal reaction,the CuInS_(2)/TiO_(2)coupled with protected 304 SS exhibited an excellent property when the simulated sunlight irradiation.Its mixed open circuit potential is negatively shifted to-0.99 V,at the mean time with a stable photocurrent density(118μA cm^(-2)).The results indicate that CuInS_(2)and TiO_(2)established a p-n heterojunction with wellmatched energy level,which can effectively facilitate the carrier separation and retain the strong redox capbility of photo-induced electrons and holes.
文摘The environmental conditions around the first offshore HZ 21- 1 steel wellhead platform in the South China Sea are characterized by deep water, frequent typhoons, rough waves, high water temperature, severely corrosive seawater, and thick fouling organism attachments. The design and effectiveness of galvanic anode protection system are presented, and several methods are described, which are the calculation method of the protective current density considering the variation of water depth, the method of determining protection parameters considering various factors, the arrangement of anodes based on potential distribution and current requirements at different water depths, and the method of anode installation. Finally the effect of the accuracy of selected cathodic protection parameters on the economic benefits of offshore projects is also discussed..
基金Funded by the Specialized Research Fund for the Doctoral Program of Higher Education (No. 20070247063)National Natural Science Foundation of China (No. 50978200)
文摘The behavior of a new type of secondary anode material made of carbon fiber reinforced cement used for cathodic protection of steel in concrete was studied. The mechanical, electrical and electrochemical properties of this conductive mortar were investigated. Results indicate that the addition of carbon fiber enhances the strength and ductility of the mortar, as well as the electrical property. The anodic polarization behavior was tested on specimens immersed in aqueous solutions of saturated Ca（OH）2 in the presence or absence of 3% NaCl. Based on impedance measurements the electrochemical parameters of conductive mortar were calculated. It is shown that the investigated conductive mortar can be used in cathodic protection of reinforced concrete. The study also shows that the optimum fiber content in mortar should be in the range from 0.5 vol% to 0.7 vol%.
文摘This paper introduces the research status and present situation of application of Pt/Ta composite anode materials for cathodic protection in China. It also introduces the corrosion resistance, bending properties and electrochemical performance in seawater and freshwater of the Pt/Ta composite anode materials for cathodic protection. It points out that compared with other platinum composite anodes, the Pt/Ta composite anode has the advantage of small volume, light weight, big drainage rate, long service life, it possesses superiority to be used in the confluence environment of sea water and fresh water and in the medium condition of resistivity changes at all times.
基金Supported by the National Natural Science Foundation of China(Nos.41576114,41676069)the State Key Laboratory for Marine Corrosion and Protection,Luoyang Ship Material Research Institute,China(No.614290101011703)the Qingdao Innovative Leading Talent Foundation(No.15-10-3-15-(39)-zch)。
文摘The Cu2O/TiO2 p-n heterojunction composite photoelectrodes were prepared by depositing Cu 2 O nanoparticles on the surface of TiO 2 nanotubes via anodic oxidation and constant current deposition.Field emission scanning electron microscopy(SEM)and high-resolution transmission electron microscopy(HRTEM)analyses showed that Cu 2 O nanoparticles not only deposited on the surface of TiO 2 nanotube array,but also on the wall of TiO 2 nanotubes.The Cu 2 O deposition amount could be adjusted by changing the deposition time.The photoelectrochemical cathodic protection(PECCP)performance of the prepared photoelectrodes for 316L stainless steel(SS)was tested under visible light.The constant current deposition time had a signifi cant eff ect on the PECCP performance of Cu 2 O/TiO 2-X photoelectrodes and Cu 2 O/TiO 2-20 had the best PECCP performance for the coupled 316L SS.This was attributed to the appropriate amount and thickness of Cu 2 O to form p-n heterojunctions with TiO 2,in which separation of the photogenerated carriers was accelerated and transfer of the photogenerated electrons to 316L SS for PECCP was facilitated.
文摘The long and short fatigue crack growth (FCG) behavior of 12CrNi3MoV (S1) and 10CrNi5MoV(S2) steel was investigated at cathodic protection in 3.5 % NaCl solution and artificial seawater. The results indicate that long and short FCG show different behavior at cathodic protection. Short FCG is apparently hindered at appropriate cathodic protection potential (-900 mV SCE) and accelerated at over protection potential(-1200 mV SCE). Cathodic protection increases long FCG rate, and the more negative the cathodic protection potential, the greater the long FCG rate. At the same amplitude of stress intensity ( ΔK ), short FCG rate is greater than the long one and their difference becomes less at cathodic protection. The FCG rate in 3.5 % NaCl solution is greater than in artifitial seawater. The FCG rate of S2 steel is bigger then that of S1 steel. The FCG rate of weld bond of S2 steel is lower than that of parent metal and weld beam. In above cases, the anode dissolution, the wedging of corrosion products or deposit and hydrogen embrittlement in long and hort crack tip are also discussed.
基金supported by the Sichuan Science and Technology Program(No.2024NSFJQ0034)the National Natural Science Foundation of China(No.52271073)+1 种基金the Education and Teaching Reform Program for Graduate Students of Sichuan Province(No.YJGXM24-C047)the Innovation Team Funds of China West Normal University(No.KCXTD2024-1).
文摘A novel and long-lasting N_(3)BD/TiO_(2) composite photoanode with stable and superior photoelectrochemical and photoelectrochemical cathodic protection(PECCP)performances was achieved by synthesizing and depositing covalent organic framework(N_(3)BD)on titanium oxide(TiO_(2))nanotube arrays.The composite's increased visible light absorption capability enhanced the galvanic corrosion protection of nickel-phosphorus alloy-coated magnesium alloy(Mg/Ni)through PECCP technology.The open circuit potential(OCP)drops of the Mg/Ni electrode coupling with the N_(3)BD/TiO_(2) composite were 310 and 630 mV at dark state and under illumination,respectively.They remained relatively stable under intermittent visible light irradiation within 72 h,demonstrating excellent long-term stability.The superior photoelectrochemical and PECCP properties of the N_(3)BD/TiO_(2) are attributed to forming S-scheme heterojunctions,which effectively promote the separation and transfer of photogenerated electron-hole pairs and retain a strong redox capacity.This finding provides new insight into the design and synthesis of COF-modified photoanode with highly efficient and stable photoelectrochemical and PECCP performances.
基金financially supported by the Henan Province Key R&D and Promotion Project(Technology Research)(NO.232102230011)the Fundamental Research Fund of Henan Academy of Sciences(NO.230618026)+1 种基金Joint Fund of Henan Province Science and Technology R&D Program(NO.225200810120)High-level Talent Research Start-up Project Funding of Henan Academy of Sciences(NOs.231818022 and 232018001).
文摘Constructing a photoanode with both high dark-state protection performance and high stability remains a top priority for photoelectrochemical cathodic protection technology,especially in a marine environment(dark-state or rainy conditions)without hole scavenging agents.In this work,we developed a class of energy-storage quasi-planar heterojunctions(WO_(3)-Nb_(2)O_(5)-ZnIn_(2)S_(4))with directional paths(low onset potential and well-matched energy band)and embedded morphology.The co-design of embedded and directional paths reduces the carrier transport energy barrier at the composite interface,and increases the interface contact area,thereby achieving highly stable and sensitive dark-state energy storage and photoelectrochemical cathodic protection performance in 3.5 wt.%NaCl solution without hole scavenging agent(Dark-state energy storage efficiency increased by 43%.For carbon steel,the performance retention rate is 99.6%after 500 cycles,the performance retention rate is 89%after 5000 s).
基金financially supported by the Natural Science Foundation of Shandong(No.ZR2023QD152)the National Natural Science Foundation of China(No.42476212).
文摘Photogenerated electrons generated by photoexcitation of semiconductor materials can be transferred to metal materials to provide corrosion protection.Conversely,the accumulation of photogenerated holes accelerates the recombination of photogenerated carriers.Consequently,the development of efficient strategies for the consumption of photogenerated holes has emerged as a critical challenge in the field of photoelectrochemical cathodic protection technology.In this paper,TiO_(2)/TiOBr heterojunction photoelectrode was firstly prepared by simple hydrothermal method,and NiCo-LDH(layered double hydroxide)was further deposited on TiO_(2)/TiOBr to obtain TiO_(2)/TiOBr/NiCo-LDH photoelectrode.The construction of a heterojunction between TiO_(2)and TiOBr promotes the separation of photogenerated carriers,while the deposition of NiCo-LDH reduces the overpotential for hole oxidation.Hence,the photoinduced potential drop and photoinduced current density of TiO_(2)/TiOBr/NiCo-LDH photoelectrode coupled with 316 L stainless steel in 3.5 wt%NaCl under simulated sunlight irradiation can be up to 303 mV and 25.87μA/cm^(2),respectively.This study provides a new idea for the design and preparation of TiO_(2)-based photoelectrodes with excellent photocathodic protection under visible light.
