Aiming at the high temperature corrosion in a coal-fired boiler,the effect of H2S and SO2 on the corrosion of 12 CrlMoV under the water wall condition has been investigated by experiments.The results indicate that H2 ...Aiming at the high temperature corrosion in a coal-fired boiler,the effect of H2S and SO2 on the corrosion of 12 CrlMoV under the water wall condition has been investigated by experiments.The results indicate that H2 S can promote the corrosion significantly,and the coarse porous oxide film formed cannot stop the progress of corrosion.While SO2 presents little effect on the corrosion.The main composition of the surface of 12 CrlMoV corrosion products is Fe2 O3.With H2S in the atmosphere,the corrosion gradually develops into deeper layers by forming FeS,FeO and Fe2 O3 alternately.The corrosion rate is doubled for every 50℃ inerease in temperature at 400-500℃.展开更多
The corrosion behavior of C100 steel in simulated environments with high H2S and CO2 content was studied through high-temperature and high-pressure autoclave, and the HaS stress corrosion cracking （SSC） resistance o...The corrosion behavior of C100 steel in simulated environments with high H2S and CO2 content was studied through high-temperature and high-pressure autoclave, and the HaS stress corrosion cracking （SSC） resistance of C100 steel was evaluated by SSC tests. Scanning electron microscopy （SEM）, transmission electron microscope （TEM） and X-ray diffraction （XRD） technique were employed to characterize the corrosion products and the metal matrix. The results indicate that all of the corrosion products in this investigation are mainly composed of different types of iron sulfide such as Fe0.95S, FeS0.9, F0.985S, Fe7S8 and FeS, and the absence of iron carbonate in the corrosion scales suggests that the corrosion process is governed by H2S corrosion. The corrosion rate decreases in the initial stage and then increases with the enhancement of the temperature. There exists a minimum corrosion rate at about 110 ℃. Under the partial pressure of H2S lower than 9 MPa, the corrosion rate decreases with the increase of P112S While over 9 MPa, a higher P112S will result in a faster corrosion process. When the applied stress is 72%, 80% and 85% of actual yield strength （AYS）, all tested specimens show no crack, which reveals a superior SSC resistance.展开更多
Based on an analysis of the existing models of CO 2 corrosion in literatures and the autoclave simulative experiments, a predictive model of corrosion rate (r corr) in CO 2/H 2S corrosion for oil tubes has been ...Based on an analysis of the existing models of CO 2 corrosion in literatures and the autoclave simulative experiments, a predictive model of corrosion rate (r corr) in CO 2/H 2S corrosion for oil tubes has been established, in which r corr is expressed as a function of pH, temperature (T), pressure of CO 2 (P CO 2) and pressure of H 2S (P H 2S). The model has been verified by experimental data obtained on N80 steel. The improved features of the predictive model include the following aspects: (1) The influence of temperature on the protectiveness of corrosion film is taken into consideration for establishment of predictive model of the r corr in CO 2/H 2S corrosion. The Equations of scale temperature and scale factor are put forward, and they fit the experimental result very well. (2) The linear relationship still exists between ln r corr and ln P CO 2 in CO 2/H 2S corrosion (as same as that in CO 2 corrosion). Therefore, a correction factor as a function of P H 2S has been introduced into the predictive model in CO 2/H 2S corrosion. (3) The model is compatible with the main existing models.展开更多
The present work studied the corrosion properties around the fusion boundaries of 2.25Cr-1Mo steel with stainless steel strip overlay joints under as welded condition and after post-weld heat treatment (PWHT) in H2 S ...The present work studied the corrosion properties around the fusion boundaries of 2.25Cr-1Mo steel with stainless steel strip overlay joints under as welded condition and after post-weld heat treatment (PWHT) in H2 S containing solution (NACE TM-01-77 standard) with different time. An in-situ observation method was introduced for evaluating corrosive progress in the fusion boundary in H2 S containing solution, that is, the samples were marked firstly at the boundary and then treated in the solution for variant time. Each time after the corrosion treatment, the observations were kept to focus at the same marked area by using scanning electron microscopy (SEM) to observe the corrosion progress. The results reveal that the fusion boundary is the worst region for corrosion resistance when comparing with other boundaries, and a broad fusion boundary has a stronger resistance for "hydrogen induced disbonding" than a narrow one.展开更多
The corrosion of an Fe-based alloy containing 15 wt pct Y in H2-H2S mixtures under 10-3 Pa S2 was studied at 600~800℃ in an attempt to find materials with improved sulphidation resistance with respect to pure Fe. The...The corrosion of an Fe-based alloy containing 15 wt pct Y in H2-H2S mixtures under 10-3 Pa S2 was studied at 600~800℃ in an attempt to find materials with improved sulphidation resistance with respect to pure Fe. The presence of Y has been shown to be beneflcial, but not sufficient to the level expected. In fact, the alloy is able to form at all tested temperatures an external FeS layer, beneath which a zone containing a mixture of the two sulphides is also present. Thus,Fe can still diffuse through this region to form the outer FeS layer with non-negligible rate. The corrosion rate of Fe is considerably reduced by the Y addition. but the alloy corrodes still much more rapidly than Y. The sulphidation kinetics is generally rather irregular for both the pure metals, while the corrosion rate of the alloy decreases with time and tends to become parabolic after an initial period of 12~17 h. The sulphidation behaviour of the alloys is discussed by taking into account the presence of an intermetallic compound Fe17Y2 and the limited solubility of Y in Fe展开更多
Two 5-substituted tetrazoles, 5-(2-thienyl)-1,2,3,4-tetrazole (2-THTT) and 5-(4-pyridyl)-1,2,3,4-tetrazole (4-PYTT), as copper corrosion inhibitors in aerated 0.5 M H2SO4 solution were studied by using potentiodynamic...Two 5-substituted tetrazoles, 5-(2-thienyl)-1,2,3,4-tetrazole (2-THTT) and 5-(4-pyridyl)-1,2,3,4-tetrazole (4-PYTT), as copper corrosion inhibitors in aerated 0.5 M H2SO4 solution were studied by using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and quantum chemical calculation. Polarization curves indicate that inhibition efficiencies of tetrazoles increase with increasing inhibitors concentration. The electrochemical results show that the inhibition efficiency of 2-THTT is higher than that of 4-PYTT. Inhibition efficiency of 2-THTT reached 98.9% at very low concentrations (0.25 mM) by EIS, which makes 2-THTT an efficient inhibitor in aerated 0.5 M H2SO4 solution. The adsorption of 5-substituted tetrazoles on copper surface obeys the Langmuir isotherm. All the computed quantum chemical parameters are found to correlate well with experimental inhibition efficiencies of inhibitors.展开更多
In the present work, the susceptibility of API 5L X52 steel to corrosion processes was evaluated in the presence of high contents of hydrogen sulfide and carbon dioxide. Gravimetric tests and surface analyses were car...In the present work, the susceptibility of API 5L X52 steel to corrosion processes was evaluated in the presence of high contents of hydrogen sulfide and carbon dioxide. Gravimetric tests and surface analyses were carried out to establish both the corrosion rate and damage type exhibited by the metal. The obtained results indicate that the hydrogen sulfide is the most active gas in the corrosion processes that took place, quite above carbon dioxide. The main observed corrosion products were iron sulfides and the typical damage associated with hydrogen sulfide presence was Sulfide Stress Cracking (SSC). The surface damage evidences the presence of cracks with considerable magnitude and metal loss as consequences of the corrosion processes. Likewise, the presence of oxygen in the system modifies the displayed corrosion type, where corrosion products such as iron oxides and reduction in the number and extent of cracks are observed. On the other hand, the addition of a film-forming corrosion inhibitor based on modified imidazolines eliminates completely the development of cracks, although under certain test conditions, it can favor localized pitting corrosion.展开更多
基金supported by the National Key Research and Development Plan of China (No. 2018YFB0604203)
文摘Aiming at the high temperature corrosion in a coal-fired boiler,the effect of H2S and SO2 on the corrosion of 12 CrlMoV under the water wall condition has been investigated by experiments.The results indicate that H2 S can promote the corrosion significantly,and the coarse porous oxide film formed cannot stop the progress of corrosion.While SO2 presents little effect on the corrosion.The main composition of the surface of 12 CrlMoV corrosion products is Fe2 O3.With H2S in the atmosphere,the corrosion gradually develops into deeper layers by forming FeS,FeO and Fe2 O3 alternately.The corrosion rate is doubled for every 50℃ inerease in temperature at 400-500℃.
基金Funded by Key National Science&Technology Specific Projects(No.2008ZX05017-002)
文摘The corrosion behavior of C100 steel in simulated environments with high H2S and CO2 content was studied through high-temperature and high-pressure autoclave, and the HaS stress corrosion cracking （SSC） resistance of C100 steel was evaluated by SSC tests. Scanning electron microscopy （SEM）, transmission electron microscope （TEM） and X-ray diffraction （XRD） technique were employed to characterize the corrosion products and the metal matrix. The results indicate that all of the corrosion products in this investigation are mainly composed of different types of iron sulfide such as Fe0.95S, FeS0.9, F0.985S, Fe7S8 and FeS, and the absence of iron carbonate in the corrosion scales suggests that the corrosion process is governed by H2S corrosion. The corrosion rate decreases in the initial stage and then increases with the enhancement of the temperature. There exists a minimum corrosion rate at about 110 ℃. Under the partial pressure of H2S lower than 9 MPa, the corrosion rate decreases with the increase of P112S While over 9 MPa, a higher P112S will result in a faster corrosion process. When the applied stress is 72%, 80% and 85% of actual yield strength （AYS）, all tested specimens show no crack, which reveals a superior SSC resistance.
基金TheResearchProjectofTubularGoodsRe searchCenterofChinaNationalPetroleumCorporation (No .2 3 5 2 4)andtheResearchProjectofHenanUniversityofScienceandTechnology (No .2 0 0 10 1)
文摘Based on an analysis of the existing models of CO 2 corrosion in literatures and the autoclave simulative experiments, a predictive model of corrosion rate (r corr) in CO 2/H 2S corrosion for oil tubes has been established, in which r corr is expressed as a function of pH, temperature (T), pressure of CO 2 (P CO 2) and pressure of H 2S (P H 2S). The model has been verified by experimental data obtained on N80 steel. The improved features of the predictive model include the following aspects: (1) The influence of temperature on the protectiveness of corrosion film is taken into consideration for establishment of predictive model of the r corr in CO 2/H 2S corrosion. The Equations of scale temperature and scale factor are put forward, and they fit the experimental result very well. (2) The linear relationship still exists between ln r corr and ln P CO 2 in CO 2/H 2S corrosion (as same as that in CO 2 corrosion). Therefore, a correction factor as a function of P H 2S has been introduced into the predictive model in CO 2/H 2S corrosion. (3) The model is compatible with the main existing models.
文摘The present work studied the corrosion properties around the fusion boundaries of 2.25Cr-1Mo steel with stainless steel strip overlay joints under as welded condition and after post-weld heat treatment (PWHT) in H2 S containing solution (NACE TM-01-77 standard) with different time. An in-situ observation method was introduced for evaluating corrosive progress in the fusion boundary in H2 S containing solution, that is, the samples were marked firstly at the boundary and then treated in the solution for variant time. Each time after the corrosion treatment, the observations were kept to focus at the same marked area by using scanning electron microscopy (SEM) to observe the corrosion progress. The results reveal that the fusion boundary is the worst region for corrosion resistance when comparing with other boundaries, and a broad fusion boundary has a stronger resistance for "hydrogen induced disbonding" than a narrow one.
文摘The corrosion of an Fe-based alloy containing 15 wt pct Y in H2-H2S mixtures under 10-3 Pa S2 was studied at 600~800℃ in an attempt to find materials with improved sulphidation resistance with respect to pure Fe. The presence of Y has been shown to be beneflcial, but not sufficient to the level expected. In fact, the alloy is able to form at all tested temperatures an external FeS layer, beneath which a zone containing a mixture of the two sulphides is also present. Thus,Fe can still diffuse through this region to form the outer FeS layer with non-negligible rate. The corrosion rate of Fe is considerably reduced by the Y addition. but the alloy corrodes still much more rapidly than Y. The sulphidation kinetics is generally rather irregular for both the pure metals, while the corrosion rate of the alloy decreases with time and tends to become parabolic after an initial period of 12~17 h. The sulphidation behaviour of the alloys is discussed by taking into account the presence of an intermetallic compound Fe17Y2 and the limited solubility of Y in Fe
文摘Two 5-substituted tetrazoles, 5-(2-thienyl)-1,2,3,4-tetrazole (2-THTT) and 5-(4-pyridyl)-1,2,3,4-tetrazole (4-PYTT), as copper corrosion inhibitors in aerated 0.5 M H2SO4 solution were studied by using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and quantum chemical calculation. Polarization curves indicate that inhibition efficiencies of tetrazoles increase with increasing inhibitors concentration. The electrochemical results show that the inhibition efficiency of 2-THTT is higher than that of 4-PYTT. Inhibition efficiency of 2-THTT reached 98.9% at very low concentrations (0.25 mM) by EIS, which makes 2-THTT an efficient inhibitor in aerated 0.5 M H2SO4 solution. The adsorption of 5-substituted tetrazoles on copper surface obeys the Langmuir isotherm. All the computed quantum chemical parameters are found to correlate well with experimental inhibition efficiencies of inhibitors.
文摘In the present work, the susceptibility of API 5L X52 steel to corrosion processes was evaluated in the presence of high contents of hydrogen sulfide and carbon dioxide. Gravimetric tests and surface analyses were carried out to establish both the corrosion rate and damage type exhibited by the metal. The obtained results indicate that the hydrogen sulfide is the most active gas in the corrosion processes that took place, quite above carbon dioxide. The main observed corrosion products were iron sulfides and the typical damage associated with hydrogen sulfide presence was Sulfide Stress Cracking (SSC). The surface damage evidences the presence of cracks with considerable magnitude and metal loss as consequences of the corrosion processes. Likewise, the presence of oxygen in the system modifies the displayed corrosion type, where corrosion products such as iron oxides and reduction in the number and extent of cracks are observed. On the other hand, the addition of a film-forming corrosion inhibitor based on modified imidazolines eliminates completely the development of cracks, although under certain test conditions, it can favor localized pitting corrosion.
