Electrochemical studies of the effect of hydrodynamic conditions on corrosion inhibition of Cu-Ni （90/10） alloy in synthetic seawater and sulphide containing synthetic seawater by 1,2,3-benzotriazole （BTAH） are pr...Electrochemical studies of the effect of hydrodynamic conditions on corrosion inhibition of Cu-Ni （90/10） alloy in synthetic seawater and sulphide containing synthetic seawater by 1,2,3-benzotriazole （BTAH） are presented. Impedance, potentiodynamic polarization and cyclic voltammetric （CV） studies are employed in the present investigation. The studies are carried out by using Cu-Ni （90/10） alloy rotating disc electrode at different rotation speeds and at different immersion periods. Reynolds numbers at each rotation speed infer that the flow of seawater is laminar. With increasing rotation speed of the electrode immersed in seawater without sulphide and BTAH, both the charge transfer resistance （Rot） and film resistance （Rf^lm） are increased. However, in the presence of sulphide ions and without BTAH, both the Rot and Rf,m are found to decrease with increasing rotation speed at identical immersion periods. Interestingly, when BTAH is added to seawater or seawater containing sulphide, both the Rot and Rf,m are increased to such a great extent that an inhibition efficiency of 99.99% is obtained. In the presence of BTAH, the phase angle Bode plots are more broadened and the maximum values of phase angle are increased to a value close to 90~ as the rotation speed is increased. The BTAH film is highly protective even under hydrodynamic condition also. Potentiodynamic polarization studies infer that BTAH functions as a mixed inhibitor under hydrodynamic conditions also. CV studies reveal that the protective BTAH film is stable even at anodic potentials of ＋850 mV vs Ag/AgCI.展开更多
针对传统的层次聚类算法每次迭代只将距离最小的那对类簇合并,容易受离群点影响,偏向于发现凸状或球状簇等缺点,受CURE算法启发,采用簇中固定数量代表点来代表簇对象进行距离的计算,并结合90_10规则,提出了一种改进的层次聚类算法REPBFC...针对传统的层次聚类算法每次迭代只将距离最小的那对类簇合并,容易受离群点影响,偏向于发现凸状或球状簇等缺点,受CURE算法启发,采用簇中固定数量代表点来代表簇对象进行距离的计算,并结合90_10规则,提出了一种改进的层次聚类算法REPBFC(REpresentative Points Based Fast Clustering),实验表明该算法是有效的。展开更多
Two kinds of 90Cu10 Ni tubes with different service lives（more than 3 years and only 1 year,respectively）under identical working conditions were studied by an immersion test in a 3.5 wt% NaCl solution and the electr...Two kinds of 90Cu10 Ni tubes with different service lives（more than 3 years and only 1 year,respectively）under identical working conditions were studied by an immersion test in a 3.5 wt% NaCl solution and the electron backscattered diffraction（EBSD） technique.The morphology after immersion showed severer corrosion attack at the grain boundaries of the tube with shorter service life compared with the tube with longer service life.The grain boundary characterization distributions（GBCDs） of the two tubes obtained by EBSD revealed more Σ3 boundaries and twins,and larger random boundary meshes in the tube with longer service life.A short immersion test in a modified Livingston＇s solution was conducted to evaluate the tendency to corrosion attack of different types of the grain boundaries.SEM and AFM were used to characterize the corrosion morphologies of the boundaries.A strong correlation between varying depths of corrosion grooves and types of the grain boundaries was obtained.The influence of deviation angle of low Σ boundaries on corrosion resistance of the grain boundaries was also discussed.It is concluded that a special ‘‘grain boundary engineering＇＇（GBE） treatment has been performed on the tube with longer service life.It is proposed that the optimized GBCD is responsible for the better service performance of the tube.展开更多
基金Naval Research Board(NRB), Govt.of IndiaRajiv Gandhi National Fellowship(RGNF),UGC,Govt.of India
文摘Electrochemical studies of the effect of hydrodynamic conditions on corrosion inhibition of Cu-Ni （90/10） alloy in synthetic seawater and sulphide containing synthetic seawater by 1,2,3-benzotriazole （BTAH） are presented. Impedance, potentiodynamic polarization and cyclic voltammetric （CV） studies are employed in the present investigation. The studies are carried out by using Cu-Ni （90/10） alloy rotating disc electrode at different rotation speeds and at different immersion periods. Reynolds numbers at each rotation speed infer that the flow of seawater is laminar. With increasing rotation speed of the electrode immersed in seawater without sulphide and BTAH, both the charge transfer resistance （Rot） and film resistance （Rf^lm） are increased. However, in the presence of sulphide ions and without BTAH, both the Rot and Rf,m are found to decrease with increasing rotation speed at identical immersion periods. Interestingly, when BTAH is added to seawater or seawater containing sulphide, both the Rot and Rf,m are increased to such a great extent that an inhibition efficiency of 99.99% is obtained. In the presence of BTAH, the phase angle Bode plots are more broadened and the maximum values of phase angle are increased to a value close to 90~ as the rotation speed is increased. The BTAH film is highly protective even under hydrodynamic condition also. Potentiodynamic polarization studies infer that BTAH functions as a mixed inhibitor under hydrodynamic conditions also. CV studies reveal that the protective BTAH film is stable even at anodic potentials of ＋850 mV vs Ag/AgCI.
文摘针对传统的层次聚类算法每次迭代只将距离最小的那对类簇合并,容易受离群点影响,偏向于发现凸状或球状簇等缺点,受CURE算法启发,采用簇中固定数量代表点来代表簇对象进行距离的计算,并结合90_10规则,提出了一种改进的层次聚类算法REPBFC(REpresentative Points Based Fast Clustering),实验表明该算法是有效的。
基金supported by the National Natural Science Foundation of China (No.51131008)the Shanghai Science and Technology Commission (No.13520500500)
文摘Two kinds of 90Cu10 Ni tubes with different service lives（more than 3 years and only 1 year,respectively）under identical working conditions were studied by an immersion test in a 3.5 wt% NaCl solution and the electron backscattered diffraction（EBSD） technique.The morphology after immersion showed severer corrosion attack at the grain boundaries of the tube with shorter service life compared with the tube with longer service life.The grain boundary characterization distributions（GBCDs） of the two tubes obtained by EBSD revealed more Σ3 boundaries and twins,and larger random boundary meshes in the tube with longer service life.A short immersion test in a modified Livingston＇s solution was conducted to evaluate the tendency to corrosion attack of different types of the grain boundaries.SEM and AFM were used to characterize the corrosion morphologies of the boundaries.A strong correlation between varying depths of corrosion grooves and types of the grain boundaries was obtained.The influence of deviation angle of low Σ boundaries on corrosion resistance of the grain boundaries was also discussed.It is concluded that a special ‘‘grain boundary engineering＇＇（GBE） treatment has been performed on the tube with longer service life.It is proposed that the optimized GBCD is responsible for the better service performance of the tube.
