The corrosion of rebar in reinforced concrete in marine environments causes significant damage to structures built in ocean environments. Studies on the process and mechanism of corrosion of rebar in the presence of m...The corrosion of rebar in reinforced concrete in marine environments causes significant damage to structures built in ocean environments. Studies on the process and mechanism of corrosion of rebar in the presence of multiple ions may help to control damage and predict the service life of reinforced concrete structures in such environments. The effect of interactions between sulfate and chloride ions and calcium hydroxide on the electrochemical behavior ofrebar are also important for evaluation of structure durability. In this work, electrochemical impedance spectroscopy （EIS） plots of rebar in Ca（OH）2 solution and cement grout, including NaC1 and Na2SO4 as aggressive salts, were measured for different immersion times. The results show that corrosion of rebar was controlled by the rate of charge transfer as the rebar was exposed to chloride solution. In the presence of high concentrations of sulfate ions in the electrolyte, generation and dissolution of the passive film proceeded simultaneously and corrosion was mainly controlled by the diffusion rate. When Na2SO4 and NaC1 were added to Ca（OH）2 solution, the instantaneous corrosion rate decreased by a factor of 10 to 20 as a result of the higher pH of the corroding solution.展开更多
Spherical Ni（OH）2 particles were prepared by an aqueous solution precipitation route. The structure of spherical Ni（OH）2 was investigated by scanning electron microscopy and transmission electron microscopy and co...Spherical Ni（OH）2 particles were prepared by an aqueous solution precipitation route. The structure of spherical Ni（OH）2 was investigated by scanning electron microscopy and transmission electron microscopy and compared with that of traditional Ni（OH）2. The results show that the spherical nickel hydroxide consists of （Ni（OH）2） spheres with a reticulate structure of platelet-like, which is almost arranged radially and the crystalline grains intervene and connect with each other to form a three-dimensional net. The spherical Ni（OH）2 particle is full of pores, crannies between cleave planes. It is supposed that this structure is beneficial to the structural stability for the spherical particles during the charge/discharge processes and can improve the cycle life of the electrode; the pores and the crannies in spherical particles can shorten the proton diffusion distance and speed its velocity, which may result in that the local polarization is lowered. The electrochemical performances of the spherical Ni（OH）2 are improved by enhancing the conducting properties of the crystalline lattice due to its quick proton diffusion.展开更多
The hydrothermal reaction of isonicotinic acid (4-C5H4N-COOH), Cu(ClO4)(2). 6H(2)O and water at 170 degreesC gave the title compound, [Cu(OH)(2)(H2O)(2)(4-C5H4N-COOH)(2)] (1), which was analyzed by single-crystal X-ra...The hydrothermal reaction of isonicotinic acid (4-C5H4N-COOH), Cu(ClO4)(2). 6H(2)O and water at 170 degreesC gave the title compound, [Cu(OH)(2)(H2O)(2)(4-C5H4N-COOH)(2)] (1), which was analyzed by single-crystal X-ray diffraction, The complex crystallizes in triclinic space group PY with unit cell parameters: a = 6.337(2), b = 6.894(3), c = 9.178(3). alpha = 99.40(3), beta = 105.26(3), gamma 108.17(5)degrees, V = 354.1(2)Angstrom (3), Z = 1, C12H16CuN2O8, M-r = 379.81, D-c = 1.791 Mg/m(3), F(000) 197, mu (MoK alpha) = 1.589 mm(-1). The final R and wR are 0.068 and 0.170 for 1249 observed reflections with I greater than or equal to2 sigma (I). The central copper ion is in a distorted octahedron geometry completed by two nitrogen atoms from carboxylic ligand, two oxygen atoms from hydroxyl groups and two oxygen atoms from coordinated water molecules. The intermolecular hydrogen bonding leads to the formation of a three-dimensional supramolecular structure.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.51178230,51378269,5142010501)the National Basic Research Program of China(973 Program)(No.2015CB655100)the Qingdao Science and Technological Foundation(Nos.13-1-4-176-jch,13-1-4-115-jch)
文摘The corrosion of rebar in reinforced concrete in marine environments causes significant damage to structures built in ocean environments. Studies on the process and mechanism of corrosion of rebar in the presence of multiple ions may help to control damage and predict the service life of reinforced concrete structures in such environments. The effect of interactions between sulfate and chloride ions and calcium hydroxide on the electrochemical behavior ofrebar are also important for evaluation of structure durability. In this work, electrochemical impedance spectroscopy （EIS） plots of rebar in Ca（OH）2 solution and cement grout, including NaC1 and Na2SO4 as aggressive salts, were measured for different immersion times. The results show that corrosion of rebar was controlled by the rate of charge transfer as the rebar was exposed to chloride solution. In the presence of high concentrations of sulfate ions in the electrolyte, generation and dissolution of the passive film proceeded simultaneously and corrosion was mainly controlled by the diffusion rate. When Na2SO4 and NaC1 were added to Ca（OH）2 solution, the instantaneous corrosion rate decreased by a factor of 10 to 20 as a result of the higher pH of the corroding solution.
基金Project(50134020) supported by the National Natural Science Foundation of China
文摘Spherical Ni（OH）2 particles were prepared by an aqueous solution precipitation route. The structure of spherical Ni（OH）2 was investigated by scanning electron microscopy and transmission electron microscopy and compared with that of traditional Ni（OH）2. The results show that the spherical nickel hydroxide consists of （Ni（OH）2） spheres with a reticulate structure of platelet-like, which is almost arranged radially and the crystalline grains intervene and connect with each other to form a three-dimensional net. The spherical Ni（OH）2 particle is full of pores, crannies between cleave planes. It is supposed that this structure is beneficial to the structural stability for the spherical particles during the charge/discharge processes and can improve the cycle life of the electrode; the pores and the crannies in spherical particles can shorten the proton diffusion distance and speed its velocity, which may result in that the local polarization is lowered. The electrochemical performances of the spherical Ni（OH）2 are improved by enhancing the conducting properties of the crystalline lattice due to its quick proton diffusion.
文摘The hydrothermal reaction of isonicotinic acid (4-C5H4N-COOH), Cu(ClO4)(2). 6H(2)O and water at 170 degreesC gave the title compound, [Cu(OH)(2)(H2O)(2)(4-C5H4N-COOH)(2)] (1), which was analyzed by single-crystal X-ray diffraction, The complex crystallizes in triclinic space group PY with unit cell parameters: a = 6.337(2), b = 6.894(3), c = 9.178(3). alpha = 99.40(3), beta = 105.26(3), gamma 108.17(5)degrees, V = 354.1(2)Angstrom (3), Z = 1, C12H16CuN2O8, M-r = 379.81, D-c = 1.791 Mg/m(3), F(000) 197, mu (MoK alpha) = 1.589 mm(-1). The final R and wR are 0.068 and 0.170 for 1249 observed reflections with I greater than or equal to2 sigma (I). The central copper ion is in a distorted octahedron geometry completed by two nitrogen atoms from carboxylic ligand, two oxygen atoms from hydroxyl groups and two oxygen atoms from coordinated water molecules. The intermolecular hydrogen bonding leads to the formation of a three-dimensional supramolecular structure.
