Electroless copper plating on diamond particles precoated with 1%Cr was carried out to evaluate the effects of various experimental parameters on coating quality and deposition rate to obtain the optimized reaction pa...Electroless copper plating on diamond particles precoated with 1%Cr was carried out to evaluate the effects of various experimental parameters on coating quality and deposition rate to obtain the optimized reaction parameters. The formulated samples under optimized parameters were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectra and optical microscopy. The best parameters, where uniform and maximum coating thickness was achieved, are etching with 20%NaOH for 30 min, sensitization and activation with SnCl2 and PdCl2 for 5 and 20 min, respectively. The composition of the copper solution bath was 16 g/L CuSO4＆#183;5H2O, 35 mL/L formaldehyde （HCHO）, 23 g/L KNaC4H4O6 at 60 ℃, pH=13 and stirring at （350±15） r/min under ultrasonication.展开更多
The welding joints of Zircaloy 4 plates obtained by diffusion welding at 800°C under pressure in vacuum were cracked during autoclave tests at 400°C superheated steam after exposure longer than 150 days. T...The welding joints of Zircaloy 4 plates obtained by diffusion welding at 800°C under pressure in vacuum were cracked during autoclave tests at 400°C superheated steam after exposure longer than 150 days. The section of specimens was examined by optical microscopy and the composition at the tips of cracking was analyzed by electron microprobe. The result shows that the combination of oxidation and hydriding induced cracking is responsible for this failure of the welding joints.展开更多
In order to investigate the effect of lanthanum ion implantation on theoxidation behavior of zircaloy at 500℃, Zircaloy specimens were implanted by lanthanum ions with adose range from 5xl0^(16) to 2xl0^(17) ions/cm^...In order to investigate the effect of lanthanum ion implantation on theoxidation behavior of zircaloy at 500℃, Zircaloy specimens were implanted by lanthanum ions with adose range from 5xl0^(16) to 2xl0^(17) ions/cm^2 at room temperature, and then oxidized at 500℃ for100 min. The valence of the oxides in the scale was analyzed by X-ray Photoelectron Spectroscopy(XPS). The phase structures of the oxides in the scale were examined by Glancing Angle X-rayDiffraction (GAXRD). With the increase of implanted lanthanum ions dose, the phase structures in theoxide scale are transformed from monoclinic zirconia to hexagonal one and then to monoclinic oneagain. The measurement of weight gain showed that a similar change from the decreased gain toincreased one again is achieved in the oxidation behavior of lanthanum ion implanted zircaloycompared with that of as-received zircaloy.展开更多
To investigate the degradation of corrosion resistance of Zircaloy-4 in LiOHaqueous solution, SIMS (secondary ion mass spectrometry) analysis was performed to examine theprofiles of Li^+, K^+, and OH^- in oxide layers...To investigate the degradation of corrosion resistance of Zircaloy-4 in LiOHaqueous solution, SIMS (secondary ion mass spectrometry) analysis was performed to examine theprofiles of Li^+, K^+, and OH^- in oxide layers formed in the same concentration (0.1 mol/L) LiOHand KOH solutions. Even though the oxide layers have an equal thickness, the pene-tration depth ofK^+ is shallower than that of Li^+, and the penetration depth of OH^- corroded in KOH solution isalso shal-ower than that corroded in LiOH solution. It shows that the diffusion of OH^- into oxidelayer is accompanied by the corresponding cation. The difference of degradation effect of LiOH andKOH solutions on the corrosion resistance of Zircaloy-4 was discussed.展开更多
In this work, hydrogen absorption and the permeation behavior of the passive layer formed on zircaloy-4 are in- vestigated. Potentiodynamic polarization, Mott-Schottky analysis, electrochemical impedance spectroscopy,...In this work, hydrogen absorption and the permeation behavior of the passive layer formed on zircaloy-4 are in- vestigated. Potentiodynamic polarization, Mott-Schottky analysis, electrochemical impedance spectroscopy, and Raman scattering spectroscopy are employed to characterize the passive defects before and after hydrogen permeation. It is found that the nanoscale passive ZrO2 films play an important role in the resistance against corrosion; hydrogen impingement, however, reduces the passive impedance towards hydrothermal oxidation. The increase of defects （vacancies） in passive film is probably attributed to the degradation. We believe that this finding will provide valuable insight into the understanding of the corrosion mechanism of zircaloys used in light water reactors.展开更多
Fatigue dislocation configurations of Zircaloy-4 at 470℃×1h stress-relieved condition and 620℃×1h recrystallized condition were analyzed using TEM. Theresults show that: {1 0 1 0} prismatic slip is the pri...Fatigue dislocation configurations of Zircaloy-4 at 470℃×1h stress-relieved condition and 620℃×1h recrystallized condition were analyzed using TEM. Theresults show that: {1 0 1 0} prismatic slip is the primary deformation mode at RT. Prismatic and pyramidal slips are activated simultaneously at 400℃. The typicalsubstructure is the elongated dislocation lines at RT; whereas at 400℃, it is rectangularcells in stress-relieved specimens, and elongated cells plus dipole perpendicular cellboundary in recrystallized specimens. The relationship map among dislocation configuration, test temperature and cyclic strain range is established, finally.展开更多
The microstructural evolution of zircaloy-4 was studied, including the amorphization and recrystallization of Zr（Fe, Cr）2 precipitates, and the density of dislocations under in situ Ne ion irradiation and post annea...The microstructural evolution of zircaloy-4 was studied, including the amorphization and recrystallization of Zr（Fe, Cr）2 precipitates, and the density of dislocations under in situ Ne ion irradiation and post annealing. The results show that irradiation at a relatively high temperature and dose induces the formation of nanocrystals in pre-amorphized Zr（Fe, Cr）2 precipitates. The recrystallized nanocrystals also have the structure of hcp-Zr（Fe, Cr）2. The formation of the nanocrystals is thought to be the consequence of competition between atomistic disordering and the recrystallization of precipitates under ion irradiation. The free energy of the nanocrystal is lower than that of the amorphous state, which is another reason for the recrystallization of the precipitates. With increased annealing temperature, the density of the nanocrystals is increased. The dislocation density sharply decreases with the increase in the annealing temperature, and its size increases.展开更多
Fatigue lifetime curves of Zircaloy-4 at different temperatures were measured, and the fatigued dislocation configurations were investigated using transmission electron microscopy. Ii was found that prismatic slip is ...Fatigue lifetime curves of Zircaloy-4 at different temperatures were measured, and the fatigued dislocation configurations were investigated using transmission electron microscopy. Ii was found that prismatic slip is the primary deformation mode. for Zircaloy-4fatigued at RT prismatic plus Pyramidal slip at 400℃,and prismatic plus (0001) basic slip at 600℃. The corresponding dislocation configurations are parallel dislocation lines al RT, elongated cells at 400℃ and two sets of mutually Perpendicular dislocation bands at 600℃.respectively. The relationship among. fatigue deformation mode, dislocation configuration and lifetime is discussed.展开更多
The precipitation process of zirconium hydrides induced by stress and strain was investigated by means of electron microscopy in-situ.The precipitating hydrides induced by stress were found to be γ phase with orienta...The precipitation process of zirconium hydrides induced by stress and strain was investigated by means of electron microscopy in-situ.The precipitating hydrides induced by stress were found to be γ phase with orientation relationship of (110)_γ‖(110)_(αZr),(001)_γ‖ (0001)_(αZr) between γ-hydrides and surrounding matrix.The growth rate of γ-hydrides which was much faster along [110] direction brought them in taper shape.After fracture of y-hydrides,a new one will precipitate at the tip of cracks.This is the essential process of hydrogen-induced delayed cracking in Zircaloy.The precipitating hydrides induced by strain were found to be δ phase with both orientation relationships of(111)_δ‖(0001)_(αZr),(110)_δ‖ (110)_(αZr) or (010)_δ‖(0001)_(αZr),(001)_δ‖(110)_(αZr)between δ-hydride and surrounding matrix.The δ-hydrides become much finer as the strain rate increased.展开更多
Zircaloy 4 was implanted with nitrogen at 120 keV with various ion doses between 1×10 13 and 1×10 14 ions/m 2. Fretting wear tests were performed at various cycles and loads under water immersion condition b...Zircaloy 4 was implanted with nitrogen at 120 keV with various ion doses between 1×10 13 and 1×10 14 ions/m 2. Fretting wear tests were performed at various cycles and loads under water immersion condition by the fretting simulator, The implanted surfaces were analyzed by Auger electron spectroscopy (AES) and transmission electron microscope (TEM). Micro hardness tester measured surface hardness. It is shown that nitrogen implantation produced Zirconium nitride oxide and high density dislocations in implanted layer, surface hardness was enhanced from HK280 for unimplanted specimen to HK1 800 for a total ion dose of 1×10 14 ions/m 2. The nitrogen ion implantation treatment provided significant improvements in the resistance of fretting damage.展开更多
In order to investigate the ion irradiation effect on the corrosion behavior and microstructure of Zircaloy-4, the Zircaloy-4 film were prepared by electron beam deposition on the Zircaloy-4 specimen surface and irra...In order to investigate the ion irradiation effect on the corrosion behavior and microstructure of Zircaloy-4, the Zircaloy-4 film were prepared by electron beam deposition on the Zircaloy-4 specimen surface and irradiated by Kr ions using an accelerator at an energy of 300 keV with the dose from 1×1015 to 3×1016ions/cm2. The post-irradiation corrosion tests were conducted to rank the corrosion resistance of the resulting specimens by potentiodynamic polarization curve measurements in a 0.5 mol/L H2SO4 water so- lution at room temperature. Transmission electron microscopy (TEM) was employed to examine the microstructural change in the surface. The potentiodynamic tests show that with the irradiation dose increasing, the passive current density, closely related to the surface corrosion resistance, decreases firstly and increases subsequently. The mechanism of the corrosion behavior transformation is due to the amorphous phase formation firstly and the amorphous phase destruction and the polycrystalline structure formation in the irradiated surface subsequently.展开更多
In the present work, the expansion coefficient due to hydrogen incorporation was measured for the axial direction of a Zircaloy-4 cooling channel, similar to that installed in the Atucha I PHWR, Argentina, trying to s...In the present work, the expansion coefficient due to hydrogen incorporation was measured for the axial direction of a Zircaloy-4 cooling channel, similar to that installed in the Atucha I PHWR, Argentina, trying to simulate the nuclear power reactor operating conditions. As a first step, the solubility curve of hydrogen in Zircloy-4 was determined by two techniques: differential scanning calorimetry and differential dilatometry. The comparison with classical literature curves showed a good agreement with them, although the calorimetric technique proved to be more accurate for these determinations. Dilatometry was able to detect the end of hydride dissolution from concentrations around 60 wppm-H up to 650 wppm-H, where the eutectoid reaction: α + δ→α + β takes place (at 550oC). We assume that this ability is a good indicator of the aptitude of the technique to measure dimensional changes in the given hydrogen concentration range. Then, the expansion of Zircaloy-4 homogeneously hydrided samples was measured at 300oC, the typical operating temperature of a nuclear power reactor, obtaining a relative expansion of 2.21 * 10-4% per wppm-H. Considering the relative expansion observed for Zircaloy-4 at room temperature due to hydriding, starting from a hydrogen free sample, the total relative expansion rate is calculated to be 5.21 * 10-4% per wppm-H.展开更多
The specimens were implanted with aluminum ions with fluence ranging from 1× 10^16 to 1× 10^17 ions/cm^2 to study the effect of aluminum ion implantation on the aqueous corrosion behavior of zircaloy-2 by me...The specimens were implanted with aluminum ions with fluence ranging from 1× 10^16 to 1× 10^17 ions/cm^2 to study the effect of aluminum ion implantation on the aqueous corrosion behavior of zircaloy-2 by metal vapor vacuum arc source （MEVVA） at an extraction voltage of 40 kV. The valence states and depth distributions of elements in the surface layer of the samples were analyzed by X-ray photoelectron spectroscopy （XPS） and Auger electron spectroscopy （AES）, respectively. Transmission electron microscopy （TEM） was used to examine the microstructure of the aluminum-implanted samples. Glancing angle X-ray diffraction （GAXRD） was employed to examine the phase transformation due to the aluminum ion implantation. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted zircaloy-2 in a 1 M H2SO4 solution. It is found that a significant improvement was achieved in the aqueous corrosion resistance of zircaloy-2 implanted with aluminum ions. Finally, the mechanism of the corrosion behavior of aluminum- implanted zircaloy-2 was discussed.展开更多
To simulate irradiation damage, argon ion was implanted in the Zircaloy-4 with the fluence ranging from 1 × 10^16 to 1 × 10^17 cm^-2, using accelerating implanter at an extraction voltage of 190 kV and liqui...To simulate irradiation damage, argon ion was implanted in the Zircaloy-4 with the fluence ranging from 1 × 10^16 to 1 × 10^17 cm^-2, using accelerating implanter at an extraction voltage of 190 kV and liquid nitrogen temperature. Then the influence of argon ion implantation on the aqueous corrosion behavior of Zircaloy-4 was studied. The valence states of elements in the surface layer of the samples were analyzed using X-ray photoelectron spectroscopy （XPS）. Transmission electron microscopy （TEM） was used to examine the microstructure of the argon-implanted samples. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted Zircaloy-4 in 1 mol/L HzSO4 solution. It is found that there appear bubbles on the surface of the samples when the argon fluence is 1 × 10^16 cm^-2. The microstructure of argon-implanted samples changes from amorphous to partial amorphous, then to polycrystalline, and again to amorphous. The corrosion resistance of implanted samples linearly declines with the increase of fluence approximately, which is attributed to the linear increase of the irradiation damage.展开更多
The zircaloy-4 is an alloy of zirconium, which has a very weak thermal neutron absorption, satisfactory mechanical properties and good corrosion resistance at high temperature. For these reasons, zircaloy-4 is used as...The zircaloy-4 is an alloy of zirconium, which has a very weak thermal neutron absorption, satisfactory mechanical properties and good corrosion resistance at high temperature. For these reasons, zircaloy-4 is used as a material of cladding fuel rod of nuclear reactors. In this environment, it is submitted to different severe conditions of temperature and pressure. The objective of this work is to study the oxidation kinetics of zircaloy-4 in air by the X-ray diffraction technique. The experiments were realized in a “HTK1200” furnace installed as a sample holder in the diffractometer at different temperatures;25°C, 350°C, 500°C, 830°C and 1000°C. The results show that the monoclinic and the tetragonal phases are formed at 350°C temperature. The volume fraction of these phases increased with the temperature until 1000°C where the α phase disappears completely. For simulating the case of loss-of-coolant-accident (LOCA), we have done x-ray diffraction of Zry-4 samples water quenched at 1050°C with different ageing times at this temperature. At 10 seconds and more, there is an important evolution of monoclinic and tetragonal zirconias, which leads to the degradation of zircaloy-4 properties.展开更多
基金Project(9140A12060110BQ03)supported by the National Key Laboratory of Science and Technology on Materials under Shock and Impact,China
文摘Electroless copper plating on diamond particles precoated with 1%Cr was carried out to evaluate the effects of various experimental parameters on coating quality and deposition rate to obtain the optimized reaction parameters. The formulated samples under optimized parameters were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectra and optical microscopy. The best parameters, where uniform and maximum coating thickness was achieved, are etching with 20%NaOH for 30 min, sensitization and activation with SnCl2 and PdCl2 for 5 and 20 min, respectively. The composition of the copper solution bath was 16 g/L CuSO4＆#183;5H2O, 35 mL/L formaldehyde （HCHO）, 23 g/L KNaC4H4O6 at 60 ℃, pH=13 and stirring at （350±15） r/min under ultrasonication.
文摘The welding joints of Zircaloy 4 plates obtained by diffusion welding at 800°C under pressure in vacuum were cracked during autoclave tests at 400°C superheated steam after exposure longer than 150 days. The section of specimens was examined by optical microscopy and the composition at the tips of cracking was analyzed by electron microprobe. The result shows that the combination of oxidation and hydriding induced cracking is responsible for this failure of the welding joints.
文摘In order to investigate the effect of lanthanum ion implantation on theoxidation behavior of zircaloy at 500℃, Zircaloy specimens were implanted by lanthanum ions with adose range from 5xl0^(16) to 2xl0^(17) ions/cm^2 at room temperature, and then oxidized at 500℃ for100 min. The valence of the oxides in the scale was analyzed by X-ray Photoelectron Spectroscopy(XPS). The phase structures of the oxides in the scale were examined by Glancing Angle X-rayDiffraction (GAXRD). With the increase of implanted lanthanum ions dose, the phase structures in theoxide scale are transformed from monoclinic zirconia to hexagonal one and then to monoclinic oneagain. The measurement of weight gain showed that a similar change from the decreased gain toincreased one again is achieved in the oxidation behavior of lanthanum ion implanted zircaloycompared with that of as-received zircaloy.
基金This work was financially supported by the National Natural Science Foundation of China (Nos. 50301009 and 50171039)the Education Development Foundation of Shanghai (No. 03AK24)
文摘To investigate the degradation of corrosion resistance of Zircaloy-4 in LiOHaqueous solution, SIMS (secondary ion mass spectrometry) analysis was performed to examine theprofiles of Li^+, K^+, and OH^- in oxide layers formed in the same concentration (0.1 mol/L) LiOHand KOH solutions. Even though the oxide layers have an equal thickness, the pene-tration depth ofK^+ is shallower than that of Li^+, and the penetration depth of OH^- corroded in KOH solution isalso shal-ower than that corroded in LiOH solution. It shows that the diffusion of OH^- into oxidelayer is accompanied by the corresponding cation. The difference of degradation effect of LiOH andKOH solutions on the corrosion resistance of Zircaloy-4 was discussed.
基金Project supported by the National Basic Research Program of China(Grant No.2011CB610501)the Funds from the State Key Laboratory of Surface and Chemistry,China(Grant No.SPC 201102)the Reactor Fuel and Materials Laboratory,China(Grant No.STRFML-2013-05)
文摘In this work, hydrogen absorption and the permeation behavior of the passive layer formed on zircaloy-4 are in- vestigated. Potentiodynamic polarization, Mott-Schottky analysis, electrochemical impedance spectroscopy, and Raman scattering spectroscopy are employed to characterize the passive defects before and after hydrogen permeation. It is found that the nanoscale passive ZrO2 films play an important role in the resistance against corrosion; hydrogen impingement, however, reduces the passive impedance towards hydrothermal oxidation. The increase of defects （vacancies） in passive film is probably attributed to the degradation. We believe that this finding will provide valuable insight into the understanding of the corrosion mechanism of zircaloys used in light water reactors.
文摘Fatigue dislocation configurations of Zircaloy-4 at 470℃×1h stress-relieved condition and 620℃×1h recrystallized condition were analyzed using TEM. Theresults show that: {1 0 1 0} prismatic slip is the primary deformation mode at RT. Prismatic and pyramidal slips are activated simultaneously at 400℃. The typicalsubstructure is the elongated dislocation lines at RT; whereas at 400℃, it is rectangularcells in stress-relieved specimens, and elongated cells plus dipole perpendicular cellboundary in recrystallized specimens. The relationship map among dislocation configuration, test temperature and cyclic strain range is established, finally.
基金Project supported by the Key Laboratory of Neutron Physics of China Academy of Engineering Physics(Grant No.2012AB02)the Fundamental Research Funds for the Central Universities of China(Grant No.ZYGX2012YB017)the Major Program of the National Natural Science Foundation of China(Grant No.91126001)
文摘The microstructural evolution of zircaloy-4 was studied, including the amorphization and recrystallization of Zr（Fe, Cr）2 precipitates, and the density of dislocations under in situ Ne ion irradiation and post annealing. The results show that irradiation at a relatively high temperature and dose induces the formation of nanocrystals in pre-amorphized Zr（Fe, Cr）2 precipitates. The recrystallized nanocrystals also have the structure of hcp-Zr（Fe, Cr）2. The formation of the nanocrystals is thought to be the consequence of competition between atomistic disordering and the recrystallization of precipitates under ion irradiation. The free energy of the nanocrystal is lower than that of the amorphous state, which is another reason for the recrystallization of the precipitates. With increased annealing temperature, the density of the nanocrystals is increased. The dislocation density sharply decreases with the increase in the annealing temperature, and its size increases.
文摘Fatigue lifetime curves of Zircaloy-4 at different temperatures were measured, and the fatigued dislocation configurations were investigated using transmission electron microscopy. Ii was found that prismatic slip is the primary deformation mode. for Zircaloy-4fatigued at RT prismatic plus Pyramidal slip at 400℃,and prismatic plus (0001) basic slip at 600℃. The corresponding dislocation configurations are parallel dislocation lines al RT, elongated cells at 400℃ and two sets of mutually Perpendicular dislocation bands at 600℃.respectively. The relationship among. fatigue deformation mode, dislocation configuration and lifetime is discussed.
文摘The precipitation process of zirconium hydrides induced by stress and strain was investigated by means of electron microscopy in-situ.The precipitating hydrides induced by stress were found to be γ phase with orientation relationship of (110)_γ‖(110)_(αZr),(001)_γ‖ (0001)_(αZr) between γ-hydrides and surrounding matrix.The growth rate of γ-hydrides which was much faster along [110] direction brought them in taper shape.After fracture of y-hydrides,a new one will precipitate at the tip of cracks.This is the essential process of hydrogen-induced delayed cracking in Zircaloy.The precipitating hydrides induced by strain were found to be δ phase with both orientation relationships of(111)_δ‖(0001)_(αZr),(110)_δ‖ (110)_(αZr) or (010)_δ‖(0001)_(αZr),(001)_δ‖(110)_(αZr)between δ-hydride and surrounding matrix.The δ-hydrides become much finer as the strain rate increased.
文摘Zircaloy 4 was implanted with nitrogen at 120 keV with various ion doses between 1×10 13 and 1×10 14 ions/m 2. Fretting wear tests were performed at various cycles and loads under water immersion condition by the fretting simulator, The implanted surfaces were analyzed by Auger electron spectroscopy (AES) and transmission electron microscope (TEM). Micro hardness tester measured surface hardness. It is shown that nitrogen implantation produced Zirconium nitride oxide and high density dislocations in implanted layer, surface hardness was enhanced from HK280 for unimplanted specimen to HK1 800 for a total ion dose of 1×10 14 ions/m 2. The nitrogen ion implantation treatment provided significant improvements in the resistance of fretting damage.
文摘In order to investigate the ion irradiation effect on the corrosion behavior and microstructure of Zircaloy-4, the Zircaloy-4 film were prepared by electron beam deposition on the Zircaloy-4 specimen surface and irradiated by Kr ions using an accelerator at an energy of 300 keV with the dose from 1×1015 to 3×1016ions/cm2. The post-irradiation corrosion tests were conducted to rank the corrosion resistance of the resulting specimens by potentiodynamic polarization curve measurements in a 0.5 mol/L H2SO4 water so- lution at room temperature. Transmission electron microscopy (TEM) was employed to examine the microstructural change in the surface. The potentiodynamic tests show that with the irradiation dose increasing, the passive current density, closely related to the surface corrosion resistance, decreases firstly and increases subsequently. The mechanism of the corrosion behavior transformation is due to the amorphous phase formation firstly and the amorphous phase destruction and the polycrystalline structure formation in the irradiated surface subsequently.
文摘In the present work, the expansion coefficient due to hydrogen incorporation was measured for the axial direction of a Zircaloy-4 cooling channel, similar to that installed in the Atucha I PHWR, Argentina, trying to simulate the nuclear power reactor operating conditions. As a first step, the solubility curve of hydrogen in Zircloy-4 was determined by two techniques: differential scanning calorimetry and differential dilatometry. The comparison with classical literature curves showed a good agreement with them, although the calorimetric technique proved to be more accurate for these determinations. Dilatometry was able to detect the end of hydride dissolution from concentrations around 60 wppm-H up to 650 wppm-H, where the eutectoid reaction: α + δ→α + β takes place (at 550oC). We assume that this ability is a good indicator of the aptitude of the technique to measure dimensional changes in the given hydrogen concentration range. Then, the expansion of Zircaloy-4 homogeneously hydrided samples was measured at 300oC, the typical operating temperature of a nuclear power reactor, obtaining a relative expansion of 2.21 * 10-4% per wppm-H. Considering the relative expansion observed for Zircaloy-4 at room temperature due to hydriding, starting from a hydrogen free sample, the total relative expansion rate is calculated to be 5.21 * 10-4% per wppm-H.
基金the National Natural Science Foundation of China (No.50501011, G 2000067207-1)Postdoctoral Research Foundation of China (37th batch, No.2005037079)
文摘The specimens were implanted with aluminum ions with fluence ranging from 1× 10^16 to 1× 10^17 ions/cm^2 to study the effect of aluminum ion implantation on the aqueous corrosion behavior of zircaloy-2 by metal vapor vacuum arc source （MEVVA） at an extraction voltage of 40 kV. The valence states and depth distributions of elements in the surface layer of the samples were analyzed by X-ray photoelectron spectroscopy （XPS） and Auger electron spectroscopy （AES）, respectively. Transmission electron microscopy （TEM） was used to examine the microstructure of the aluminum-implanted samples. Glancing angle X-ray diffraction （GAXRD） was employed to examine the phase transformation due to the aluminum ion implantation. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted zircaloy-2 in a 1 M H2SO4 solution. It is found that a significant improvement was achieved in the aqueous corrosion resistance of zircaloy-2 implanted with aluminum ions. Finally, the mechanism of the corrosion behavior of aluminum- implanted zircaloy-2 was discussed.
基金the National Nature Science Foundation of China(No.50501011)the Postdoctoral Research Foundation of China(No.2005037079)
文摘To simulate irradiation damage, argon ion was implanted in the Zircaloy-4 with the fluence ranging from 1 × 10^16 to 1 × 10^17 cm^-2, using accelerating implanter at an extraction voltage of 190 kV and liquid nitrogen temperature. Then the influence of argon ion implantation on the aqueous corrosion behavior of Zircaloy-4 was studied. The valence states of elements in the surface layer of the samples were analyzed using X-ray photoelectron spectroscopy （XPS）. Transmission electron microscopy （TEM） was used to examine the microstructure of the argon-implanted samples. The potentiodynamic polarization technique was employed to evaluate the aqueous corrosion resistance of implanted Zircaloy-4 in 1 mol/L HzSO4 solution. It is found that there appear bubbles on the surface of the samples when the argon fluence is 1 × 10^16 cm^-2. The microstructure of argon-implanted samples changes from amorphous to partial amorphous, then to polycrystalline, and again to amorphous. The corrosion resistance of implanted samples linearly declines with the increase of fluence approximately, which is attributed to the linear increase of the irradiation damage.
文摘The zircaloy-4 is an alloy of zirconium, which has a very weak thermal neutron absorption, satisfactory mechanical properties and good corrosion resistance at high temperature. For these reasons, zircaloy-4 is used as a material of cladding fuel rod of nuclear reactors. In this environment, it is submitted to different severe conditions of temperature and pressure. The objective of this work is to study the oxidation kinetics of zircaloy-4 in air by the X-ray diffraction technique. The experiments were realized in a “HTK1200” furnace installed as a sample holder in the diffractometer at different temperatures;25°C, 350°C, 500°C, 830°C and 1000°C. The results show that the monoclinic and the tetragonal phases are formed at 350°C temperature. The volume fraction of these phases increased with the temperature until 1000°C where the α phase disappears completely. For simulating the case of loss-of-coolant-accident (LOCA), we have done x-ray diffraction of Zry-4 samples water quenched at 1050°C with different ageing times at this temperature. At 10 seconds and more, there is an important evolution of monoclinic and tetragonal zirconias, which leads to the degradation of zircaloy-4 properties.
