Yuhai QIAN
,
Meishuan LI
材料科学技术（英文）
A kind of new deflection technique has been developed for measuring the growth stress of thermally growing oxide scales during high temperature oxidation of alloys. The average growth stresses in oxide scales such as Al2O3, NiO and Cr2O3 formed on the surface of the superalloys can be investigated by this technique. Unlike the conventional deflection method, the novel method does not need to apply a coating for preventing one main face of thin strip specimen from oxidizing and can be used under the condition of longer time and higher temperature.
关键词:
Oxide film
,
null
,
null
Weimin MAO
,
Dong LI
材料科学技术（英文）
The image stress of straight screw dislocations parallel to the medium surface covered by thin heterogeneous films was analyzed and deduced, in order to calculate the image shear stress. The relationship between image stress and distance from the screw dislocation to the interface of pure aluminum and its oxide covering was calculated based on the analysis. It was shown quantitatively that a sign conversion of the image stress appears in the case of thin oxide covering, while dislocation would pile up near the interface because of the possible slips of the screw dislocations induced by the image stress, which might break down the very thin oxide covering. Further investigation on edge dislocations or other dislocation configurations need to be done.
关键词:
Dislocation
,
null
,
null
,
null
,
null
,
null
,
null
A.A.El-Meligi
材料科学技术（英文）
Potentiodynamic polarisation, potential-time measurements, X-ray diffraction (XRD) and infrared spectroscopy (IR) have been used to investigate the effect of different concentrations of Na2SO4 in the absence and presence of NaCl, on the corrosion of Cu-alloy. The electrochemical measurements showed that the increase of Na2SO4 concentration led to increase the corrosion current density of Cu alloy and vice versa. The presence of NaCl shifted the potential to more cathodic potential, which had a great influence on the protectiveness of the Cu oxide layer formed on the surface in presence of Na2SO4. The spectrometric measurements indicated the constituents of the film formed on the alloy surface were mainly Cu2O, in addition to the oxides, NiO and Fe2O3, which were traced by XRD analysis.
关键词:
Cu-alloy
,
null
,
null
,
null
,
null
,
null
Fu LIU
,
Fuping WANG
,
Tadao Shimizu
,
Kaoru Igarashi
,
Liancheng ZHAO
材料科学技术（英文）
The ceramic coating was formed by using microarc oxidation (MAO) in the electrolytic solution of β-Glycerophosphate sodium salt pentahydrate (β-GP) and calcium acetate (CA). The microstructure, phase structure and phase composition were investigated with scanning electron microscopy (SEM), atomic force microscope (AFM), energy dispersive X-ray microanalyser (EDX), X-ray photoelectron spectroscopy (XPS), electron probe micro analyzer (EPMA) and X-ray diffraction (XRD). Investigation of the chemical composition of the coating with EDX revealed that Ca and P of high concentration existed in oxide films. XRD patterns indicated that the oxide film was composed of only anatase at low voltage discharge, and that rutile peaks appear in addition to anatase peak with increasing MAO voltage. Despite the existence of Ca and P, compounds concerning Ca and P were not detected in the oxide film.
关键词:
Microarc oxidation
,
null
,
null
