Effects of jet velocity,sand concentration and impingement angle on the surface roughness of Al-brass alloy were investigated after erosion and erosion?corrosion tests.The tests were performed using a jet impingement ...Effects of jet velocity,sand concentration and impingement angle on the surface roughness of Al-brass alloy were investigated after erosion and erosion?corrosion tests.The tests were performed using a jet impingement rig.The eroded surfaces were characterized using2-D and3-D surface profilometery and scanning electron microscopy(SEM).The results showed that there was an increase in the surface roughness of the erosion?corrosion samples as sand concentration was increased to1,5and10g/L at jet velocities of9,6and3m/s,respectively.However,the surface roughness decreased with a further increase in sand concentration.This decrease in the surface roughness was attributed to the higher work hardening of the surface,rebounding or blanketing effect and very high frequency of the impacts at the higher sand concentrations.The surface roughness increased as the jet velocity increased.The results also showed that the change in the surface roughness with impingement angle was not significant at two jet velocities of3and6m/s.However,at a higher jet velocity of9m/s,formation of ripples on the erosion surfaces at oblique angles resulted in a higher surface roughness as compared with the normal impingement angle.展开更多
The corrosion behaviors of Al-brass in stagnant and flowing marine water as a function of combinative rare earths （Ce and La） ad-dition were investigated by electrochemical techniques, X-ray diffraction （XRD） and ...The corrosion behaviors of Al-brass in stagnant and flowing marine water as a function of combinative rare earths （Ce and La） ad-dition were investigated by electrochemical techniques, X-ray diffraction （XRD） and scanning electron microscopy （SEM）. It was demon-strated that RE elements could make the corrosion product layer more protective and strengthen the cohesion between the film and matrix in stagnant seawater. The electrochemical impedance spectroscopy （EIS） and scanning electron microscopy （SEM） analysis confirmed that a duplex layer, which was mainly composed of an inner Al2O3 with trace amounts of RE compounds and an outer basic chloride of copper or zinc like （Cu, Zn）2Cl（OH）3, Cu（OH）Cl and CuCl2·3Cu（OH）2 layer was formed on RE-contained Al-brass surface and that the inner layer was responsible for the good corrosion resistance of the alloy. While only a porous and non-protective corrosion product layer was formed on the Al-brass alloy without RE addition, which made small values of the corrosion resistance. Additionally, in flowing marine water with velocity about 2 m/s, pitting corrosion occurred on the Al-brass surface and RE addition could availably decrease pitting sensitivity of the alloy.展开更多
文摘Effects of jet velocity,sand concentration and impingement angle on the surface roughness of Al-brass alloy were investigated after erosion and erosion?corrosion tests.The tests were performed using a jet impingement rig.The eroded surfaces were characterized using2-D and3-D surface profilometery and scanning electron microscopy(SEM).The results showed that there was an increase in the surface roughness of the erosion?corrosion samples as sand concentration was increased to1,5and10g/L at jet velocities of9,6and3m/s,respectively.However,the surface roughness decreased with a further increase in sand concentration.This decrease in the surface roughness was attributed to the higher work hardening of the surface,rebounding or blanketing effect and very high frequency of the impacts at the higher sand concentrations.The surface roughness increased as the jet velocity increased.The results also showed that the change in the surface roughness with impingement angle was not significant at two jet velocities of3and6m/s.However,at a higher jet velocity of9m/s,formation of ripples on the erosion surfaces at oblique angles resulted in a higher surface roughness as compared with the normal impingement angle.
基金supported by the Science and Technology Payoffs Transformation Program of Jiangsu Province (DA2006034)the Program of National College Student Creative Experiment (081053309)
文摘The corrosion behaviors of Al-brass in stagnant and flowing marine water as a function of combinative rare earths （Ce and La） ad-dition were investigated by electrochemical techniques, X-ray diffraction （XRD） and scanning electron microscopy （SEM）. It was demon-strated that RE elements could make the corrosion product layer more protective and strengthen the cohesion between the film and matrix in stagnant seawater. The electrochemical impedance spectroscopy （EIS） and scanning electron microscopy （SEM） analysis confirmed that a duplex layer, which was mainly composed of an inner Al2O3 with trace amounts of RE compounds and an outer basic chloride of copper or zinc like （Cu, Zn）2Cl（OH）3, Cu（OH）Cl and CuCl2·3Cu（OH）2 layer was formed on RE-contained Al-brass surface and that the inner layer was responsible for the good corrosion resistance of the alloy. While only a porous and non-protective corrosion product layer was formed on the Al-brass alloy without RE addition, which made small values of the corrosion resistance. Additionally, in flowing marine water with velocity about 2 m/s, pitting corrosion occurred on the Al-brass surface and RE addition could availably decrease pitting sensitivity of the alloy.
