Observation and measurement were conducted to investigate contact angle andits hysteresis on rough surface. The experimental results indicate that the increase in solidsurface roughness enlarges advancing contact angl...Observation and measurement were conducted to investigate contact angle andits hysteresis on rough surface. The experimental results indicate that the increase in solidsurface roughness enlarges advancing contact angle and decreases receding contact angle, resultingin enhanced hysteresis. It was observed that when Young''s contact angle θ_Y 【 90°, as theroughness of solid surface increased the extent of the decrease in receding contact angle exceededthat of the increase in advancing contact angle. Based on the experimental observations, the conceptof hysteresis tension was introduced to describe the contact angle hysteresis behavior on roughsolid surface. The model provides a thoughtful understanding of the physical nature of contact anglehysteresis, in particular an instructive description of the influence of surface roughness on thehysteresis. The prediction of the model is found in quite good agreement with the experimentalobservation and measurement.展开更多
All position MAG welding is widely applied in pipeline processing. Whereas, welding defects easily happen when welding current is beyond 200 A. In this paper, the force equilibrium condition and influence mechanism of...All position MAG welding is widely applied in pipeline processing. Whereas, welding defects easily happen when welding current is beyond 200 A. In this paper, the force equilibrium condition and influence mechanism of weld pool instability were discussed. Using the hysteresis tension theory on liquid interface, the radial and tangential force imposing on weld pool was analyzed to obtain the mechanical instability criterion on weld pool formation. The criterion provides a good explanation for those corresponding measures promoting weld pool formation in practice.展开更多
文摘Observation and measurement were conducted to investigate contact angle andits hysteresis on rough surface. The experimental results indicate that the increase in solidsurface roughness enlarges advancing contact angle and decreases receding contact angle, resultingin enhanced hysteresis. It was observed that when Young''s contact angle θ_Y 【 90°, as theroughness of solid surface increased the extent of the decrease in receding contact angle exceededthat of the increase in advancing contact angle. Based on the experimental observations, the conceptof hysteresis tension was introduced to describe the contact angle hysteresis behavior on roughsolid surface. The model provides a thoughtful understanding of the physical nature of contact anglehysteresis, in particular an instructive description of the influence of surface roughness on thehysteresis. The prediction of the model is found in quite good agreement with the experimentalobservation and measurement.
基金Supported by the National Natural Science Foundation of China （ No. 51075299）, Natural Science Foundation of Tianjin （ No. 10JCZDJC23500） and Key Technologies R＆D Program of Tianjin （No. 10ZCKFGX03900）.
文摘All position MAG welding is widely applied in pipeline processing. Whereas, welding defects easily happen when welding current is beyond 200 A. In this paper, the force equilibrium condition and influence mechanism of weld pool instability were discussed. Using the hysteresis tension theory on liquid interface, the radial and tangential force imposing on weld pool was analyzed to obtain the mechanical instability criterion on weld pool formation. The criterion provides a good explanation for those corresponding measures promoting weld pool formation in practice.
