Comparative studies on the relationship between the welding parameters and joining efficiency in the friction welding of hybrid Al203-reinforced aluminum composites were conducted. Metal matrix composites （MMCs） wit...Comparative studies on the relationship between the welding parameters and joining efficiency in the friction welding of hybrid Al203-reinforced aluminum composites were conducted. Metal matrix composites （MMCs） with 37% （volume fraction） aluminum particle were joined by friction welding. The results show that the effects of the rotation speed on the reduction rate of particle size are greater than those of the upset pressure, and the area of the MMC weld zone decreases as the joining efficiency increases, while it is considered that the joining efficiency does not increase as the reduction rate of particle size decreases. During the macro-examination of the bonding interlace, a gray discolored region was observed on the bonding interface, and the center of the region was dark gray. After the micro-examination of the bonding interface, base metal made some second particulate formed by condensed alumina particulate but discoloration part distributed minute alumina particulate without second particulate. Consequently, it was also observed that rotational speed of 3 000 r/min and upset pressure of 63.6 MPa showed a very good.joint.展开更多
The aim of this work was to carry out a sensitivity analysis of a valve recession model. For the sensitivity study, the effects of the parameters on the valve recession model were investigated, for both, light duty an...The aim of this work was to carry out a sensitivity analysis of a valve recession model. For the sensitivity study, the effects of the parameters on the valve recession model were investigated, for both, light duty and heavy duty engines. For light duty engines, it was observed that the impact wear of component parameters had the greatest effect on valve recession and for heavy duty engines, the sliding wear of component parameters had an increasing contribution to the overall valve recession.展开更多
The aim of this work was to investigate the sliding wear coefficient k, using an experimental sliding wear study on the valve-seat insert contact. Commercial inlet valve and seat inserts were used as test specimens. T...The aim of this work was to investigate the sliding wear coefficient k, using an experimental sliding wear study on the valve-seat insert contact. Commercial inlet valve and seat inserts were used as test specimens. The tests were performed at room temperature and at 200℃, using test duration of 72,000 cycles and 18,000 cycles, respectively, and both in dry sliding conditions. A load of 5 N, an average speed of 22 mm/s and sliding distance of 2.2 mm were used for all tests. The sliding wear coefficients were calculated using experimental and analytical methods. The wear volume was higher in the tests at 200℃ both in valve and seat insert specimens. The principal wear mechanisms observed in valve specimen were oxidation and abrasion.展开更多
基金Project (2010-0008-277) partly supported by the National Core Research Center Program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology
文摘Comparative studies on the relationship between the welding parameters and joining efficiency in the friction welding of hybrid Al203-reinforced aluminum composites were conducted. Metal matrix composites （MMCs） with 37% （volume fraction） aluminum particle were joined by friction welding. The results show that the effects of the rotation speed on the reduction rate of particle size are greater than those of the upset pressure, and the area of the MMC weld zone decreases as the joining efficiency increases, while it is considered that the joining efficiency does not increase as the reduction rate of particle size decreases. During the macro-examination of the bonding interlace, a gray discolored region was observed on the bonding interface, and the center of the region was dark gray. After the micro-examination of the bonding interface, base metal made some second particulate formed by condensed alumina particulate but discoloration part distributed minute alumina particulate without second particulate. Consequently, it was also observed that rotational speed of 3 000 r/min and upset pressure of 63.6 MPa showed a very good.joint.
文摘The aim of this work was to carry out a sensitivity analysis of a valve recession model. For the sensitivity study, the effects of the parameters on the valve recession model were investigated, for both, light duty and heavy duty engines. For light duty engines, it was observed that the impact wear of component parameters had the greatest effect on valve recession and for heavy duty engines, the sliding wear of component parameters had an increasing contribution to the overall valve recession.
文摘The aim of this work was to investigate the sliding wear coefficient k, using an experimental sliding wear study on the valve-seat insert contact. Commercial inlet valve and seat inserts were used as test specimens. The tests were performed at room temperature and at 200℃, using test duration of 72,000 cycles and 18,000 cycles, respectively, and both in dry sliding conditions. A load of 5 N, an average speed of 22 mm/s and sliding distance of 2.2 mm were used for all tests. The sliding wear coefficients were calculated using experimental and analytical methods. The wear volume was higher in the tests at 200℃ both in valve and seat insert specimens. The principal wear mechanisms observed in valve specimen were oxidation and abrasion.
