To investigate the fretting wear of steel wires in hoisting ropes, specimenswere made of 6X19 point contact ropes. A model for the fretting ear was developed and a frettingwear test rig was deigned in laboratory. A se...To investigate the fretting wear of steel wires in hoisting ropes, specimenswere made of 6X19 point contact ropes. A model for the fretting ear was developed and a frettingwear test rig was deigned in laboratory. A series of experiments were performed on this test rig.The wear volume was taken as a characteristic parameter to describe the fretting wear in relation tothe contact load, reciprocating cycles and amplitude. Moreover, the wear mechanisms were discussedin the fretting process.展开更多
Caterpillar construction machines play an important part in many fields such as hydraulic and electric engineering, the construction of highway, for its particular of structure. The walking system of caterpillar const...Caterpillar construction machines play an important part in many fields such as hydraulic and electric engineering, the construction of highway, for its particular of structure. The walking system of caterpillar construction machines is always under the condition of three-body abrasive wear. The abrasive wear of walking system is very severe, which always results in damages of components or structures of walking system of caterpillar construction machines. It is very important to repair the walking system by cladding technique. The abrasive wear properties of four kinds coatings produced by the shielded flux-cored wire surfacing for the repair of the damaged components of walking system of caterpillar construction machines have been studied experimentally on an MLS-23 type wet sand rubber wheel abrasive tester. The surfaces morphologies of the abrasively worn specimens and their microstructures are investigated by transmitting electron microscopy (TEM) after wear testing. Results show that the wear mechanism of cladding metals of the flux-cored wire No.1 and the No.2 is micro-cutting while that of the No.3 and the No.4 is micro-ploughing. The four kinds of flux-cored wire coatings present great potential applications for the repairing of caterpillar construction machines in the Three Gorges Engineering.展开更多
The suitable test equipment for wire-drawing was designed. Wire-drawing tests were carried on with this equipment for TiC/Al2O3 ceramic wire-drawing die. Effect of lubrication medium and drawing velocity on the drawin...The suitable test equipment for wire-drawing was designed. Wire-drawing tests were carried on with this equipment for TiC/Al2O3 ceramic wire-drawing die. Effect of lubrication medium and drawing velocity on the drawing force was investigated. The wear mechanisms of the ceramic drawing dies were investigated. Worn bore surfaces of the ceramic drawing dies were examined by scanning electron microscopy. The results show that lubricant media have great influence on the drawing force. The drawing force is the smallest when a grease lubricant is used. But alteration of drawing velocity has scarcely any influence on the drawing force. Detailed observations and analyses of the die wear surface reveal that the most common failure of the ceramic drawing die is the wear in the invariable zone and bearing zone owing to the greater press stresses. Abrasive and adhesive wear are found to be the predominant wear mechanisms for ceramic drawing die.展开更多
It is expected that the welding hardfacing of continuous casting rolls has better welding performance and higher wear resistance. A new type of submerged-arc hardfacing flux-cored wire has been developed through nitro...It is expected that the welding hardfacing of continuous casting rolls has better welding performance and higher wear resistance. A new type of submerged-arc hardfacing flux-cored wire has been developed through nitrogen replacing part of carbon and addition of the nitrogen-fixing elements of niobium and titanium. And microstructure, degree of hardness and high-temperature wear resistance of its deposited metal samples were also investigated. It is found that the microstructure is martensite, residual austenite and carbonitride precipitates. As a result, the hardfacing metal with homogeneous distribution of very fine carbonitride particles had high hardness and excellent wear-re- sisting property during high-temperature wear, which could significantly extend the service life of continuous casting rolls.展开更多
The influence of Nb on the microstructure and wear resistance of the surfacing layer was investigated by using the Fe-based flux-cored wire in the Fe-Cr-C-B system. The microstructure, microhardness and wear resistanc...The influence of Nb on the microstructure and wear resistance of the surfacing layer was investigated by using the Fe-based flux-cored wire in the Fe-Cr-C-B system. The microstructure, microhardness and wear resistance properties of the samples were investigated by X-ray diffraction, scanning electron microscopy, microhardness testing and abrasive wear testing, respectively. The results indicate that microstructures of the alloy are composed of martensite, retained austenite, M23（C,B）6 and NbC. Boride M23（C,B）6 is distributed along the grain boundaries, while NbC in shape-regular quadrilateral is distributed in martensite. The microhardness is distributed from the substrate to the surfacing layer gradiently. NbC significantly improved the wear resistance of surfacing layer.展开更多
The ultrasonic wedge bonding with d25 μm copper wire was achieved on Au/Ni plated Cu substrate at ambient temperature.Ultrasonic wedge bonding mechanism was investigated by using SEM/EDX,pull test,shear test and micr...The ultrasonic wedge bonding with d25 μm copper wire was achieved on Au/Ni plated Cu substrate at ambient temperature.Ultrasonic wedge bonding mechanism was investigated by using SEM/EDX,pull test,shear test and microhardness test.The results show that the thinning of the Au layer occurs directly below the center of the bonding tool with the bonding power increasing.The interdiffusion between copper wire and Au metallization during the wedge bonding is assumed negligible,and the wedge bonding is achieved by wear action induced by ultrasonic vibration.The ultrasonic power contributes to enhance the deformation of copper wire due to ultrasonic softening effect which is then followed by the strain hardening of the copper wedge bonding.展开更多
基金This work was financially supported by the Ministry of Coal Industry, China(the Research Foundation of Mining Science) and the L
文摘To investigate the fretting wear of steel wires in hoisting ropes, specimenswere made of 6X19 point contact ropes. A model for the fretting ear was developed and a frettingwear test rig was deigned in laboratory. A series of experiments were performed on this test rig.The wear volume was taken as a characteristic parameter to describe the fretting wear in relation tothe contact load, reciprocating cycles and amplitude. Moreover, the wear mechanisms were discussedin the fretting process.
文摘Caterpillar construction machines play an important part in many fields such as hydraulic and electric engineering, the construction of highway, for its particular of structure. The walking system of caterpillar construction machines is always under the condition of three-body abrasive wear. The abrasive wear of walking system is very severe, which always results in damages of components or structures of walking system of caterpillar construction machines. It is very important to repair the walking system by cladding technique. The abrasive wear properties of four kinds coatings produced by the shielded flux-cored wire surfacing for the repair of the damaged components of walking system of caterpillar construction machines have been studied experimentally on an MLS-23 type wet sand rubber wheel abrasive tester. The surfaces morphologies of the abrasively worn specimens and their microstructures are investigated by transmitting electron microscopy (TEM) after wear testing. Results show that the wear mechanism of cladding metals of the flux-cored wire No.1 and the No.2 is micro-cutting while that of the No.3 and the No.4 is micro-ploughing. The four kinds of flux-cored wire coatings present great potential applications for the repairing of caterpillar construction machines in the Three Gorges Engineering.
基金Project(B0614) supported by the Natural Science Foundation of University of Jinan, ChinaProject(20030422105) supported by the Specialized Research Fund for Doctoral Program of Higher Education, China+1 种基金Project(Y2004F08) supported by the Natural Science Foundation of Shandong Province, ChinaProject(NCET-04-0622) supported by the Program for New Century Excellent Talents in University, China.
文摘The suitable test equipment for wire-drawing was designed. Wire-drawing tests were carried on with this equipment for TiC/Al2O3 ceramic wire-drawing die. Effect of lubrication medium and drawing velocity on the drawing force was investigated. The wear mechanisms of the ceramic drawing dies were investigated. Worn bore surfaces of the ceramic drawing dies were examined by scanning electron microscopy. The results show that lubricant media have great influence on the drawing force. The drawing force is the smallest when a grease lubricant is used. But alteration of drawing velocity has scarcely any influence on the drawing force. Detailed observations and analyses of the die wear surface reveal that the most common failure of the ceramic drawing die is the wear in the invariable zone and bearing zone owing to the greater press stresses. Abrasive and adhesive wear are found to be the predominant wear mechanisms for ceramic drawing die.
基金Item Sponsored by National Natural Science Foundation of China (51101050)Fundamental Research Funds for Central Universities of China (2009B30214)Natural Science Foundation of Jiangsu Province of China (BK2011257)
文摘It is expected that the welding hardfacing of continuous casting rolls has better welding performance and higher wear resistance. A new type of submerged-arc hardfacing flux-cored wire has been developed through nitrogen replacing part of carbon and addition of the nitrogen-fixing elements of niobium and titanium. And microstructure, degree of hardness and high-temperature wear resistance of its deposited metal samples were also investigated. It is found that the microstructure is martensite, residual austenite and carbonitride precipitates. As a result, the hardfacing metal with homogeneous distribution of very fine carbonitride particles had high hardness and excellent wear-re- sisting property during high-temperature wear, which could significantly extend the service life of continuous casting rolls.
文摘The influence of Nb on the microstructure and wear resistance of the surfacing layer was investigated by using the Fe-based flux-cored wire in the Fe-Cr-C-B system. The microstructure, microhardness and wear resistance properties of the samples were investigated by X-ray diffraction, scanning electron microscopy, microhardness testing and abrasive wear testing, respectively. The results indicate that microstructures of the alloy are composed of martensite, retained austenite, M23（C,B）6 and NbC. Boride M23（C,B）6 is distributed along the grain boundaries, while NbC in shape-regular quadrilateral is distributed in martensite. The microhardness is distributed from the substrate to the surfacing layer gradiently. NbC significantly improved the wear resistance of surfacing layer.
基金Prpject(E052104/50705021)supported by the National Natural Science Foundation of ChinaProject(2006:01504489)supported by the Development Program for Outstanding Young Teachers in HIT
文摘The ultrasonic wedge bonding with d25 μm copper wire was achieved on Au/Ni plated Cu substrate at ambient temperature.Ultrasonic wedge bonding mechanism was investigated by using SEM/EDX,pull test,shear test and microhardness test.The results show that the thinning of the Au layer occurs directly below the center of the bonding tool with the bonding power increasing.The interdiffusion between copper wire and Au metallization during the wedge bonding is assumed negligible,and the wedge bonding is achieved by wear action induced by ultrasonic vibration.The ultrasonic power contributes to enhance the deformation of copper wire due to ultrasonic softening effect which is then followed by the strain hardening of the copper wedge bonding.
