A simple impact-sliding wear test rig is designed for studying the wear behavior between solid materials on a repetitive normal impact accompanied with the tangential sliding. The test rig consists of a cantilever bea...A simple impact-sliding wear test rig is designed for studying the wear behavior between solid materials on a repetitive normal impact accompanied with the tangential sliding. The test rig consists of a cantilever beam forced by the dynamoelectric vibration exciter and a rotational shaft driven by a spindle. It has a widely adjustable range of testing parameters, including the impact frequency, the impact load and the sliding velocity. The avail- able maximum impact frequency, impact load and sliding velocity are 100 Hz, 200 N and 4.52 m/s, respectively. To evaluate the capability of the test rig, tests are carried out and the impact load is measured. Results show that the test rig has the good repeatability under the same test conditions and the repeatable error is less than 7%. Furthermore, non-destructive examination results by the mass loss method, two-dimensional profilometry and the scanning electron microscopy （SEM） show that the test rig can meet the demands for the impact-sliding wear.展开更多
The driving force for using powder metallurgy(PM)mostly relies on its near net-shape ability and cost-performance ratio.The automotive application is a main market of PM industry,requiring parts with competitive mecha...The driving force for using powder metallurgy(PM)mostly relies on its near net-shape ability and cost-performance ratio.The automotive application is a main market of PM industry,requiring parts with competitive mechanical or functional performance in a mass production scale.As the automobile technology transforms from traditional internal combustion engine vehicles to new energy vehicles,PM technology is undergoing significant changes in manufacturing and materials development.This review outlines the challenges and opportunities generated by the changes in the automotive technology for PM.Low-cost,high-performance and light-weight are critical aspects for future PM materials development.Therefore,the studies on PM lean-alloyed steel,aluminum alloys,and titanium alloy materials were reviewed.In addition,PM soft magnetic composite applied to new energy vehicles was discussed.Then new opportunities for advanced processing,such as metal injection molding(MIM)and additive manufacturing(AM),in automotive industry were stated.In general,the change in automotive industry raises sufficient development space for PM.While,emerging technologies require more preeminent PM materials.Iron-based parts are still the main PM products due to their mechanical performance and low cost.MIM will occupy the growing market of highly flexible and complex parts.AM opens a door for fast prototyping,great flexibility and customizing at low cost,driving weight and assembling reduction.展开更多
The influence of microstructure,heat treatment and alloying addition on mechanical and fracture properties of Ti3Al-basedintermetallic at room and elevated temperatures was studied.Ti3Al?11Nb?1Mo(mole fraction,%)alloy...The influence of microstructure,heat treatment and alloying addition on mechanical and fracture properties of Ti3Al-basedintermetallic at room and elevated temperatures was studied.Ti3Al?11Nb?1Mo(mole fraction,%)alloy was consolidated viapowder metallurgy processing by mechanical alloying(MA)and hot pressing(HP).MA powders were characterized using XRD andSEM-EDS.Optimum MA duration was25h and HP conditions of1350°C,2h,35MPa.After HP,solution treatment at1050°C for1h and water quenchingα2+βWidmanst?tten microstructure is present,while subsequent aging at800°C during24h induces smallcontent of O-phase.High fraction ofβ-phase is a direct consequence of Mo.Compression tests were performed from roomtemperature to750°C in vacuum.The yield strength of compacts increases with temperature up to250°C(pyramidal slip systemsactivation),after which it decreases.Ductility increases throughout the whole temperature range.The presence of O phasecontributed to ductility increase in aged alloys,while negligibly lowering yield strength.Registered drop in the yield strength of agedalloys compared with non-aged ones was mostly influenced by precipitation ofα″2particles.Mixed fracture modes are operative atall temperatures.展开更多
The process of laser cladding procedure has a closely relation with properties of composite cladding layers. When the input power of laser is certain, the low scanning velocity makes substrate with ahead of laser beam...The process of laser cladding procedure has a closely relation with properties of composite cladding layers. When the input power of laser is certain, the low scanning velocity makes substrate with ahead of laser beam heat for a long time, which worsens interface bonding from surface oxidized; much higher scanning velocity makes the powder’s synthesis near substrate uncompleted fully, the remained powder in interface worsens interface bonding as well. Otherwise, the input specific energy of laser influences on in-situ synthesis courses. If the input energy is lower, the synthesis is not completed fully. In addition, the low temperature effects not only restrict the dispersion of particle leading uneven distribution of TiC, but also form some regions consisting of Al and Al 3Ti.展开更多
基金Supported by the National Basic Research Program of China("973"Program)(2007CB607602)~~
文摘A simple impact-sliding wear test rig is designed for studying the wear behavior between solid materials on a repetitive normal impact accompanied with the tangential sliding. The test rig consists of a cantilever beam forced by the dynamoelectric vibration exciter and a rotational shaft driven by a spindle. It has a widely adjustable range of testing parameters, including the impact frequency, the impact load and the sliding velocity. The avail- able maximum impact frequency, impact load and sliding velocity are 100 Hz, 200 N and 4.52 m/s, respectively. To evaluate the capability of the test rig, tests are carried out and the impact load is measured. Results show that the test rig has the good repeatability under the same test conditions and the repeatable error is less than 7%. Furthermore, non-destructive examination results by the mass loss method, two-dimensional profilometry and the scanning electron microscopy （SEM） show that the test rig can meet the demands for the impact-sliding wear.
基金Project(51625404)supported by the National Science Fund for Distinguished Young Scholars,China。
文摘The driving force for using powder metallurgy(PM)mostly relies on its near net-shape ability and cost-performance ratio.The automotive application is a main market of PM industry,requiring parts with competitive mechanical or functional performance in a mass production scale.As the automobile technology transforms from traditional internal combustion engine vehicles to new energy vehicles,PM technology is undergoing significant changes in manufacturing and materials development.This review outlines the challenges and opportunities generated by the changes in the automotive technology for PM.Low-cost,high-performance and light-weight are critical aspects for future PM materials development.Therefore,the studies on PM lean-alloyed steel,aluminum alloys,and titanium alloy materials were reviewed.In addition,PM soft magnetic composite applied to new energy vehicles was discussed.Then new opportunities for advanced processing,such as metal injection molding(MIM)and additive manufacturing(AM),in automotive industry were stated.In general,the change in automotive industry raises sufficient development space for PM.While,emerging technologies require more preeminent PM materials.Iron-based parts are still the main PM products due to their mechanical performance and low cost.MIM will occupy the growing market of highly flexible and complex parts.AM opens a door for fast prototyping,great flexibility and customizing at low cost,driving weight and assembling reduction.
基金financially supported by the Ministry of Education,Science and Technological Development of the Republic of Serbia through the Project(No.172005).
文摘The influence of microstructure,heat treatment and alloying addition on mechanical and fracture properties of Ti3Al-basedintermetallic at room and elevated temperatures was studied.Ti3Al?11Nb?1Mo(mole fraction,%)alloy was consolidated viapowder metallurgy processing by mechanical alloying(MA)and hot pressing(HP).MA powders were characterized using XRD andSEM-EDS.Optimum MA duration was25h and HP conditions of1350°C,2h,35MPa.After HP,solution treatment at1050°C for1h and water quenchingα2+βWidmanst?tten microstructure is present,while subsequent aging at800°C during24h induces smallcontent of O-phase.High fraction ofβ-phase is a direct consequence of Mo.Compression tests were performed from roomtemperature to750°C in vacuum.The yield strength of compacts increases with temperature up to250°C(pyramidal slip systemsactivation),after which it decreases.Ductility increases throughout the whole temperature range.The presence of O phasecontributed to ductility increase in aged alloys,while negligibly lowering yield strength.Registered drop in the yield strength of agedalloys compared with non-aged ones was mostly influenced by precipitation ofα″2particles.Mixed fracture modes are operative atall temperatures.
基金National Natural Science Foundation ofChina (No.5 98710 3 8)
文摘The process of laser cladding procedure has a closely relation with properties of composite cladding layers. When the input power of laser is certain, the low scanning velocity makes substrate with ahead of laser beam heat for a long time, which worsens interface bonding from surface oxidized; much higher scanning velocity makes the powder’s synthesis near substrate uncompleted fully, the remained powder in interface worsens interface bonding as well. Otherwise, the input specific energy of laser influences on in-situ synthesis courses. If the input energy is lower, the synthesis is not completed fully. In addition, the low temperature effects not only restrict the dispersion of particle leading uneven distribution of TiC, but also form some regions consisting of Al and Al 3Ti.
