The tribological behavior of a Zr-based bulk metallic glass（BMG） was investigated using pin-on-disk sliding measurements in two different environments,i.e.,air and argon,against an yttria-stabilized zirconia counter...The tribological behavior of a Zr-based bulk metallic glass（BMG） was investigated using pin-on-disk sliding measurements in two different environments,i.e.,air and argon,against an yttria-stabilized zirconia counterface.It was found that the wear of the Zr-based BMG was reduced by more than 45% due to the removal of oxygen from the test environment at two different loads,i.e.,16 N and 23 N.The wear pins were examined using X-ray diffractometry,differential scanning calorimetry,scanning electron microscopy and optical surface profilometry.A number of abrasive particles and grooves presented on the worn surface of the pin tested in air,while a relatively smooth worn surface was observed in the specimens tested in argon.The wear mechanism of the pin worn in air was dominated by abrasive wear compared with an adhesive wear controlled process in the tests performed in argon.展开更多
Given that fretting wear causes failure in steel wires, we carried out tangential fretting wear tests of steel wires on a self-made fretting wear test rig under contact loads of 9 and 29 N and fretting amplitudes rang...Given that fretting wear causes failure in steel wires, we carried out tangential fretting wear tests of steel wires on a self-made fretting wear test rig under contact loads of 9 and 29 N and fretting amplitudes ranging from 5 to 180 μm. We observed morphologies of fretted steel wire surfaces on an S-3000N scanning electron microscope in order to analyze fretting wear mecha-nisms. The results show that the fretting regime of steel wires transforms from partial slip regime into mixed fretting regime and gross slip regime with an increase in fretting amplitudes under a given contact load. In partial slip regime, the friction coefficient has a relatively low value. Four stages can be defined in mixed fretting and gross slip regimes. The fretting wear of steel wires in-creases obviously with increases in fretting amplitudes. Fretting scars present a typical morphology of annularity, showing slight damage in partial slip regime. However, wear clearly increases in mixed fretting regime where wear mechanism is a combination of plastic deformation, abrasive wear and oxidative wear. In gross slip regime, more severe degradation is present than in the other regimes. The main fretting wear mechanisms of steel wires are abrasive wear, surface fatigue and friction oxidation.展开更多
Titanium alloy Ti6A14V, as difficult-to-cut material, has poor machinability. Conventional cutting fluid serves as a coolant and lubricant. In green drilling, water vapor is recognized as an effective coolant; however...Titanium alloy Ti6A14V, as difficult-to-cut material, has poor machinability. Conventional cutting fluid serves as a coolant and lubricant. In green drilling, water vapor is recognized as an effective coolant; however, its lubrication properties are not well known in drilling. This paper investigates the friction characteristics between chip and tool in green drilling Ti6A14V, compared with that in sliding and turning process. A friction evaluation model is developed based on the equivalent model of drilling, then is used to calculate the effective friction coefficient. drilling by in drilling, chisel edge Results indicate that the friction coefficient on the tool-chip interface is considerably reduced in water vapor, so the drilling forces decrease, too. which is different from the law of sliding tests; increases. The friction coefficient decreases as velocity increases the friction coefficient increases when the distance to展开更多
基金Project(DE-FG02-07ER46392) supported by U.S.Department of Energy,Office of Basic Energy ScienceProject(2011JQ002) supported by the Fundamental Research Funds for the Central Universities,ChinaProject supported by the Open-End Fund for the Valuable and Precision Instruments of Central South University,China
文摘The tribological behavior of a Zr-based bulk metallic glass（BMG） was investigated using pin-on-disk sliding measurements in two different environments,i.e.,air and argon,against an yttria-stabilized zirconia counterface.It was found that the wear of the Zr-based BMG was reduced by more than 45% due to the removal of oxygen from the test environment at two different loads,i.e.,16 N and 23 N.The wear pins were examined using X-ray diffractometry,differential scanning calorimetry,scanning electron microscopy and optical surface profilometry.A number of abrasive particles and grooves presented on the worn surface of the pin tested in air,while a relatively smooth worn surface was observed in the specimens tested in argon.The wear mechanism of the pin worn in air was dominated by abrasive wear compared with an adhesive wear controlled process in the tests performed in argon.
基金supported by the National Natural Science Foundation of China (No 50875252)the Program for New Century Excellent Talents in Universities (NoNCET-06-0479)the Natural Science Foundation of Jiangsu Province (NoBK2008005)
文摘Given that fretting wear causes failure in steel wires, we carried out tangential fretting wear tests of steel wires on a self-made fretting wear test rig under contact loads of 9 and 29 N and fretting amplitudes ranging from 5 to 180 μm. We observed morphologies of fretted steel wire surfaces on an S-3000N scanning electron microscope in order to analyze fretting wear mecha-nisms. The results show that the fretting regime of steel wires transforms from partial slip regime into mixed fretting regime and gross slip regime with an increase in fretting amplitudes under a given contact load. In partial slip regime, the friction coefficient has a relatively low value. Four stages can be defined in mixed fretting and gross slip regimes. The fretting wear of steel wires in-creases obviously with increases in fretting amplitudes. Fretting scars present a typical morphology of annularity, showing slight damage in partial slip regime. However, wear clearly increases in mixed fretting regime where wear mechanism is a combination of plastic deformation, abrasive wear and oxidative wear. In gross slip regime, more severe degradation is present than in the other regimes. The main fretting wear mechanisms of steel wires are abrasive wear, surface fatigue and friction oxidation.
基金the Scientific Research Foundation of Harbin Institute of Technology at Weihai (No.HIT(WH)X201104)
文摘Titanium alloy Ti6A14V, as difficult-to-cut material, has poor machinability. Conventional cutting fluid serves as a coolant and lubricant. In green drilling, water vapor is recognized as an effective coolant; however, its lubrication properties are not well known in drilling. This paper investigates the friction characteristics between chip and tool in green drilling Ti6A14V, compared with that in sliding and turning process. A friction evaluation model is developed based on the equivalent model of drilling, then is used to calculate the effective friction coefficient. drilling by in drilling, chisel edge Results indicate that the friction coefficient on the tool-chip interface is considerably reduced in water vapor, so the drilling forces decrease, too. which is different from the law of sliding tests; increases. The friction coefficient decreases as velocity increases the friction coefficient increases when the distance to
