The corrosion, corrosive wear and dry sliding wear of nanocomposites, are extremely complicated and involve various chemical, physical anbd mechanical factors. The aim of this work is to investigate the effects of nan...The corrosion, corrosive wear and dry sliding wear of nanocomposites, are extremely complicated and involve various chemical, physical anbd mechanical factors. The aim of this work is to investigate the effects of nanosized SiC content on the hardness, dry sliding wear, corrosion and corrosive wear of Al/SiC nanocomposites synthesized by mechanical milling cold pressing and hot extrusion. The corrosion resistance of these composites in 3%NaCl solution was investigated by electrochemical polarization testing and their dry sliding as well as corrosive wear resistance in the same solution was evaluated using a pin-on-disc tester. The microstructures of the samples and their worn surfaces were examined using scanning electron microscopy. It was shown that the dry sliding wear and corrosion resistance of these nanocomposites were improved with the increase of SiC content. It was concluded that due to the lubrication effect of the solution, both the friction coefficient and frictional heat that might soften the material were reduced. In addition, the improved strength of the nanocomposites combined with their better corrosion resistance contributed to their increased corrosive wear resistance, compared with the base alloy. The prominent wear mechanism in the unreinforced alloy was adhesive wear, in the Al/SiC nanocomposites, the wear mechanism changed to abrasive.展开更多
Tribological behavior and wear mechanisms of mechanically milled Al5083 alloy and Al5083−5wt.%B4C composite at room temperature and 200°C were discussed.Results revealed that due to the oxidative wear at room tem...Tribological behavior and wear mechanisms of mechanically milled Al5083 alloy and Al5083−5wt.%B4C composite at room temperature and 200°C were discussed.Results revealed that due to the oxidative wear at room temperature,a mechanically mixed layer(MML)was formed to protect the surface of the samples.Under 80 N of load at room temperature,the milled Al5083 and the Al5083−5wt.%B4C samples showed evidence of abrasion with limited volume loss.In this case,the wear rates were 5.8×10−7 and 4.4×10−7 mm3/(m·N),respectively.At 200°C and under 80 N of applied load,severe wear occurred in the milled Al5083 sample,and wear rate reached 10.8×10−7 mm3/(m·N)while the Al5083−5wt.%B4C sample showed mild wear with local 3-body abrasion and the wear rate reached 5.3×10−7 mm3/(m·N).Strengthening mechanisms such as dislocation pinning and the Hall−Petch theory,high hardness and the load transfer effect were crucial in determining the wear behavior of the Al5083−5wt.%B4C composite.On the other hand,the milled Al5083 sample represented a relatively high wear rate at 200°C,which seemed to be related to the local grain growth and a drop in its hardness.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Iranian Nanotechnology Initiative (INI) for finical support of the research work
文摘The corrosion, corrosive wear and dry sliding wear of nanocomposites, are extremely complicated and involve various chemical, physical anbd mechanical factors. The aim of this work is to investigate the effects of nanosized SiC content on the hardness, dry sliding wear, corrosion and corrosive wear of Al/SiC nanocomposites synthesized by mechanical milling cold pressing and hot extrusion. The corrosion resistance of these composites in 3%NaCl solution was investigated by electrochemical polarization testing and their dry sliding as well as corrosive wear resistance in the same solution was evaluated using a pin-on-disc tester. The microstructures of the samples and their worn surfaces were examined using scanning electron microscopy. It was shown that the dry sliding wear and corrosion resistance of these nanocomposites were improved with the increase of SiC content. It was concluded that due to the lubrication effect of the solution, both the friction coefficient and frictional heat that might soften the material were reduced. In addition, the improved strength of the nanocomposites combined with their better corrosion resistance contributed to their increased corrosive wear resistance, compared with the base alloy. The prominent wear mechanism in the unreinforced alloy was adhesive wear, in the Al/SiC nanocomposites, the wear mechanism changed to abrasive.
基金Authors would like to appreciate the former chief of Faculty of Materials&Manufacturing Processes of the Malek-Ashtar University of Technology,Professor EHSANI and the chief of the Composite Department,Dr.POURHOSSEINI along with the Razi and Kimiazi SEM labs and mechanical properties and SEM labs of Iran University of Science and Technology.Furthermore,the authors would like to thank Professor REZAEI,Ms.HAMIDI,and Ms.DAYYANI,Mr.SA'ADAT,and Mr.ATAEI from Iran University of Science and Technology.Special thanks to Mrs.KESHAVARZ,Ms.HAMEDANIZADEH,Ms.SHABANI,Ms.SHOJAEI and Mr.GANDOMKAR for their help and support.
文摘Tribological behavior and wear mechanisms of mechanically milled Al5083 alloy and Al5083−5wt.%B4C composite at room temperature and 200°C were discussed.Results revealed that due to the oxidative wear at room temperature,a mechanically mixed layer(MML)was formed to protect the surface of the samples.Under 80 N of load at room temperature,the milled Al5083 and the Al5083−5wt.%B4C samples showed evidence of abrasion with limited volume loss.In this case,the wear rates were 5.8×10−7 and 4.4×10−7 mm3/(m·N),respectively.At 200°C and under 80 N of applied load,severe wear occurred in the milled Al5083 sample,and wear rate reached 10.8×10−7 mm3/(m·N)while the Al5083−5wt.%B4C sample showed mild wear with local 3-body abrasion and the wear rate reached 5.3×10−7 mm3/(m·N).Strengthening mechanisms such as dislocation pinning and the Hall−Petch theory,high hardness and the load transfer effect were crucial in determining the wear behavior of the Al5083−5wt.%B4C composite.On the other hand,the milled Al5083 sample represented a relatively high wear rate at 200°C,which seemed to be related to the local grain growth and a drop in its hardness.
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
