A more suitable method is introduced about testing friction coefficient on deep drawingcondition. It is pointed out that many ways to mesture friction coefficient. However, if a study of thefriction and lubrication in...A more suitable method is introduced about testing friction coefficient on deep drawingcondition. It is pointed out that many ways to mesture friction coefficient. However, if a study of thefriction and lubrication in sheet metal deep drawing process is made, the testing method recom-mended in this paper should be used. As it is identical with the actual working condition accordingto its testing principle and state of stress.展开更多
We describe a direct atomic layer deposition method to grow lubricant tungsten disulfide(WS_2) films. The WS_2 films were deposited on a Si(100) substrate and a zinc sulfide(ZnS) film coated the Si(100) substrate usin...We describe a direct atomic layer deposition method to grow lubricant tungsten disulfide(WS_2) films. The WS_2 films were deposited on a Si(100) substrate and a zinc sulfide(ZnS) film coated the Si(100) substrate using tungsten hexacarbonyl and hydrogen sulfide as precursors. The ZnS film served as an intermediate layer to facilitate the nucleation and growth of the WS_2 films. The thickness of the WS_2 films was measured via scanning electron microscope, the microstructure was probed with an X-ray diffractometer and a transmission electron microscope. The friction coefficient was measured with a ball-on-disk tester under dry nitrogen. The results reveal that the WS_2 films deposited on both substrates are ~175 nm and have(002) and(101) crystal orientations. The WS_2 film deposited on the ZnS coated Si substrate exhibits a stronger(002) orientation and a denser crystal structure than that deposited on the Si substrate. The WS_2 films on both substrates have low friction coefficients. However, due to the stronger(002) orientation and denser crystal structure, the friction coefficient of the WS_2 film deposited on ZnS coated Si substrate is smaller with longer wear life.展开更多
In this work, the influence of crystal structure on the friction coefficient of zinc oxide(ZnO) films was studied. The ZnO films were deposited on a Si(100) substrate using an atomic layer deposition process, and the ...In this work, the influence of crystal structure on the friction coefficient of zinc oxide(ZnO) films was studied. The ZnO films were deposited on a Si(100) substrate using an atomic layer deposition process, and the crystal structure of the ZnO films was changed by adjusting the substrate temperature. The surface morphology and the crystal structure of the Zn O films were measured by an atomic force microscope and an X-ray diffractometer, respectively, and the friction coefficient of the ZnO films was measured by a ball-on-disk dry sliding tester. The results show that the ZnO films deposited at substrate temperatures below 200°C are dominated by(100),(002) and(101)-orientated crystals, while the ZnO films deposited at substrate temperatures above 250°C are dominated by(002)-orientated crystals, and that the crystal structure influences the friction coefficient of ZnO films greatly. The ZnO films with(002)-orientated crystals possess a larger friction coefficient than those with other orientated crystals. In order to verify this conclusion, we measured the friction behavior of the ZnO single crystals with different orientations. The results are consistent well with our conclusion.展开更多
In a nanoscale friction test,wear of an atomic force microscope(AFM)tip is inevitable.The shape of the worn tip influences the friction force measured.In order to eliminate the influence,nanowear pretreatment should b...In a nanoscale friction test,wear of an atomic force microscope(AFM)tip is inevitable.The shape of the worn tip influences the friction force measured.In order to eliminate the influence,nanowear pretreatment should be conducted for the AFM tip.In our study,pretreatment of three kinds of tips,i.e.Si3N4 tip,Si tip and silica colloidal tip,was performed using AFM.The results show that the shape of the tips changes with the increase of sliding distance,which leads to the variety of friction force.Whereas,when the tip gets blunt,the shape of tip tends to become stable and the friction force becomes stable correspondingly.To a certain degree,it reveals that the pretreated tips can be applied to study the friction force of samples.展开更多
Friction law is researched in rectangular parts deep drawing using simulation test ma-chine that is used to assess lubricants performance in deep drawing process. Friction coefficientsin different positions on die sur...Friction law is researched in rectangular parts deep drawing using simulation test ma-chine that is used to assess lubricants performance in deep drawing process. Friction coefficientsin different positions on die surface in deep drawing process are measured through probe sensors.Friction coefficients of flange corner, near straight border and far straight border are verified anddescribed quantitatively. It plays an important role in using appropriate lubricants in auto-bodypanel deep drawing process.展开更多
文摘A more suitable method is introduced about testing friction coefficient on deep drawingcondition. It is pointed out that many ways to mesture friction coefficient. However, if a study of thefriction and lubrication in sheet metal deep drawing process is made, the testing method recom-mended in this paper should be used. As it is identical with the actual working condition accordingto its testing principle and state of stress.
基金supported by the National Natural Science Fundation of China(Grant Nos.50825501,51321092&51335005)the National Science and Technology Major Project(Grant No.2008ZX02104-001)
文摘We describe a direct atomic layer deposition method to grow lubricant tungsten disulfide(WS_2) films. The WS_2 films were deposited on a Si(100) substrate and a zinc sulfide(ZnS) film coated the Si(100) substrate using tungsten hexacarbonyl and hydrogen sulfide as precursors. The ZnS film served as an intermediate layer to facilitate the nucleation and growth of the WS_2 films. The thickness of the WS_2 films was measured via scanning electron microscope, the microstructure was probed with an X-ray diffractometer and a transmission electron microscope. The friction coefficient was measured with a ball-on-disk tester under dry nitrogen. The results reveal that the WS_2 films deposited on both substrates are ~175 nm and have(002) and(101) crystal orientations. The WS_2 film deposited on the ZnS coated Si substrate exhibits a stronger(002) orientation and a denser crystal structure than that deposited on the Si substrate. The WS_2 films on both substrates have low friction coefficients. However, due to the stronger(002) orientation and denser crystal structure, the friction coefficient of the WS_2 film deposited on ZnS coated Si substrate is smaller with longer wear life.
基金supported by the National Science Fund for Distinguished Young Scholars(Grant No.50825501)the Science Fund for Creative Research Groups(Grant No.51321092)+1 种基金the National Natural Science Foundation of China(Grant Nos.51335005 and 91323302)the National Science and Technology Major Project(Grant No.2008ZX02104-001)
文摘In this work, the influence of crystal structure on the friction coefficient of zinc oxide(ZnO) films was studied. The ZnO films were deposited on a Si(100) substrate using an atomic layer deposition process, and the crystal structure of the ZnO films was changed by adjusting the substrate temperature. The surface morphology and the crystal structure of the Zn O films were measured by an atomic force microscope and an X-ray diffractometer, respectively, and the friction coefficient of the ZnO films was measured by a ball-on-disk dry sliding tester. The results show that the ZnO films deposited at substrate temperatures below 200°C are dominated by(100),(002) and(101)-orientated crystals, while the ZnO films deposited at substrate temperatures above 250°C are dominated by(002)-orientated crystals, and that the crystal structure influences the friction coefficient of ZnO films greatly. The ZnO films with(002)-orientated crystals possess a larger friction coefficient than those with other orientated crystals. In order to verify this conclusion, we measured the friction behavior of the ZnO single crystals with different orientations. The results are consistent well with our conclusion.
基金supported by the National Science Fund for Distinguished Young Scholars(Grant No.50825501)the Science Fund for Creative Research Groups(Grant No.51321092)+1 种基金the National Natural Science Foundation of China(Grant No.51335005)the National Science andTechnology Major Project(Grant No.2008ZX02104-001)
文摘In a nanoscale friction test,wear of an atomic force microscope(AFM)tip is inevitable.The shape of the worn tip influences the friction force measured.In order to eliminate the influence,nanowear pretreatment should be conducted for the AFM tip.In our study,pretreatment of three kinds of tips,i.e.Si3N4 tip,Si tip and silica colloidal tip,was performed using AFM.The results show that the shape of the tips changes with the increase of sliding distance,which leads to the variety of friction force.Whereas,when the tip gets blunt,the shape of tip tends to become stable and the friction force becomes stable correspondingly.To a certain degree,it reveals that the pretreated tips can be applied to study the friction force of samples.
文摘Friction law is researched in rectangular parts deep drawing using simulation test ma-chine that is used to assess lubricants performance in deep drawing process. Friction coefficientsin different positions on die surface in deep drawing process are measured through probe sensors.Friction coefficients of flange corner, near straight border and far straight border are verified anddescribed quantitatively. It plays an important role in using appropriate lubricants in auto-bodypanel deep drawing process.
