Resin matrix carbon brush composites(RMCBCs)are critical materials for high-powered electric tools.However,effectively improving their wear resistance and heat dissipation remains a challenge.RMCBCs prepared with flak...Resin matrix carbon brush composites(RMCBCs)are critical materials for high-powered electric tools.However,effectively improving their wear resistance and heat dissipation remains a challenge.RMCBCs prepared with flake graphite powders that were evenly loaded with tungsten copper composite powder(RMCBCs-W@Cu)exhibited a low wear rate of 1.63 mm^(3)/h,exhibiting 48.6%reduction in the wear rate relative to RCMBCs without additives(RMCBCs-0).In addition,RMCBCs-W@Cu achieved a low friction coefficient of 0.243 and low electric spark grade.These findings indicate that tungsten copper composite powders provide particle reinforcement and generate a gradation effect for the epoxy resin(i.e.,connecting phase)in RMCBCs,which weakens the wear of RMCBCs caused by fatigue under a cyclic current-carrying wear.展开更多
(Fe_(73)Ga_(27−x)Al_(x))_(99.8)Tb_(0.2)(x=0,1,2,3,4,5)alloys were prepared by vacuum arc furnace to investigate the effect of Al addition on the microstructure,magnetic properties,and mechanical properties of alloys.R...(Fe_(73)Ga_(27−x)Al_(x))_(99.8)Tb_(0.2)(x=0,1,2,3,4,5)alloys were prepared by vacuum arc furnace to investigate the effect of Al addition on the microstructure,magnetic properties,and mechanical properties of alloys.Results show that the phase structure of the alloys is still A2 phase and Tb2Fe17 phase,and the metallographic structure is composed of cellular crystal and columnar dendrite.The decrease in lattice constant,the intensification of(100)orientation,and the generation of Tb2Fe17 phase at the grain boundary exert significant effect on the magnetostrictive properties.The fracture morphology of the alloys is intergranular brittle fracture and cleavage fracture,and the causes of fracture occurrence include the segregation of Tb and Al elements.The parallel magnetostrictive strain(λ∥)of(Fe_(73)Ga_(24)Al_(3))_(99.8)Tb_(0.2)alloy peaks at 1.04×10^(−4).It is worth noting that compared with those of(Fe_(73)Ga_(27))_(99.8)Tb_(0.2)alloy,theλ∥and elongation of(Fe_(73)Ga_(26)Al_(1))_(99.8)Tb_(0.2)alloy increase by 18.3%and 53.4%,respectively.Besides,(Fe_(73)Ga_(26)Al_(1))_(99.8)Tb_(0.2)alloy possesses the characteristics of high saturation magnetization(Ms),low remanent magnetization(Mr),and coercivity(Hc),which is beneficial to reduce the cost in actual production,but its tensile strength and Vickers hardness decrease to a certain extent.Therefore,the investigation on the micro-mechanism of Al addition on Fe-Ga alloys is of great significance for the development of Fe-Ga alloy devices.展开更多
基金Projects(51772081,51837009,51971091)supported by the National Natural Science Foundation of ChinaProject(HFZL2018CXY003-4)supported by the Industry-University-Research Cooperation of AECC,ChinaProject(kq1902046)supported by the Major Science and Technology Projects of Changsha City,China。
文摘Resin matrix carbon brush composites(RMCBCs)are critical materials for high-powered electric tools.However,effectively improving their wear resistance and heat dissipation remains a challenge.RMCBCs prepared with flake graphite powders that were evenly loaded with tungsten copper composite powder(RMCBCs-W@Cu)exhibited a low wear rate of 1.63 mm^(3)/h,exhibiting 48.6%reduction in the wear rate relative to RCMBCs without additives(RMCBCs-0).In addition,RMCBCs-W@Cu achieved a low friction coefficient of 0.243 and low electric spark grade.These findings indicate that tungsten copper composite powders provide particle reinforcement and generate a gradation effect for the epoxy resin(i.e.,connecting phase)in RMCBCs,which weakens the wear of RMCBCs caused by fatigue under a cyclic current-carrying wear.
基金Inner Mongolia Autonomous Region Science and Technology Plan Project(2020GG0284)。
文摘(Fe_(73)Ga_(27−x)Al_(x))_(99.8)Tb_(0.2)(x=0,1,2,3,4,5)alloys were prepared by vacuum arc furnace to investigate the effect of Al addition on the microstructure,magnetic properties,and mechanical properties of alloys.Results show that the phase structure of the alloys is still A2 phase and Tb2Fe17 phase,and the metallographic structure is composed of cellular crystal and columnar dendrite.The decrease in lattice constant,the intensification of(100)orientation,and the generation of Tb2Fe17 phase at the grain boundary exert significant effect on the magnetostrictive properties.The fracture morphology of the alloys is intergranular brittle fracture and cleavage fracture,and the causes of fracture occurrence include the segregation of Tb and Al elements.The parallel magnetostrictive strain(λ∥)of(Fe_(73)Ga_(24)Al_(3))_(99.8)Tb_(0.2)alloy peaks at 1.04×10^(−4).It is worth noting that compared with those of(Fe_(73)Ga_(27))_(99.8)Tb_(0.2)alloy,theλ∥and elongation of(Fe_(73)Ga_(26)Al_(1))_(99.8)Tb_(0.2)alloy increase by 18.3%and 53.4%,respectively.Besides,(Fe_(73)Ga_(26)Al_(1))_(99.8)Tb_(0.2)alloy possesses the characteristics of high saturation magnetization(Ms),low remanent magnetization(Mr),and coercivity(Hc),which is beneficial to reduce the cost in actual production,but its tensile strength and Vickers hardness decrease to a certain extent.Therefore,the investigation on the micro-mechanism of Al addition on Fe-Ga alloys is of great significance for the development of Fe-Ga alloy devices.
