In the study, for the composite materials reinforced by brass fibers, theinfluence of dominant ingredients, such as organic adhesion agent, cast iron debris, brass fiber,and graphite powder, on the friction-wear chara...In the study, for the composite materials reinforced by brass fibers, theinfluence of dominant ingredients, such as organic adhesion agent, cast iron debris, brass fiber,and graphite powder, on the friction-wear characteristics was investigated. The friction-wearexperiment was carried out on the block-on-ring tribometer MM 200. The worn surfaces of the frictionpair consisting of the composite materials and grey cast iron HT 200 under dry sliding frictionwere examined using scanning electron microscope (SEM), energy dispersive analysis (EDX) anddifferential thermal analysis-thermogravimetric analysis (DTA-TAG). The experimental results showedthat the friction coefficient and the wear loss of the composite material increase obviously withthe increase of cast iron debris content, but decrease obviously with the increase of graphitepowder content, and increase a little when the mass fraction of brass fiber was over 19 percent, andthe orientation of brass fiber has obvious influence on friction-wear property. When the massfraction of organic adhesion agent was about 10-11 percent, the composite materials have anexcellent friction-wear performance. The friction heat can pyrolyze organic ingredient in wornsurface layer.展开更多
A 40 Cr steel was formed into a chain-wheel using a warm extrusion technology. The surface roughness and micro-structure, micro-hardness and phases of the extruded samples at different temperatures were analyzed using...A 40 Cr steel was formed into a chain-wheel using a warm extrusion technology. The surface roughness and micro-structure, micro-hardness and phases of the extruded samples at different temperatures were analyzed using a three-dimensional optical microscope(OM), micro-hardness tester, and X-ray diffraction(XRD), respectively. The morphologies, chemical element distributions and phases of worn tracks at the extrusion temperatures of 550, 650 and 750 ℃ were analyzed using a scanning electron microscopy(SEM), energy disperse spectroscopy(EDS), and XRD, respectively. The friction-wear behaviors of extruded samples under oil-lubrication condition were observed using a wear test. And the effects of extrusion temperatures on the wear mechanism were discussed. The results show that residual austenite and pearlite exist on the sample at the extrusion temperature of 550 ℃ with the corresponding grain size and surface micro-hardness of 32.7 nm and 370.33 HV, respectively. The average coefficient of friction(COF) of extruded sample at the temperature of 550 ℃ is 0.196 5, and the wear mechanism is fatigue and abrasive wear. While the acicular martensite exists on the extruded samples at the extrusion temperatures of 650 and 750 ℃, the corresponding grain sizes are 30.0 and 29.1 nm, respectively. The average COF(coefficient of friction) of extruded sample at the temperatures of 650 and 750 ℃ are 0.187 4 and 0.163 6, respectively, and the wear mechanism is abrasive wear. As a result, the friction performance of extruded sample at the temperatures of 650 and 750 ℃ is better than that at the temperature of 550 ℃.展开更多
文摘In the study, for the composite materials reinforced by brass fibers, theinfluence of dominant ingredients, such as organic adhesion agent, cast iron debris, brass fiber,and graphite powder, on the friction-wear characteristics was investigated. The friction-wearexperiment was carried out on the block-on-ring tribometer MM 200. The worn surfaces of the frictionpair consisting of the composite materials and grey cast iron HT 200 under dry sliding frictionwere examined using scanning electron microscope (SEM), energy dispersive analysis (EDX) anddifferential thermal analysis-thermogravimetric analysis (DTA-TAG). The experimental results showedthat the friction coefficient and the wear loss of the composite material increase obviously withthe increase of cast iron debris content, but decrease obviously with the increase of graphitepowder content, and increase a little when the mass fraction of brass fiber was over 19 percent, andthe orientation of brass fiber has obvious influence on friction-wear property. When the massfraction of organic adhesion agent was about 10-11 percent, the composite materials have anexcellent friction-wear performance. The friction heat can pyrolyze organic ingredient in wornsurface layer.
基金Funded by Jiangsu Province Science and Technology Support Program(Industry)(No.BE2014818)the Research Project of Scientific Research Innovation for Graduate Students of Jiangsu Province(No.KYLX16-0631)
文摘A 40 Cr steel was formed into a chain-wheel using a warm extrusion technology. The surface roughness and micro-structure, micro-hardness and phases of the extruded samples at different temperatures were analyzed using a three-dimensional optical microscope(OM), micro-hardness tester, and X-ray diffraction(XRD), respectively. The morphologies, chemical element distributions and phases of worn tracks at the extrusion temperatures of 550, 650 and 750 ℃ were analyzed using a scanning electron microscopy(SEM), energy disperse spectroscopy(EDS), and XRD, respectively. The friction-wear behaviors of extruded samples under oil-lubrication condition were observed using a wear test. And the effects of extrusion temperatures on the wear mechanism were discussed. The results show that residual austenite and pearlite exist on the sample at the extrusion temperature of 550 ℃ with the corresponding grain size and surface micro-hardness of 32.7 nm and 370.33 HV, respectively. The average coefficient of friction(COF) of extruded sample at the temperature of 550 ℃ is 0.196 5, and the wear mechanism is fatigue and abrasive wear. While the acicular martensite exists on the extruded samples at the extrusion temperatures of 650 and 750 ℃, the corresponding grain sizes are 30.0 and 29.1 nm, respectively. The average COF(coefficient of friction) of extruded sample at the temperatures of 650 and 750 ℃ are 0.187 4 and 0.163 6, respectively, and the wear mechanism is abrasive wear. As a result, the friction performance of extruded sample at the temperatures of 650 and 750 ℃ is better than that at the temperature of 550 ℃.
