The hardness values and the wear resistance of Al2O3P/ Zn-Al composite, prepared by means of rheological casting technology,are investigated separately in this work. The results show that the addition of Al2O3P increa...The hardness values and the wear resistance of Al2O3P/ Zn-Al composite, prepared by means of rheological casting technology,are investigated separately in this work. The results show that the addition of Al2O3P increases the hardness values of the matrix at both room and high temperature and improves the wear resistance of the material.The hardness values and the wear resistance of the composite rise with the increase of the particle volume fraction or the decrease of the particle size.The raising of test temperature results in a rapid descending of its hardness values.However, the addition of Al2O3P improves the property of high temperature resistance of Zn-Al alloys significantly.Moreover,the effect of quenching, tempering or cycling heat treatment on the hardness values of the composite is also studied.展开更多
The effect of reinforcement on the wear mechanism of metal matrix composites （MMCs） was investigated by considering different parameters, such as sliding distance （6 km）, pressure （0.14-1.1 MPa） and sliding spe...The effect of reinforcement on the wear mechanism of metal matrix composites （MMCs） was investigated by considering different parameters, such as sliding distance （6 km）, pressure （0.14-1.1 MPa） and sliding speed （230-1480 r/min）. The wear mechanisms of an MMC and the corresponding matrix material under similar experimental conditions were compared on a pin-on-disc wear machine. The pins were made of 6061 aluminum matrix alloy and 6061 aluminum matrix composite reinforced with 10% Al2O3 （volume fraciton） particles （6-18μm）. The disc was made of steel. The major findings are as follows： the MMC shows much higher wear resistance than the corresponding matrix material; unlike that of matrix material, the wear of MMC is very much linear and possible to predict easily; the wear mechanism is similar for both materials other than the three-body abrasion in the case of MMC; the reinforced particles resist the abrasion and restrict the deformation of MMCs which causes high resistance to wear. These results reveal the roles of the reinforcement particles on the wear resistance of MMCs and provide a useful guide for a better control of their wear.展开更多
A series of wear and flame resistant polyamide 6(PA6)composites were prepared using glass fiber(GF)and talc(T)as reinforcer,polytetrafluoroethylene(PTFE)and graphite(Gr)as solid lubricants,red phosphorus(RP)and zinc b...A series of wear and flame resistant polyamide 6(PA6)composites were prepared using glass fiber(GF)and talc(T)as reinforcer,polytetrafluoroethylene(PTFE)and graphite(Gr)as solid lubricants,red phosphorus(RP)and zinc borate(ZB)as flame retardant.The tribological property,mechanical property,flame retardant property and the flame retardant mechanism were investigated.The tests show that the formula of the wear resistant PA6 composite(WRPA 6)is PA6/GF/T/PTFE/Gr in the ratio of 100/15/5/10/5 by mass.Because this composite exhibits the lowest friction coefficient(0.1429)and no wear mass loss,the introduction of RP and ZB can increase the flame resistance of WRPA6,and the synergistic effect of RP and ZB is obtained.Detailedly,the composite with 4 parts of ZB and 12 parts of RP shows the best flame retardant property,achieving the highest limiting oxygen index(LOI)(30.2 vol%)and a UL94 V-0 rating,and the flame retardant mechanisms may be gas phase along with condense phase mechanism.展开更多
The effect of rotational speed in the friction surfacing of nickel-aluminide reinforced Al-Zn-Mg-Cu alloy matrix composite on commercially pure aluminum was investigated. The nickel-aluminide reinforcement was fabrica...The effect of rotational speed in the friction surfacing of nickel-aluminide reinforced Al-Zn-Mg-Cu alloy matrix composite on commercially pure aluminum was investigated. The nickel-aluminide reinforcement was fabricated by in-situ methods based on adding nickel powders to Al-Zn-Mg-Cu alloy melt during the semi-solid casting process.The findings showed that an increase in the rotational speed from 600 to 1000 r/min raised the coating efficiency from 65% to 76%. Besides, there was no significant difference between coating efficiencies in the coating with and without nickel-aluminide. The outcomes showed that if the coating was applied at a rotational speed of 1000 r/min, a traverse speed of 100 mm/min, and an axial feeding rate of 125 mm/min, the hardness and shear strength of the substrate increased by up to 225% and 195%, respectively. But the wear rate of the substrate dropped by 75%. Although the hardness of the coating containing nickel-aluminide increases by up to 32% compared to the coating without nickel-aluminide, nickel-aluminide does not affect the thermal stability of the coating.展开更多
Hybrid materials were prepared using a silane coupling agent, tetraethoxysilane （ TEOS ） as the precursor, dilute hydrochloric acid as the catalyst, and epoxy as the matrices. The films coated with hybrid materials ...Hybrid materials were prepared using a silane coupling agent, tetraethoxysilane （ TEOS ） as the precursor, dilute hydrochloric acid as the catalyst, and epoxy as the matrices. The films coated with hybrid materials were expected to improve abrasion resistance and mechanical properties. The morphology, mechanical properties, adhesion, and abrasion resistance of the polyethylene terephthalate （PET） films were characterized using an atomic force microscope, a tensile testing machine, a bagger knife, and a reciprocating fabric abrasion tester. The result of research indicated that the modification significantly affected the abrasion resistance and roughness. The-tensile strength and abrasion resistance of the modified PET films increased by 40% and 50% respectively at 3 % TEOS mass fraction.展开更多
The effect of brake oil on sliding behavior of carbon/carbon(C/C) and carbon/carbon-silicon carbide(C/C-SiC) composites was investigated with the variation of laminate orientation and surface conformity. The partial a...The effect of brake oil on sliding behavior of carbon/carbon(C/C) and carbon/carbon-silicon carbide(C/C-SiC) composites was investigated with the variation of laminate orientation and surface conformity. The partial and low conformity contacts with the normal and parallel orientations of laminates were considered. The normal load was varied from 50 to 90 N in a step of 10 N. The friction and wear behavior was investigated under reciprocating sliding conditions. The results showed that friction coefficient and wear loss of composites with normal orientation of laminates were larger as compared to those of composites with parallel orientation of laminates. C/C composites with normal orientation of laminates yielded the highest value of friction coefficient. Wear loss decreased by a maximum of 78%, and friction coefficient decreased by a maximum of 49% in low conformity contacts as compared to partial conformity contacts. The presence of brake oil reduced the adhesion tendency of compacted wear debris because the formation of friction film was difficult, and thus, friction behavior was affected. The wear debris retention between the contact surfaces due to confined area motion in reciprocating sliding depicted the tribological behavior.展开更多
文摘The hardness values and the wear resistance of Al2O3P/ Zn-Al composite, prepared by means of rheological casting technology,are investigated separately in this work. The results show that the addition of Al2O3P increases the hardness values of the matrix at both room and high temperature and improves the wear resistance of the material.The hardness values and the wear resistance of the composite rise with the increase of the particle volume fraction or the decrease of the particle size.The raising of test temperature results in a rapid descending of its hardness values.However, the addition of Al2O3P improves the property of high temperature resistance of Zn-Al alloys significantly.Moreover,the effect of quenching, tempering or cycling heat treatment on the hardness values of the composite is also studied.
文摘The effect of reinforcement on the wear mechanism of metal matrix composites （MMCs） was investigated by considering different parameters, such as sliding distance （6 km）, pressure （0.14-1.1 MPa） and sliding speed （230-1480 r/min）. The wear mechanisms of an MMC and the corresponding matrix material under similar experimental conditions were compared on a pin-on-disc wear machine. The pins were made of 6061 aluminum matrix alloy and 6061 aluminum matrix composite reinforced with 10% Al2O3 （volume fraciton） particles （6-18μm）. The disc was made of steel. The major findings are as follows： the MMC shows much higher wear resistance than the corresponding matrix material; unlike that of matrix material, the wear of MMC is very much linear and possible to predict easily; the wear mechanism is similar for both materials other than the three-body abrasion in the case of MMC; the reinforced particles resist the abrasion and restrict the deformation of MMCs which causes high resistance to wear. These results reveal the roles of the reinforcement particles on the wear resistance of MMCs and provide a useful guide for a better control of their wear.
基金Project(149929)supported by the Postdoctoral Fund of Central South University,ChinaProject(16C0292)supported by the Hunan Education Department,ChinaProject(2016TP1022)supported by the Hunan Provincial Key Lab of Dark Tea and Jin-hua,China
文摘A series of wear and flame resistant polyamide 6(PA6)composites were prepared using glass fiber(GF)and talc(T)as reinforcer,polytetrafluoroethylene(PTFE)and graphite(Gr)as solid lubricants,red phosphorus(RP)and zinc borate(ZB)as flame retardant.The tribological property,mechanical property,flame retardant property and the flame retardant mechanism were investigated.The tests show that the formula of the wear resistant PA6 composite(WRPA 6)is PA6/GF/T/PTFE/Gr in the ratio of 100/15/5/10/5 by mass.Because this composite exhibits the lowest friction coefficient(0.1429)and no wear mass loss,the introduction of RP and ZB can increase the flame resistance of WRPA6,and the synergistic effect of RP and ZB is obtained.Detailedly,the composite with 4 parts of ZB and 12 parts of RP shows the best flame retardant property,achieving the highest limiting oxygen index(LOI)(30.2 vol%)and a UL94 V-0 rating,and the flame retardant mechanisms may be gas phase along with condense phase mechanism.
文摘The effect of rotational speed in the friction surfacing of nickel-aluminide reinforced Al-Zn-Mg-Cu alloy matrix composite on commercially pure aluminum was investigated. The nickel-aluminide reinforcement was fabricated by in-situ methods based on adding nickel powders to Al-Zn-Mg-Cu alloy melt during the semi-solid casting process.The findings showed that an increase in the rotational speed from 600 to 1000 r/min raised the coating efficiency from 65% to 76%. Besides, there was no significant difference between coating efficiencies in the coating with and without nickel-aluminide. The outcomes showed that if the coating was applied at a rotational speed of 1000 r/min, a traverse speed of 100 mm/min, and an axial feeding rate of 125 mm/min, the hardness and shear strength of the substrate increased by up to 225% and 195%, respectively. But the wear rate of the substrate dropped by 75%. Although the hardness of the coating containing nickel-aluminide increases by up to 32% compared to the coating without nickel-aluminide, nickel-aluminide does not affect the thermal stability of the coating.
基金Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education of China(No.2005-383)
文摘Hybrid materials were prepared using a silane coupling agent, tetraethoxysilane （ TEOS ） as the precursor, dilute hydrochloric acid as the catalyst, and epoxy as the matrices. The films coated with hybrid materials were expected to improve abrasion resistance and mechanical properties. The morphology, mechanical properties, adhesion, and abrasion resistance of the polyethylene terephthalate （PET） films were characterized using an atomic force microscope, a tensile testing machine, a bagger knife, and a reciprocating fabric abrasion tester. The result of research indicated that the modification significantly affected the abrasion resistance and roughness. The-tensile strength and abrasion resistance of the modified PET films increased by 40% and 50% respectively at 3 % TEOS mass fraction.
文摘The effect of brake oil on sliding behavior of carbon/carbon(C/C) and carbon/carbon-silicon carbide(C/C-SiC) composites was investigated with the variation of laminate orientation and surface conformity. The partial and low conformity contacts with the normal and parallel orientations of laminates were considered. The normal load was varied from 50 to 90 N in a step of 10 N. The friction and wear behavior was investigated under reciprocating sliding conditions. The results showed that friction coefficient and wear loss of composites with normal orientation of laminates were larger as compared to those of composites with parallel orientation of laminates. C/C composites with normal orientation of laminates yielded the highest value of friction coefficient. Wear loss decreased by a maximum of 78%, and friction coefficient decreased by a maximum of 49% in low conformity contacts as compared to partial conformity contacts. The presence of brake oil reduced the adhesion tendency of compacted wear debris because the formation of friction film was difficult, and thus, friction behavior was affected. The wear debris retention between the contact surfaces due to confined area motion in reciprocating sliding depicted the tribological behavior.
