高性能氯化丁基橡胶复合阻尼材料的制备技术及力学阻尼性能研究

采用机械共混改性方法制备了高性能氯化丁基橡胶(CIIR)/四[甲基-β-(3,5-二叔丁基-4-羟基苯基)丙酸酯]季戊四醇酯(AO-60)/酚醛树脂(PF)复合减振材料。研究了硫化体系、混炼温度和酚醛树脂用量等对复合减振材料力学阻尼性能的影响。结果表明:在CIIR/AO-60复合材料体系中,采用氧化锌硫化体系制备的减振材料的力学阻尼性能较佳;在混炼条件110℃×30min下制备的复合减振材料的综合阻尼性能和相态结构分布都优于常温下制得的阻尼材料;在CIIR/AO-60材料体系中,随着PF用量的增加,复合减振材料的力学性能、贮能模量和损耗模量都得到提高,复合减振材料的动态力学性能曲线向高温方向移动,材料体系的最大损耗因子值有一定的降低;当PF用量为5份时,所制备的高性能氯化丁基橡胶复合减振材料具有更好的综合力学阻尼性能。

铸造Mg-Zr-Er-Zn合金的力学性能和阻尼行为

通过电子显微镜、阻尼性能和力学性能测试等研究Mg-0.6Zr-0.6Er-1Zn合金力学性能和阻尼行为。结果表明:加入0.6%Er+1%Zn后,在晶界附近存在含Er和Zn的质点减缓了枝晶生长,起到细化Mg-0.6Zr合金组织的作用,使得其晶粒尺寸减小至60μm左右,抗拉强度、屈服强度和伸长率分别达到198.8MPa、83.0MPa和24.5%,较Mg-0.6Zr合金均有不同程度的提高,且比阻尼为48.1%,仍具有较高的阻尼性能。

Improving comprehensive properties of Cu-11.9Al-2.5Mn shape memory alloy by adding multi-layer graphene carried by Cu_(51)Zr_(14)inoculant particles

In order to improve the comprehensive properties of the Cu-11.9Al-2.5Mn shape memory alloy(SMA),multilayer graphene(MLG)carried by Cu_(51)Zr_(14)inoculant particles was incorporated and dispersed into this alloy through preparing the preform of the cold-pressed MLG-Cu_(51)Zr_(14)composite powders.In the resultant novel MLG/Cu-Al-Mn composites,MLG in fragmented or flocculent form has a good bonding with the Cu-Al-Mn matrix.MLG can prevent the coarsening of grains of the Cu-Al-Mn SMA and cause thermal mismatch dislocations near the MLG/Cu-Al-Mn interfaces.The damping and mechanical properties of the MLG/Cu-Al-Mn composites are significantly improved.When the content of MLG reaches 0.2 wt.%,the highest room temperature damping of 0.0558,tensile strength of 801.5 MPa,elongation of 10.8%,and hardness of HV 308 can be obtained.On the basis of in-depth observation of microstructures,combined with the theory of internal friction and strengthening and toughening theories of metals,the relevant mechanisms are discussed.

Mechanism of improving strength and damping properties of powder-extruded Al/Zn composite after diffusion annealing

In order to develop high strength,high damping and low density Al matrix composites,the Al/Zn composite bar samples with Zn mass fraction of 10%-40%were prepared by powder extrusion.The tensile strength and damping properties of the samples are improved by controlling both the Zn/Al diffusion degree and the precipitation of the interfacial phases.The results show that the tensile strength of the samples with Zn mass fraction of 10%-30%increases with the increases of both the Zn content and annealing temperature.When the Zn mass fraction increases to 40%,the tensile strength of the sample remains basically unchanged or decreases slightly,and the plasticity decreases gradually.Alloying of Al matrix and the formation of Zn/Al interface layer are mainly responsible for improving the strength of the annealed samples.The damping properties increase with the increases of both the Zn content and annealing temperature.The Zn/Al eutectoid lamella eliminates the detrimental effects on damping properties due to both alloying of the Al matrix and reduction of pure Zn in the Al matrix.The Al-30%Zn sample annealed at 350°C for 0.5 h has good comprehensive properties,including the tensile strength of 330 MPa,the elongation to failure of 10%and the room-temperature damping properties(tanθ)of 0.025.

Effects of Y on mechanical properties and damping capacity of ZK60 magnesium alloys

The microstructure,mechanical properties and damping capacity of ZK60-xY(x=0,1.5%,2.5%,4.0%,mass fraction) magnesium alloys were investigated by using the optical microscope(OM),X-ray diffractometer(XRD),universal tensile testing machine and dynamic mechanical analyzer(DMA).The mechanisms for damping capacity of referred alloys were discussed by Granato-Lücke theory.The results show that Y additions remarkably reduce grain size(the average grain size is 21.6,13.0,8.6 and 4.0μm,respectively),and the tensile properties are enhanced with grain refining(the yield tensile strength increases to 292 MPa from 210 MPa and ultimate tensile strength increases to 330 MPa from 315 MPa).For the ZK60-xY(x=0,1.5%,4.0%)alloys,the damping capacity decreases with the increase of Y content.However,for the ZK60-xY(x=2.5%)alloy,the damping capacity improves abnormally,which is possibly related to the formation of Mg3Y2Zn3(W)FCC phase in this alloy.

Effects of Y and Zn on mechanical properties and damping capacity of Mg-Cu-Mn alloy

Optical microscope,X-ray diffractometer,scanning electron microscope,tensile tester and dynamic mechanical analyzer(DMA) were applied to investigate the effects of Y and Zn additions on microstructure,mechanical properties and damping capacity of Mg-3Cu-1Mn(CM31) alloy.The results show that with the increase of Y and Zn contents,the secondary dendrite arm spacing of alloys is reduced;meanwhile,the yield strength is increased.In low strain amplitude,the damping capacity of alloys with Y and Zn addition is lower than that of CM31 alloy.However,in strain amplitude over 5×10-3,the damping capacity of alloy with a trace of Y and Zn addition(1%Y and 2%Zn,mass fraction) increases abnormally with the increase of strain amplitude and is near to that of pure Mg,probably due to the increase of dislocation density caused by the precipitation of secondary phase.The temperature dependence of damping capacity of above alloy was also tested and discussed.

大跨径悬索桥退役黏滞阻尼器性能研究

为研究在役大跨径悬索桥的退役黏滞阻尼器的病害和力学性能,通过开展外观检查、力学性能试验、内部结构检查,研究其病害及发展程度,结合桥梁梁端位移实测数据分析诱因,针对性提出改进建议。研究结果表明,该退役黏滞阻尼器的主要病害为硅油泄漏与硅油污染、内部结构磨损等,综合作用引起阻尼力的衰减,1.2 mm/s速度下的衰减率达61.3%,造成减振效果变差。建议在进行大跨度悬索桥黏滞阻尼器设计、选型时,应关注毫米级速度下阻尼力输出情况,并采取优化结构、提高加工精度等措施预防内部结构磨损。