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Effect of hot rolling on microstructure and tribology behaviors of Ti-50.8Ni alloy 被引量:2
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作者 Rui YANG Wei MA +2 位作者 Chao wang Ting-mei wang qi-hua wang 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2021年第4期967-979,共13页
We link different microstructures to tribological behaviors of Ti-50.8 Ni(mole fraction, %) in reciprocating mode at room temperature(20 ℃). Hot-rolled alloys with B2 phase exhibit lower coefficient of friction and w... We link different microstructures to tribological behaviors of Ti-50.8 Ni(mole fraction, %) in reciprocating mode at room temperature(20 ℃). Hot-rolled alloys with B2 phase exhibit lower coefficient of friction and wear rate compared to the ones with B19?. Stress-induced martensitic transformation occurs during sliding. However, multi-pass hot rolling weakens the wear resistance. In this study, microstructures were characterized through electron backscatter diffraction and transmission electron microscopy(EBSD/TEM). From the concept of energy conservation, the effects of weak intensity of hot-rolled textures on the wear resistance are minimal. Based on the result that the alloy with a higher portion of coincidence site lattice boundaries shows lower martensitic start transformation temperature in the DSC curves than that with higher KAM values, the delay on B2-B19? transformation from {112}B2 twins outweighs dislocations. Moreover, widely distributed small-angle grain boundaries owing to dynamic recovery improve the wear resistance effectively compared to those that are well-recrystallized. 展开更多
关键词 Ti-50.8Ni alloy tribological performance small angle grain boundaries coincidence site lattice(CSL)boundary
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盾构机主驱动密封用聚氨酯脲弹性体密封材料的研究 被引量:3
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作者 杨靖 李彦辉 +4 位作者 陈守兵 张新瑞 王廷梅 王齐华 张耀明 《高分子学报》 SCIE CAS CSCD 北大核心 2023年第12期1857-1869,共13页
以聚四氢呋喃二醇(PTMEG)、甲苯2,4-二异氰酸酯(TDI)和3,3'-二氯-4,4'-二氨基二苯基甲烷(MOCA)为原料,通过使用不同含量的有机硅树脂(PDMS)对其改性,制备了4种浇注型聚氨酯脲弹性体(PUU-s).系统地研究了PDMS的含量对聚氨酯脲弹... 以聚四氢呋喃二醇(PTMEG)、甲苯2,4-二异氰酸酯(TDI)和3,3'-二氯-4,4'-二氨基二苯基甲烷(MOCA)为原料,通过使用不同含量的有机硅树脂(PDMS)对其改性,制备了4种浇注型聚氨酯脲弹性体(PUU-s).系统地研究了PDMS的含量对聚氨酯脲弹性体力学性能、耐热性能、耐疲劳性能、可回复性能、耐介质性能以及摩擦学性能的影响.结果表明,PDMS改性的PUU-s弹性体,不仅具有较高的机械性能,且具有优异的耐磨性和耐介质性以及较高的可回复性,可作为苛刻工况下的密封材料.其有望作为盾构机主驱动密封用材料,提高了密封部件的长寿命服役,解决了磨损失效等问题. 展开更多
关键词 聚氨酯脲 摩擦学性能 有机硅树脂 密封材料
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Tribology behaviors of Ti-Ni51.5 at% shape memory alloy with different microstructures and textures 被引量:3
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作者 Rui Yang Song Li +3 位作者 Nan Zhang Chao wang Ting-Mei wang qi-hua wang 《Rare Metals》 SCIE EI CAS CSCD 2021年第12期3616-3626,共11页
The microstructure characteristics of TiNi alloy were investigated to elucidate the active deformation mechanisms during hot rolling and the corresponding tribology performance.The deformation was mainly dominated by ... The microstructure characteristics of TiNi alloy were investigated to elucidate the active deformation mechanisms during hot rolling and the corresponding tribology performance.The deformation was mainly dominated by a combination of mechanical twinning involving the {114}_(B2) and {112}_(B2) twins,dislocations,and stacking faults during the manufacturing process.Moreover,various heat treatments were performed to differentiate the discrepancies in tribological behaviors of hot-rolled and heattreated alloys.Hot-rolled microstructures with high defect density approximate to nanoscale precipitates through aging as the wear resistance of the alloy improves,albeit it is softer compared to the aged one.As demonstrated by the X-ray diffraction(XRD) results of the wear tracks,microstructures undergo the stress-induced martensitic(SIM) transformation during dry sliding.From differential scanning calorimetry(DSC) analysis,the martensitic transformation temperature is lowered by defects in the austenite phase.The activation of the SIM transformation can be a sluggish process owing to the effect of twinning,where both primary and secondary twins are involved.Furthermore,a reversible transformation that is related to pseudoelasticity causes a decrease in wear volume at room temperature,which is higher than the austenite finish temperature.Meanwhile,abrasive wear advances toward adhesion.Additionally,the hot-rolled sheet with y fiber-{111}//ND(normal direction) exhibits better wear resistance compared to the sheet with α fiber-{100}//ND. 展开更多
关键词 B2 twin Texture PRECIPITATES Tribology performance Ti-Ni51.5 at%
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Quantile Regression under Local Misspecification 被引量:1
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作者 Xiao-gang DUAN qi-hua wang 《Acta Mathematicae Applicatae Sinica》 SCIE CSCD 2020年第4期790-802,共13页
The frequentist model averaging(FMA)and the focus information criterion(FIC)under a local framework have been extensively studied in the likelihood and regression setting since the seminal work of Hjort and Claes kens... The frequentist model averaging(FMA)and the focus information criterion(FIC)under a local framework have been extensively studied in the likelihood and regression setting since the seminal work of Hjort and Claes kens in 2003.One inconvenience,however,of the existing works is that they usually require the involved criterion function to be twice differentiable which thus prevents a direct application to the case of quantile regression(QR).This as well as some other intrinsic merits of QR motivate us to study the FIC and FMA in a locally misspecified linear QR model.Specifically,we derive in this paper the explicit asymptotic risk expression for a general submodel-based QR estimator of a focus parameter.Then based on this asymptotic result,we develop the FIC and FMA in the current setting.Our theoretical development depends crucially on the convexity of the objective function,which makes possible to establish the asymptotics based on the existing convex stochastic process theory.Simulation studies are presented to illustrate the finite sample performance of the proposed method.The low birth weight data set is analyzed. 展开更多
关键词 frequentist model averaging focus information criterion local framework quantile regression
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