旋转机械动态测量实验台的研制

介绍了旋转机械动态测量实验台的研制与开发。详细阐述了实验台的结构组成、实验内容及实验原理,并介绍了实验台的硬件实现方法。该实验台能同时测量多个动态参数,能同时检测传动系统的振动噪声及传动误差,进行在线分析,准确地找出故障位置,有一定的先进性,很适用于教学实验与科学研究。

Fabrication of lightweight 3D interpenetrated NiTi@Mg composite with superior bending properties

A NiTi@Mg interpenetrating phase composite with high strength and lightweight was prepared by additive manufacturing(AM)and infiltration technology,and the interface bonding,three-point bending properties and cyclic compressive properties of NiTi@Mg composites were investigated.The results show that the metallurgically bonded interface is formed at the NiTi/Mg interfaces.The bending strength and compressive strength of the NiTi@Mg composite are 2.5 and 1.7 times higher than those of the NiTi scaffold,respectively.During the bending deformation process,a large number of dislocations are observed to accumulate in the soft Mg area at the interface.Furthermore,the finite element model showed that the stress accumulation area,where the bending crack is initiated,is located at the interface of NiTi and Mg.The strengthening mechanism of NiTi@Mg composites is attributed to the twinning strengthening of Mg and heterogeneous structure strengthening.

气穴对滑动轴承摩擦学性能影响的CFD分析

气穴对滑动轴承性能影响一直为人们所关注,而传统的分析方法不能真实刻画气穴的作用。为寻求合理的气穴研究方法,并由之改进轴承的摩擦学性能,基于计算流体动力学(CFD)与Rayleigh-Plesset(PRE)气穴理论,应用商业软件ANSYS中CFX模块分析了气穴现象对滑动轴承摩擦性能的影响。结果表明:随着偏心率、宽径比和转速的增加,考虑气穴模型后气穴现象会降低润滑剂粘度,轴承油膜的摩擦力和摩擦系数会减小;随着偏心率、宽径比和转速的增加,润滑剂的平均气化率变大。

Influence of different rolling routes on mechanical anisotropy and formability of commercially pure titanium sheet

Influence of three different rolling routes on mechanical anisotropy and formability of commercially pure titanium sheetwas investigated.Route A and Route B are unidirectional rolling(UR)where the rolling direction is along initial rolling direction(RD)and transverse direction(TD),respectively.Route C is cross rolling(CR)where the rolling direction is changed by90°aftereach rolling pass.The microstructure and texture,tensile mechanical properties including strength and elongation,and also theanisotropy of the UR and CR sheets were investigated at room temperature.The XRD results indicate that the texture intensity ofrolled samples gradually weakens from Route A to Route C.Compared with Route A and Route B rolled samples,the Route C rolledsamples show a smaller planar anisotropy.The deep drawing tests reveal that cross rolling can avoid the occurrence of earing.Erichsen tests indicate that rolling routes have an effect on stretch formability of pure titanium sheet.

Microstructures and mechanical properties of AZ91D/0Cr19Ni9 bimetal composite prepared by liquid-solid compound casting

The liquid-solid compound casting technology was used to produce the AZ91D/0Cr19Ni9 bimetal composite without and with hot dipping aluminium, respectively. The influences of Al coating on microstructures and mechanical properties of AZ91D/0Cr19Ni9 interface were investigated. The results showed that the mechanical bonding was obtained between AZ91D and bare steel 0Cr19Ni9 where a gap existed at the interface; the metallurgical bonding was formed between AZ91D and Al-coated 0Cr19Ni9, which could be divided into two different intermetallic layers: layer Ⅰ was mainly composed of α-Mg+β-Mg17Al12 eutectic structure and a small amount of MgAl2O4, and layer Ⅱ mainly comprised of Fe2Al5 intermetallic compound. Furthermore, the hardness value of interface was obviously higher than that of AZ91D matrix, and the average hardness values of layers Ⅰ and Ⅱ were HV 158 and HV 493, respectively. The shear strength of AZ91D/Al-coated 0Cr19Ni9 interface was higher than that of AZ91D/bare 0Cr19Ni9 interface, which confirmed that Al coating could improve the adhesive strength between AZ91D and 0Cr19Ni9 during liquid-solid compound casting process.

Microstructures and mechanical properties of TC4/AZ91D bimetal prepared by solid-liquid compound casting combined with Zn/Al composite interlayer

To achieve Ti/Mg bimetallic composite with high strength and metallurgical bonding interface,Al interlayer and Zn/Al composite interlayer were used to prepare TC4/AZ91D bimetal composite with metallurgical bonding interface by solid-liquid compound casting,respectively.Al interlayer was prepared on the surface of TC4 alloy by hot dipping,and Zn/Al composite interlayer was prepared by electroplating process.The results suggested that the phases across the interface were Al Ti andα(Al)+Mg_(21)(Al,Zn)_(17)when Zn/Al composite interlayer was used.When Al interlayer was used as interlayer,Al Mg Ti ternary structure and Al_(12)Mg_(17)+δ-Mg eutectic structure were the main phases at the interface.The shear strength of TC4/AZ91D bimetal with Zn/Al composite interlayer was much higher than that with pure Al interlayer,and the value of the shear strength was increased from 48.5 to 67.4 MPa.Thermodynamic models based on different compositions of the interface were established to explain the microstructure evolution of the interfacial zone.

Effect of scratch on corrosion resistance of calcium phosphate conversion coated AZ80 magnesium alloy

In order to analyze the effect of scratch on the corrosion behaviour of a calcium phosphate conversion coating(CPCC)on AZ80,the electrochemical testing,scanning vibrating electrode technique(SVET),immersion test and hydrogen evolution experiment were performed to study the corrosion resistance of AZ80,AZ80 with CPCC and coated AZ80 with scratch.The results show that the coating improves the corrosion resistance of the AZ80 from a current density of(85±4)to(4±1)μA/cm^(2).When the coating was damaged,its protection on substrate would be reduced.The scratch with a length of around 12 mm on the coating reduced the corrosion resistance to a current density of(39±1)μA/cm^(2).In addition,the corrosion occurred initially in the scratch area and the corrosion site first occurred at the junction of the scratch and the coating.Besides,the micro corrosion mechanism of the specimen containing scratch was clarified.