Influence of yield-to-tensile strength ratio（Y/T） on failure assessment of defect-free and corroded X70 steel pipeline

The effect of yield-to-tensile strength ratio（Y/T） on failure pressure of X70 pipeline without and with corrosion defects was investigated.The stress-strain response of materials was characterized by a power-law hardening curve.Two formulas to estimate the strain hardening exponent n for a special Y/T were obtained by least squared regression method and the influence of Y/T on n was analyzed.As an application of n-Y/T expression,the analytical solutions of burst pressure for X70 pipeline without and with corrosion defects were also obtained.The results indicate that the burst pressure of defect-free X70 pipe without corrosion defects is a function of the Y/T,pipe geometry t0/D0 and engineering tensile strength,and increases as Y/T or t0/D0 increases; whilst the burst pressure of corroded X70 pipe decreases with the increase of defect depths,d/t.Comparisons indicate that the present analytical solutions closely match available experimental and numerical data.     

聚苯硫醚短纤维纺丝油剂的研制

采用了烷基磷酸酯盐、烷基醚磷酸酯盐和两性表面活性剂的复合抗静电体系,并以特种聚醚为摩擦调整剂,开发出具有优异的抗静电性、较高的油膜强度、适宜的摩擦特性以及良好表面特性的聚苯硫醚短纤维纺丝油剂.实践表明:该油剂具有很好的可纺性、梳理性和成纱性,能满足聚苯硫醚短纤维纺丝和后加工的要求.     

Characterization of functionally graded ZrO_2 thermal barrier coatings sprayed by supersonic plasma spray with dual powder feed ports

1INTRODUCTION Thermalbarriercoatings(TBCs)arewidelyusedintheaerospaceandautomotiveindustriesfor increasedoperationtemperatureofimportantther malcomponentsofsystemssuchastheturbineen gineanddieselengineinordertoachieveanin creaseintheefficiency,performance…     

烷基磷酸酯钾盐乳液性能的研究

基于聚苯硫醚短纤维纺丝和加工工艺对烷基磷酸酯钾盐的性能要求,研究烷基磷酸酯钾盐的表面张力、润湿性、乳化性、起泡性、乳液稳定性等乳液性能及其影响因素.结果表明:随着烷基磷酸酯钾盐烷基链的增加,表面张力增大,润湿性降低,起泡性逐渐减小,泡沫稳定性增强;烷基链的长度对烷基磷酸酯钾盐的乳化性影响不大;随着pH值增大,烷基磷酸酯钾盐乳液的发泡能力减小,泡沫稳定性变差;随着烷基磷酸酯钾盐乳液粒径的减小,离心量减少,乳液稳定性增强;随着温度的升高,乳液的稳定性增强.     

Characterization of functionally graded ZrO2 thermal barrier coatings sprayed by supersonic plasma spray with dual powder feed ports

The functionally graded thermal barrier coatings (FG-TBCs) with 80% ZrO₂-13%CeO₂-7%Y₂O₃ (CYSZ)/NiCoCrAlY were prepared using a recently developed supersonic plasma spraying (S-PS) with dual powder feed ports system. The thermal shock experiment of FG-TBCs specimens was carried out by means of the automatic thermal cycle device, in which the samples were heated to 1 200 °C by oxygen-acetylene flame jet then water-quenched to ambient temperature. The temperature—time curves of specimens and photographs can be watched online and recorded by a computer during the test. The results show that the totally 1 mm-thick FG-TBCs have excellent thermal shock resistance due to the fact that the coatings have no any peeling-off after 200 thermal cycles. The microstructures and morphologies of FG-TBCs were characterized and analyzed by SEM. Foundation item: Projects(50235030; 90305023) supported by the National Natural Science Foundation of China     

Interfacial microstructure and properties of Ti(C,N)/Ni bonded by transient liquid-phase diffusion

Effects of the main process parameters(temperature and time) on microstructure and properties of Ti(C, N)/Ni interface bonded by (Cu+Nb) interlayer in a vacuum diffusion bonding device were investigated. The interfacial microstructures consisted initially of Ni₃Nb metallic compound and eutectic of Ni₃Nb+CuNi_SS, and finally transformed to (Ti, Nb) (C, N)+Ni₃Nb near Ti (C, N) and NiCu_SS+Ni₃Nb near Ni when diffusion bonding temperature was 1 523–1 573 K. It was clear that Cu was a constituent in the transient liquid phase (TLP) into which Ni was dissolved by forming Cu-Ni transition liquid. Nb was dissolved in Cu-Ni transition liquid rapidly. Ti (C, N) conld be wetted by resultant Ni-Nb-Cu transient liquid phase which was followed by a little (Ti, Nb) (C, N) solid solution formed at interface. This increased the interface combining capability. Ultimately the interface shear strength was able to reach 140 MPa. The theoretle analysis and experimental results show that the growth of interfacial reaction layer Ni₃Nb accords with parabola law, and the activation energy of diffusion reaction is 115.0±0.5 kJ/mol, while the diffusion reaction speed constant is 12.53 mm/s^1/2. Funded by the National Natural Science Foundation of China (No. 50074017/E0408)     

基于可规律性移动锚节点和接收信号强度指示器的改进DV-Hop定位算法及其性能分析

针对DV-Hop定位算法进行了缺陷分析,提出了一种基于可规律性移动锚节点(RMAN)和RSSI测距技术辅助定位的算法RRDV-Hop。采用OMNET++作为仿真平台,分别从算法的平均定位精度、开销、硬件成本和稳定性等方面对两种定位算法的仿真结果进行了对比和分析。实验结果表明,在相同网络条件下,与DV-Hop算法相比,RRDV-Hop算法近似实现了锚节点的均匀分布,能够在随机分布的网络中提高平均定位精度和保持更好的算法稳定性;同时减少了锚节点个数,从而降低了网络的硬件成本。因此,RRDV-Hop算法更能适应随机分布的无线传感器网络。     

热台原子力显微镜研究PVDF/PBA共混物的表面结晶形态

制备了低温结晶的聚偏氟乙烯（PVDF）/聚己二酸丁二酯（PBA）共混物薄膜.使用热台原子力显微镜跟踪研究PVDF/PBA共混物薄膜样品的原位熔融过程,从片晶尺度上考察不同的共混比例对相分离形态结构的影响规律.结果表明,当PVDF/PBA共混体系在低温下结晶时,PBA组分主要在PVDF的片晶间的区域内分布;共混比例影响两组分都结晶后的片晶排列方式;PBA组分含量较低时,两组分片晶的排列方式主要为＂ABABABAB＂,PBA中等含量时,两组分片晶的排列方式主要为＂ABBBABBB＂;片晶间分相结构对PBA的结晶扩散有抑制作用,PBA组分要充分结晶需要较高的过冷度或者足够长的结晶时间.     

High temperature strength and ductility of the （C＋N） strengthening Fe-Cr-Mn（W, V） steels

Fe-Cr-Mn(W, V) austenite steels used as low radioactive structural materials in fusion reactor have been investigated. The resuits show that the high temperature strength and the creep fracture life of Fe-Cr-Mn(W, V) steels can be effectively improved through (C N) complex-strengthening, so can be the high temperature ductility. The strength and ductility of the steels are superior to that of SUS316 steels and JPCAS below 673 K. The relationship between strength, ductility and the formation temperature is related to the evolution of deformation microstructure. The fracture and microstructure observation above 673 K indicates that the main way to further improve ductility at high temperature is the control of carbide coarsening at the grain boundaries.     

双剪统一强度理论下钢管混凝土承载力的理论分析及试验研究

制作了25个钢管混凝土试件,进行了钢管混凝土试件的轴心受压和偏心受压试验,得出了其荷载变形曲线及极限荷载,以双剪统一强度理论为基础,推导出钢管混凝土核心混凝土抗压强度的计算公式,并进行了钢管混凝土承载力的理论计算,所得理论结果与试验结果基本一致,说明双剪统一强度理论对于钢管混凝土的理论计算有非常好的适用性,为钢管混凝土的分析计算提供了一定的理论依据.     

Wafer bonding technique used for the integration of cubic GaN/GaAs (001) with Si substrate

We successfully used the metal mediated-wafer bonding technique in transferring the as-grown cubic GaN LED structure of Si substrate. The absorbing GaAs substrate was removed by using the chemical solutions of NH4OH : H2O2=1 : 10. SEM and PL resuls show that wafer bonding technique could transfer the cubic GaN epilayers uniformly to Si without affecting the physical and optical properties of epilayers. XRD result shows that there appeared new peaks related to AgGa2 and Ni4N diffraction, indicating that the metals used as adhesive and protective layers interacted with the p-GaN layer during the long annealing process. It is just the reaction that ensures the reliability of the integration of GaN with metal and minor contact resistance on the interface.