Ag含量对NiFe2O4基金属陶瓷惰性阳极性能的影响

为了提高NiFe2O4陶瓷阳极材料的力学性能和抗热震性,向原料中加入金属Ag,采用粉末冶金法制备了Ag/NiFe2O4金属陶瓷惰性阳极.研究了Ag含量对材料微观结构、抗弯强度以及抗热震性的影响.研究结果表明随着Ag含量的增加,惰性阳极材料的晶粒尺寸逐渐减小,说明Ag能够有效抑制陶瓷基体晶粒的长大.而且随着Ag含量的增加,材料的结构越来越致密,说明Ag在一定程度上能够促进烧结.对材料的力学性能和抗热震性测试结果发现,Ag能提高材料的强度,随着Ag含量的增加,材料的抗弯强度逐渐增大,抗热震性在银含量为10%处达到最大值.     

Co64Fe11Nb5Si12B8合金磁导率与温度的关系

采用铁芯测试仪测得合金样品的初始磁导率随温度的变化曲线, 用磁化强度小角旋转法测量非晶及晶化合金条带的饱和磁致伸缩系数λs;研究了不同温度退火后Co64Fe11Nb5Si12B8合金的磁导率随温度的变化、磁性以及磁致伸缩系数;结果表明:合金在580、590℃热处理磁性变好的反常现象是由于磁致伸缩系数变小所致.     

NiFe2O4隋性阳极的制备及其电解腐蚀机理

以Fe2O3和NiO为主要原料，添加2％（按质量计）MnO2，采用固相烧结工艺制备了NiFe2O4惰性阳极。用X射线衍射和扫描电子显微镜对材料的组成和微观结构进行了研究，测量了样品在冰晶石熔盐中不同电流密度下的电解腐蚀速率，并对其腐蚀机理作了初步探讨。结果表明：惰性阳极由NiO和NiFe2O4尖晶石两相组成，MnO2作为固溶体在尖晶石晶界处富集。电解腐蚀呈现出物理化学溶解过程，熔盐对试样的电解腐蚀首先要在晶界处发生反应生成更稳定的FeAl2O4相，而FeAl2O4相结构致密，冰晶石熔盐通过该相向NiFe2O4尖晶石晶粒内扩散速度减慢，从而降低了腐蚀速率。     

用EDTA络合法制备BaHfO3:Ce3+纳米粒子

采用乙二胺四乙酸(ethylene diamine tetracetic acid,EDTA)络合溶胶-凝胶法制备掺杂Ce3+的BaHfO3纳米粒子.用热重-差热分析、X射线衍射、扫描电镜、透射电镜及荧光光度仪等手段表征样品的物相、形貌及光谱特性,分析Ce3+在BaHfO3基体中的固溶行为.结果表明:添加乙二醇条件下制...     

钢铁产品生命周期的铁资源效率研究

我国是铁矿石资源贫乏国家,矿石品位低,开采成本高。特别是近年来随着我国钢铁产能的迅速提升,铁矿石资源的利用问题愈发突出。本文以资源效率作为衡量天然资源节约程度的指标,设计了一张有时间概念的钢铁产品生命周期铁流图,在此基础上研究铁的排放率、大循环率、产量年均变化率和平均使用寿命对铁资源效率的影响规律,以此指导铁矿资源的高效利用。     

Quantitative Analysis of Work Hardening and Dynamic Softening Behavior of low carbon alloy Steel Based on the Flow Stress

In this study, the constitutive equation and DRX(Dynamic recrystallization) model of Nuclear Pressure Vessel Material 20MnNiMo steel were established to study the work hardening and dynamic softening behavior based on the flow behavior, which was investigated by hot compression experiment at temperature of 950 °C, 1050 °C, 1150 °C and 1250 °C with strain rate of 0.01 s⁻¹, 0.1 s⁻¹ and 10 s⁻¹ on a thermo-mechanical simulator THE RMECMASTOR-Z. The critical conditions for the occurence of dynamic recrystallization were determined based on the strain hardening rate curves of 20MnNiMo steel. Then the model of volume fraction of DRX was established to analyze the DRX behavior based on flow curves. At last, the strain rate sensitivity and activation volume V^* of 20MnNiMo steel were calculated to discuss the mechanisms of work hardening and dynamic softening during the hot forming process. The results show that the volume fraction of DRX is lower with the higher value of Z (Zener–Hollomon parameter), which indicated that the DRX fraction curves can accurately predicte the DRX behavior of 20MnNiMo steel. The storage and annihilation of dislocation at off-equilibrium saturation situation is the main reason that the strain has significant effects on SRS(Strain rate sensitivity) at the low strain rate of 0.01 s⁻¹ and 0.1 s⁻¹. While, the effects of temperature on the SRS are caused by the uniformity of microstructure distribution. And the cross-slip caused by dislocation piled up which beyond the grain boundaries or obstacles is related to the low activation volume under the high Z deformation conditions. Otherwise, the coarsening of DRX grains is the main reason for the high activation volume at low Z under the same strain conditions.     

A synergistic approach to light-free catalysis using zinc oxide embedded multi-walled carbon nanotube paper

Nanoparticle embedded carbon nanotube papers can produce flexible functional films, whose function is based on the electronic coupling of the nanoparticles with the network of carbon nanotubes. Here we report on the expansion of a synergistic light-free catalyst system that requires both the molecular wire capability of multi-walled carbon nanotubes and the piezoelectric properties of ZnO nanoparticles. The electron–hole pairs can be induced by the piezoelectric effect of ZnO nanoparticles under the effect of pressure. The strong oxidizing radicals interact with the electron–hole pairs and aqueous solution to induce the degradation of methylene blue without the requirement of light. This study highlights the use of nanoparticles for the piezoelectric – light free catalyst system and the limitations of increased nanoparticle loading on the catalytic degradation of methylene blue.     

Quality control for bloom casting of YQ450NQR1 steel

To reduce surface depression of a bloom,the primary cooling intensity was decreased,and the water distribution of mold wide and narrow faces was optimized.The length of secondary cooling zones and the specific water flow were increased,and the water flow distribution among the secondary cooling zones was adjusted to eliminate central defects,such as center looseness,central segregation,and center line cracks.The operation showed that the proportion of surface depression decreased from 37.22% to 2.87%,whereas the proportion of center looseness for < 1.0 increased from 79.71% to 90.70%,the proportion of central segregation for <0.5 increased from 1.45% to 44.19%,and the proportion of center line cracks that are flee increased from 39.13% to 62.79%.The quali-fied blooms are delivered to produce 310 Z-beam,whose yield strength is greater than 450 MPa.     

Study on Mechanical Properties and Fracture Mechanisms of B4 C-CeB6/A1 Composites

B₄C-CeB₆/Al composites were first fabricated by pressureless infiltration technology. The mechanical properties of B₄C-CeB₆/Al composites were tested. The results show that the density, the flexibility strength and the fracture toughness of B₄C-CeB₆/Al composites were greatly improved compared with those of monolithic boron carbide, but the hardness of it decreased. The analysis of B₄C-CeB₆/Al composites by using the fracture scanning electric microscope and the back-scattering equipment showed that, the fracture way of B₄C-CeB₆/Al composites was intercrystalline rupture. The flexibility strength and the fracture toughness of B₄C-CeB₆/Al composites were greatly improved for two major reasons. Firstly the flexibility strength and the fracture toughness of B₄C-CeB₆ porous perform were improved because for the CeB₆ existing. Secondly the ductility of aluminum was manifested in B₄C-CeB₆/Al composites.     

Preparation of in situ TiCP/LY12 composite and its microstructure and mechanical properties

Mechanical properties of TiC_P/LY12 Al-based composites prepared by an in situ synthesis method were studied. The micro-structure, morphology, and distribution of TiC_p particles in the LY12 Al alloy matrix were also investigated by XRD, SEM, and HRTEM. The phase composition of the TiC_P/LY12 composites, interfacial structure of TiC particle-to-particle and TiC particle-to-Al matrix, and structure of triple phase among TiC particle, Al₂Cu phase, and Al matrix were also studied. There are no detectable Al₃Ti phases in TiC_P/LY12 composites, and a strong cohesive interface between TiC particles and Al-based alloy matrix was observed in the in situ synthesized TiC_P/LY12 composites. After heat treatment using T6 procedure, it was found that ultimate strength (σ_b), yield strength (σ_s), and Young's modulus (E) of TiC_P/LY12 composites increased but the elongation ratio decreased with increasing of the mass fraction of TiC particles.