金隆闪速炉高热负荷生产实践

随着闪速炉投料量的不断增加,金隆公司闪速炉在增料过程中出现反应生料多、炉体损坏严重等一系列问题,通过采取参数优化、炉体改造及操作控制等方式进行解决,使金隆闪速炉炉成功稳定运行在高热负荷状态下,本文着重分析问题形成的主要原因并描述采取的应对措施的同时,通过对历年生产与能耗进行对比,阐述了闪速炉高热负荷条件下生产节能降耗方面存在的显著优势,为闪速炉生产技术进一步向集约化和节能降耗方向发展提供参考。

一种含铼多晶铸造高温合金的凝固行为

在多晶铸造高温合金中加入铼并观察其铸态组织,发现在(γ+γ′)共晶附近有μ相和类树枝晶γ′相析出,测定合金中各种相的形成顺序和共晶反应偏析,分析了初生μ相和类树枝晶γ′相的形成机理,研究了Re在多晶铸造高温合金凝固过程中的作用和对合金凝固组织的影响.

Near-fault directivity pulse-like ground motion effect on high-speed railway bridge

The vehicle-track-bridge(VTB)element was used to investigate how a high-speed railway bridge reacted when it was subjected to near-fault directivity pulse-like ground motions.Based on the PEER NAG Strong Ground Motion Database,the spatial analysis model of a vehicle-bridge system was developed,the VTB element was derived to simulate the interaction of train and bridge,and the elasto-plastic seismic responses of the bridge were calculated.The calculation results show that girder and pier top displacement,and bending moment of the pier base increase subjected to near-fault directivity pulse-like ground motion compared to far-field earthquakes,and the greater deformation responses in near-fault shaking are associated with fewer reversed cycles of loading.The hysteretic characteristics of the pier subjected to a near-fault directivity pulse-like earthquake should be explicitly expressed as the bending moment-rotation relationship of the pier base,which is characterized by the centrally strengthened hysteretic cycles at some point of the loading time-history curve.The results show that there is an amplification of the vertical deflection in the girder's mid-span owing to the high vertical ground motion.In light of these findings,the effect of the vertical ground motion should be used to adjust the unconservative amplification constant 2/3 of the vertical-to-horizontal peak ground motion ratio in the seismic design of bridge.

Dual solidification mechanisms of liquid ternary Fe-Cu-Sn alloy

Liquid ternary Fe47.5Cu47.5Sn5 alloy displayed dual solidification mechanisms when it was undercooled by up to 329 K （0.19TL）. Below a critical undercooling of about 196 K, it solidified just like a normal peritectic alloy, even though metastable phase separation occurred to a microscopic extent. Once bulk undercooling exceeds 196 K, macroscopic segregation played a domi- nant role in solidification. In both cases, the solidification process was always characterized by two successive peritectic trans- formations： firstly primary yFe dendrites reacted with liquid phase to form （Cu） phase, and subsequently the （Cu） phase reacted with residual liquid phase to yield β-Cu5.6Sn intermetallic compound. The primary yFe dendrites achieved a maximum growth velocity of 400 mm/s and experienced a growth kinetics transition as a result of macrosegregation. Since the （Cu） phase was both the product phase of the first peritectic transformation and also the reactant phase for the second peritectic transformation, it appeared as two layers in solidification microstructures due to the microsegregation of Sn solute. The boundary continuity between the macroscopically separated Fe-rich and Cu-ricb zones was enhanced with the increase of undercooling.

DFT calculation analysis of oxygen reduction activity and stability of bimetallic catalysts with Pt-segregated surface

The stability and oxygen reduction reaction （ORR） activity of the Pt-segregated surface in various Pt-M alloys （M： transition metals） are investigated through systematic DFT calculations on the thermodynamic （alloy formation energy and Pt surface segregation energy）, surface chemical property （oxygen binding energy） and electronic （d-band center） properties. Factors af- fecting these properties, such as the atomic radii and surface energy of M and the electronic ligand interaction between Pt and M are analyzed as a function of outmost d electron numbers of M. It is shown that the electronic ligand interaction plays de- termining role in the alloy formation energy of various Pt-M alloys; the formation of Pt-segregated surface in Pt-M alloys is faw）red when alloying metals have higher surface energy and smaller radii than Pt; the oxygen binding energy on the Pt-segregated surface in Pt-M alloys varies approximately linearly with the d-band center of surface Pt atoms; the lattice strain and electronic ligand effects are simply additive in Pt-M alloys; the stain effect in Pt-M alloys nearly linearly affects the d-band center of the Pt-segregated surface in Pt-M alloys; transition metals with less than 10 d electrons mostly exhibit electron ligand effects which result in downshift of the d-band center of the segregated surface Pt atoms, while those with ten d electrons exhibit electron ligand effect upshifting the d-band center of the segregated Pt atoms.