Microscopic defects formation and dynamic mechanical response analysis of Q345 steel plate subjected to explosive load

As the basic protective element, steel plate had attracted world-wide attention because of frequent threats of explosive loads. This paper reports the relationships between microscopic defects of Q345 steel plate under the explosive load and its macroscopic dynamics simulation. Firstly, the defect characteristics of the steel plate were investigated by stereoscopic microscope(SM) and scanning electron microscope(SEM). At the macroscopic level, the defect was the formation of cave which was concentrated in the range of 0-3.0 cm from the explosion center, while at the microscopic level, the cavity and void formation were the typical damage characteristics. It also explains that the difference in defect morphology at different positions was the combining results of high temperature and high pressure. Secondly, the variation rules of mechanical properties of steel plate under explosive load were studied. The Arbitrary Lagrange-Euler(ALE) algorithm and multi-material fluid-structure coupling method were used to simulate the explosion process of steel plate. The accuracy of the method was verified by comparing the deformation of the simulation results with the experimental results, the pressure and stress at different positions on the surface of the steel plate were obtained. The simulation results indicated that the critical pressure causing the plate defects may be approximately 2.01 GPa. On this basis, it was found that the variation rules of surface pressure and microscopic defect area of the Q345 steel plate were strikingly similar, and the corresponding mathematical relationship between them was established. Compared with Monomolecular growth fitting models(MGFM) and Logistic fitting models(LFM), the relationship can be better expressed by cubic polynomial fitting model(CPFM). This paper illustrated that the explosive defect characteristics of metal plate at the microscopic level can be explored by analyzing its macroscopic dynamic mechanical response.

导电共聚物衍化新策略制备硫、氮共掺杂碳纳米管及其对改善PtCu纳米晶分散性与甲醇电催化氧化的促进作用

有效调控碳纳米材料的几何和电子结构的协同效应和缺陷是获得优良电化学性能的关键.然而,如何设计一种具有优势结构的杂化材料及对其电催化机理的认识尚不清楚.本文提出了一种聚(3,4-乙撑二氧噻吩)/聚苯胺导电共聚物热解策略来制备S和N共掺杂多壁碳纳米管(MWCNTs),发现改变前驱体溶液中两种单体的比例可以调控掺杂MWCNTs中S和N原子的含量与表面活性位结构.S和N的共掺杂明显增大了碳纳米管表面的缺陷程度并暴露出更丰富的活性位点,从而有利于超细Pt和PtCu纳米颗粒的均匀分布和沉积.透射电镜和扫描透射电镜结果表明,所制备S和N共掺杂MWCNTs(SN-MWCNTs)负载的催化剂中Pt和PtCu纳米颗粒以及掺杂的S和N原子都均匀地分布在MWCNTs上,且沉积的Pt和PtCu纳米颗粒的平均尺寸仅分别为2.30和2.87 nm.X射线光电子能谱结果表明,S和N共掺杂MWCNTs与负载的Pt基纳米颗粒之间存在强烈的电荷转移相互作用,明显改变了贵金属Pt的表面电子结构.电化学测试结果表明,与Pt/SN-MWCNTs,Pt/N-MWCNTs,Pt/S-MWCNTs和商业Pt/C催化剂相比,Pt_(1)Cu_(2)/SN-MWCNTs表现出更大的电化学活性表面积(148.85 m^(2) g^(−1)),更高的甲醇氧化质量活性(1589.9 mA mg_(Pt)^(−1))、电化学稳定性和抗CO毒化能力.密度泛函理论研究表明,S和N共掺杂导致碳纳米管极大地变形,同时极化和激活了相邻的C原子.因此,增强了Pt_(1)Cu_(2)纳米颗粒在SN-MWCNTs上的吸附以及随后甲醇分子的吸附.此外,Pt_(1)Cu_(2)/SN-MWCNTs对甲醇氧化的电催化活性均在热力学和动力学上优于相应的CNTs和N-CNTs基材料.本文提供了一种新颖的在碳基材料上构建高度分散且稳定的Pt基纳米颗粒高性能燃料电池电催化剂的方法.

Surface-Modified Graphene Oxide/Lead Sulfide Hybrid Film-Forming Ink for High-Efficiency Bulk Nano-Heterojunction Colloidal Quantum Dot Solar Cells

Solution-processed colloidal quantum dot solar cells(CQDSCs) is a promising candidate for new generation solar cells.To obtain stable and high performance lead sulfide(PbS)-based CQDSCs,high carrier mobility and low non-radiative recombination center density in the PbS CQDs active layer are required.In order to effectively improve the carrier mobility in PbS CQDs layer of CQDSCs,butylamine(BTA)-modified graphene oxide(BTA@GO) is first utilized in PbS-PbX2(X=I-,Br-) CQDs ink to deposit the active layer of CQDSCs through one-step spin-coating method.Such surface treatment of GO dramatically upholds the intrinsic superior hole transfer peculiarity of GO and attenuates the hydrophilicity of GO in order to allow for its good dispersibility in ink solvent.The introduction of B TA@GO in CQDs layer can build up a bulk nano-heterojunction architecture,which provides a smooth charge carrier transport channel in turn improves the carrier mobility and conductivity,extends the carriers lifetime and reduces the trap density of PbS-PbX2 CQDs film.Finally,the BTA@GO/PbS-PbX2 hybrid CQDs film-based relatively large-area(0.35 cm2) CQDSCs shows a champion power conversion efficiency of 11.7% which is increased by 23.1% compared with the control device.

A Compound Cycle for Power Generation by Utilizing Residual Heat of Flue Gas in Electric Steelmaking Process

Electric furnace short process steelmaking is one of the most important steelmaking methods in the world today, and the waste heat recovery potential of electric furnace flue gas is huge.?The research on the recovery of electric furnace flue gas waste heat is of great significance. In order to make better use of this part of the heat,?in this paper, a compound cycle of nitrogen Brayton cycle as a first-order cycle and toluene transcritical Rankine cycle as a second-order cycle is proposed to recover waste heat from furnace flue gas in steelmaking process for power generation. A mathematical model was established with the net output power as the objective function and the initial expansion pressure, the final expansion pressure, the initial expansion temperature and the initial pressure of the second cycle as the independent variables. The effect of multivariate on the net output power of the waste heat power generation cycle is studied, and then, the optimal parameters of the compound cycle are determined. The results show that under the general electric furnace steelmaking process, the power generation efficiency of this new cycle can be increased by 21.02% compared with the conventional cycle.

Catalytic oxidation effect of MnSO_(4) on As(Ⅲ) by air in alkaline solution

The catalytic oxidation effect of MnSO_(4)on As(Ⅲ) by air in an alkaline solution was investigated.According to the X-ray diffraction (XRD),scanning electron microscope-energy dispersive spectrometer (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) analysis results of the product,it was shown that the introduction of MnSO_(4)in the form of solution would generate Na_(0.55)Mn_(2)O_(4)·1.5H_(2)O with strong catalytic oxidation ability in the aerobic alkaline solution,whereas the catalytic effect of the other product MnOOH is not satisfactory.Under the optimal reaction conditions of temperature 90℃,As/Mn molar ratio 12.74:1,air flow rate1.0 L/min,and stirring speed 300 r/min,As(Ⅲ) can be completely oxidized after 2 hr reaction.The excellent catalytic oxidation ability of MnSO_(4)on As(Ⅲ) was mainly attributed to the indirect oxidation of As(Ⅲ) by the product Na_(0.55)Mn_(2)O_(4)·1.5H_(2)O.This study shows a convenient and efficient process for the oxidation of As(Ⅲ) in alkali solutions,which has potential application value for the pre-oxidation of arsenic-containing solution or the detoxification of As(Ⅲ).

Tribological properties of onion like fullerenes and NiFe2O4 nanocomposites in reciprocating motion

A novel way for a compressor to improve its coefficient of performance and enhance its reliability by employing nano-refrigeration lubricant oil was proposed. Onion like fullerenes (OLFs) and NiFe2O4 nano-composites, modified by Span 80, were dispersed in refrigeration oil KFR22 by solid grinding (SG). Morphologies of NiFe2O4 nano-composites were characterized by using transmission electron microscope (TEM). The tribological properties as a refrigeration lubricants additive were investigated using SRV (II), a multi-functional reciprocating friction and wear tester. The results showed that the friction coefficient was decreased from 0.15 to 0.04.

Performance of rolling piston type rotary compressor using fullerenes(C70)and NiFe204 nanocomposites as lubricants additives

A novel way for a compressor to improve its coefficient of performance was proposed in this paper.Fullerenes(C70)and NiFe2O4 nanocomposites were modified by span 80 and dispersed in refrigeration oil by solid grinding(SG).Besides,the tribological properties of the nanocomposites were investigated using a four ball friction tester.The results show that when the mass concentration of fullerenes nanocomposite is higher than 60 ppm and the concentration of nano-oil is 2 g/L,the friction coefficient decreases from 0.13 to 0.06 which means the wear is reduced.The coefficient of performance of the compressor under the air conditioning test condition can be raised by 1.23%.

Hybrid method based on flame volume concept for lean blowout limits prediction of aero engine combustors

The Lean Blowout(LBO)limit is crucial for the aircraft engines.The semi-empirical(such as Lefebvre’s LBO model and Flame Volume(FV)model),numerical and hybrid methods are widely utilized for the LBO limit quick prediction.An innovative hybrid method based on the FV concept is proposed.This method can be classified as a semi-empirical/physical based hybrid prediction method.In this hybrid method,it is assumed that the flame volume varies nearly linearly with the fuel/air ratio near the LBO.The flame volume is obtained directly by the numerical simulation using the threshold value of the visible flame boundary as 900 K.Then the final LBO limits is determined by the FV model.On the premise of keeping the good generality of prediction,the hybrid method based on the FV concept can further improve the prediction accuracy.The comparison with the prediction of the existing available methods on fifteen combustors shows that the hybrid method based on the FV concept achieves better prediction accuracy.The prediction uncertainties between the experimental results and the predicted values by the hybrid method based on the FV concept are within about±10%.