聚碳酸酯的拉伸力学行为

本文通过拉伸实验研究了国产聚碳酸酯板的力学行为,得到了这种材料在不同应变速率下的真实应力—应变曲线。实验结果表明:聚碳酸酯为应变率敏感材料,在达到峰值应力之前,泊松比接近0.5,出现颈缩之后,其泊凇比远超过极限值O.5。     

Hot deformation behavior of Super304H austenitic heat resistant steel

The hot compression tests of Super304H austenitic heat resistant steel were carried out at 800-1200℃and 0.005-5 s~(-1) using a Gleeble 3500 thermal-mechanical simulator,and its deformation behavior was analyzed.The results show that the flow stress of Super304H steel decreases with the decrease of strain rate and the increase of deformation temperature;the hot deformation activation energy of the steel is 485 kJ/mol.The hot deformation equation and the relationship between the peak stress and the deforma...     

Synthesis and characterization of spinel Li_(1.05)Cr_(0.1)Mn_(1.9)O_(4-z)F_z as cathode materials for lithium-ion batteries

Samples with the nominal stoichiometry Li_(1.05)Cr_(0.1)Mn_(1.9)O_(4-z)F_z(z=0,0.05,0.1,0.15,and 0.2) were synthesized via the solid-state reaction method and characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),galvanostatic charge/discharge, and slow rate cyclic voltammetry(SSCV) techniques.The results show that the pure spinel phase indexed to Fd3m can be obtained when z=0, 0.05,and 0.1.The substitution of F for O with z≤0.1 contributes to the increase of initial capacity c...     

Relationship between polymerization degree and cementitious activity of iron ore tailings

The aim of this study is to understand the relationship between the polymerization degree and cementitious activity of iron ore tailings.In light of the poor usage of iron ore tailings,stockpile samples from Tangshan were studied in terms of their ability to become cementitious materials.Compound thermal activation was used to improve the cementitious properties of the tailings,while analyzing methods,such as X-ray diffraction (XRD),infrared spectroscopy (IR),nuclear magnetic resonance (NMR),and X-ray photo...     

Cemented backfilling performance of yellow phosphorus slag

The experiments on the cemented backfilling performance of yellow phosphorus slag,including physical-mechanical properties,chemical compositions,optimized proportion,and cementation mechanisms,were carried out to make good use of yellow phosphorus slag as well as tackle with environment problems,safety problems,geological hazards,and high-cost issues during mining in Kaiyang Phosphorus Mine Group,Guizhou.The results show that yellow phosphorus slag can be used as the cement substitute for potential coagulat...     

Structure and electrochemical properties of LiLaxMn2-xO4 cathode material by the ultrasonic-assisted sol-gel method

Powders of spinel LiLaxMn2_xO4 were successfully synthesized by the ultrasonic-assisted sol-gel (UASG) method.The structure and properties of LiLaxMn2_xO4 were examined by X-ray diffraction (XRD),Fourier transform infrared (FT-IR) spectros-copy,scanning electronic microscopy (SEM),galvanostatic charge-discharge test,and cyclic voltammetry (CV).XRD results showthat the La3+ can partially replace Mn3+ in the spinel and the doped materials with La3+ have a larger lattice constant compared with pristine LiMn2O4.FT-IR indicates that the absorption peak of Mn3+-O and Mn4+-O bonds has a red and blue shift with the increase of doping lanthanum in LiLaxMn2_xO4,respectively.The charge-discharge test exhibits that the initial discharge capacity of LiLaxMn2_xO4 drops off,and the capacity retention increases gradually at C/5 discharge rate with the increase of doping lanthanum,and LiLa0.01Mn1.99O4 has a higher discharge capacity and a better cycling performance at 1C discharge rate.CV reveals that the dop-ing La3+ is beneficial to the reversible extraction and intercalation of Li+ ions.     

Synthesis and electrochemical characteristics of xLi2MnO3·（1-x）Li- （Ni1/3Co1/3Mn1/3）O2 compounds

xLi2MnO3·(1-x)Li(Ni1/3Co1/3Mn1/3)O2 (x=0.25, 0.40, 0.55) compounds were prepared by low-heating solid state reaction. In the voltage range of 2.70-4.35 V, the discharge capacity of the electrode decreased with the increase of x, with a better cyclability. However, when cycled between 2.7 and 4.6 V, the cathodes delivered much larger capacities and their capacities increased with the introduction of Li2MnO3. Moreover, it was found that the discharge capacity gradually increased with the cycle number. The rea...     

Effect of nano-SiC particles on the corrosion resistance of NiP-SiC composite coatings

NiP-SiC (≈11wt% P) composite coatings were electroplated in a Brenner type plating bath. The coatings had amorphous nano-phase composite structure. Direct current and alternating current electrochemical tests were carried out on such coatings in a 3.5wt% solution of NaCl to evaluate their corrosion resistance. The potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) tests, and exposure experiments all show that the corrosion resistance of NiP-SiC coatings first increases and then decre...     

Effect of Fe metal on the growth of silicon oxide nanowires

Silicon oxide (SiOx) nanowires are generally grown on Si substrate under the catalysis of Au in N2 atmosphere at elevated temperatures. Because the price of Au metal is quite high, Fe metal is then used to replace a part of Au for catalyzing the growth of SiOx nanowires. The results show that the Fe film can be used as the diffusion barrier of Au. SiOx nanowires are grown on Au/Fe/Si substrate at 1030°C. Under the catalysis of Fe/Au, the efficiency for the growth of SiOx nanowires is promoted.