Advanced Materials Research Vol. 421

Abstract: The structure, working characteristics and main parts failure types of construction machinery were discussed in this paper. The reasons of failures are analyzed too. Based on producing theory, the remanufacturing technology of different failures for construction machinery is discussed. It was proved that the remanufacturing technology is feasible and practical, and has theoretical and applicable values.

Abstract: This paper researched the bacteriostatic of Salicornia herbacea (SH)extracts by method of spectrophotometry and plate culture, which showed Salicornia herbacea extracts have certain inhibition to both bacteria and streptomyces, and the inhibition rate to bacteria higher than which to streptomyces. At same times, this research studied the antioxidant of Salicornia herbacea extracts on peanut oil by iodometry. And the results showed that the POV (peroxide value) which added a certain amount of Salicornia herbacea extracts to peanut oil were smaller than the reference.

Abstract: Push-pull pickling line of a branch of WISCO frequently comes up the faults that rotary shear axial locking is unreliable and the cutting precision is low. To solve this problem, two kinds of sickle-like curve have been analyzed, the graphic method and the finite element method were used. The research come to the conclusion that frequent appearance sickle-like curve would produce additional axial impact load on rotary shear's shear blade and also calculated value of axial static load. These are the main reason why the faults appear. After took the proposed solutions accordingly to improve the locking force, the down time were greatly reduced and the cutting precision were improved significantly.

Abstract: The size and roundness tolerance are common defects of the heavy caliber seamless tube after rolling and heat treatment. In order to disclosure the straightening mechanism of the heavy caliber seamless tube with ten cross rollers straightening machine, a nonlinear finite element model was set up on the platform of MSC.MARC. In this model, a heavy caliber seamless tube of Φ750 × 37 mm with initial roundness tolerance was used. The simulation results show that, the roundness tolerance declined from 1% to 0.2% after straightening, so that the initial roundness tolerance was almost eliminated. And the strain and stress distribution of the tube, the straightening force fluctuating caused by the roundness tolerance were presented and discussed. The analysis results obtained may provide a theoretical foundation not only for establishing the straightening process, but for the machine structure designing.

Abstract: Proton electrolyte membrane fuel cells (PEMFC) have near zero carbon dioxide and hazardous pollutant emission. Thus, it is considered as one of energy sources for transportation and other application which can improve environmental performance by decreasing the emission of greenhouse gases and other air pollutant. In accordance with its environmental preservation values, graphite waste product from electric arc furnace (graphite EAF) was chosen as a potential candidate material for bipolar plate for PEMFC. The utilization of graphite waste product is expected to result in light-weight and cost-effective bipolar plates. In this paper, we used graphite EAF as a filler together with carbon black and epoxy resin as a binder. We examined the effects of differential pressure applied on compression molding process on density, porosity, flexural strength and electrical conductivity of the resulting carbon polymer composite bipolar plate. Pressure was applied from 30 MPa - 60 MPa in increments of 5 MPa while maintaining constant temperature operation at 700C for 4 hours. Maximum value of bipolar plate density was achieved at application 55 MPa, of 1.69 g/cm3. At this condition, the flexural strength was measured to be 48 MPa with the porosity of 0.7%, and electrical conductivity of 1.03 S/cm. Taken together, we demonstrated that graphite EAF is a good candidate for the manufacturing of polymer composite bipolar plates.

Abstract: Solidification heat transfer in continuous casting slab was simulated with the business software CALCOSOFT. The position on solidification end point which obviously effect on soft reduction was predicted and verified by nail—shooting technique. It is shown from the numerical simulation that the casting speed affected the position significantly: the solidification end point moved backward 3 or 4m as the casting speed increased by 0.2m /min, while the casting temperature has little effect that the solidification end point moved backward only 0.2 or 0.25mm as it increased 6°C or 7°C.

Abstract: A modified fly ash (MFA) was prepared from fly ash (FA) and tetraethylenepentamine-multi dithiocarbamate (TEPAMDT). The structure of MFA was characterized by FTIR, and the morphology was observed by using scanning electron microscope (SEM). Its removal perfermance towards heavy metals was assessed by employing it to the treatment of simulated wastewater containing Cu2+ and comparing with TETAMDT. The results show that the fine particles in FA assemble to form a porous crystal with high specific surface area after being modified due to the pozzolanic reaction. The dosage of MFA is far lower than that of FA and the treatment cost is less than that of TEPAMDT. The removal rate of Cu2+ can reach 100% at the dosage of MFA 412 mg/L when the Cu2+ simulated wastewater concentration is 50 mg/L. Compared with TEPAMDT, using MFA can not only increase the sedimentation rate of flocs but also reduce the volume of precipitates, and the MFA-Cu precipitate obtained is more stable than TEPAMDT-Cu in acid solution and would not cause the threat of instantly releasing heavy metal under weak acidic and alkaline environment.

Abstract: The mechanism of die erosion in Al-Si alloys was investigated based on the formation behavior of iron-containing intermetallics. And the metallurgical parameters affecting on the erosion tendency were discussed as functions of chemical composition for a guideline of melt control in Al-Si foundry. It was found that the intermetallic layers of α-AlFeSi, β-AlFeSi and θ-AlFe were formed through metallurgical reactions. The erosion tendency of die material was determined by not only the gradient of iron content through the interface between die material and molten alloy but also the relative formation temperature of primary intermetallics.

Abstract: In this paper, the optimum media supplemented to the basic substrate wheat bran (WB) for getting maximum soluble dietary fiber (SDF) production under solid state fermentation (SSF) by Hericium erinaceus was investigated. Soybean meal was suitable for mycelial growth as nitrogen source, four inorganic salts (KH2PO4、ZnSO4、FeSO4 and MgCl2) could increase SDF production significantly. Artificial neural networks (ANNs) and genetic algorithms (GA) formalisms were used for modeling the non-linear relationship between the fermentation media and SDF production and optimizing the model, respectively. After optimization, parameters of the five media supplemented to WB were (mg g-1 WB): soybean meal 124.3, KH2PO4 0.18, ZnSO4 0.6, FeSO4 0.2, MgCl2, 1.2. The SDF production increased to 13.06±0.51 g 100g-1 in the validation experiment, which was 4.68 fold as compared with control.

Abstract: To understand the dendrite formation during solidification phase-field model has become a powerful numerical method of simulating crystal growth in recent years. Two phase-field models due to Wheeler et al. and Karma et al., respectively, have been employed for modeling the dendrite growth worldwidely. The comparison of the two models was performed. Then using the adaptive finite element method, both models were solved to simulate a free dendrite growing from highly undercooled melts of nickel at various undercoolings. The simulated results showed that the discrepancy between the two phase-field models is negligible. Careful comparison of the phase-filed simulations with LKT(BCT) theory and experimental data were carried out, which demonstrated that the phase-field models are able to quantitatively simulate the dendrite growth of nickel at low undercoolings, however, at undercoolings above ten percent of the melting point (around 180K), the simulated velocities by Wheeler and Karma model as well as the analytical predictions overestimated the reported experiment results.