Advanced Materials Research Vols. 148-149

Abstract: The low qualified rate of coloring inspection about the bevel gear had puzzled the producer for a long time. This paper tried to solve this problem by applying 6σ methodology. It analyzed the influence factors about the qualified rate of bevel gear coloring inspection and found out the main influence factors firstly; then on base of the analysis results, this paper proposed some improvement measures by applying the DOE analysis; finally, this paper validated the effects of these improvement measures by carrying out some tests. The improvement measures proposed in this paper had improved the qualified rate of coloring inspection obviously.

Abstract: In order to get rid of thermal interferences, the experiment was conducted to test the temperature drops of 40Cr by embedding thermocouple in central part of the steel specimen under the air cooling conditions. The cooling rate of the center was obtained and the phase transition temperature at the start and end points were determined. By comparing with 40Cr CCT curves, obvious effects of the metal phase transition latent heat on cooling rate were shown. The results should be revised when CCT curves which obtained form constant-speed cooling rate conditions were used to determined phase transition start and end temperature in non-constant cooling rate conditions.

Abstract: This article investigated deformation behavior and microstructure of AZ31 magnesium alloy in equal channel angular pressing (ECAP) process at 250 C. The proper process parameters were obtained through investigating the deformation behavior and properties of AZ31 magnesium alloy by using finite element (FE) simulation under different deformation conditions. The ECAP experiments were also carried out by using the optimized design of the channel die. The micro-structures of experimentally pressed work-pieces are in good agreement with finite element analysis results. The research results provided reliable basis for the further development and use of magnesium alloy precision forming.

Abstract: Extending the investigations on (Bi0.5Na0.5)TiO3-based solid solution for lead-free piezoelectric ceramics, this paper consider the complex solid-solution system (Bi0.5Na0.5)TiO3-Ba(Sn,Ti)O3. X-ray diffraction analysis revealed that, during sintering, all of the Ba(Sn,Ti)O3 diffuses into the lattice of (Bi0.5Na0.5)TiO3 to form a solid solution, in which a rhombohedral phase with a perovskite structure was found. It was found that the samples with a low content of Ba(Sn0.06Ti0.94)O3 exhibit relatively good physical and electric properties. For 0.98(Bi0.5Na0.5)TiO3-0.02Ba(Sn0.06Ti0.94)O3 ceramics, the electromechanical coupling coefficients of the planar mode kp and the thickness mode kt reach 0.16 and 0.57, respectively, at the sintering of 1100oC for 3 h. The ratio of thickness coupling coefficient to planar coupling coefficient is 3.56. For 0.98(Bi0.5Na0.5)TiO3-0.02Ba(Sn0.06Ti0.94)O3 ceramics, the relative density and the thickness coupling coefficient kt reach 98.1% and 0.58, respectively, at the sintering of 1100oC for 5 h. With suitable Ba(SnxTi1-x)O3 concentration and sintering condition, a dense microstructure and good electrical properties were obtained.

Abstract: The anodic electrodeposition of polyaniline (PANI) on Pb substrate was performed by both potentiostatic and galvanostatic method. Influences of the applied potential and current density on the formation of PANI were investigated. The electrocatalytic effect of Pb electrode modified by PANI on the oxygen evolution reaction (OER) in sulfuric acid was examined via anodic polarization measurements. The results indicated that a significantly enhanced catalytic activity was obtained on Pb electrodes modified by PANI. The overpotential for OER drops 0.14V~0.42V and the exchange current density rises by one to three orders of magnitude compared to the blank Pb electrode. As a new kind of OER anodes in acidic electrolytes, the Pb electrode coated by PANI shows a potential application prospect in the electrowinning of non-ferrous metals.

Abstract: Magnesium alloy tailor-welded blanks(MTWBs) of AZ31 and AZ80 sheet had been manufactured by gas tungsten arc welded(GTAW), which the thickness were 0.8mm. The welding properties of Magnesium alloy sheet had been analyzed, and the technology parameters of GTAW were determined by experiment study, which was that welding thread being Φ2.0mm, welding electricity 50A, welding voltage 9V, welding rate 12—13cm/min. The research results presented that the grain in welded seam was isometric crystal, and the grains were branching crystal in heat-affected zone (HAZ). For MTWBs of AZ31and AZ80 sheet which the thickness was 0.8mm, the forming parameters were that the forming temperature of AZ31 being 190-220°C, and forming temperature of AZ80 being 310°C-350°C, and the temperature of tools is 180°C~200°C.

Abstract: Corn cobs are potential feedstock for producing heat, power, fuels, and chemicals. Densification of corn cobs into briquettes/pellets would improve their bulk handling, transportation, and storage properties. The objective of this study was to investigate the densification characteristics and specific energy requirements for the compression of corn cobs under four pressure levels (10, 12, 14, 16MPa) and with two particle size levels (2.41mm, 0.86mm). The compression behavior of ground corn cobs was studied using a hydraulic press briquetteing machine whose cylindrical die diameter was about 30 mm. The corn cobs moisture content and preheat temperature before compaction was 10% (w.b.) and 75 °C, respectively. The cylindrical die temperature was maintained at 90 ± 5 °C. It was found that the briquette density ranged from 809 to 1043 kg m-3; while the total specific energy requirement to compress and extrude briquette ranged from 17 to 26 MJ t-1, with an increase in pressure. Particle size had also a significant effect on briquette density and specific energy requirement. The finer corn cob grinds (0.86mm) resulted in higher density and lower specific energy requirement than the coarser corn cob grinds (2.41mm). New statistical models were developed to describe the total specific energy consumption of ground corn cobs during densification using a multiple linear regression analysis.

Abstract: This paper investigates the effects of normal hot rolling and high rate cooling (NHR+HRC) on microstructure and mechanical properties of the rolled EH 36 hull plate. Double-hit tests were carried out to study the effect of process parameters such as the deformation temperature and soaking time on microstructures of the tested steel, and explore optimal processing parameters. Single-hit compression with various parameters was developed and the microstructures of the tested steel are analyzed to determine the cooling rate and the final cooling temperature of the normal hot rolling and high rate cooling. This study will provide experimental and theoretical base on high-temperature rolling control system. Industrial trial was performed to produce regular products. The results show that the NHR+HRC is an effective and promising method to improve the product quality of high-strength hull plate.

Abstract: This paper presents a new way of recycling aluminum and iron in boiler slag derived from coal combustion plants for the production of a sulfate-based complex coagulant containing ferric sulfate and aluminum sulfate. The boiler slag sample was determined for more complete characterization by means of scanning electron microscopy(SEM), X-ray diffraction(XRD), X-ray fluorescence(XRF) and other techniques. An analysis for the boiler slag sample collected from Baotou Steel Plant located in Inner Mongolia, PR China showed that the quantity of iron and aluminum oxides, in general, accounted for about 35% of the boiler slag. XRD analysis indicates that predominate minerals such as kaolinite, quartz, calcium silicide, hematate and metakoalin exist in this boiler slag. This boiler salg was evaluated to determine the efficiency of converting the iron and aluminum components of the material into a sulfate-based complex coagulant when heated with sulfuric acid at different temperatures and reaction times. The maximum concentrations of Fe3+ and Al3+ in the complex coagulant prepared from the boiler slag were obtained at 130 and after 3 h of reaction time. These concentrations were 0.04 M Fe3+ and 0.46 M Al3+, respectively. The corresponding conversion efficiencies of aluminum and iron were 66.2 and 95.0% in the boiler slag, respectively. Finally, the prepared sulfate-based complex coagulant proved to be an effective agent for reducing the turbidity and chemical oxygen demand(COD) of a typical domestic sewage sample.

Abstract: In order to solve lubricating problem of circular tilting pad thrust bearing in the heavy equipment, lubricating characteristics mathematical model is established based on the Computational Fluid Dynamics and lubricating theory, the Finite Element Method is used to compute the lubricating characteristics of a circular tilting pad thrust bearing, and figure out thickness distribution of oil film, pressure distribution of oil film, temperature distribution of oil film, power loss and fluid flow, etc. lubricating characteristics parameters by self-compiling software program. Experiments testify the validity of the lubricating characteristics mathematical model. Through this method, the safety of a circular tilting pad thrust bearing can be forecasted, and the optimal design of such products can be achieved, and provides reasonable data for actual design and experiment, and decreases economy loss.