Advanced Materials Research Vols. 189-193

Abstract: With the rapid development of micro injection molding, the determination of melt rheological behavior within micro mold cavity is very important for the accurate simulation modeling. Yet several investigations show the viscosity of melt decreases with the reduction of micro channel characteristic size, but there has been no sufficient experimental data for the conclusion. In this paper, depending on the capillary flow model, the measurement experiments of polymer melt viscosity were investigated when Polymethyl Methacrylate (PMMA) was extruded through the micro channel dies of 1000μm ,500μm and 350μm diameter. Test results show that, as micro-channel size decreases, the viscosity increases and the difference of viscosities in different micro channels reduces with increasing shear rate. This indicates microscopic scale melt rheological behavior of PMMA is different from that of other materials.

Abstract: In this paper, Ni-Sn-P ternary alloy coating was prepared by the electroless depositing technique. Effects of tannic chloride, reductant and pH value of the bath on the coating were studied. And, erosion behavior of the coating in the 3.5g dm^-1 sodium chloride solution was also investigated. The results show that the electroless deposited Ni-Sn-P ternary alloy is amorphous. The deposition rate and the tin content in the coating increase, but the phosphorus content in the coating decreases with increasing the stannic chloride and sodium hypophosphite contents in the bath. The deposition rate increases with the pH value of the bath in the range of 3 to 6. Mass loss of the coating increases with increasing the erosion time and the flow velocity of erosion solution, which has its maximum value as the coating impacted at an angle of 60°.

Abstract: Using the software named ABAQUS, the residual stress distributions of welding toes for the Q345C butt joints and T-joints are simulated, respectively. The simulations are performed in three cases which are as-welded, TIG remelting after welding, and chilling treatment for the welding toes after TIG remelting at different temperatures, respectively. The stress measurement is performed for these areas using the blind-hole method. The results of measurement and numerical simulation indicate that the residual stresses for the surface of the welding toes can be transformed into the biaxial compression stress when the TIG remelting zone temperature of welding toes is above 450 °C,which is availible for the improvement of fatigue strength of welded joints.

Abstract: The exhaust gas produced by the diesel engine is reclaimed to the mixing chamber where it was mixed with pure oxygen and argon. The mixture which forms "artificial air" will be used as the diesel intake to achieve the diesel engine’s working in closed cycle. The most critical part in closed cycle diesel engine control system is to control the oxygen concentration and specific heat of the intake. This paper is based on the design of GE9030-based PLC and the monitoring interface used in this paper is designed by KingView6.53, finally, the control of specific heat of the intake, concentration of the oxygen intake and pressure of the intake are realized. Moreover, real-time displaying, gathering and fault alarm of the operating parameters in this system are achieved.

Abstract: Injuries of the base of the fifth metatarsal are among the most common of all skeletal injuries of the foot. The fracture is considered by previous research to be an avulsion due to the slip fascia, however, the mechanism of the plantar slip fascia’s function still not very clear. In this study, a detailed three-dimensional (3D) finite element (FE) model was developed by reconstruction of CT images. A sensitivity study was conducted to evaluate the effect of varying stiffness of the slip fascia on the fifth metatarsal’s deformation. The results showed that the largest vertical displacement was appeared in the metatarsal’s head part, and the difference was up to 10.5%, while the Young’s modulus of the slip fascia increasing from 50MPa to 500MPa.

Abstract: Due to developing the strengthening effect of liquid jet peening on the surface modification for metallic materials, in this study, an emulsion jet peening is produced by injecting a high-speed emulsion jet into an emulsion filled tank. The test system and fixed emulsion of cavitation jet was developed. High speed photography technique was used to observe and analysis the structure of emulsion cavitation jet at various upstream pressures . The results indicate that the structure of emulsion cavitation jet in terms of jet impact pressure, intensive degree and uniformity is better than that water jet. The jet structure depends on the jet pressure. The cavitation jet length increases rapidly at the initial stage and then it stabilizes after few milliseconds. The stabilized length of jet increases and the diverges angle decreases with increasing pressures. Specimens made of plan carbon steel (Q235A, China standard) were exposed to emulsion jet peening at the stand-off distances of 20 mm with a constant upstream pressure, 20 MPa for 60 s. The fatigue test shows that the crack initiation life by treatment of emulsion jet peening increases about 12.5% and 20.2% compared to water jet and unpeened specimen respectively.

Abstract: In this paper, a novel radial hybrid magnetic bearing is proposed, which is driven by an AC 3-phase power converter, and biased magnetic fluxes are provided by an axial magnetized permanent magnet ring. Based on the introduction of the configuration and principle of the radial AC hybrid magnetic bearing (AC HMB), the methods in parameter design and design results for the prototype are presented. The parameter design results for the prototype of the radial AC HMB are simulated by 3D electromagnetic finite element method and the simulation results show that the obtained parameter is reasonable. The manufactured prototype applying to the parameter is operated and the test results also show that the design result for the prototype is available, and the AC HMB has good dynamic and static performance.

Abstract: To improve the permeate flux of ceramic membrane, commercial α-Al₂O₃ microfiltration membrane of 0.2 μm pore diameter was modified with SnO₂ nano grains by in situ synthesis method. The permeate fluxes of the membrane for pure water and treating Fe(OH)₂ suspensions were studied mainly in the paper. The results showed that the pure water stable permeate fluxes of unmodified and SnO₂ modified microfiltration membranes were 0.61 m³h^-1m^-2 and 1.87 m3h-1m-2, respectively. When treating 1L 0.01 mol∙L-1 Fe(OH)₂ suspensions, the permeate fluxes of SnO₂ modified membrane was higher than that of unmodified membrane all the time and the clarified permeate was obtained. The results indicated that in situ synthesis method can be successfully used to modify α-Al₂O₃ microfiltration membrane with SnO₂ nano grains for permeate flux increase, and the microfiltration membrane has excellent treatment effect on Fe(OH)₂ suspensions. Furthermore, the enhancement mechanism of permeate flux of SnO₂ modification microfiltration membrane was discussed initially.

Abstract: Some rust-inhibiting additives which are wildly used in water-based metalworking fluids were mixed in several lubricants which made by oleic acid, boric acid, triethanolamine and so on to prepare the experiment used solutions in a certain concentration. The phenomenon of the metal tungsten leaching from cemented carbide in these additives was examined by immersion test and electrochemical measurement experiment. According to the value of electromotive force and the results of scanning electron microscopy (SEM) analysis, the condition of the metal tungsten leaching from cemented carbide in solutions with different additives was judged. The results show that the order in ascending of the effects of these solutions on the metal tungsten leaching from cemented carbide is sodium phosphate, sodium carbonate, triethanolamine, oleate triethanolamine ester, boric acid-oleic acid triethanolamine ester, sodium molybdate, benzotriazole and sodium nitrite.

Abstract: Two different martensite stainless steel 1Cr17/Carbide-based coatings (C-1 and C-2) were prepared by electrical arc spraying technique. Microstructures of the coatings were investigated by optical microscopy (OM), X-ray diffraction (XRD), scanning election microscopy (SEM). The results show that the C-2 coating has higher hardness and finer structure than the C-1 coating. The cavitation erosion resistance was tested using a China GB6383-86 standard method in fresh water. The cavitation erosion mass loss of the C-2 coating was only 55 percent that of the C-1 coating eroded 15h, the C-2 coating has better cavitation erosion resistance.