Advanced Materials Research Vols. 418-420

Abstract: The vibration is superimposed to the filling process of aluminum and magnesium alloy in lost foam casting, and the flow lengths and the molten metal temperatures of the flow front are collected, and they compared with no-vibration. The results show that the vibration can significantly improve the filling capacity of the aluminum alloy, magnesium alloy in lost foam casting. Compared to the samples without vibration, the flow lengths of A356 alloy with vibration in lost foam casting increased by 33% and that of AZ91D alloy increased by 15%.The heat transfer of molten metal on the flow front was analyzed, and it indicates that the vibration energy extends the filling time of the molten metal on the flow front in lost foam casting.

Abstract: The model of cellular automaton (CA) for simulating the static recrystallization of Nb micro alloyed steel after hot deformation was established. The static precipitation of micro alloyed elements on the impact of static recrystallization was considered in the mode. The microstructure evolution of austenite static recrystallization of Nb micro alloyed steel was simulated dynamically, such as the the volume fraction, kinetics curve of static recrystallization, dislocation density and grain shape, were quantitatively, accurately and visually described. According to the simulation results by cellular automaton, the effects of the deformation temperature, strain rate, and other processing parameters on the microstructure of the austenite static recrystallization of Nb micro alloyed steel were analyzed. The simulation results could provide a theoretical reference for the control of the microstructure and property of Nb micro alloyed steel.

Abstract: The influence of gas nitriding on commercial pure titanium and Ti-6Al-4V (Ti64) alloy bearings by using a Q-sw laser on the wear loss during rolling contact fatigue is investigated. By optimizing the laser processing parameters, such as laser scanning speed, power and beam diameter thin TiN coats of 0.5 to 3 µm were produced. Non-coated and coated bearings made of pure Titanium and Ti-6Al-4V alloy were tested in equal conditions and it was found that the titanium nitride layers significantly improve the rolling contact fatigue performance of titanium components. For tests up to 10⁶ cycles the wear loss of the coated samples was at least ten fold lower than that of the uncoated ones and for 7.76 x 10⁶ cycles, the wear resistance improved almost 100-fold.

Abstract: With advanced high-strength steels and high value-added steels development, it is very important to improve the cooling capacity and cooling intensity of the run out table cooling system. The key technology is to break the vapor between hot strip and cold water and to increase the direct contact area. In order to realize the ultra fast cooling, Laboratory research such as jet nozzle type selection and diameter of nozzle decision and factory tests such as cooling capacity testing have been done. Experiment results show that circular nozzle has bigger hitting power than fan-type nozzle. However, drainage capacity caused by fan-type nozzle is better than that by circular nozzle. In addition, nozzles of different diameters have nearly the same cooling capacity despite of the very different water flow. Cooling power testing results show that cooling capacity is enhanced with pressure increasing and with speed decreasing.

Abstract: The numerical simulation of electron beam welding temperature field for 2090 Al-Li alloy sheet of 2 mm thickness is conducted by using the ANSYS software. The combined model of Gauss surface heat source with cylindrical body heat source in linear attenuation is used according to the unique nail-shaped weld of electron beam welding joint, and the distribution cloud image of temperature field and the instantaneous weld thermal cycle curves of Al-Li alloy electron beam welding are obtained through calculation. The effect of welding parameters such as electron beam power and welding speed on the distribution of temperature field and weld width is investigated. Results show that electron beam welding has a very high rate of both temperature ascending and descending, and the rate of temperature ascending is higher than that of descending. With the increase of electron beam power or decrease of welding speed, the temperature of fusion zone elevates, and the weld width increases. The appearance of weld obtained through numerical simulation is greatly consistent with the practical welding.

Abstract: With the recent trend of down-sizing and more efficient use of electric power in electric appliances, there is a growing need of smaller electronic components, such as multi-layered ceramic capacitors (MLCCs). However, it was found that the non-uniform deformation occurred in MLCC block during the pressing process and it hinders the miniaturization of MLCCs. In this study, compression tests of multi-layered ceramic sheets with printed electrodes were carried out and the deformation behavior was observed in situ and recorded by digital video camera. The change in area fraction and transverse displacement were evaluated and the deformation mechanism was inferred from the results.

Abstract: Magnesium slag powder from a local magnesium plant was treated to improve the volume stability for its application as building materials. The slag was mixed with borates, pressed into briquettes, and then sintered at high temperature. SEM studies show that at the higher temperature Ca₂SiO₄ polymorphs were stabilized by Na and B ions in the added borates. The free MgO content in the slag was also decreased by the sintering treatment. The slag powder, after mixing with 0.4-0.6% of borates and sintered at 1200°C in 5-6 hours, has become volume stable aggregates. It is then possible to use the treated slag in constructions, saving valuable natural resources and decreasing the global warming impact from magnesium production via Pidgeon process.

Abstract: Based on the liquid nitrogen type lang Ken cycle and refrigeration circulation to analyse Ice Making system Driven by liquid nitrogen engines and Heat source is Diesel exhaust. Puts forward the evaluation method of diesel exhaust waste heat utilization efficiency, The simulation results of Matlab show that this system has Practical value, can be used in the Small and medium fishing boat.

Abstract: Pyrolysis of high density polyethylene (HDPE) to polyethylene wax (PEW) in a 1 L continues stirred-tank reactor (CSTR) was studied at 360-420 °C with 5-240 min, yield of PEW was discussed and the properties such as the drop melting point and average molecular weight of wax were determined. The PEW had a melting point of 104-120 °C, and an average molecular weight of around 3000 with a good dispersity at 673 K. Moreover, the composition of wax determined by fourier transform infrared spectroscopy (FT-IR) indicated that it was less branched than commercial waxes.

Abstract: Waste plastics can be converted to diesel oil and lube base oil by thermal pyrolysis and dewaxing. ZEM-5, H-ZEM-5, Fe/H-ZEM-5 and Co/H-ZEM-5 catalyst were prepared. The influences of additive metals and type of molecular sieves on catalyst were discussed. The results showed that the additon of metallic components enhances the activity of catalyst, produces the low pour point diesel oil, and greatly reduces the pour point of lube base oil. The catalyst impregnated with Fe was more effective than one impregnated with Co. The qualities of oil production were also improved more with H-ZEM-5 than ZEM-5.