Research On Melt Technology Without Flux And Its Computer Simulation Of Particulate Reinforced Magnesium Matrix Composites

As we know, magnesium alloys are prone to oxidative combustion,which will introduceimpurities because of its active chemical properties. Besides, the dissolution rate ofhydrogen in the magnesium alloy is high, it tend to dissolve out and form gas porosity duringthe solidification process, which will weaken the performance of alloy. Especially, AZ91Dmagnesium alloy is sensitive to the porosity. With the development of the industrializationof magnesium alloy, worldwide demands for the purity and high performance magnesiumalloy are more and more. And rotary degassing technology is widely used in the aluminumalloy melting as a efficient way, so we should devote ourselves to promoting the applicationof this method in magnesium alloys, which is very important to develop the quality ofmagnesium alloys.Under this background, this paper mainly simulated and analyze the rotary degassingprocess with Argon gas as the purified gas, and AZ91D magnesium alloy as the researchobject.Firstly, we used the rotary injector and crucible which were designed by ourselves tocarry on the calculation modeling. We used two-dimensional simulation model to compareand analyse the flow state of melt under different gas flow, The simulation results showed thatthe turbulent kinetic energy increases with the increase of gas flow rate. The reasonable gasflow range is135-226L/h under this simulated condition.Secondly, we used three-dimensional simulation model to research the basic distributionrules of Argon gas, kinetic energy, pressure field, and the velocity field. Then the distributionof Argon gas under the different combination of rotating speed and gas flow were researched,and a simple analysis of the flow field characteristics in the process of blowing alloy was carried on.Finally, based on the computational simulation, we adopted rotary degassing as therefining process during melting the SiCP/AZ91D magnesium matrix composites and carried onthe orthogonal experiment of three factors and three levels. The influence of the three mainfactors: gas flow, rotating speed and the degassing time on mechanical properties andmicro-structure of the samples were discussed. The results of the range analysis showed thatrotary degassing purification technology significantly improved the mechanical properties ofsamples. But the effect of the three main factors on the performance was different, to thetensile strength, the effect of gas flow come the first; to the hardness, the effect of degassingtime come the first; and to the elongation, the effect of rotating speed come the first.Theoptimum process parameters are rotating speed of475r/min, gas flow of180L/h and the timeof15min. In addition, the inclusion content was reduced to0.6%from3.8%afterpurification, the research has obtained the good refining effect.