The Research Of Spray Forming Process Based On The Hot Gas

Spray forming is a new type of high-performance materials preparation technology,which can make the metal rapid solidification by reducing the size of the molten metal,then get the high performance billet. In the spray forming, the size of the atomized dropletsize is a major measure of deposition billet quality, and the refinement of droplet size is ahot spot in the atomization technology research. This research put forward to improveairflow heating energy to increase its speed, then refine droplet. This research was putforward on the basis of that the energy of a gas is proportional to the square of the velocity.The research of hot gas flow atomization is carried out in the following ways whichinclude simulation experiment, experiment measure, mechanism analysis and etc.In order to study the field of hot gas flow, the corresponding geometric model hasbeen established that according to the actual size, and the grid has been meshed, then theatomizing gas flow field simulation is performed. Through the simulation calculation, theair velocity increased by459m/s which the gas flow temperature was room temperature to547m/s which the temperature was150℃, whose air velocity increases nearly20%. Thegas pressure increased by0.5MPa which the gas flow temperature was room temperatureto0.71MPa which temperature was150℃.and the air temperature increased which belowthe atomizer with the inlet gas temperature at the same location. According to the existingknowledge deduced that increasing air temperature can decrease the droplet size.Through theoretical calculation, the rate of atomization gas is489m/s,506m/s,542m/s and570m/s respectively that the atomization gas temperature is at room temperature,50℃,100℃,150℃.The velocity increased3.4%、9%、17%respectively. At the time, thegrain size is between15μm to150μm, and the grain size is smaller with the gastemperature increases.Gas heating device was designed, and the maximum control temperature of theheating device could reach250℃which satisfied the requirement of experiment of150℃after measured. Install it on the injection molding equipment, and conduct the experiment under the different heating temperature. Though observed the metallographic of the billetwhich under the different conditions, when the gas flow temperature was room temperature,50℃,100℃and150℃,the grain size was60μm,57μm,54μm and51μm respectively,whose grain size decreases4.2%,10%,14.2%compared with the room temperature. Andthe grain size distributed more uniform, the grain shape is more round.