论文部分内容阅读
在试验工厂用限制性设计(confined design)的喷嘴进行气体雾化铝合金的试验,研究了喷嘴的几何结构对快速凝固金属粉末粒度的影响。试验中用N_2作雾化气体(以1.56兆帕的压力)雾化AA2014铝合金。结果表明,喷嘴的几何形状和尺寸对粉末粒度有很大影响。具有收敛-扩张型气体通道的小喷嘴生产的粉末较细;而仅具有收敛型气体通道的喷嘴或大直径喷嘴生产的粉末相对来说较粗一些。气体通道的喉颈面积小的喷嘴由于生产金属粉末的速率低时形成薄片,因而其使用受到了限制。当喉颈面积增大到输送气体的流速大于或等于3倍粉末生产速率时,喷嘴能很好地工作且不出现薄片。通过试验获得了输液管突出部分的高度最佳值,该高度小于或大于这个最佳值时就会形成粗大的粉粒。
Gas atomized aluminum alloys were tested in pilot plants with confined design nozzles and the effect of nozzle geometry on the particle size of rapidly solidified metal powders was investigated. N 2 was used as atomizing gas (pressure 1.56 MPa) to atomize AA2014 aluminum alloy. The results show that the nozzle geometry and size have a great influence on the particle size. Small nozzles with convergent-divergent gas channels produce smaller powders; whereas, nozzles with only convergent gas channels or large diameter nozzles produce relatively coarse powders. Nozzles with small throat area for gas passages are limited in their use due to the formation of flakes when the rate of metal powder production is low. When the throat area is increased to deliver a gas flow rate greater than or equal to 3 times the powder production rate, the nozzle works well with no lamellae. The optimum height of the projection of the infusion tube is obtained by the test. When the height is less than or equal to this optimum value, coarse particles are formed.