本研究主要以實驗方法探討金屬噴霧在正向衝擊板流及側向衝擊氣流作用下之霧化特性。首先將鉛錫合金材料Sn63Pb37經由高溫熔爐熔成金屬熔湯，接著透過液態金屬霧化器將金屬熔湯加以霧化，此金屬噴霧再利用正向衝擊板及側向衝擊流形成金屬噴霧衝擊流，噴霧粒子則以Malvern RT-sizer進行即時之粒度量測。正向衝擊板流之實驗結果顯示，當基板為單純平板(邊緣高度為0 cm)時，若基板與噴嘴出口距離從20cm增加至40cm，金屬粉末平均粒度從3.13μm增加至12.82μm，代表調整基板與噴嘴出口之距離具有控制金屬粉末粒度之效果，且能產生極細微之金屬粉末。若基板邊緣高度增加為1.5 cm及3.0cm時，亦有類似之情形，隨著基板與噴嘴出口距離從20cm增加至40cm，金屬粉末平均粒度分別從3.79μm增加至10.43μm，及從4.44μm增加至6.01μm，故之此種衝擊板流之設計為產生微細金屬粉末之甚佳控制機制，亦為文獻中傳統金屬粉末噴霧製程所難以達成者。實驗結果亦顯示，金屬粉末產生率隨基板與噴嘴出口距離增加而遞增，當基板與噴嘴出口距離從20cm增加至40cm時，金屬粉末產生率從52%增加至81%。另一方面，在基板上之金屬成型材料沉積率則隨基板與噴嘴出口距離增加而遞減，當基板與噴嘴出口距離從20cm增加至40cm時，從金屬成型材料沉積率從48%增降低至19%。故知此製程可以同時完成微細金屬粉末與金屬噴覆材料之製造，為一種相當值得推廣之製程。金屬噴霧在側向衝擊流作用下之實驗結果顯示，當側向衝擊流溫度較低時，會對金屬噴霧造成冷卻作用，故金屬噴霧之液滴未能產生碰撞破裂以形成二次霧化作用，反而在衝擊氣流作用下，噴霧粒子有碰撞結合之現象。但是當側向衝擊流溫度高於金屬噴霧之共晶點時，在低壓之側向衝擊流作用下，金屬噴霧之平均粒徑會因側向衝擊流之作用而降低；在側向衝擊流壓力增加時，金屬噴霧之平均粒徑則有遞增之現象，顯示側向衝擊流在低壓下會使金屬噴霧產生碰撞分裂現象，但當側向衝擊流壓力增加時，在噴霧中央貫穿距離會增加，對主噴霧流形成遮蔽效應，故金屬噴霧粒子反而產生碰撞結合現象，金屬粉末體積百分比V25-45亦顯著提升。故知增加側向衝擊流壓力，具有令金屬噴霧粒子分佈重新分配之效果。

　This research program investigates the characteristics of molten spray jet under impinging conditions, including the normal impingement on the substrate and side impingement by a cross jet. The material of the molten spray jet is eutectic alloy Sn63Pb37 and is firstly melted in the crucible. The melt is then injected by an internal mixing atomizer to become a spray jet. The particle size of the metal powders is measured with Malvern RT-sizer. Experiments of the impingement of the molten spray jet on the substrate show that the particle size of the metal powder increases from 3.13μm to 12.87μm when the height of the substrate ring is 0 cm as the separation distance from the exit of the atomizer to the substrate increasing from 20 cm to 40 cm. It implies that the size of the metal powder can be controlled by adjusting the position of the substrate. It’s more important that the ultra-fine metal powder can be produced by this particular design. Similarly, the particle size of the metal powder increases from 3.79μm to 10.43μm when the substrate designed with a ring of 1.5 cm height is placed at 20cm to 40cm from the atomizer. This result has not been reported in the literature using the conventional atomizers. Moreover, the production rate of metal powder increases from 52% to 81% with the separation distance from the outlet of the atomizer to the substrate increasing from 20 cm to 40 cm. On the other hand, the production of spray forming material decreases from 48% to 19% as the substrate is placed at 20 cm to 40 cm from the atomizer. It is concluded that this process can be used to produce the fine metal powders as well as the spray forming materials. Experiments of the spray with side impingement show that the size of metal powder decreases from 14.11μm to 12.94μm under an impinging pressure of 2 bar. The size of metal powder increases from 14.11μm to 16.41μm when the pressure of side impinging flow is 8 bar. This implies that the droplets within the spray jet experience the coalescence and the breakup processes during the impingement of the side flow. Hence re-distribution of the droplets can be controlled by adjusting the impingement of the side flow.

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