金屬粉末的製造方法眾多，工業應用也相當廣泛，如粉末冶金、金屬射出成型以及金屬積層製造，其中以積層製造用金屬粉末的價值最高。目前世界工業大國均將積層製造列為國家重點發展項目，但其對於金屬粉末標準的要求較嚴格，如粉末平均粒徑、粒徑分佈、粉末球型度、粉末流動性以及含氧量等有許多限制。由近年研究顯示，以氣霧化法製程所生產的粉末，最適合生產積層製造用金屬粉末且能夠滿足其嚴格的粉末要求。
不鏽鋼系列合金，由於熔點高，因此在高溫使用下其強度仍相當好，且有可塑性、高韌性以及抗腐蝕等特性，是世界用量最大的金屬合金。本研究目的在建立一套高效率之氣霧化法製程技術，以不鏽鋼316L金屬粉末製程為研究主軸，探討霧化器設計及操作參數的影響。霧化器設計參數為改變突出長度L/L0 =1.0, 1.5, 2.0, 2.5四型導液管、霧化頂角α/α0=1.0, 1.3, 1.6, 1.9四型噴嘴、口徑d/d0=0.9, 1.0兩型導液管；操作參數為霧化氣體壓力Pg=5, 10, 15, 20, 25, 30 Bar等六種，其中L0、α0、d0分別為初使設計之參數值，定義為設計基準值。
噴霧特性研究結果顯示，隨導液管突出長度L增長及噴嘴霧化頂角α增加，將使抽吸壓力減小進而降低液體質量流率提高氣液質量比，使噴霧平均粒徑也隨之減小。另外金屬製程實驗結果顯示，較短突出長度L1導液管與較大的霧化頂角α3及α4兩型噴嘴，會有金屬熔湯回流凝固在氣流道出口破壞噴嘴的狀況，不適合於金屬粉末製程使用。
金屬製程實驗結果顯示，霧化器設計參數使用霧化頂角α/α0=1.3之噴嘴、突出長度L/L0 =2.5及口徑d/d0=1.0之導液管，在霧化氣體壓力Pg=30 Bar時，不鏽鋼316L粉末平均粒徑為43 μm、10-63 μm粉末得料率為65 %。並且為進一步降低平均粒徑及提高細粉得料率，將導液管口徑縮小為d/d0=0.9，所得粉末平均粒徑為35 μm、10-63 μm粉末得料率為76 %，已能達到積層製造用金屬粉末之高標準。
粉末特性分析結果顯示，粉末形狀為圓球狀且流動性佳，並利用金相觀察內部顯微結構顯示其結晶情況較原材料細微許多，接近微晶結構，使得粉末的維克氏硬度測量平均結果為296.0 HV，與原材料測得143HV結果相比大幅提升2.06倍。由以上結果可知本研究所開發之氣霧化法製程，優於傳統噴霧製程，成功建立一套高效率氣霧化法製程，滿足積層製造用金屬粉末的嚴格要求。

Method for producing metal powder is numerous, and industrial applications is quite extensive, especially, the metal powders for MAM (Metal Additive Manufacturing) has highest value. Nowadays, the major industrial countries center on additive manufacturing and consider it as a national development project. However, the requirements of metal powder are stringent in terms of mean particle size, particle size distribution, powder shape, oxygen content and powder flowability. Recent studies revealed that the gas atomization is the most suitable way to produce the metal powder for MAM. Stainless steel, it is widely used in industry, due to the high melting point, so its strength at high temperatures is still very good. The goal of this study was to design a high efficiency gas atomization technology for producing stainless steel powder for MAM process. The atomization performance and mechanisms of this atomizer would be presented in this study. Research method is through a atomizing experiment, the supersonic nozzle with different parameters, like gas atomization pressure, protrusion length of deliver tubes, tube diameter and nozzle apex angles. The size distributions of droplet size and metal powder were measured by INSITEC RT-Sizer and Coulter LS230 particle sizer, respectively. The results show that the particles size decrease with the increasing protrusion length and apex angle, because of aspiration pressure is decreased and leads to the liquid mass flow rate is also decreased. Consequently, the GLR (Gas-to-Liquid Mass Ratio) is enhanced. In the metal atomization results, when atomizer used protrusion length is L/L0=2.5, tube diameter is d/d0=1.0, apex angle is α/α0=1.3 and atomizing pressure is 30 Bar, results show that mean particle size (Dv50) is 43 μm, yield rate (powder size at 10-63 μm) is 65%, while the tube diameter reduce to d/d0=0.9, results show Dv50 reduce to 35 μm, yield rate is rised to 76%. The micrograph of the metal powder by the scanning electron microscopy (SEM) show that the particle shape is spherical and also show the fine microstructure in the surface morphology. It can be concluded that this process is useful to produce the stainless steel powder to meet the requirements in MAM processes.

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