球磨高氮不锈钢粉末特性及注射喂料流变性能

Characteristics of High Nitrogen Stainless Steel Powder by Milling and Rheological Properties of Its MIM Feedstock

摘要:

采用高能球磨技术制备了高氮节镍不锈钢近球形复合粉末，与石蜡基多聚合物组元黏结剂混炼制成金属注射成形喂料，研究了注射喂料的黏度、剪切速率以及温度等对黏度的影响。结果表明：高能球磨能够显著改善高氮不锈钢粉末的工艺特性，球磨60 h得到的粉末颗粒细小，球形度较好，振实密度高，适合用来制作高质量的金属注射成形喂料。其中，粉末装载量为58%的喂料应变敏感因子最小(n＝0.45)，粘流活化能最低(E＝28.70 kJ/mol)，综合流变学因子最大(αSTV=2.96)，表明该喂料具有最好的综合流变性能，非常适宜进行后续注射成形工艺

Abstract:

Nearly spherical composite powders of high nitrogen nickel-saving stainless steel were synthesized by a high energy milling technique, and the MIM (metal injection molding) feedstock was prepared by mixing these metal powders with paraffin based multi-component binder. The rheological properties of MIM feedstock including feedstock viscosity and its sensitivity to the shear rate and the temperature were also investigated. The results show that the high energy milling can remarkably improve technological characteristics of the powders, and it is found that the powders milled for 60 h have fine particle size, good sphericity and high tap density, suitable for making high-quality MIM feedstock. The feedstock with powder loading of 58% presents the minimum shear rate sensitivity factor, the lowest viscous flow activation energy, and the largest general rheological index, which are n=0.45, E=28.70 kJ/mol and αSTV=2.96, respectively, exhibiting the best rheological properties and meeting process requirements for subsequent injection procedure very well