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超支化聚酯粘结剂对Fe–Fe3P混合粉末性能的影响

Effect of hyperbranched polyester binders on properties of Fe–Fe3P bonding mixed powders

  • 摘要: 以超支化聚酯(hyperbranched polyester,HBP)作为粘结剂,制备了Fe–Fe3P粘结预混合粉末。通过扫描电镜观察粉末微观形貌,研究了超支化聚酯粘结剂含量(质量分数)对Fe–Fe3P混粉以及烧结产品性能的影响。结果表明:粘结预混合粉末中粒径≤10 μm的小粒径粉末颗粒数(绝大多数为Fe3P粉)占粉末总颗粒数的比例为0.65%,远低于未粘结预混合粉末中小粒径粉末颗粒数占粉末总颗粒数的比例(5.93%),证明超支化聚酯可成功将小粒径的Fe3P粉末粘结到铁粉表面,有利于改善混合粉末中磷的均匀性和防止偏析。添加质量分数0.10%末端羟基超支化聚酯的Fe–Fe3P粘结预混合粉末具有最优的粉末流动性和松装密度;压制相同密度的Fe–Fe3P生坯,压制压力随超支化聚酯的质量分数的增加而增大;超支化聚酯粘结剂的添加可以降低烧结体烧结前后的尺寸变化率,提高烧结体横向断裂强度,同时在实际生产过程中也可以保持良好的粘结性能。

     

    Abstract: Fe–Fe3P adhesive premixed powders were prepared by using hyperbranched polyester as the binders. The microstructure of the powders was observed by scanning electron microscope. The effect of hyperbranched polyester binder content (mass fraction) on the properties of the Fe−Fe3P powder mixture and the sintered products was studied. The results show that the proportion of small particle size powders with particle size ≤10 μm (mostly Fe3P powders) in the bonded mixed powders accounts for 0.65% of the total number of powder particles, which is significantly lower than that of the un-bonded mixed powders (5.93%). Hyperbranched polyester can successfully bond the Fe3P powders to the iron powder surface, which is beneficial to improve the uniformity of phosphorus in the mixed powders and prevent segregation. The Fe–Fe3P bonded mixed powders with 0.10% terminal hydroxyl hyperbranched polyester show the best powder fluidity and loose packing density. The pressing pressure of the Fe–Fe3P green billets with the same density increases with the increase of the mass fraction of hyperbranched polyester. The addition of hyperbranched polyester binder can reduce the size change rate of the sintered body before and after sintering, improve the transverse fracture strength of the sintered body, and maintain good bonding property in the actual production process.

     

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