微细Fe_2O_3粉在Fe-2%Ni-1%Cu-0.6%C粉末冶金材料中的助烧结特性

Assist-sintering characteristics of ultrafine Fe_2O_3 powder in Fe-2%Ni-1%Cu-0.6%C powder metallurgy material

在Fe-2%Ni-1%Cu-0.6%C混合料中加入了少量微细Fe2O3粉末作为烧结助剂,研究Fe2O3粉末的添加量对混合料的压缩性、烧结合金的密度和强度以及氧和碳含量等的影响,研究微细Fe2O3粉末对合金的助烧结行为。结果表明:混合料中Fe2O3含量大于0.3%(质量分数)时,会导致成形生坯密度下降;当Fe2O3添加量为0.3%时,烧结合金的密度最高,经1120℃烧结0.5和1 h后,合金的抗弯强度比同等烧结条件下未添加Fe2O3样品的分别提高6.5%和4.2%。少量Fe2O3粉在材料烧结时对碳含量损失率的影响较小,然而可以降低烧结体中的氧含量。在压坯的烧结过程中,Fe2O3还原后于750℃左右开始加速基体颗粒间的连结,虽然在1050℃以上时微细粉的助烧结作用减弱,但烧结体中孔隙更趋于球化。

Fe-2%Ni-1%Cu-0.6%C powder premix was prepared with minor ultrafine Fe2O3 powder as a sintering aid. The effects of Fe2O3 addition on compressibility of the mixture, sintered density, strength of the alloy and its oxygen and carbon content were studied. The assist-sintering behavior of ultrafine Fe2O3 powder was also investigated. The results show that the green density decreases when the Fe2O3 content is above 0.3%, while the highest density of sintered alloy is obtained with 0.3% Fe2O3 addition. And the flexural strengths of the alloy sintered at 1120 ~C for 0.5 h and 1 h increase by 6.5% and 4.2%, respectively, compared with that of sample without Fe2O3 powder addition. Minor ultrafme Fe2O3 powder has slight effect on the loss rate of C content of the sintered alloy, and yet the oxygen content is reduced. It is observed that the metallurgy bonding between matrix particles is accelerated from about 750 ℃ for the reduction of Fe2O3 particles. Though the assist-sintering function ofultrafine powder weakens when the temperature is above 1050 ℃, the pole shape in the sintered alloy is apt to spheroidize.