Process analysis of binder treatment on iron-based alloy powder

Abstract

Binder treatment technology is a widely used method of bonding fine powders to coarse particles using a binder liquid. In this paper, binder treatment experiments were carried out for binary Fe-C mixture and multicomponent mixture (alloy powders exceeding 15 wt.%). The differences of particle size distribution and microstructural of conventional mixing and binder treatment mixing in Fe-C mixture were compared, and the fine particles were evenly bonded to the coarse iron particles surface and preferentially filled into the pits after binder treatment. The physical properties of the multicomponent mixture after binder treatment were improved, the flowrate and fine particles adhesion ratio achieved 30 s/50 g and 96%, respectively, and the segregation was obviously reduced. Further, the phenomenon of small particles bonded to large particles was explained by capillary force and snowball effect. Meanwhile, the theory that small particles migration caused by spontaneous capillary flow during drying and consolidation was proposed.

Improving the homogeneity and properties of ferrous powder mixes by a novel powder mixing process

“…These advantages of binder treated powder mixes are beneficial to producing high performance powder metallurgy parts, especially for high hardness, high tensile strength and complex shape parts which also need excellent die filling characteristics [13]. In the previous works, many researches focus on the preparation technology [14] and binder selection [15], but there have few reports about the bonding mechanism of different kind of binders and the friction behaviour of binder treated powders during compaction. Especially in hybrid system, the bonding mechanism is important for bonding different alloyed powders on different iron or alloyed iron powders.…”

Thixotropic properties of multi-functional binder and compaction behaviour of the low alloyed binder-treated powder

“…Chawla [1] compared the fatigue behaviour of binder-treated versus diffusion bonded powder metallurgy steels and found PM materials processed using binder treatment have equivalent tensile and fatigue to conventional diffusion bonded materials. Zhang [21] carried out binder treatment experiments on Fe-C mixture by using single binder of epoxy resin, and the bonding mechanism of small particles on large iron particles was explained by the migration of small particles caused by spontaneous capillary flow. Although a large number of patents and papers emerged for binder treatment technology, most of them focused on the binder with simple component, or the compaction behaviour of the mixture by using the binder without the introduction of the detailed composition.…”