Research On Structure Property And Corrosive Wear Mechenism Of Co-Base Dip-Roll Bushing In Hot-Dip Galvanizing

According to the problem of the molten zinc-corrosion to dip-roll bushing in hot-dip galvanizing industry,the research on the dip-roll bushing materials of Co-base alloys in this paper. Through analyzing effections of the element Si on the microstructure and property,theory basis is prepared for further research and selected champion materisl.It's found that alloy elements have great effection on the Co-base alloys,especially the element Si. Though Si is only a minor constituent of the alloys, it influence the microstructure, mechanical properties and corrosion resistance of the materials. With the addition of the Si from 1.2% to 3.4wt% the alloy transfers to hypereutectic from hypoeutectic, the primary phase transfers to Laves phase from the solid solution. At the same time the corrosion resistance also vary as the amount of Si adding . Particularly as the addition of the Si from 2.43% to 3.4%, the corosion rate rapidly fall down, the corrosion resistance of the materials increased greatly. As the addition of the Si the macrohardness of the alloys grow,but the bending strength gradually fall off. 1.2wt%Si alloy has best bending strength and happens ductile rupture,while 3.4 wt%Si alloy has worst bending strength easily happens mixed failure.Though the micro-analysis for Co-base alloy,it's found that hypoeutectic and hypereutectic are compose of two phases the solid solution and the Co3Mo2Si.But the structure of the solid solution is different, it's fcc in hypoeutectic while with hcp in hypereutectic.It also found that the large amount of intermetallic compounds in hypereutectic have good propertity to impede the zinc corrosion,and the solid solution is priority corroded for it's bad corrosion resistance.When the solid solution are corroded greatly, the products generate certain wedging stress. At the same time the binding force between the Co3Mo2Si particles and the matrix weaks,so the Co3Mo2Si particles easily pull-out and the alloys are corroded gradually. In addition the eutectic phase has better corrosion resistance than the solid solution in the hypoeutectic.The corrosion wear mechanism of the Co-base alloys in zinc bath is mainly grinding ,plastic deformation,brittle fracture ,pull-out. The materials's microstructure , mechanical property of the materials and the microstructure of the ceram are the main influencing factor of the wear-out-failure.