The Low Friction Phenomenon on a High-carbon Sintered Steel by Pack-Chromizing Coating Process

摘要

Recently, the sintered stainless parts of automobile have explosively increased however it isneeded high energy and expensive, most manufacturer have to find a material an anti-corrosive and goodprice substituted with high performance. A well-known of good performance in severe environment packchromizingcoating process is considered as a simple treatment procedure to improve process, anti-wearand uniform coating property. In this study, the sintered-steel by pack-chromizing can have naturallyshown a good anti-corrosion property, outside of that the surface morphology of the sintered-steel coatedpack-chromizing was made up a ‘Dimple’ a frictional coefficient decreased up to near 0.1. For morespecific inspections, there are the coated samples analyzing a ball-on-disk tribological on chromiumcoating surface diffused a pack-chromizing and the results compared to bearing steels. Sample surfacehad tried to figure out the reasons of the low friction coefficient by EDAX, XPS analysis. The morphologyof coating surface was considerably made to change phase complicated and dense carbide mixture withphase diagram, although the sintered steels had originally porosity surface. Thus it is concluded that thelow friction coefficient property stems from not only the intrinsic porosity but also the dimple morphologymade up of the hardened carbides. After chromizing, chromium carbides ((Cr,Fe)_(23)C_6) and chromium-ironcarbides (Cr_3C_2) were synthesized on the surface of the sintered steels. By the way, results of XPS andEDAX analyzed surface was showed a chromium-carbide phase with as same to XRD (Cr,Fe)_(23)C_6 andmetal-chloride complex. In this study, the pack-chromizing sintered-steel has been affected low frictioncoefficient phenomenon by the concentration metal-chloride complex to be hardened structure withchromium-iron carbide included high-chromium coating.