Microstructure of compacted graphite iron under cryogenic conditions
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In this paper the effect of compacted graphite iron (CGI) microstructure have been investigated in tribological strategy. From industrial context two coatings have been chosen: a single layer coating (PVD) and a multilayer coating (CVD). Pin-on-disk tests have been done to analyze wear mechanisms and to directly obtain the coefficient of friction. Rotation speed of the disk have been adjusted to get the same linear velocity on different disk radii to get up to 150 m.min-1 similar to machining condition. Three-dimensional profilometer, scanning electron microscopy and nano-identation were used to observe the track profiles, the pin and the disk wears and to measure the hardness of microstructure components respectively. Results showed that PVD coating was more abrasive and had more volume of sticking materials. CVD coating which could be the most appropriate for machining CGI, has a real anti-sticking property and has less friction coefficient than PVD coating. But the presence of small TiCN precipitates in CGI material have a proven negative effects in CVD coating lifetime.