THE DECREASING MICROSTRUCTURE DEGRADATION OF FIBER BASE FEEDER SLEEVE WITH VARIOUS REFRACTORY COATINGS

摘要

Feeder sleeves are consisted of insulation, exothermic and binder components. Fiber base feeder sleeves are commonly used because of low cost, high yield, too low weight and easy moldability. However, intreaction with molten metal occurs a bit on long time depend of porosity structure. This phenomena can cause contamining same ingeradient to molten metal. Especially for ductile iron alloys, when spherodial graphites are occurred, metalic aluminum in sleeve can cause degradation. So the mechanical properties of casting part can get worse In this study, experimental design and analysis procedure are determined for explaining this phenomena and inhibiting this degradation. Rich and poor metalic aluminyum included feeder sleeves are prepared. Then some of them are coated with different refractory coating. All sleeves are used with same ductile iron alloy. The metal sample in sleeves are examined with optical and scanning electro microscope for microstructure analysis. The chemical composition change in structure is determine with EDS analysis. Finally, the hardness testing were applied to determine mechanical differences between zones.