Çelikler üzerine NbC kaplama

SUMMARY NbC layers were formed on DIN115Cr\/3 steel o substrates at temperatures between 850-1000 C by dipping into molten borax bath containing 20% Fe-Nb powder additions, for 2-4-6 hours time periods. The composition of bath was kept constant while, the treatment temperature and time were varied systematically. The thickness and microstructure of coated specimens were investigated by optical microscopy and the characterization of bath and coated layers were made by XRD analysis. Hardness of coated layers and substrate were measured by microhardness tester. It was seen by optical microscopy that the layers were smooth, uniform and pore free and the thickness range was between 2-17 microns. The hardness of layers were measured between 3000-4200 Hv. The process was found to be diffusion controlled and the activation energy Df carbide formation was calculated as V 30 Kcal/mol. XRD analysis of bath revealed Nb0" as the oxide which causes the bath to become active.