Microstructural Observation of SiC Surface Alloyed Carbon Steel
EPS (expanded polystyrene spheres) template with a 5 mm coating on a surface that is mainly consisted of SiC particles are prepared. Carbon steels are then poured in the templates using V-EPC (Vacuum Expandable Pattern Casting) process. The microstructures are observed and analyzed using optical microscope, SEM and EDS. Macrostructural observation showed that the surface alloyed zone is dense and there are no obvious defects, such as gas bubbles, occluded gas holes and delimitation. Microstructural investigations indicated that the samples from top to bottom are obviously consisted of three different layers, i.e., the surface compound layer, the interim transitional layer and the bottom matrix layer. SiC particles are totally decomposed during infiltration. The microstructures in the surface compound layer are consisted of a large amount of graphite flakes, carbides, Si rich ferrites and dendritic pearlites. There is a fine pearlite strip at the top of the transitional layer and small amounts of carbide particles within the matrix grains and net carbides at the grain boundaries can be also observed in this layer.
C. Q. Guo "Microstructural Observation of SiC Surface Alloyed Carbon Steel", Advanced Materials Research, Vols. 308-310, pp. 2565-2568, 2011