Kinetics of (Fe,Cr)7C3/Fe dense ceramic layer prepared by in situ synthesis

Abstract

In this study, the (Fe,Cr)7C3/Fe dense ceramic layer was produced by in situ synthesis method with subsequent heat treatment. According to the results of thermal analysis, the as-cast specimen was subjected to heat treatment at 1186, 1208, 1230 °C for 1–5 h in argon atmosphere respectively. The microstructures of the compound region were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the kinetics of the (Fe,Cr)7C3 dense ceramic layer were analyzed. The results show that a-Fe and (Fe,Cr)7C3 are the predominant crystalline phases in the composite obtained. Depending on the layer process time and temperature, the thickness of the reaction layer formed on the substrate ranged from 12.3 to 32.6 mm. The kinetics of dense ceramic layer by the in situ synthesis method was also studied and the activation energy for the diffusion process was estimated to be 292 kJ/mol. Moreover, an attempt was made to investigate the possibility of predicting the iso-thickness of chromium carbide layer variation and to establish some empirical relationships between process parameters and dense ceramic layer thickness.