سينتيك تشكيل كاربيد كروم بر روي فولاد 1020، با استفاده از تكنولوژي نفوذ فعال حرارتي (TRD)

Kinetics of Chromium Carbide Formation on AISI 1020 Steel by TRD Process

Using thermal reactive diffusion (TRD) process in order to produce a carbide or nitride layer (such as chromium carbide) onto metals and alloys is one of the techniques for increasing surface hardness and enhancing oxidation, corrosion and wear resistance. In this research, kinetics of chromium carbide coating formation onto AISI 1020 steel by salt bath method at 950, 1000. 1050 ｰC for 3- 9 h has been studied. The presence of (Cr,Fe)7C3 on steel surface was shown by XRD analysis. Observations using optical and SEM microscopes from sample cross sections show a rather smooth and compact layer of chromium carbide onto samples surface. Surface micro hardness of coated steel, measured by Vickers method, is equal to 1350 HV0 050Kg • Kinetic study of carbide coating, formed by this process, shows firstly a parabolic relationship between carbide thickness and treated time, secondly the activation energy for chromium carbide formation on 1020 steel in borax salt bath is equal to 225.6 KJ/mol. In addition, for predicting carbide layer thickness, contour diagrams are suggested. Yet the possibility of using a series of mathematical equations for predicting carbide thickness from treated time and bath temperature has been discussed.