M. Azizi, M. Soltanieh,
Volume 11, Issue 3 (9-2014)
Abstract
In the present research, to form niobium carbide coating on the surface of AISI L2 steel Thermo-Reactive
Deposition method (TRD) in a molten bath was used. Niobium carbide coating treatment was carried out at 1173 K,
1273 K, and 1373 K for 2, 4, and 8 hours. The molten bath contained 20wt.% borax (Na2B4O7), 5 wt.% boric acid
(B2O3), and 75 wt.% ferro-niobium. The presence and properties of the coated layer were studied by means of Optical
Microscopy (OM), Scanning Electron Microscopy (SEM), and X-Ray Diffraction (XRD) analysis. The thickness of
coating ranged between 6.6 µm to 33µm depending on treatment time, and temperature. The effects of treatment time
and temperature on the coating thickness were studied. Kinetic study of the formation of NbC coating showed that
growth of the coating is under the control of diffusion. The activation energy of the process was estimated to be 122
kJ/mol. A practical formula to estimate the coating thickness was suggested.
