Journal of Materials Engineering and Performance, vol.32, no.19, pp.8972-8980, 2023 (SCI-Expanded)
Niobium carbide (NbC) coatings were carried out by means of the thermo-reactive diffusion (TRD) on AISI D3 cold work tool steel, in the powder mixture composed of 25 wt.% ferro-niobium, 70 wt.% alumina and 7.5 wt.% ammonium chloride at 1173, 1273 and 1373 K for 2, 4 and 6 h. NbC coatings were inspected with scanning electron microscopy, x-ray diffractometer, Vickers micro-hardness testing. Homogeneous, crack-free and uniform NbC coatings with 8.75-17.10 µm thickness and 1586-2263 HV0.025 hardness were obtained on AISI D3 steel by TRD process. The integral method-based model was used for studying the carbon diffusion by forming NbC coatings. The value of 45.93 kJ mol−1 was determined as the necessary activation energy required for the niobizing process of AISI D3 steel.