Kinetics of titanium nitride coatings deposited by thermo-reactive deposition technique

In this study, the growth kinetics of titanium nitride layer deposited on pre-nitrided AISI 1020 steel samples by thermo-reactive diffusion (TRD) techniques in a solid medium was reported. Steel was at first tufftrided and then titanium nitride coating treatment was performed in a powder mixture consisting of ferro-titanium, ammonium chloride and alumina at 1173, 1223 and 1273 K for 1-4 h. Titanium nitride layer thickness on the titanium nitride coated AISI 1020 steel ranged from 5.5 to 19.2 μm depending on treatment time and temperature. Layer growth kinetics was analyzed by measuring the depth of titanium nitride layer as a function of time and temperature. The kinetics equation of the reaction has also been determined with Arhenius equation K=K_oexp(−Q/(RT). The result showed that the diffusion coefficient (K) of the process increased with treatment temperature. Activation energy (Q) for TRD process was calculated as 187.09 kJ/mol. The diffusion coefficients (K) changed between 6.637×10⁻¹¹ and 2.097×10⁻¹⁰ cm²/s depending on the process temperature.