A Comparative Study on the Corrosion Behaviour of Gas Nitrided and TiAlN Coated AISI D2 Steel by Thermo-Reactive Diffusion Technique

Abstract

In this study, the corrosion behaviors of nitride and titanium aluminum nitride (TiAlN) layers deposited on AISI D2 steel samples are reported. Steel was at rst nitrided in a nitrogen and ammonia atmosphere at 575• C for 8 h and then titanium nitride coating treatment was performed in the powder mixture consisting of ferro-titanium, aluminum, ammonium chloride and alumina at 1000• C for 2 h by thermo-reactive diusion technique. Phase analysis and corrosion tests were realized on the titanium aluminum nitride coated steel. The corrosion properties of uncoated and coated samples were characterized by potentiostatic polarization test. The tests were conducted using a three-electrode system test unit with a platinum counter electrode of 2.269 cm 2 and an Ag/AgCl, 3 M KCl electrode as the reference electrode. Nitrided and TiAlN coated steel specimens exhibited higher corrosion resistance than uncoated steel in 0.5 M H2SO4 solution. Conclusively, the application of nitride and TiAlN lms on AISI D2 steel increased surface hardness and corrosion resistance. TiAlN coating exhibits the highest corrosion resistance.

Corrosion Properties of CrAlN and TiAlN Coatings Deposited by Thermoreactive Deposition Process

“…2, the CrAlN coated sample has got the highest E corr value which is coming upon the upper site of passive region of the uncoated and TiAlN coated AISI D2 steels, and current density of the CrAlN coated steel is lower than that of the uncoated and TiAlN coated steels. These electrochemical characteristics demonstrated the capacity of the TiAlN and CrAlN coating for providing corrosion protection to the underlying substrate [19,20]. Scanning electron micrographs (SEM) along with energy dispersive X-ray spectroscopy (EDS) analysis for TiAlN and CrAlN coatings are shown in Fig.…”