In the present study, the corrosion behaviors of chromium aluminum nitride (CrAlN) and titanium aluminum nitride (TiAlN) coatings deposited on AISI D2 steel samples are reported. Steel samples were pre-nitrided at 575 • C for 8 h in the rst step of the coating process, and then TiAlN and CrAlN coatings were performed by thermoreactive deposition process in a powder mixture consisting of alumina, ammonium chloride, aluminum and ferrous titanium or ferrous chromium for TiAlN or CrAlN, respectively. Coating treatments were realized at 1000 • C for 2 h. Coated samples were characterized by X-ray di raction analysis, optical microscopy, scanning electron microscopy, and microhardness tester. The corrosion properties of uncoated and coated samples were characterized by potentiostatic polarization test. CrAlN and TiAlN coated steel specimens exhibited the higher corrosion resistance than uncoated steels in a 0.5 M NaCl solution.

Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions. In the present study, three di erent alloy compositions of the Fe Nb B were used for hardfacing of the AISI 1020 steel by tungsten inert gas welding process and analyzed. The coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the range of −45 µm particle size with di erent ratio. The coatings' thickness was set to 2 3 mm on the substrate. Microstructure, phase analysis and hardness of the manufactured hardfacing alloys were characterized. Deposition results indicate good quality thick coating and porosity free of the hardfacings. X-ray di raction analyses showed that the alloyed layers include iron borides, FeNbB and iron phases. It was shown that surface alloyed layer has composite structure including steel matrix and well distributed boride phases.

The wear properties of uncoated, chromium aluminum nitride (CrAlN) and titanium aluminum nitride (TiAlN) coated AISI D2 steel were investigated and compared using ball-on-disc method at 0.3 m/s sliding speed and under the loads of 2.5 N, 5 N, and 10 N against Si3N4 ball as a counter material. Steel samples were nitrided at 575 • C for 8 h in the rst step of the coating process, and then titanium aluminum nitride coating and chromium aluminum nitride were performed by thermoreactive deposition (TRD) process at 1000 • C for 2 h. Coated samples were characterized by X-ray diraction analysis, scanning electron microscopy, microhardness, and ball on disk wear tests. The results of friction coecient and wear rate of the tested materials showed that the TiAlN coating presents the lowest results.

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.