In this study, chromium aluminum nitride coating was applied on pre-nitrided AISI D2 steel by the thermo--reactive deposition technique in a powder mixture consisting of ferrochromium, aluminum, ammonium chloride, and alumina at 1000 • C for 2 h. Steels were gas nitrided for the purpose to enrich the surfaces with nitrogen of the steels in a nitrogen and ammonia atmosphere at 560 • C for 8 h. The eect of aluminum content in the powder mixture on the CrAlN layer properties was investigated. The coated samples were characterized by X-ray diraction analysis, scanning electron microscope, and micro-hardness tests. Chromium aluminum nitride layer formed on the pre-nitrided AISI D2 steel was compact and homogeneous. Electron dispersive spectrometer results showed that coating layer includes chromium, aluminum, and nitrogen. X-ray studies showed that the phases formed in the coating layers on the steel surfaces are Cr2N, (Cr,Fe)2N1−x, AlN, and Fe2N. The depth of the CrAlN layer ranged from 10.01 ± 1.2 to 13.2 ± 1.7 µm, depending on the aluminum content. The hardness of the coated layers produced on AISI D2 steel are changing from 1743 ± 150 HV0.01 to 2067 ± 160 HV0.01 depending on bath compositions.
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.
Abstract.Weld overlay coatings also known as hardfacing is a method which involves melting of the alloys and solidification for applied coatings. 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, the coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the ranges of -45 μm particle size with different ratio.
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