The states of nitrogen atoms in the processing of Ni–Cr alloy surface nitriding modification

Zhang, Z.P.; Lei, Ming

doi:10.1016/j.apsusc.2014.02.076

Cited by 3 publications

(2 citation statements)

References 24 publications

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“…That is, only the two of the six metal atoms were displaced farther apart, but the rest of the atoms merely changed their positions or were slightly contracted to each other. In the literature, a similar deformation of the O-site has been reported for carbon and nitrogen binding in other bcc metals. ,,, Such deformation can be explained by energy minimization. The increased free energy due to lattice expansion upon nitrogen binding would be overcompensated by the lowered energy from the stabilized interaction between nitrogen and V in a deformed O-site.…”

Section: Resultssupporting

confidence: 71%

“…Nitrogen binding in the bcc metals and their alloys has been widely reported both theoretically and experimentally. In the literature, multiple experiments to measure nitrogen binding and diffusion have been performed for various metals (e.g., V, ,− Nb, , Ta, ,,, Cr, − Mo, ,− and Fe). , Also, theoretical studies focusing on nitrogen in the bulk metals have supported the O-site binding of nitrogen in V, W, and Fe. , Lattice expansion often occurs due to the large atomic size of nitrogen compared to the size of interstitial sites. ,, When other defect sites, such as vacancies, grain boundaries, and dislocations, exist in metal structures, those sites tend to exhibit stronger binding of nitrogen. ,, However, only limited number of nitrogen binds to those sites since the defect concentrations are limited, and the mobility of defects decreases with nitrogen binding. Introducing nitrogen to metals is often referred to as “nitriding.” In steel manufacture, nitriding is a metal strengthening process to enhance mechanical properties of steels.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical Study of Nitrogen Absorption in Metals

et al. 2017

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Nitrogen binding in open structure body-centered-cubic (bcc) metals was studied to understand atomic nitrogen absorption in these systems in order to assess their feasibility as membrane materials for nitrogen separation and subsequent reactivity for ammonia production. For a metallic membrane to be feasible for this application, it must exhibit adequate solubility that allows for sufficient permeability. Using first-principle calculations it was demonstrated that nitrogen is too soluble in pure vanadium due to its strong binding in this metal (i.e., binding energy of −2.80 eV/atom), but through alloying, the binding energy may be tuned to mimic the weaker hydrogen binding exhibited in Group V metals, leading to high permeability. In particular, alloys of Ru and Mo were investigated. The Bader charge and density of states analyses showed that nitrogen binding in pure V is enhanced by the electrostatic and covalent interaction between nitrogen and surrounding V atoms, whereas repulsive interaction with an alloying component, Ru or Mo, with nitrogen resulted in the less stable binding of nitrogen in the alloys. Reduced binding energies were observed in both alloys (e.g., −1.64 eV/atom for both V53Ru and V15Mo alloys). In particular, Mo13V3 alloy showed a nitrogen BE of −0.041 eV, which is very similar to the BE of H in Pd. The nitrogen solubility in Mo was estimated based upon a thermodynamic equilibrium assumption with systematic corrections to the calculated vibrational frequencies, showing agreement to the experimental solubility. Using the same correction scheme, nitrogen solubility in V–Mo was estimated to be 4 orders of magnitude higher at 1000 K for a 25 at. % V alloy composition compared to pure Mo. This theoretical study provides useful guidance for the discovery of promising materials for metallic membranes for ammonia synthesis.

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Section: Resultssupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Theoretical Study of Nitrogen Absorption in Metals

et al. 2017

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Improved wear resistance of AISI-1045 steel by hybrid treatment of plasma nitriding and post-oxidation

Naeem

Díaz-Guillén

Khalid

et al. 2022

Tribology International

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Effect of plasma nitriding substrate current density on the adhesion strength of in situ PVD TiN coatings

Zhang

Tian

Gong

et al. 2023

Journal of Vacuum Science &Amp; Technology A

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TiN coatings were in situ deposited on un-nitrided and nitrided M2 high speed steels by electrically enhanced cathodic arc evaporation technology. The morphology, microstructure, phase composition, as well as microhardness and nano-hardness of the samples were analyzed by scanning electron microscope, optical microscope, X-ray diffraction, Vickers hardness tester, and nano-indentation, respectively. In especially, the effect of nitriding substrate current density on the adhesion strength of in situ TiN coatings was investigated by Rockwell indentation and scratch tests. The results showed that the nitrided layer thickness increased with increasing substrate current density and “bright” nitrided layer was achieved. In the Rockwell indentation test, the radial cracks on the surface of the duplex-treated samples originated from the hard and brittle nitrided layer as compared to the nitrided substrate, which corresponded to the failure mechanism of brittle fracture. In the scratch test, the adhesion strength of coating to substrates was significantly improved by nitriding pretreatment. Furthermore, the critical load of the duplex-treated samples increased with the increase of nitriding substrate current density. In addition, tensile cracks only occurred in the case of the N120/TiN sample.

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The states of nitrogen atoms in the processing of Ni–Cr alloy surface nitriding modification

Cited by 3 publications

References 24 publications

Theoretical Study of Nitrogen Absorption in Metals

Theoretical Study of Nitrogen Absorption in Metals

Improved wear resistance of AISI-1045 steel by hybrid treatment of plasma nitriding and post-oxidation

Effect of plasma nitriding substrate current density on the adhesion strength of in situ PVD TiN coatings

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