First-principles analysis on the role of rare-earth doping in affecting nitrogen adsorption and diffusion at Fe surface towards clarified catalytic diffusion mechanism in nitriding

Yang, Yang; Dai, Xuewu; Yang, Xia-Wei; Zhang, S.H.; Li, D.Y.

doi:10.1016/j.actamat.2020.06.020

Cited by 45 publications

(6 citation statements)

References 49 publications

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“…The research on the hydrogen storage capacity of the Nb 4 AlC 3 MAX phase cannot only focus on the adsorption of H. The study of FIA in materials should consider its diffusion behavior [ 45 ]. According to the calculation results of system energy change and bonding properties, it can be known that H has three stable sites in the Nb-Al layer.…”

Section: Resultsmentioning

confidence: 99%

Exploring Hydrogen Incorporation into the Nb4AlC3 MAX Phases: Ab Initio Calculations

Gao

et al. 2022

Materials

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The Nb4AlC3 MAX phase can be regarded as a TMC structure with stacking faults, which has great potential as a novel solid hydrogen storage material. Herein, we used ab initio calculations for understanding the hydrogen incorporation into Nb4AlC3 MAX phases, including equilibrium structural characteristics, energy changes, electronic structures, bonding characteristics, and diffusion paths. According to the calculated results, H has thermal stability in the interstice of the Nb-Al layer, and the most probable insertion site is an octahedron (3-site) composed of three Nb atoms and three Al atoms. When C vacancies are introduced, the Nb-C layer has a specific storage capacity for H. In addition, Al vacancies can also be used as possible sites for H incorporation. Moreover, the introduction of vacancies significantly increase the hydrogen storage capacity of the MAX phase. According to the electronic structure and bonding characteristics, the excellent hydrogen storage ability of the Nb4AlC3 structure may be due to the formation of ionic bonds between H and Nb/Al. It is worth noting that the H-Al bond in the 1-site is a covalent bond and an ionic bond key mixture. The linear synchronous transit optimization study shows that only H diffusion in Al vacancies is not feasible. In conclusion, the Nb-Al layer in Nb4AlC3 can provide favorable conditions for the continuous insertion and subsequent extraction of H, while the vacancy structure is more suitable for H storage. Our work provides solid theoretical results for understanding the hydrogen incorporation into Nb4AlC3 MAX phases that can be helpful for the design of advanced hydrogen storage materials.

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Section: Resultsmentioning

confidence: 99%

Exploring Hydrogen Incorporation into the Nb4AlC3 MAX Phases: Ab Initio Calculations

Gao

et al. 2022

Materials

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“…Plasma nitriding is an effective metal-surface-strengthening process wherein a plasma formed by gas ionization enters the surface of a metal matrix, thereby improving the hardness, wear resistance, and corrosion resistance of the metal surface [1][2][3][4][5]. Recently, the hollow-cathode effect has been used to enhance the impact of plasma diffusion.…”

Section: Introductionmentioning

confidence: 99%

Simulation of hollow-cathode-nitriding plasma and design of diffusion equipment with DC and RF dual discharge

Zhang¹,

Wang²,

Shao³

et al. 2023

Phys. Scr.

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The formation and diffusion of plasma are complex and critical processes in plasma nitriding. A stable and high-concentration plasma atmosphere can effectively increase the diffusion rate and the thickness of the diffusion layer. In this study, a two-dimensional multi-physics model integrating physical kinetics, energy transfer, mass transfer, and electromagnetic induction was developed. The effect of a hollow-cathode structure on plasma distribution was investigated, and the edge effect observed on nitrided metals was eliminated. The impacts of the essential plasma diffusion parameters were simulated using the developed model. A simple but effective experiment was designed to validate the model. A diffusion furnace with DC and RF dual discharge was designed by adding a high-frequency coil to existing equipment. Subsequently, the effects of the two plasma excitation sources on the overall distribution of plasma were analyzed. Notably, the proposed model is a high-fidelity one based on actual device dimensions; therefore, it can be used to simulate, predict, and control the plasma formation process in the diffusion furnace. In addition, the model can provide reference data and guidance for optimizing the diffusion process and structural design of diffusion furnaces.

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“…Owing to their biodegradability, deformability, porosity, and low toxicity, polyvinyl alcohol (PVA) hydrogels have been used to develop artificial scaffolds for tissue repairs. ,,, However, the limited biocompatibility and insufficient mechanical strength of pure PVA hydrogels still hinder their utilization in practical applications . Various methods have thus been introduced to modify PVA hydrogels with improved biocompatibility and mechanical properties. , For instance, the incorporation of natural polymers, such as gelatin, heparin, and bacterial cellulose, endows PVA hydrogels with increased cell affinity as the biocompatible scaffolds, yet, with no improvements in mechanical performances. − On the other hand, the incorporation of stiff nanofillers, such as nano-HA (hydroxyapatite) or graphene oxide, with PVA hydrogels enables a significant enhancement in mechanical strength. − These filler-incorporation methods are simple and effective, but the resulting hydrogels typically lack dynamic features to interact with biological tissues in physiological environments . Compared to the abovementioned incorporation strategies, catechol-amine interactions derived from the biological functions of the proteinaceous cuticles on mussel threads have demonstrated their potential to crosslink macromolecules with reinforced mechanical properties. − This is mainly due to the reversible imine bonds between the catechol quinones and amine groups that can undergo association/dissociation in response to the environment conditions. , On the other hand, inspired by the mussel foot proteins (Mfps), engineering synthetic polymers with catechol groups imparts the polymer to interact with amino acids of proteinaceous substrates, forming hydrogen bonds and imine bonds for adhesion. − Herein, by leveraging the mussel-inspired catechol chemistry, we incorporated the tyrosine–dopamine conjugates as dynamic crosslinkers into the PVA matrix to generate desirable functionalities for its application as biomedical scaffolds.…”

Section: Introductionmentioning

confidence: 99%

Poly(vinyl Alcohol) (PVA)-Based Hydrogel Scaffold with Isotropic Ultratoughness Enabled by Dynamic Amine–Catechol Interactions

Shui

Pan

et al. 2022

Chem. Mater.

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Hydrogels, serving as promising load-bearing materials, often suffer from limited long-term stability due to their insufficient mechanical strength. One of the viable methods is to engineer hydrogels with muscle-like anisotropic structures to enable mechanical reinforcement along the alignment direction (e.g., artificial tendons) while sacrificing the mechanical strength in the perpendicular direction. However, for connective tissues such as the fibrous membranes of the articular capsule with fibers interwoven to resist excessive stretching and distension in multiple directions, isotropic mechanical strength is highly demanding. In this work, inspired by the dynamic amine-catechol interactions derived from mussel foot proteins (Mfps), an innovative strategy is developed to incorporate Mfps-like conjugates as elastic connections into the poly(vinyl alcohol) (PVA) matrix, mimicking the multidirectional fibrous bundles of connective tissues. Superior isotropic tensile strength (13.3 ± 0.5 MPa), ultratoughness (60.1 ± 2.6 MJ/m3), and resilience are achieved in this hydrogel, which surpasses most of the reported biocompatible hydrogels. Additionally, this hydrogel exhibits diverse functionalities such as underwater adhesion and conductivity due to the multiple dynamic amine-catechol interactions engineered in the hydrogel. The versatility of this hydrogel offers a broad range of possibilities as artificial scaffolds with enhanced isotropic mechanical strength and cell affinity for the long service term.

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First-principles analysis on the role of rare-earth doping in affecting nitrogen adsorption and diffusion at Fe surface towards clarified catalytic diffusion mechanism in nitriding

Cited by 45 publications

References 49 publications

Exploring Hydrogen Incorporation into the Nb4AlC3 MAX Phases: Ab Initio Calculations

Exploring Hydrogen Incorporation into the Nb4AlC3 MAX Phases: Ab Initio Calculations

Simulation of hollow-cathode-nitriding plasma and design of diffusion equipment with DC and RF dual discharge

Poly(vinyl Alcohol) (PVA)-Based Hydrogel Scaffold with Isotropic Ultratoughness Enabled by Dynamic Amine–Catechol Interactions

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