Nanostructure of Surface Films on Ni18P Alloy in Sulfate Solutions by the Maximum Entropy Method

Exploration of the Corrosion Behavior of Electroless Plated Ni-P Amorphous Alloys via X-ray Photoelectron Spectroscopy

A Ni-P amorphous alloy was deposited on a low carbon steel substrate via electroless plating. Further, the prepared samples were crystallized under the high temperature with a range from 200 °C to 500 °C in air for 1 h. The crystallization process was studied via XRD, AFM, and XPS, and anodic electrochemical behavior was investigated by potentiostatic methods in a 3.5 wt% NaCl solution. The experimental results indicate that the diffusion, dissolution, and enrichment of the component elements in the Ni-P alloy are essential during crystallization because the various corrosion behaviors corresponding to Ni and P are directly affected. More importantly, under the 400 °C treatment, H₂PO_2^- was enriched in the alloy, which effectively hinders the anodic dissolution of nickel and forms a complete adsorption layer on the surface of the alloy. Our results demonstrate that P can effectively block the anodic dissolution of Ni during the corrosion process, and the crystallization process can effectively promote the surface enrichment of P to improve the corrosion resistance of the coating.

Molecular dynamics simulations of amorphous Ni-P alloy formation by rapid quenching and atomic deposition

A combined experimental and simulation study is carried out to compare the properties of amorphous Ni_100-x P _x alloys obtained by electroless deposition and rapid melt-quenching. The onset of crystallization of experimental electroless deposited amorphous films is measured by differential scanning calorimetry experiments. Classical molecular dynamics simulations using Embedded Atom Model-based interactions are performed to obtain glassy Ni-P by melt-quenching the liquid with various quenching rates, as well as via low-energy chemical deposition to mimic experimental electroless deposition. It is shown that the deposited amorphous and glassy states display similar short-range order. The amorphous deposit corresponds to a glassy state obtained with a cooling rate of 10⁹ K s^-1, indicating that deposition yields generally more relaxed amorphous structures. The appearance of phosphorus-enriched surface on the simulated deposited thin film, comparable to experimental observations, is discussed.

Insights into the Interfacial Process in Electroless Ni-P Coating on Supercritical CO2 Transport Pipeline as Relevant to Carbon Capture and Storage

To reduce the amount of greenhouse gas emissions and remedy related environmental damage, the research on carbon capture and storage (CCS) is gaining momentum and so is the search for a more effective way to control corrosion of pipeline steel used to transport impure supercritical (SC) CO₂. Herein, we prepared an electroless high-phosphorus Ni-P coating and, for the first time, systematically explored the underlying mechanism of the interfacial process in applying Ni-P coating to protect pipeline steel that transports impure SC CO₂. It is found that, benefiting from the formation of a protective surface film, Ni-P coating significantly mitigates the corrosion effects from SC CO₂ and impurities (e.g., O₂ and NO₂), especially the synergistic effect of impurities. Concurrently, it effectively avoids the localized corrosion resulting from nonuniform adsorption of the aqueous phase. Although O₂ and NO₂ can degrade the coating through boosting water precipitation, deteriorating the water chemistry, and reducing the surface film protectiveness, the corrosion inhibition efficiency of Ni-P coating is invariably higher than 80%, independent of the varying causticity of SC CO₂ streams, demonstrating that the coating has a superior stability toward corrosion attack. The as-prepared Ni-P coating undoubtedly holds great potential as an alternative for corrosion control of CO₂ transport pipeline in the CCS industry. This work provides a new, feasible method to ensure the safe and efficient operation of CCS.