The mechanism of iron phosphide formation during boundary friction in the presence of organic phosphates and phosphites

Pavelko, G. F.

doi:10.3103/s1068366612020092

Cited by 7 publications

(6 citation statements)

References 28 publications

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“…water, oxygen, hydrogen) were available to contribute to the TCP-surface reactions. [31][32][33][34] In the simulations, the composition of the material chemisorbed to the surface was quantified in terms of surface density of individual elements that originated from TCP molecules. Figure 7 shows that the chemisorbed material consisted of C, O and P atoms.…”

Section: Resultsmentioning

confidence: 99%

“…The chemical reactions described above are the starting point for film formation. Therefore, the composition of the material chemisorbed to the surface in the simulations can be analyzed in the context of previous experimental measurements; specifically, experiments performed in oxygen-deficient environments, where the iron was expected to have a native oxide, but only small amounts of outside reactants (e.g., water, oxygen, hydrogen) were available to contribute to the TCP–surface reactions. − In the simulations, the composition of the material chemisorbed to the surface was quantified as the surface density of individual elements that originated from TCP molecules. Figure shows that the chemisorbed material consisted of C, O, and P atoms.…”

Section: Results and Discussionmentioning

confidence: 99%

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Statistical Analysis of Tri-Cresyl Phosphate Conversion on an Iron Oxide Surface Using Reactive Molecular Dynamics Simulations

Khajeh

Mohammadtabar

et al. 2019

J. Phys. Chem. C

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Parallel reactive molecular dynamics simulations were used to statistically analyze chemical reactions between tri-cresyl phosphate (TCP) and an amorphous iron oxide surface. To accurately model this system, a new parameter set for Fe/P/O interactions within the ReaxFF framework was developed. Using the new parameter set, 100 parallel simulations of a single TCP molecule on an amorphous iron oxide surface were run to capture multiple possible reactions at temperatures ranging from 300 to 700 K. The frequency of TCPsurface reactions for each atom type and each unique reaction site on the TCP was analyzed across the range of temperatures. Finally, the composition of the material chemisorbed to the surface was determined and compared to results from previously reported experimental measurements of TCP films in oxygen deficient environments. The results are specifically relevant to TCP, but the parallel reactive simulation approach and statistical analysis of reaction sites can be applied more generally to a range of chemical systems, particularly those involving complex molecules and disordered surfaces where many different reactions are possible.

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Section: Resultsmentioning

confidence: 99%

Section: Results and Discussionmentioning

confidence: 99%

Statistical Analysis of Tri-Cresyl Phosphate Conversion on an Iron Oxide Surface Using Reactive Molecular Dynamics Simulations

Khajeh

Mohammadtabar

et al. 2019

J. Phys. Chem. C

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“…In the phosphidation process using NaH 2 PO 2 , NaH 2 PO 2 is thermally decomposed at temperatures greater than 250°C and produces PH 3 gas as a phosphorus source 35 . The phosphidation reaction occurs according to the following equation 35,36

2 Na H_{2} normalP O_{2} \to normalN a_{2} HP O_{4} + normalP H_{3} ↑

xM + yP H_{3} \to M_{x} P_{y} + 3 / 2 \cdot {yH}_{2} ↑ .

…”

Section: Resultsmentioning

confidence: 99%

“…35 The phosphidation reaction occurs according to the following equation. 35,36 2NaH 2 PO 2 ! Na 2 HPO 4 + PH 3 "…”

Section: Electrochemical Characterizationmentioning

confidence: 99%

Highly active and stable electrocatalytic transition metal phosphides ( Ni ₂ P and FeP ) nanoparticles on porous carbon cloth for overall water splitting at high current density

2020

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Highly active and stable hydrogen production at high current densities is required for practical application of electrocatalytic water splitting. In this study, highly active self-supporting electrodes with excellent durability were designed and developed for high-performance overall water splitting at a high current density. First, a colloid-based dip-coating method using porous carbon cloth (PCC) was introduced to obtain uniformly coated Ni and Fe nanoparticles on a conductive substrate. Then, the desired phase transitions of Ni and Fe to Ni 2 P and FeP, respectively, proceeded by thermal phosphidation at optimum temperature. The uniformly interconnected Ni 2 P layers on the PCC substrate (Ni 2 P@PCC) and FeP layers on the PCC substrate (FeP@PCC) exhibited outstanding oxygen and hydrogen evolution reactions, respectively. When each electrode was adopted as an anode and a cathode for the overall water splitting cell, excellent performance was achieved, with a low operational voltage of 1.76 V and high durability for 100 hours at a high current density of 50 mA cm −2 .

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“…Saba et al 23,27−29 also found that TCP molecules reacted on Fe-based surfaces to form nodular films of iron polyphosphate rather than iron phosphide, as some thought. 30,31 Moreover, experiments have shown that TCP molecules form thicker thermal films but thinner tribofilms on steel surfaces. 32,33 Although there have been some studies on TCP and TNBP antiwear additives, these studies have not provided a systematic elucidation and comparison of the tribochemical reactions and tribological properties of the two additives.…”

Section: ■ Introductionmentioning

confidence: 99%

Tribological Properties of Phosphate Ester Confined between Iron-Based Surfaces

Yang,

Duan

2024

Langmuir

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Recent studies have revealed that phosphate ester lubricant additives undergo decomposition and polymerization when confined between two iron-based surfaces, forming tribofilms that play a crucial role in antiwear and friction reduction. However, the behaviors of decomposition and polymerization, as well as the mechanisms behind the antiwear and friction-reducing properties of these tribofilms, remain largely unexplored. To address these gaps, we employed reactive force field molecular dynamics (ReaxFF-MD) to investigate the tribochemical reactions and tribological properties of tricresyl phosphate (TCP) and tri-n-butyl phosphate (TNBP) confined between three types of iron-based substrates with varying oxygen content: α-Fe⟨110⟩, amorphous FeO (a-FeO), and amorphous Fe2O3 (a-Fe2O3) surfaces. Our findings indicate that TCP and TNBP molecules primarily undergo dissociation of P–O and C–O bonds, a process influenced by both the oxygen content of the substrates and the molecular structure of the additives. Following the dissociation of these bonds, the released carbon–hydrogen groups adsorb onto the substrates, leading to the formation of adsorbed carbon films on the surfaces. Simultaneously, the dissociation of P–O and C–O bonds triggers polymerization reactions, resulting in the creation of organic polyphosphate iron groups confined between the surfaces coated with adsorbed carbon films. Due to the difference in the contact state and shearing behavior between the carbon films and the organic polyphosphate iron groups, substrates with higher oxygen content exhibit relatively higher friction forces for both TCP and TNBP molecules. Additionally, TCP molecules demonstrate lower friction forces compared to those of TNBP molecules on all three iron-based substrates.

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The mechanism of iron phosphide formation during boundary friction in the presence of organic phosphates and phosphites

Cited by 7 publications

References 28 publications

Statistical Analysis of Tri-Cresyl Phosphate Conversion on an Iron Oxide Surface Using Reactive Molecular Dynamics Simulations

Statistical Analysis of Tri-Cresyl Phosphate Conversion on an Iron Oxide Surface Using Reactive Molecular Dynamics Simulations

Highly active and stable electrocatalytic transition metal phosphides ( Ni ₂ P and FeP ) nanoparticles on porous carbon cloth for overall water splitting at high current density

Tribological Properties of Phosphate Ester Confined between Iron-Based Surfaces

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The mechanism of iron phosphide formation during boundary friction in the presence of organic phosphates and phosphites

Cited by 7 publications

References 28 publications

Statistical Analysis of Tri-Cresyl Phosphate Conversion on an Iron Oxide Surface Using Reactive Molecular Dynamics Simulations

Statistical Analysis of Tri-Cresyl Phosphate Conversion on an Iron Oxide Surface Using Reactive Molecular Dynamics Simulations

Highly active and stable electrocatalytic transition metal phosphides ( Ni 2 P and FeP ) nanoparticles on porous carbon cloth for overall water splitting at high current density

Tribological Properties of Phosphate Ester Confined between Iron-Based Surfaces

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Product

Resources

About

Highly active and stable electrocatalytic transition metal phosphides ( Ni ₂ P and FeP ) nanoparticles on porous carbon cloth for overall water splitting at high current density