scholarly journals Substituent Effects on the Thermal Decomposition of Phosphate Esters on Ferrous Surfaces

2021 ◽  
Author(s):  
James Ewen ◽  
Carlos Ayestaran Latorre ◽  
Chiara Gattinoni ◽  
Arash Khajeh ◽  
Joshua Moore ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
High Temperature ◽  
Film Formation ◽  
Substituent Effects ◽  
Md Simulations ◽  
Tribological Performance ◽  
Phosphate Esters ◽  
Antiwear Additives ◽  
Phosphate Ester

<p></p><p>Phosphate esters have a wide range of industrial applications, for example in tribology where they are used as vapour phase lubricants and antiwear additives. An atomic-level understanding of phosphate ester tribofilm formation mechanisms is required to improve their tribological performance. A process of particular interest is the thermal decomposition of phosphate esters on steel surfaces, since this initiates polyphosphate film formation. In this study, reactive force field (ReaxFF) molecular dynamics (MD) simulations are used to study the thermal decomposition of phosphate esters with different substituents on several ferrous surfaces. The ReaxFF parameterisation was validated for a representative system using density functional theory (DFT) calculations. During the MD simulations on Fe 3 O 4 (001) and α-Fe(110), chemisorption interactions between the phosphate esters and the surfaces occur even at room temperature, and the number of molecule-surface bonds increases as the temperature increases from 300 to 1000 K. Conversely, on hydroxylated, amorphous Fe 3 O 4 , most of the molecules are physisorbed and some desorption occurs at high temperature. Thermal decomposition rates were much higher on Fe 3 O 4 (001) and particularly α-Fe(110) compared to hydroxylated, amorphous Fe 3 O 4. This suggests that water passivates ferrous surfaces and inhibits phosphate ester chemisorption, decomposition, and ultimately polyphosphate film formation. For the alkyl phosphates, thermal decomposition proceeds mainly through CO and C-H cleavage on Fe 3 O 4 (001). Aryl phosphates show much higher thermal stability, and decomposition on Fe 3 O 4 (001) only occurs through P-O and C-H cleavage, which require very high temperature. The onset temperature for CO cleavage on Fe 3 O 4 (001) increases as: tertiary alkyl < secondary alkyl < primary linear alkyl ≈ primary branched alkyl < aryl. This order is consistent with experimental observations for the thermal stability of antiwear additives with similar substituents. The simulation results clarify a range of surface and substituent effects on the thermal decomposition of phosphate esters on steel that should be helpful for the design of new molecules with improved tribological performance.<br></p><p></p>

Substituent Effects on the Thermal Decomposition of Phosphate Esters on Ferrous Surfaces

2019 ◽  
Author(s):  
James Ewen ◽  
Carlos Ayestaran Latorre ◽  
Arash Khajeh ◽  
Joshua Moore ◽  
Joseph Remias ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Film Formation ◽  
Substituent Effects ◽  
Vapour Phase ◽  
Industrial Applications ◽  
Phosphate Esters ◽  
Antiwear Additives ◽  
Formation Mechanisms ◽  
Phosphate Ester ◽  
Wide Range

<p>Phosphate esters have a wide range of industrial applications, for example in tribology where they are used as vapour phase lubricants and antiwear additives. To rationally design phosphate esters with improved tribological performance, an atomic-level understanding of their film formation mechanisms is required. One important aspect is the thermal decomposition of phosphate esters on steel surfaces, since this initiates film formation. In this study, ReaxFF molecular dynamics simulations are used to study the thermal decomposition of phosphate esters with different substituents on several ferrous surfaces. On Fe<sub>3</sub>O<sub>4</sub>(001) and α-Fe(110), chemisorption interactions between the phosphate esters and the surfaces occur even at room temperature, and the number of molecule-surface bonds increases as the temperature is increased from 300 to 1000 K. Conversely, on hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>, most of the molecules are physisorbed, even at high temperature. Thermal decomposition rates were much higher on Fe<sub>3</sub>O<sub>4</sub>(001) and particularly α-Fe(110) compared to hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>. This suggests that water passivates ferrous surfaces and inhibits phosphate ester chemisorption, decomposition, and ultimately film formation. On Fe<sub>3</sub>O<sub>4</sub>(001), thermal decomposition proceeds mainly through C-O cleavage (to form surface alkyl and aryl groups) and C-H cleavage (to form surface hydroxyls). The onset temperature for C-O cleavage on Fe<sub>3</sub>O<sub>4</sub>(001) increases in the order: tertiary alkyl < secondary alkyl < primary linear alkyl ≈ primary branched alkyl < aryl. This order is in agreement with experimental observations for the thermal stability of antiwear additives with similar substituents. The results highlight surface and substituent effects on the thermal decomposition of phosphate esters which should be helpful for the design of new molecules with improved performance.</p>

Substituent Effects on the Thermal Decomposition of Phosphate Esters on Ferrous Surfaces

2020 ◽  
Author(s):  
James Ewen ◽  
Carlos Ayestaran Latorre ◽  
Chiara Gattinoni ◽  
Arash Khajeh ◽  
Joshua Moore ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Film Formation ◽  
Substituent Effects ◽  
Vapour Phase ◽  
Industrial Applications ◽  
Phosphate Esters ◽  
Antiwear Additives ◽  
Formation Mechanisms ◽  
Phosphate Ester ◽  
Wide Range

<p>Phosphate esters have a wide range of industrial applications, for example in tribology where they are used as vapour phase lubricants and antiwear additives. To rationally design phosphate esters with improved tribological performance, an atomic-level understanding of their film formation mechanisms is required. One important aspect is the thermal decomposition of phosphate esters on steel surfaces, since this initiates film formation. In this study, ReaxFF molecular dynamics simulations are used to study the thermal decomposition of phosphate esters with different substituents on several ferrous surfaces. On Fe<sub>3</sub>O<sub>4</sub>(001) and α-Fe(110), chemisorption interactions between the phosphate esters and the surfaces occur even at room temperature, and the number of molecule-surface bonds increases as the temperature is increased from 300 to 1000 K. Conversely, on hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>, most of the molecules are physisorbed, even at high temperature. Thermal decomposition rates were much higher on Fe<sub>3</sub>O<sub>4</sub>(001) and particularly α-Fe(110) compared to hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>. This suggests that water passivates ferrous surfaces and inhibits phosphate ester chemisorption, decomposition, and ultimately film formation. On Fe<sub>3</sub>O<sub>4</sub>(001), thermal decomposition proceeds mainly through C-O cleavage (to form surface alkyl and aryl groups) and C-H cleavage (to form surface hydroxyls). The onset temperature for C-O cleavage on Fe<sub>3</sub>O<sub>4</sub>(001) increases in the order: tertiary alkyl < secondary alkyl < primary linear alkyl ≈ primary branched alkyl < aryl. This order is in agreement with experimental observations for the thermal stability of antiwear additives with similar substituents. The results highlight surface and substituent effects on the thermal decomposition of phosphate esters which should be helpful for the design of new molecules with improved performance.</p>

scholarly journals Substituent Effects on the Thermal Decomposition of Phosphate Esters on Ferrous Surfaces

2020 ◽  
Author(s):  
James Ewen ◽  
Carlos Ayestaran Latorre ◽  
Chiara Gattinoni ◽  
Arash Khajeh ◽  
Joshua Moore ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Film Formation ◽  
Substituent Effects ◽  
Vapour Phase ◽  
Industrial Applications ◽  
Phosphate Esters ◽  
Antiwear Additives ◽  
Formation Mechanisms ◽  
Phosphate Ester ◽  
Wide Range

<p>Phosphate esters have a wide range of industrial applications, for example in tribology where they are used as vapour phase lubricants and antiwear additives. To rationally design phosphate esters with improved tribological performance, an atomic-level understanding of their film formation mechanisms is required. One important aspect is the thermal decomposition of phosphate esters on steel surfaces, since this initiates film formation. In this study, ReaxFF molecular dynamics simulations are used to study the thermal decomposition of phosphate esters with different substituents on several ferrous surfaces. On Fe<sub>3</sub>O<sub>4</sub>(001) and α-Fe(110), chemisorption interactions between the phosphate esters and the surfaces occur even at room temperature, and the number of molecule-surface bonds increases as the temperature is increased from 300 to 1000 K. Conversely, on hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>, most of the molecules are physisorbed, even at high temperature. Thermal decomposition rates were much higher on Fe<sub>3</sub>O<sub>4</sub>(001) and particularly α-Fe(110) compared to hydroxylated, amorphous Fe<sub>3</sub>O<sub>4</sub>. This suggests that water passivates ferrous surfaces and inhibits phosphate ester chemisorption, decomposition, and ultimately film formation. On Fe<sub>3</sub>O<sub>4</sub>(001), thermal decomposition proceeds mainly through C-O cleavage (to form surface alkyl and aryl groups) and C-H cleavage (to form surface hydroxyls). The onset temperature for C-O cleavage on Fe<sub>3</sub>O<sub>4</sub>(001) increases in the order: tertiary alkyl < secondary alkyl < primary linear alkyl ≈ primary branched alkyl < aryl. This order is in agreement with experimental observations for the thermal stability of antiwear additives with similar substituents. The results highlight surface and substituent effects on the thermal decomposition of phosphate esters which should be helpful for the design of new molecules with improved performance.</p>

scholarly journals High-temperature heterogeneous catalysis in platinum nanoparticle – molten salt suspensions

2020 ◽  
Vol 10 (3) ◽  
pp. 625-629
Author(s):  
Behzad Tangeysh ◽  
Clarke Palmer ◽  
Horia Metiu ◽  
Michael J. Gordon ◽  
Eric W. McFarland
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
High Temperature ◽  
Heterogeneous Catalysis ◽  
Co Oxidation ◽  
Molten Salt ◽  
Platinum Nanoparticles ◽  
Platinum Nanoparticle ◽  
Oxidation Activity

Suspensions of platinum nanoparticles (PtNPs) were formed in molten LiCl–LiBr–KBr via thermal decomposition of H2PtCl6, and subsequently evaluated for thermal stability and CO oxidation activity.

Influence of WS2/SnS2 on the tribological performance of copper-free brake pads

2019 ◽  
Vol 71 (3) ◽  
pp. 398-405 ◽  
Author(s):  
Justin Antonyraj I. ◽  
Vijay R. ◽  
Lenin Singaravelu D.
Keyword(s):  
Thermal Stability ◽  
Profile Analysis ◽  
Film Formation ◽  
Three Dimensional ◽  
Solid Lubricants ◽  
Tribological Performance ◽  
Mechanical And Thermal Properties ◽  
Content Type ◽  
Brake Pads ◽  
Lubrication Film

Purpose The purpose of this study is to investigate the influence of solid lubricants (tungsten disulfide [WS2]/ Tin disulfide [SnS2]) on the tribological performance of brake pads. Design/methodology/approach In this study, the brake pads were developed by varying the solid lubricants (WS2/SnS2) without varying the other ingredients. The brake pads were developed as per the industrial procedure. Thermal stability was found for varying ingredients and developed pads. The physical, mechanical and thermal properties of the developed brake pads were analyzed as per the industrial standards. The tribological properties were analyzed using the Chase test. The worn surface analysis was done using scanning electron microscopy, elemental mapping and three-dimensional profile analysis. Findings The experimental results indicate that the WS2-based brake pads possess good physical, chemical and mechanical properties with stable friction and less wear rate due to its good lubrication film formation and thermal stability natures of WS2. Originality/value This paper explains the effect of solid lubricants in brake pads for enhancing the tribological performance by the shearing of crystal structure, thermal stability and tribo film properties of the lubricants.

scholarly journals Substituent Effects on the Thermal Decomposition of Phosphate Esters on Ferrous Surfaces

2020 ◽  
Vol 124 (18) ◽  
pp. 9852-9865 ◽  
Author(s):  
James P. Ewen ◽  
Carlos Ayestarán Latorre ◽  
Chiara Gattinoni ◽  
Arash Khajeh ◽  
Joshua D. Moore ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Substituent Effects ◽  
Phosphate Esters

scholarly journals Effect of Alkaline Treatment on the Thermal Stability of Pineapple Leaf Fibers

2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Mohit Mittal ◽  
Rajiv Chaudhary
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
High Temperature ◽  
Natural Fiber ◽  
Alkaline Treatment ◽  
Gravimetric Analysis ◽  
High Temperature Stability ◽  
Pineapple Leaf Fiber ◽  
Thermal Stability Of ◽  
Leaf Fiber

Recently, most of the industries are looking towards to incorporate sustainable, renewable, eco- friendly and affordable raw materials and production process. To achieve this goal, engineers and technologist are working on biocomposite material. The primary reason behind the selection of natural fiber based material in the automobile, construction, and aerospace industry is its low cost, lightweight, high specific strength and modulus, biodegradability, and friendly processing. Inspite of all beneficial features, one of the main barriers to their utilization in all mentioned sectors is thermal degradability. Natural fibers can be subjected to thermal degradation during composite processing and their application in the high-temperature field. So it is practically significant to understand the thermal decomposition of lignocellulosic fibers and to modify it for the purpose of high-temperature stability. In this work, alkaline treatment of varying concentrations (2%, 4%, 6%, 8%, and 10 wt %) was used to study the effect of alkaline treatment on thermal stability of pineapple leaf fibers. The thermal behavior of untreated and alkali treated pineapple leaf fiber was examined by using a thermal gravimetric analysis instrument (TGA). The results show that 4 wt% NaOH treated pineapple leaf fiber have maximum thermal stability. The decomposition of untreated and treated PALF was a two-stage process attributed to the thermal decomposition of hemicellulose, cellulose, and lignin. The results also showed that the temperature of initial degradation 251 0C increased to 285 0C after 4% alkaline treatment due to partial removal of hemicellulose and lignin.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

NIPPON/SUMITOMO SUPER625

Alloy Digest ◽  
2017 ◽  
Vol 66 (12) ◽  
Keyword(s):  
Thermal Stability ◽  
Fracture Toughness ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Nickel Alloy ◽  
Hot Workability ◽  
Temperature Performance ◽  
Compositional Elements

Abstract Nippon Sumitomo Super625 is a nickel alloy with an optimization of compositional elements for thermal stability and hot workability. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance and corrosion resistance as well as forming. Filing Code: Ni-740. Producer or source: Sumitomo Metal USA Corporation.

Non-Isothermal Decomposition Kinetic of Polypropylene/Hydrotalcite Composite

2019 ◽  
Vol 19 (11) ◽  
pp. 7493-7501 ◽  
Author(s):  
Sheng Xu ◽  
Min Zhang ◽  
Siyu Li ◽  
Moyu Yi ◽  
Shigen Shen ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
Nitrogen Atmosphere ◽  
Heating Rates ◽  
Decomposition Reactions ◽  
Kinetic And Thermodynamic Parameters ◽  
Málek Method ◽  
Boundary Reaction ◽  
Phase Boundary Reaction ◽  
Thermal Stability Of

P3O5-10 pillared Mg/Al hydrotalcite (HTs) as a functional fire-retarding filler was successfully prepared by impregnation-reconstruction, where the HTs was used to prepare polypropylene (PP) and HTs composite (PP/HTs). Thermal decomposition was crucial for correctly identifying the thermal behavior for the PP/HTs, and studied using thermogravimetry (TG) at different heating rates. Based on single TG curves and Málek method, as well as 41 mechanism functions, the thermal decompositions of the PP/HTs composite and PP in nitrogen atmosphere were studied under non-isothermal conditions. The mechanism functions of the thermal decomposition reactions for the PP/HTs composite and PP were separately “chemical reaction F3” and “phase boundary reaction R2,” which were also in good agreement with corresponding experimental data. It was found that the addition of the HTs increased the apparent activation energy Ea of the PP/HTs comparing to the PP, which improved the thermal stability of the polypropylene. A difference in the set of kinetic and thermodynamic parameters was also observed between the PP/HTs and PP, particularly with respect to lower ΔS≠ value assigned to higher thermal stability of the PP/HTs composite.

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