Structure and Growth Kinetics of Films Formed by the Thermal Decomposition of CCl<sub>4</sub>on Iron Surfaces

Lara, J.; Molero, Hebert; Ramirez-Cuesta, and A.; Tysoe, Wilfred T.

doi:10.1021/la9503515

Cited by 23 publications

(18 citation statements)

References 42 publications

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“…[10][11][12] Suitable modifications of this model have allowed us to explain the EP properties of other additives such as chloroform 13 and carbon tetrachloride. 14 The work described below extends these investigations to examine the extreme-pressure properties of another important class of additivessthose containing sulfur. There are a wide variety of these additives, but an important class of these consists of hydrocarbon molecules with sulfur linkages.…”

Section: Introductionmentioning

confidence: 94%

Surface Chemistry and Extreme-Pressure Lubricant Properties of Dimethyl Disulfide

et al. 1998

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The growth kinetics of a film formed by the thermal decomposition of dimethyl disulfide on an iron foil are measured using a microbalance where the growth kinetics are parabolic (film thickness X varies with time as X 2 ∝ t) at high reaction temperatures and pressures, indicating that it is limited by diffusion through the film. The activation energy for this process is 54.5 ( 0.5 kcal/mol. The growth rate becomes linear as the reaction temperature and/or reactant pressure is lowered, indicating that, under these circumstances, the reaction rate is limited by thermal decomposition of dimethyl disulfide at the growing interface. The activation energy for thermal decomposition at the interface is found to be 37.6 ( 0.7 kcal/mol, and a half-order kinetics pressure dependence for the surface reaction rate is found consistent with a reaction limited by the rate of dimethyl disulfide dissociation. Analysis of the resulting film using Raman and X-ray photoelectron spectroscopies as well as X-ray diffraction reveal the formation of FeS, which may be slightly nonstoichiometric. This film is similar to that formed by methanethiol, suggesting that they may both initially form a surface thiolate species that further reacts to form FeS. The half-order reaction kinetics noted above are consistent with this. Measurement of dimethyl disulfide as an extreme-pressure (antiseizure) additive reveals a plateau at an applied load of ∼4000 N in the seizure load versus additive concentration curve. It has previously been suggested that the plateau corresponds to the load at which the interface reaches the melting point of the solid lubricant layer (in this case proposed to be FeS). Estimation of the interfacial temperature using a method developed previously yields an interfacial temperature of ∼1480 K, in good agreement with the melting point of FeS.

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Section: Introductionmentioning

confidence: 94%

Surface Chemistry and Extreme-Pressure Lubricant Properties of Dimethyl Disulfide

et al. 1998

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“…Since the 1980s several papers have been published on this topic using incineration technology like burning, catalytic oxidation or even plasma technology. Most of these papers are experimental work [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. In our previous papers, the decomposition of CCl 4 in thermal RF plasma was investigated in inert (CCl 4 -Ar) [20] and in oxidative (CCl 4 -O 2 -Ar) [21] environments.…”

Section: Introductionmentioning

confidence: 99%

CCl4 Decomposition in RF Thermal Plasma in Inert and Oxidative Environments

Kovács

Turányi

Szépvölgyi

2010

Plasma Chem Plasma Process

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The decomposition of carbon tetrachloride was investigated in an RF inductively coupled thermal plasma reactor in inert CCl 4 -Ar and in oxidative CCl 4 -O 2 -Ar systems, respectively. The exhaust gases were analyzed by gas chromatography-mass spectrometry. The kinetics of CCl 4 decomposition at the experimental conditions was modeled in the temperature range of 300-7,000 K. The simulations predicted 67.0 and 97.9% net conversions of CCl 4 for CCl 4 -Ar and for CCl 4 -O 2 -Ar, respectively. These values are close to the experimentally determined values of 60.6 and 92.5%. We concluded that in RF thermal plasma much less CCl 4 reconstructed in oxidative environment than in an oxygen-free mixture.

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“…The growth rates of films formed by the reaction of carbon tetrachloride with clean iron have been measured previously using a microbalance [12]. The film growth kinetics depend on pressure, varying from parabolic growth (X 2 / t) at high pressures (above $4 Torr) to linear at low pressures (below $2 Torr).…”

Section: Resultsmentioning

confidence: 99%

“…In the following, the tribological properties of films formed by the reaction of carbon tetrachloride vapor with iron surfaces is investigated [5,11]. The growth kinetics of these films has been studied previously, where film growth rates were measured on an iron foil using a microbalance, from the change in sample mass as a function of time [12]. This resulted in the deposition of an FeCl 2 film, along with the rapid diffusion of carbon into the bulk of the iron sample [13].…”

Section: Introductionmentioning

confidence: 99%

Tribological Properties of Films Formed by the Reaction of Carbon Tetrachloride with Iron

2005

Self Cite

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The tribological properties of halide films grown on iron by reaction with carbon tetrachloride vapor at a temperature of 617 K and a pressure of 1.7 Torr are compared, in ultrahigh vacuum, with FeCl 2 films evaporated onto the surface. It is found that the reactively formed film has a slightly lower limiting friction coefficient than the evaporated layer ($0.06 compared to $0.08), which may be due either to the diffusion of some carbon into the substrate or the formation of a more oriented layer when this is formed reactively. The major difference between the reactively grown and evaporated film is that the evaporated layer attains the minimum friction when $40 Å of FeCl 2 has been evaporated, while the reactively formed layer has a minimum friction coefficient when a film of 6±2 Å has been deposited. In the case of the evaporated FeCl 2 film, the growth of second and subsequent layers proceeds before the first layer is complete. It has been shown that the friction coefficient reaches its minimum value after completion of the first monolayer, a process that is complete after the evaporation of $40 Å of FeCl 2 . In the case of the film formed by reaction with CCl 4 , the halide film grows directly on the surface implying that the FeCl 2 monolayer thickness is $6 Å . This value is in good agreement with the layer thickness in bulk ferrous chloride.

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Structure and Growth Kinetics of Films Formed by the Thermal Decomposition of CCl₄on Iron Surfaces

Cited by 23 publications

References 42 publications

Surface Chemistry and Extreme-Pressure Lubricant Properties of Dimethyl Disulfide

Surface Chemistry and Extreme-Pressure Lubricant Properties of Dimethyl Disulfide

CCl4 Decomposition in RF Thermal Plasma in Inert and Oxidative Environments

Tribological Properties of Films Formed by the Reaction of Carbon Tetrachloride with Iron

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Structure and Growth Kinetics of Films Formed by the Thermal Decomposition of CCl4on Iron Surfaces

Cited by 23 publications

References 42 publications

Surface Chemistry and Extreme-Pressure Lubricant Properties of Dimethyl Disulfide

Surface Chemistry and Extreme-Pressure Lubricant Properties of Dimethyl Disulfide

CCl4 Decomposition in RF Thermal Plasma in Inert and Oxidative Environments

Tribological Properties of Films Formed by the Reaction of Carbon Tetrachloride with Iron

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Structure and Growth Kinetics of Films Formed by the Thermal Decomposition of CCl₄on Iron Surfaces