Oxidation of nanocrystalline Mo–Si–N and nanolayered Mo–Si–N/SiC coatings

1999 ◽  
Vol 14 (9) ◽  
pp. 3552-3558 ◽  
Author(s):  
P. Torri
Keyword(s):  
Activation Energy ◽  
Water Vapor ◽  
Oxidation Resistance ◽  
Rate Constant ◽  
Arrhenius Plot ◽  
Single Layer ◽  
Water Vapor Atmosphere ◽  
Oxidation Properties ◽  
Sputter Deposited ◽  
Sic Coatings

Oxidation of sputter-deposited nanocrystalline Mo–Si–N (MoSi2.2N2.5) coatings in oxygen–water vapor atmosphere has been studied in the temperature range 400–850 °C. In addition, the oxidation properties of nanolayered Mo–Si–N/SiC coatings at 700 °C were studied and compared to those of single-layer coatings of both components. No pest disintegration was observed in Mo–Si–N up to 200 h of oxidation. A preexponential rate constant of (3.7 ± 0.5) × 109 (1015 atoms/cm2)2/h and activation energy 1.03 ± 0.02 eV were determined from an Arrhenius plot for parabolic oxygen buildup on Mo–Si–N. Up to 20% less oxygen was detected in the oxidized nanolayered coatings compared to either of the components as a single layer, indicating an improvement in oxidation resistance.

Thermal change of amorphous indium tin oxide films sputter-deposited in water vapor atmosphere

2008 ◽  
Vol 516 (17) ◽  
pp. 5809-5813 ◽  
Author(s):  
M.H. Wang ◽  
Y. Onai ◽  
Y. Hoshi ◽  
H. Lei ◽  
T. Kondo ◽  
...  
Keyword(s):  
Water Vapor ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Oxide Films ◽  
Thermal Change ◽  
Water Vapor Atmosphere ◽  
Sputter Deposited ◽  
Tin Oxide Films

scholarly journals The rate of water vapor evaporation from ice substrates in the presence of HCl and HBr: implications for the lifetime of atmospheric ice particles

2003 ◽  
Vol 3 (4) ◽  
pp. 1131-1145 ◽  
Author(s):  
C. Delval ◽  
B. Fluckiger ◽  
M. J. Rossi
Keyword(s):  
Activation Energy ◽  
Water Vapor ◽  
Vapor Pressure ◽  
Absorption Spectra ◽  
Mole Fraction ◽  
Rate Constant ◽  
Enthalpy Of Sublimation ◽  
Experimental Uncertainty ◽  
Ice Particles ◽  
Ftir Absorption Spectra

Abstract. Using a multidiagnostic approach the rate Rev [ molec cm-3 s-1] or flux Jev [ molec cm-2 s-1] of evaporation of H2O and its corresponding rate constant for condensation, kcond [s-1 ], on a 1 µm thick ice film have been studied in the temperature range 190 to 240 K as well as in the presence of small amounts of HCl and HBr that left the vapor pressure of H2O on ice unchanged. The resulting Arrhenius expressions for pure ice are Jev = 1.6 · 10 28 ± 1 · exp  (- 10.3 ± 1.2/ RT)  [ molec cm-2 s-1] , kcond = 1.7 · 10 - 2 ± 1 · exp  (+ 1.6 ± 1.5/ RT ) [s -1], in the presence of a HCl mole fraction in the range 3.2 · 10 - 5 - 6.4 · 10 - 3 : Jev = 6.4 · 10 26 ± 1 · exp  (- 9.7 ± 1.2/ RT)  [ molec cm-2 s-1] , kcond = 2.8 · 10 - 2 ± 1 · exp ( + 1.5 ± 1.6 /RT)  [s -1], and a HBr mole fraction smaller than 6.4 · 10 - 3 : Jev = 7.4 · 10 25 ± 1 · exp ( - 9.1 ± 1.2 /RT)  [ molec cm-2 s-1] , kcond = 7.1 · 10 - 5 ± 1 · exp (+ 2.6 ± 1.5/ RT) [s -1]. The small negative activation energy for H2O condensation on ice points to a precursor mechanism. The corresponding enthalpy of sublimation is DHsubl = Eev - Econd = 11.9 ± 2.7 kcal mol-1 , DHsubl = 11.2 ± 2.8 kcal mol-1, and DHsubl = 11.7 ± 2.8 kcal mol-1 whose values are identical within experimental uncertainty to the accepted literature value of 12.3 kcal mol-1 . Interferometric data at 633 nm and FTIR absorption spectra in transmission support the kinetic results. The data are consistent with a significant lifetime enhancement for HCl- and HBr-contaminated ice particles by a factor of 3–6 and 10–20, respectively, for submonolayer coverages of HX once the fraction of the ice not contaminated by HX has evaporated.

scholarly journals In-situ NiO nanostructure growth during heating in water vapor atmosphere

2021 ◽  
Vol 27 (S1) ◽  
pp. 2102-2103
Author(s):  
Boyi Qu ◽  
Klaus van Benthem
Keyword(s):  
Water Vapor ◽  
Water Vapor Atmosphere

scholarly journals Oxidation Behavior of Maraging 300 Alloy Exposed to Nitrogen/Water Vapor Atmosphere at 500 °C

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1021
Author(s):  
Mauro Andres Cerra Florez ◽  
Gemma Fargas Ribas ◽  
Jorge Luiz Cardoso ◽  
Antonio Manuel Mateo García ◽  
Joan Josep Roa Rovira ◽  
...  
Keyword(s):  
Water Vapor ◽  
Oxide Layer ◽  
Magnetic Layer ◽  
Adhesive Force ◽  
Point Of View ◽  
Maraging Steels ◽  
Cobalt Spinel ◽  
Water Vapor Atmosphere ◽  
Iron Nickel ◽  
Ferrite Cobalt

Aging heat treatments in maraging steels are fundamental to achieve the excellent mechanical properties required in several industries, i.e., nuclear, automotive, etc. In this research, samples of maraging 300 alloy were aged using a novel procedure that combines different steps with two atmospheres (nitrogen and water vapor) for several hours. The oxidized surface layer was chemical, microstructural and micromechanically characterized. Due to the thermodynamic and kinetic conditions, these gases reacted and change the surface chemistry of this steel producing a thin iron-based oxide layer of a homogeneous thickness of around 500 nm. Within the aforementioned information, porosity and other microstructural defects showed a non-homogeneous oxide, mainly constituted by magnetite, nickel ferrite, cobalt ferrite, and a small amount of hematite in the more external parts of the oxide layer. In this sense, from a chemical point of view, the heat treatment under specific atmosphere allows to induce a thin magnetic layer in a mixture of iron, nickel, and cobalt spinel ferrites. On the other hand, the oxide layer presents an adhesive force 99 mN value that shows the capability for being used for tribological applications under sliding contact tests.

Evaluation of Li mass loss from Li2TiO3 with excess Li pebbles in water vapor atmosphere

2018 ◽  
Vol 136 ◽  
pp. 362-366 ◽  
Author(s):  
Kazunari Katayama ◽  
Haruaki Sakagawa ◽  
Tsuyoshi Hoshino ◽  
Satoshi Fukada
Keyword(s):  
Water Vapor ◽  
Mass Loss ◽  
Water Vapor Atmosphere

Crystallization of Amorphous Silicon-Aluminum thin Films: IN-SITU Observation and Thermal Analysis.

1991 ◽  
Vol 237 ◽  
Author(s):  
Toyohiko J. Konno ◽  
Robert Sinclair
Keyword(s):  
Activation Energy ◽  
Amorphous Alloys ◽  
Amorphous Matrix ◽  
In Situ Observation ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Higher Temperature ◽  
Sputter Deposited

ABSTRACTThe crystallization of sputter-deposited Si/Al amorphous alloys was examined by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). In-situ high-resolution TEM reveals the existence of an Al layer between the amorphous matrix and the growing crystalline phase. The activation energy for the growth is about 1.2eV, roughly corresponding to the activation energy of Si diffusion in Al. These two observations support the view that a crystallization mechanism, in which an Al buffer layer provides the shortest reaction path, is responsible for the reaction. The product microstructure exhibits secondary crystallization at a higher temperature.

Oxidation Resistance of HfB2-SiC Coatings for Pro...

2005 ◽  
Author(s):  
P. Lespade ◽  
N. Richet ◽  
P. Goursat
Keyword(s):  
Oxidation Resistance ◽  
Sic Coatings

Evolution of Oxide Film of T91 Steel in Water Vapor Atmosphere at 750 °C

2013 ◽  
Vol 81 (3-4) ◽  
pp. 383-392 ◽  
Author(s):  
Guangming Liu ◽  
Caifu Wang ◽  
Fei Yu ◽  
Jihong Tian
Keyword(s):  
Water Vapor ◽  
Oxide Film ◽  
Water Vapor Atmosphere

ON THE DIELECTRIC BEHAVIOR OF LiCo3/5Fe2/5VO4 CERAMICS

2010 ◽  
Vol 24 (07) ◽  
pp. 665-670
Author(s):  
MOTI RAM
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Frequency Dependence ◽  
Chemical Method ◽  
Arrhenius Plot ◽  
Dielectric Behavior ◽  
Tangent Loss ◽  
Low Frequencies ◽  
Different Temperatures ◽  
Tan Δ

The LiCo 3/5 Fe 2/5 VO 4 ceramics has been fabricated by solution-based chemical method. Frequency dependence of the dielectric constant (εr) at different temperatures exhibits a dispersive behavior at low frequencies. Temperature dependence of εr at different frequencies indicates the dielectric anomalies in εr at Tc (transition temperature) = 190°C, 223°C, 263°C and 283°C with (εr) max ~ 5370, 1976, 690 and 429 for 1, 10, 50 and 100 kHz, respectively. Frequency dependence of tangent loss ( tan δ) at different temperatures indicates the presence of dielectric relaxation in the material. The value of activation energy estimated from the Arrhenius plot of log (τd) with 103/T is ~(0.396 ± 0.012) eV.

THE OXIDATION OF NITRITE AND IODATE IONS BY HYPOCHLORITE IONS

1961 ◽  
Vol 39 (8) ◽  
pp. 1645-1651 ◽  
Author(s):  
M. W. Lister ◽  
P. Rosenblum
Keyword(s):  
Activation Energy ◽  
Aqueous Solution ◽  
Rate Constant ◽  
Hypochlorous Acid ◽  
Slow Stage ◽  
Iodate Ions

The oxidation of nitrite ions and of iodate ions by hypochlorite ions in aqueous solution has been examined. The oxidation of nitrite is really a reaction of hypochlorous acid, with the slow stage HOCl + NO2− + H2O → H3O+ + Cl− + NO3−. The rate constant is given by log k = 7.36−6450/RT (time in minutes, and the activation energy in calories). The oxidation of iodate is chiefly a reaction of hypochlorite ions, probably ClO− + IO3− → Cl− + IO4−, although the rate is somewhat increased by a higher concentration of hydroxide ions. The rate constant is given by log k = 16.15−26,100/RT. These results are compared with other oxidations by hypochlorite ions, to see if any general trends are apparent.

Sign in / Sign up

Export Citation Format

Share Document