Kinetics of MoSi[sub 2] pest during low-temperature oxidation

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · Journal of Materials Research; (United States)

DOI:https://doi.org/10.1557/JMR.1993.1605· OSTI ID:5304248

Chou, T C ^[1]; Nieh, T G ^[2]

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1. Lockheed Research and Development Division, O/93-10, B/204, 3251 Hanover St., Palo Alto, California 94304-1191 (United States)
2. Lawrence Livermore National Laboratory, P. O. Box 808, L-350, Livermore, California 94550 (United States)

The kinetics of MoSi[sub 2] pest, caused by oxidation in air, has been studied. Experimental results indicated that pest disintegration occurred at temperatures between 375 and 500 [degree]C. The volumes of test samples increased with oxidation duration. Analysis of change in sample volume versus oxidation duration revealed that the pest disintegration consisted of two stages, namely nucleation (or incubation) and growth.The onset of growth stage depended on the test temperature. More importantly, changes in sample volume were found to obey a linear relationship with time during the growth stage. Equations were formulated to demonstrate that the growth kinetics of pest disintegration was proportional to the rates of change in sample volume. The rates of volume change during MoSi[sub 2] pest were calculated to be 4.9[times]10[sup [minus]6], 2.8[times]10[sup [minus]5], 3.7[times]10[sup [minus]5], and 5.4[times]10[sup [minus]5] cm[sup 3]/s at 375, 400, 425, and 450 [degree]C, respectively; the growth kinetics increased with oxidation temperature. The activation energy for the growth stage of pest disintegration was determined to be 27.6 kcal/mole, which agrees well with the activation energy for the low-temperature oxidation of MoSi[sub 2].

• OSTI ID: 5304248
• Journal Information: Journal of Materials Research; (United States), Journal Name: Journal of Materials Research; (United States) Vol. 8:7; ISSN JMREEE; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360205* -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
ACTIVATION ENERGY
AIR
BUILDING MATERIALS
CHEMICAL REACTIONS
DECOMPOSITION
ENERGY
EQUATIONS
FLUIDS
GASES
GROWTH
KINETICS
MATERIALS
MOLYBDENUM COMPOUNDS
MOLYBDENUM SILICIDES
NUCLEATION
OXIDATION
REFRACTORY METAL COMPOUNDS
SILICIDES
SILICON COMPOUNDS
TEMPERATURE RANGE
TEMPERATURE RANGE 0400-1000 K
TRANSITION ELEMENT COMPOUNDS