Kinetics of carbothermal reduction snythesis of boron carbide

Journal Article · Tue Sep 01 00:00:00 EDT 1992 · Journal of the American Ceramic Society; (United States)

OSTI ID:7182572

Pratsinis, S E ^[1]; Weimer, A W; Moore, W G; Roach, R P; Hitt, J E; Dixit, R S ^[2]

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1. Dept. of Chemical Engineering, Univ. of Cincinnati, Cincinnati, OH (United States)
2. Dow Chemical Co., Midland, MI (United States)

This paper reports that carbothermal reduction kinetics to synthesize boron carbide are studied under conditions of high carbon/boron oxide precursor heating rates ([gt] 10[sup 3] K/s) and intermediate temperatures (1803 K [lt] T [lt] 2123 K). For these conditions, fractional carbon conversion, X, can be described by a nucleation---growth rate expression: ln (1 [minus] X) = [minus](kt)[sup 3], where k[sub 0] = 3.86 [times] 10[sub 6] s[sup [minus]1] and E[sub a] = 301 [plus minus] 55 kJ/mol for the temperature range (1803 [lt] T [lt] 1976 K) and k[sub 0] =-2 [times] 10[sup 20] s[sup [minus]1] and E[sub a] = 820 [plus minus] 89 kJ/mol for the temperature range (1976 [lt] T [lt] 2123 K), respectively. Boron carbide formation is highly dependent upon the phase change of reactant boron oxide from solid to liquid to gaseous boron suboxides and the effect of reaction environment (i.e., heating rate and ultimate temperature) on the rate at which the phase changes occur.

• OSTI ID: 7182572
• Journal Information: Journal of the American Ceramic Society; (United States), Vol. 75:9; ISSN 0002-7820
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BORON CARBIDES
SYNTHESIS
THERMODYNAMIC PROPERTIES
BORON OXIDES
PHASE TRANSFORMATIONS
CARBON
CHEMICAL REACTION KINETICS
GASES
LIQUIDS
PRECURSOR
REDOX REACTIONS
SOLIDS
TEMPERATURE RANGE 1000-4000 K
BORON COMPOUNDS
CARBIDES
CARBON COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
ELEMENTS
FLUIDS
KINETICS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
REACTION KINETICS
TEMPERATURE RANGE
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies
360204 - Ceramics
Cermets
& Refractories- Physical Properties
400201 - Chemical & Physicochemical Properties