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Role of the Interfacial Thermal Barrier in the Effective Thermal Diffusivity/Conductivity of SiC‐Fiber‐Reinforced Reaction‐Bonded Silicon Nitride
Author(s) -
Bhatt Hemanshu,
Donaldson Kimberly Y.,
Hasselman D.P.H.,
Bhatt R. T.
Publication year - 1990
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1990.tb06511.x
Subject(s) - thermal diffusivity , materials science , thermal conductivity , thermal conduction , silicon carbide , composite material , silicon nitride , composite number , silicon , nitride , thermal contact conductance , fiber , thermal resistance , thermal , layer (electronics) , thermodynamics , physics , metallurgy
Experimental thermal diffusivity data transverse to the fiber direction for composites composed of a reaction bonded silicon nitride matrix reinforced with uniaxially aligned carbon‐coated silicon carbide fibers indicate the existence of a significant thermal barrier at the matrix‐fiber interface. Calculations of the interfacial thermal conductances indicate that at 300°C and 1‐atm N 2 , more than 90% of the heat conduction across the interface occurs by gaseous conduction. The magnitude of the interfacial conductance is decreased significantly under vacuum or by removal of the carbon surface layer from the fibers by selective oxidation. Good agreement is obtained between thermal conductance values for the oxidized composite at 1 atm calculated from the thermal conductivity of the N 2 gas and those inferred from the data for the effective composite thermal conductivity.