Journal of the Ceramic Society of Japan
Online ISSN : 1882-1022
Print ISSN : 0914-5400
ISSN-L : 0914-5400
Growth Behavior of Manganese-Metallized Layer on Silicon-Nitride Ceramics
Toshiyuki TAKASHIMATsuyoshi YAMAMOTOToshio NARITA
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1991 Volume 99 Issue 1148 Pages 324-328

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Abstract

The initial stage growth of a metallized layer of silicon-nitride ceramics was investigated by the Vapor-diffusion method. The metallization was carried out using manganese powder as a vapor source under a dynamic vacuum condition from 1073 to 1273K up to 129.6ks. The metallization process was found to be divided in to two reaction stages. At the initial stage a two layer structure was found; the surface layer of Mn6Si and alpha-Mn(Si), and the bottom layer of MnSiN2 and oxide additives. The thickness of the bottom layer increased rapidly at the onset of the initial stage. This change in layer thickness is due to the reaction of Si3N4 ceramics with manganese gas molecules supplied directly through opening and pores in the growing surface layers. After the initial transition period, the surface layer became compact, and a middle layer, a mixture of alpha-Mn(Si), Mn6Si and oxide additives, was newly formed by decomposition of the bottom layer. Consequently, the thickness of the bottom layer decrese. Thereafter, it remained almost constant at 6.0μm at 1173K, 4.8μm at 1223K and 4.0μm at 1273K. Under steady state condition, it was found that the growth of the surface layer and bottom plus middle layer obeyed the parabolic rate law, respectively.

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