Formation Mechanism of SiC Gradient in Carbon Materials

Abstract

High-density isotropic graphite substrates with and without a notch produced at the surface were contactedwith metallic silicon and heated at 1350 and 1450°C. The contribution of open pores in the substrates for the formationof SiC-gradient was discussed. At 1350°C, no SiC-gradient was observed at the surface of the substrate without thenotch, but the gradient in the substrate was formed at 1450°C. On the substrates with notch, fibers were formed on thenotch wall of the substrate heated at 1350°C. By heating at 1450°C, however, SiC was detected at the portion beyondthe nose of notch. In present study, it was expected that small amount of 02 are enclosed in the open pores and in thenotch. Based on the expected reactions among silicon, carbon and oxygen, the formation of SiC-gradient in thesubstrate at 1450°C was found to be possibly formed due to the reaction between carbon on the wall of pores and SiOgas through the open pores from the surface of the substrate.