Phase content prediction in polymer‐derived ceramics with metal additives
Ni Yang, Kathy Lu
Abstract
Abstract In this study, silicon oxycarbide (SiOC) is selected as the base polymer to derive a SiOC ceramic (PDC) matrix, and four transition metals M (M = Ni, Mo, Co, and Zr) are individually introduced into the SiOC base to form various SiOC/M systems. SiOC‐Ni, SiOC‐MoC x , and SiOC‐CoSi x are obtained by pyrolysis at 1100°C, whereas SiOC‐ZrO x forms upon pyrolysis at 1400°C. The selected SiOC/M systems encompass four different types of phase separation pathways—pure metal, metal carbide, metal silicide, and metal oxide (SiC‐SiO 2 ‐C‐Ni, SiC‐SiO 2 ‐C‐MoC x , SiC‐SiO 2 ‐C‐CoSi x , and SiC‐SiO 2 ‐C‐ZrO x ). The driving force for crystallization has been analyzed using a Gibbs free energy minimization method and phase fractions of these different PDC systems are calculated based on the lever rule. This work also reveals the energetics related to the quaternary systems and provides guidance to synthesizing metal‐containing PDCs with desired phase contents. In addition, we have examined the broad applicability of the phase content prediction method for a variety of other SiOC/M systems.