Chemical composition and porous structure of polymer‐derived silicoboron carbonitride ceramics prepared via a monomer route

Abstract

Polymer‐derived silicoboron carbonitride (SiBCN) ceramics were facilely prepared using organosilicon monomers tris(dichloromethylsilylethyl)borane and bis(trimethylsilyl)carbodiimide as the starting materials. The polymer precursors were obtained either without adding styrene or by adding an appropriate amount of styrene into the mixture of the organosilicon monomers, followed by heat treatment and purifying. The chemical composition and pore structure of the polymer‐derived SiBCN ceramics were studied. It was found that styrene diluted the monomers and hindered their chemical reaction from forming the polymeric network. The polymer precursor prepared with styrene was composed of boron‐modified polysilylcarbodiimide as the matrix and dispersed polystyrene mainly of sizes 20–50 μm. Accordingly, a polymer‐derived SiBCN ceramic with a three‐dimensional continuous macroporous structure containing pores mainly of 20.9–58.1 μm with a total porosity of 74% was achieved. The B/N atomic ratio reached 0.58 with low oxygen content of 2.81 wt%, which satisfied the requirement for high‐temperature application.