Coefficients of thermal expansion of low texture and isotropic pyrocarbon deposited on stationary substrates

Abstract

Low texture and isotropic pyrocarbon were prepared by hot wall reactor chemical vapor deposition between 950°C and 1050°C using natural gas as the carbon source. The morphology and texture of the pyrocarbon was characterized by transmission electron microscopy, and the coefficients of thermal expansion (CTE) were measured in the directions of parallel and perpendicular to the specimen thickness direction using a Netszch Dilatometer 402C. The results showed that as the deposition temperature increased from 950°C to 1050°C, the fracture surface of the pyrocarbon became rougher and the length of the graphene layers was gradually increased and the pyrocarbon changed from low texture to isotropic. The CTEs in both directions were almost the same and negative below 300°C.