Crack Formation in Ceramic Films Used in Solid Oxide Fuel Cells

TL;DR

This study investigates crack formation in ceramic films for solid oxide fuel cells, revealing how defects originate and evolve during drying, binder burn-out, and sintering, with implications for manufacturing defect-free films.

Contribution

It provides new insights into defect formation mechanisms in ceramic films and demonstrates how controlled processing can mitigate cracking during sintering.

Findings

Mud cracks originate from drying-induced cracks in green films.

Crack opening increases during constrained sintering.

Initial cracks can be healed during co-sintering.

Abstract

The manufacture of solid oxide fuel cells (SOFCs) involves fabrication of a multilayer ceramic structure, for which constrained sintering is a key processing step in many cases. Defects are often observed in the sintered structure, but their formation during sintering is not well understood. In this work, various ceramic films were fabricated by screen printing and a variety of defects observed. Some films showed mud-cracking defects, whereas others presented distributed large pores. Mud cracking defects were found to originate from a network of fine cracks present in the green film and formed during drying and binder burn-out. Control of these early stages is essential for producing crack-free films. In order to investigate how defects evolve during sintering, artificial cracks were introduced in the green films using indentation. It was observed that crack opening always increased during constrained sintering. In contrast, similar initial cracks could be closed and healed during co-sintering.