3D Mapping Of Density And Crack Propagation Through Sintering Of Catalysis Tablets By X-Ray Tomography

For hydrogen production, by steam reforming, porous ceramics are broadly used as catalyst support, due to their stability and ease in shaping. Catalyst supports in the form of tablets are conventionally produced by powder pressing and subsequent sintering. However, if the process is not done properly, cracks may arise and propagate during the sintering of the tablets. This can lead to weak sintered tablets that get rejected in the quality control. For this work, crack-containing samples of rejected tabletized support were provided. The formation, growth and closure of internal cracks during sintering of the rejected tabletized support material are studied by 3D X-ray tomography. This is a powerful technique, which due to its nondestructive nature is suitable to study the development of internal cracks in the tablets during sintering. Cracks could be identified in the green tablet (before sintering), which may indicate an uneven compaction of the powder, leading to an uneven spring-back after compaction. During sintering, some of the initial cracks were observed to close, while others were observed to open. Furthermore new cracks were also observed to arise during sintering. The different cracks locations and developments were analyzed in relationship to the surrounding microstructural features in an attempt to understand the underlying mechanisms.