Investigation of the (thermo-)mechanical properties and the chemical resistance towards ammonia combustion atmosphere of alumina-based model structures manufactured via Fused Granulate Fabrication

This study focuses on the fabrication of alumina-based model samples by fused granulate fabrication for the application in burner components for ammonia combustion. Three compositions were investigated: Two alumina systems with different initial grain size (A1-tabular alumina, A2-reactive alumina) and alumina (AZT) with MgO-stabilized ZrO 2 - and TiO 2 -additions. Young’s modulus and flexural strength were determined after sintering and after up to five thermal shocks. A1 exhibited the best suitability for repeated thermal shocks, followed by A3. The high interparticle porosity of A1 limited crack propagation and resulted in a slow, gradual loss in elastic modulus (maximum loss of 8.6%) and strength (maximum loss of 35.7%) with increasing number of thermal shocks. Microstructural features due to the additive manufacturing process could enhance thermal shock performance. The materials were tested in ammonia combustion atomosphere at approx. 1500°C for 1h and showed no phase alterations. Model components with application-near geometries were successfully realized.