A highly efficient waterborne bis(acyl)phosphane oxide photoinitiator (PEG-BAPO) was conveniently synthesized for 3D printing of hydrogels under blue light irradiation.

Due to the high level of light absorption and light scattering of dark colored powders connected with the high refractive indices of ceramic particles, the majority of ceramics studied via stereolithography (SLA) have been light in color, including ceramics such as alumina, zirconia and tricalcium phosphate. This article focuses on a lithography-based ceramic manufacturing (LCM) method for β-SiAlON ceramics that are derived from silicon nitride and have excellent material properties for high temperature applications. This study demonstrates the general feasibility of manufacturing of silicon nitride-based ceramic parts by LCM for the first time and combines the advantages of SLA, such as the achievable complexity and low surface roughness (R_a = 0.50 µm), with the typical properties of conventionally manufactured silicon nitride-based ceramics, such as high relative density (99.8%), biaxial strength (σf = 764 MPa), and hardness (HV₁₀ = 1500).

A key requirement for catalysts used for space propulsion applications is, amongst others, a rapid response time. This is often assessed in terms of how long it takes for a thruster to reach 95% of the steady state thrust or pressure from the moment the flow valve is opened. Equally important, however, is it to assess what the average lifetime of a pocket of fluid entering the catalyst bed is. To this end, a set of four different 3D-printed catalysts was subjected to a flow of highly concentrated hydrogen peroxide. The effectiveness of the catalyst was assessed with respect to the amount of liquid present during steady state operation. To assist the assessment, a simple depletion model was developed. For this purpose, four different gas-to-liquid conversion models were employed. It was found out that the model produces accurate results for about 65% of the initial depletion of the decomposition chamber. Given the layout of the system that was used for testing, it is believed that one of the key assumption, namely that no liquid is entering the decomposition chamber anymore, is not entirely met. Based on only the first 65% of the depletion process, it was estimated that between 18 and 29% of the accessible decomposition chamber volume is occupied by liquid during steady state operation.