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This contribution addresses the complete process chain of an annular aerospike breadboard engine fabricated by laser powder bed fusion using the nickel-based superalloy Inconel® 718. In order to qualify the material and process for this high-temperature application, an extensive material characterization campaign including density and roughness measurements, as well as tensile tests at room temperature, 700, and 900 °C, was conducted. In addition, various geometric features such as triangles, ellipses, and circular shapes were generated to determine the maximum unsupported overhang angle and geometrical accuracy. The results were taken into account in the design maturation of the manifold and the cooling channels of the aerospike breadboard engine. Postprocessing included heat treatment to increase mechanical properties, milling, turning, and eroding of interfaces to fulfill the geometrical tolerances, thermal barrier coating of thermally stressed surfaces for better protection of thermal loads, and laser welding of spike and shroud for the final assembly as well as quality assurance. This contribution goes beyond small density cubes and tensile samples and offers details on the iterations necessary for the successful printing of large complex shaped functional parts. The scientific question is how to verify the additive manufacturing process through tensile testing, simulation, and design iterations for complex geometries and reduce the number of failed prints. [ABSTRACT FROM AUTHOR]

By adjusting the thermal spraying suspension technology, coatings with excellent microstructure, surface morphology, and phase composition can be obtained to meet the application needs in mechanical, electrical or friction fields. The use of suspensions as feedstock material allows a high degree of flexibility with regard to the chemical composition of the sprayed coatings. Moreover, suspension thermal spraying (STS) is a promising technique for the production of coatings, the use of which was previously limited by expensive starting materials. A mixture of less expensive starting materials in the suspension and an "in situ" reaction to the desired product during the spraying process make this possible. Zn2TiO4 coatings are one example where the high costs of blended oxide powders as feedstock material hinder the market introduction, whereas their outstanding electrical properties and photocatalytic activity are of great interest for various industrial applications. In this work, single oxides ZnO and TiO2, Zn acetate salt as ZnO precursor, as well as a Zn2TiO4 powder were used to develop tailored aqueous suspension feedstocks suitable for thermal spraying. To follow the formation of the compositions in the system ZnO-TiO2, differential thermal analysis (DTA) measurements were performed. Preparation routes of stable suspensions and suspension-solution mixtures with low sedimentation rates, low viscosities and good flowabilities are discussed. Microstructures and phase compositions of sprayed coatings are shown, and the "in situ" formation of Zn2TiO4 phase during Suspension High Velocity Oxygen Fuel Spraying (S-HVOF) is demonstrated. This work shows the high potential of suspension feedstocks from single oxide raw materials to obtain Zn2TiO4 sprayed coatings. [ABSTRACT FROM AUTHOR]