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In this paper, we examine the long-standing problem of cracking during constrained sintering of a powder aggregate. Using binder jet 3D printing, we prepare ceramic green bodies in the form of center-notched panels, then use in situ imaging to observe how cracks nucleate and grow from the notch as the material sinters under restraint. Quantitative image analysis allows us to identify important characteristics of the sinter-cracking process, indicating a framework for analyzing the problem and developing methods for avoiding it, including representation of sinter-cracking as a creep crack growth process, use of fracture mechanics parameters to design specimen geometries that do not exceed critical stress intensities, and the possibility of exploiting the inherently ductile nature of sinter-cracking to mitigate damage. K E Y W O R D Sfracture, in situ imaging, sinter/sintering, solid freeform fabrication

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In-space manufacturing is a candidate approach for constructing next-generation space structures with larger characteristic dimensions than modern deployable structures. While many construction methods have been proposed, analysis of their performance for building precision structures, such as large-diameter reflectors, is scarce. In this paper, we present a quantitative, system-level comparison of materials and processes for in-space manufacturing. By using performance metrics for thermal stability, resistance to disturbance loads, and minimal-mass buckling strength, we identify candidate feedstock materials. Then, using the metrics of energy consumption and accuracy, we compare candidate processing methods and find that deformation processing is a promising on-orbit manufacturing method. We synthesize the analysis with a case study on the construction of a tetrahedral truss supporting a reflector surface and provide guidelines for assessing materials and processes for in-space manufacturing.