Indirect rapid manufacturing of silicon carbide composites

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Evans, Robert Scott

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Rapid manufacturing has been a goal since the development of rapid prototyping in the mid to late 1980’s. The term refers to using Rapid Prototyping techniques, capable of rendering objects directly from CAD files, to produce fully functional parts. Yet, significant barriers to realizing rapid manufacturing still exist in terms of the range and capability of materials that can be processed. Selective laser sintering (SLS) is an additive fabrication technique regarded as having the broadest set of materials. The SLS process allows parts to be built from a series of thin layers of fused powder. Still, there are only five prototyping materials commercially available for SLS. The powdered materials that have been demonstrated include single component polymers and multiple component systems where the polymers act as binders adhering particles of an inert material together to form porous parts. For many types of composite materials, manufacturing methods have not been established that promote their widespread use in finished goods. Despite advantages in material stiffness, strength and abrasion resistance, forming parts from particulate reinforced composite materials remains very challenging. In this dissertation a new binder for SLS processing is developed along with strategies for machining, polymer infiltration and metal infiltration of the porous preforms. Where material properties are established after SLS processing the overall process is called, “indirect.” Examined together these processes form a fabrication method that improves the material set available for rapid manufacturing and also provides a means of forming parts from particulate reinforced composites. As with many other technologies developed within universities, there is a significant work required to transform a technology that is established in a laboratory into one that is used in manufacturing practice. The concurrent development of a company and funding from a Texas Technology Development and Transfer Grant made the technology transfer an inherent part of this project in addition to providing thermoset materials and indirect fabrication methods for SLS. Matching funds and significant in-kind donations were provided by Advanced Laser Composites, LLC. An NCIIA E-team grant supported market research and also the ultimate creation of the company. The project served as a test case for collaborative research where academic merit and commercial viability were pursued simultaneously.