Laser-based solid freeform fabrication techniques for the direct production of ceramic and metal/ceramic shapes.

摘要

Three laser-based solid freeform fabrication techniques are developed for the direct production of ceramic and metal/ceramic shapes. Selective laser reaction sintering (SLRS) is a variation of selective laser sintering that incorporates an in-situ reaction to produce ceramic shapes. Selective area laser deposition vapor infiltration (SALDVI) uses a scanned beam to selectively infiltrate a powder bed by thermal decomposition of a gas precursor. The object is to produce monolithic and composite ceramic shapes. Vacuum selective laser sintering of nanocomposites combines atmosphere control with the novel material characteristics of nanocomposites to produce metal/ceramic nanocomposite shapes.; Each of the techniques is discussed in detail including both theoretical and experimental work. Basic process variables are characterized and proof-of concept is demonstrated for the three techniques.; It was necessary to design and build the processing equipment for these three techniques. A system description and a complete set of detail drawings are included for documentation purposes.; A discussion of laser interactions with gases and solids is also included because of its importance to these new processes. Gas absorption of beam energy, substrate reflectance and substrate absorption are discussed. Theoretical and experimental work is included with emphasis placed on the materials used in SLRS and SALDVI.