Laser Processing Advanced Ceramics Used in Optical Applications

Allison Browar, PhD Qualifying Exam

Hopeman 224

Advanced ceramics are materials that have the ability to withstand extreme environments. Their application space spans military to commercial; finding uses from high altitude jets to grocery store scanners.  However, fabrication is limited due to the current process chain.  The scope of this project is to use advanced manufacturing techniques to improve fabrication of advanced ceramics and lead to mass production of arbitrary structures only available using additive manufacturing. 

The methods are twofold.  The first process investigates parameters in selective laser melting of ceramic powders to produce a transparent part.  The second is to investigate laser polishing to increase damage threshold.  Both techniques would reduce the time and cost of parts to be fabricated by eliminating the need for a mold for forming and special tooling required for polishing.

A system based on state of the art ceramic additive manufacturing is designed and implemented. A parameter study of reactive selective laser sintering is discussed, and the resulting material is analyzed using Raman spectrometry and x-ray diffraction. Results show a breakthrough ability to create transparent ceramics with additive manufacturing. Further improvements and mechanical testing are proposed for future experiments.

As a tangential research path, laser polishing is discussed and implemented on fused silica, an amorphous glass, using the same system as above.  Investigations into applying this technique to polycrystalline materials are discussed and proposed.