Date of Award

2019

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

First Advisor

Dr. Mufeed Basti

Abstract

Additive manufacturing (AM) is becoming one of the most distinctively growing versatile technologies. In most AM techniques that requires the use of powder, the powder that is not fused into the 3D print can be replenished and used for another build. Unfused powder is generally collected on the powder-bed after an AM build is complete. In most cases, the ability to replenish unfused powder with virgin powder aids in limiting any significant change in powder’s properties that may cause compromising the quality of the 3D prints. If no powder is added to the recycled powder it is likely to shift the powder properties. Recycled powder has gained popularity due to the expansion of AM into various applications, whereas it increases the cost efficiency for AM technology. In considering the numerous forms of AM, Selective Laser Melting (SLM) out of many allows the recyclability of unfused powder. This thesis work aims to study the recyclability of a widely used 316L stainless steel (STS) powder by comparing the physical and chemical properties of the virgin and recycled powder utilized in SLM process. Characterization was conducted on recycled STS powder after 14 and 18 builds. A number of analytical techniques were used to achieve such comparison. BET data showed an increase in the surface area of the recycled powder relative to the virgin while density data remained the same. Raman spectroscopy data indicated an inconsistent change in the metal oxides peaks between virgin and recycled powder. SEM/EDXS data showed an increase in the oxygen content in the recycled powder builds. LIBS data showed the recycled powder peaks yielded a higher intensity in comparison to the corresponding virgin powder peaks. According to the acquired results, the used analytical techniques provided a significant insight on the difference in the physical and chemical properties of the virgin and recycled powders.

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