Effects of Processing Conditions on Laser Direct Deposited Alumina Ceramics

Abstract

Additive manufacturing (AM) of high-quality inherently brittle ceramics via laser direct deposition, also known as laser engineered net shaping, is challenging due to high thermal gradients, thermally induced cracks, and porosity, typically accompanied by low powder usage efficiency. It is necessary to have an improved understanding of the effects of processing conditions on the fabricated ceramic parts. In this study, alumina ceramics were fabricated with commercial alumina powders. In particular, this paper studied the effect of laser power and scan speed on single track geometries, thin-wall morphology, grain size, density, and powder efficiency during laser direct deposition of alumina ceramics. A single-track parametric study was first conducted to determine the range of processing parameters that produce quality single-tracks and to aid in matching the z-increment with layer thicknesses. The results showed that increased scan speeds promoted significant grain refinement. Average grain size was reduced by nearly 50% when scan speed was increased from 1000 mm/min to 5000 mm/min. On the other hand, densification reached a maximum of 98% at a scan speed of 1000 mm/min with a slight decrease in density was observed at higher speeds. This indicated a trade-off between porosity and grain size when altering the laser scan speed. Significant advantages of using CO2 lasers for AM of ceramics was also demonstrated with powder usage efficiencies reaching nearly 90% under optimized processing conditions.

Meeting Name

ASME 2020 15th International Manufacturing Science and Engineering Conference, MSEC 2020 (2020: Sep. 3, Virtual)

Department(s)

Mechanical and Aerospace Engineering

Keywords and Phrases

Additive manufacturing; Alumina ceramics; Laser direct deposition

International Standard Book Number (ISBN)

978-079188425-6

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2020 American Society of Mechanical Engineers (ASME), All rights reserved.

Publication Date

03 Sep 2020

Link to Full Text

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