Evaluation of Microstructural Characteristics in Alumina Produced by Selective Laser Stereolithography and Detonation Gun Spraying

The important microstructural characteristics of Al(2)O(3)produced via detonation gun spraying (DGS) deposition and laser stereolithography (3D printing) were investigated in this study. Microstructural observation indicated that microstructure of 3D-printed samples mostly consisted of alumina and voids, while coating samples contained extra features such as splat boundaries, pores, and cracks. The DGS deposited alumina was characterized by higher density with 3.0 +/- 0.6% porosity compared to the additive manufacturing processed samples with 8.1 +/- 0.8% porosity. Existence of some residual carbon was detected in 3D-printed alumina sample via energy-dispersive x-ray spectroscopy. The feedstock powder used for both processes was pure alpha-Al2O3. While the x-ray diffraction results showed no phase change in 3D-printed samples, DGS deposited alumina coating contained a mixture of alpha-Al(2)O(3)and gamma-Al(2)O(3)phases. The phase distribution discovered by x-ray diffraction was confirmed by diffraction patterns obtained from transmission electron microscopy.