Direct laser melting of Al2O3 ceramic paste for application in ceramic additive manufacturing

Abstract

We develop the direct laser melting of ceramic paste technology for application in ceramic additive manufacturing (AM). The Al2O3 ceramic paste, which is a homogeneous mixture of DI-water and Al2O3 ceramic powders, was deposited on an Al2O3 substrate using free-forming extrusion (FFE), and subsequently melted by a CO2 laser. To better control the laser melting process, the flow behavior of the laser-melted Al2O3 was investigated by evaluating the microstructure of the laser-melted Al2O3 single tracks. When the laser scanning speed increased from 1 to 3.5 mm/s at a fixed laser power, the permeation of the molten Al2O3 into the surrounding porous paste was reduced, resulting in the improvement of the surface uniformity of the laser-melted Al2O3 tracks. Through optimizing the laser scanning strategy, a fully-dense Al2O3 layer with smooth surface was achieved. The phase composition and density of the laser-melted Al2O3 layers were evaluated to study their properties. The thickness of the dense Al2O3 layer varied from ∼90 μm to ∼120 μm periodically due to the line-by-line scanning of the Gaussian laser beam. In addition, the relationship between the melting thickness and the laser scanning speed was also investigated to further improve the controllability of the laser melting process. This direct laser melting of ceramic paste technology is promising for applications in ceramic AM, such as 3D printing of ceramic components and high-temperature ceramic welding.