Fabricating ceramics with embedded microchannels using an integrated additive manufacturing and laser machining method

In this paper, we demonstrate the feasibility of an innovative method to fabricate flexibly embedded microchannels in bulk ceramics of complex geometries. This innovative method is an integration of extrusion freeforming (EFF) and picosecond (PS) laser machining. The bulk ceramic green body of complex geometries was fabricated using the extrusion method. After one green layer was extruded, in-plane microchannels with variable cross-section sizes and aspect ratios were fabricated using a picosecond laser. After the microchannels were fabricated, a cover layer was extruded. The green state processed structures ceramics were pressurelessly sintered to a bulk density of 94%. In this paper, sinuous channels, channel networks, and patterns have been demonstrated. Vertical channels can also be drilled using the picosecond laser layer-by-layer with uniform diameters. The wall between the neighboring channels can be as thin as 60m without any observable defects after firing. With the correct paste rheology, the cover layer did not sag into the microchannels and the bonding between layers was excellent. We did not observe any debonding between layers. During extrusion, the gaps between the adjacent filaments can be eliminated by controlling the filament spacing and the distance between needle tip and substrate. After firing, microchannels did not distort or collapse. The laser can cut through multiple layers without damage to the bonding between layers. Due to the uniform shrinkage during pressureless sintering, the green shapes of the microchannels were well preserved.