Fracture Toughness (K_IC) of Lithography Based Manufactured Alumina Ceramic

Precision shaped ceramic components can be obtained by an emerging technique called Lithography based Ceramic Manufacturing (LCM). A green part is made from a slurry consisting of a ceramic powder in a photocurable binder with addition of dispersant and plasticizer. Components are built in a layer–by-layer way by exposing the desired cross- sections to light. The parts are subsequently sintered to their final density. It is a challenge to produce ceramic component with this method that yield the same mechanical properties in all direction. The fracture toughness (K_Ic) of of LCM-alumina (prepared at LITHOZ GmbH, Austria) was tested by using the Single-Edge-V-Notched Beam (SEVNB) method. Notches are made into prismatic bend-bars in all three direction X, Y and Z to recognize the value of fracture toughness of the material in all three directions. The microstructure was revealed with optical microscopy as well as Scanning Electron Microscopy (SEM). The results indicate that the fracture toughness in Y-direction has the highest value (3.10 MPam^1/2) that is followed by the one in X-direction which is just a bit lower (2.90 MPam^1/2). The Z-direction is found to have a similar fracture toughness (2.95 MPam^1/2). This is supported by a homogeneous microstructure showing no hint of the layers used during production.