Pore formation model for direct laser deposition of Al2O3–ZrO2 ceramic

Pores are some of the most common defects that form during direct laser deposition of ceramic materials. A mathematical model of pore formation for Al 2 O 3 -ZrO 2 ceramic was developed. The pore formation model, which was developed from the bubble escape factor, reveals the relationship between the movement of the solid-liquid interface of the molten pool and that of the bubbles. In the frontier region of the molten pool, with increasing laser power, the proportion of bubbles that escaped and the area from which bubbles escaped increased. With increasing laser power, the actual and theoretical porosity decreased from 80 % to 40 %. At the central region of the molten pool, the bubble escape factor increased with increasing bubble diameter under the same laser power. The theoretical porosity and the actual porosity decreased with increasing laser power. The pore formation model provides a basis for fabricating high-quality Al 2 O 3 -ZrO 2 ceramics by direct laser deposition.