Control of the surface quality for ZrO₂ microstructures by powder micro-injection molding

A ZrO₂ ceramic microstructured part with the minimum size of Φ300 μm×250 μm was fabricated by powder micro-injection molding process. The effects of injection parameters, mold vacuum and silicon mold on the surface quality of microstructures were analyzed. Test results indicate that the tip of microstructures becomes more uneven with the decrease of micro-cavity size under the same injection parameters. The difference of surface quality among microstructures with different sizes can be eliminated by increasing injection pressure and mold temperature or vacuumizing mold before the injection stage. On the other hand, mold vacuum can avoid air holes on the surface of microstructures. Sub-micron ZrO₂ powder improves the surface roughness of sintered ceramic microstructures from 0.33 μm of the green part to 0.28 μm.