Pinggen Rao

Centrifugal casting of Al2O3–15 wt.%ZrO2 ceramic composites

Abstract Aqueous ceramic slurries with different solid contents (60, 70 and 78 wt.%) were prepared by mixing 85 wt.% low-temperature-sinterable high purity α-alumina and 15 wt.% ZrO 2 (3 mol% Y 2 O 3 ) in distilled water and a small amount of poly-carboxylic ammonium as the dispersion agent. Consolidation was performed by using a high-speed centrifugal casting process at 4000 rpm for 1 h. The result showed that the dispersion agent had a great influence on the viscosities of the slurries. It was also observed that the green and sintered densities of the Al 2 O 3 –15 wt.%ZrO 2 composites increased with the solid contents. Phase segregation could be effectively eliminated when the solid content of the slurry was 78 wt.%.

Low-velocity impact property of alumina/epoxy/metal laminated composites

With Al foil, Cu foil and steel mesh as the metal interlayers, respectively, three types of alumina/epoxy/metal laminated composites were fabricated with epoxy resin adhesive as a binder via a simple process. The impact tests were performed and the fracture patterns and impact response of all the three laminates were analyzed. The experimental results indicate that the absorbed energy is mainly determined by metal interlayer. The peak load depends on not only alumina substrate but also metal interlayer. The Al2O3/epoxy/Cu laminates sustain the maximum peak load and Al2O3/epoxy/steel mesh laminates have the largest threshold energy for penetration. The fracture analysis shows that the main damage modes are Al2O3 matrix cracking and metal deformation for lower impact energies, and complete breakage and penetration for higher impact energies.