High‐Frequency Induction Heat Sintering of Mechanically Alloyed Alumina–Yttria‐Stabilized Zirconia Nano‐Bioceramics

Abstract

Nanostructured alumina—20 vol% 3‐yttria‐stabilized zirconia (3YSZ) powder composites were synthesized by the wet‐milling technique. The starting materials were a mixture of alumina micropowder and 3YSZ nanopowders. The mixtures were optimized for good sintering behaviors, high hardness, and toughness. Nano‐crystalline grains were obtained after milling for 24h. The nano‐structured powders were then processed to full density at different temperatures by high‐frequency induction heat sintering. Effects of sintering temperature on the hardness, toughness, and microstructure properties have been studied. Al2O3–3YSZ composites with higher hardness, toughness, and smaller grain size have successfully been developed at relatively low temperatures by this technique.

Microwave sintering of alumina–zirconia nanocomposites

“…The micrographs of the two regions are practically identical, showing intergranular fracture, uniform grain size distribution without any observable cracks or pores and no abnormal grain growth. Note the very low grain growth, with the ratio of powder particle size to average grain size exceeding 1:2, which is higher than the values attained in conventional sintering studies (Biamino et al, 2006;Jia et al, 2006;Kim and Khalil, 2006;Jayaseelan et al, 2002;Trombini et al, 2007).…”

“…Therefore, full density in most alumina-zirconia nanocomposites is achieved by applying pressure and/or by introducing sintering aids. Nanocomposites subjected to pressure-assisted sintering (Kim and Khalil, 2006;Jayaseelan et al, 2002;Trombini et al, 2007) reach almost full density after short sintering cycles. However, these routes involve disadvantages, not the least of which is their cost, as well as a very limited shape capability.…”

“…These include the use of grain growth inhibitors in solid solution or forming discrete second phases, high-pressure densification, spark-plasma sintering and related techniques, shock densification, high-frequency induction heating and magnetic pulse compaction (Allen et al, 1996;Kim and Khalil, 2006;Godlinski et al, 2002;Krell et al, 2003;Jiang et al, 2007). However, these fabrication routes can be uneconomical for many applications or can be difficult to apply successfully.…”

Novel mechanism to improve toughness of the hydroxyapatite bioceramics using high-frequency induction heat sintering

“…The mixed composites were placed in a graphite die and then introduced into the high-frequency induction heat sintering machine in detail [7,8]. Density is determined by Archimedes' principle (buoyancy method), using an accurate balance with 0.1 mg accuracy.…”

Advanced Sintering of Nano-Ceramic Materials

“…Advanced sintering was found to show great potential in ceramics processing (S. Vijayan & H. Varma, 2002). These include the use of grain growth inhibitors in solid solution or forming discrete second phases, high-pressure densification, spark-plasma sintering and related techniques, shock densification, high-frequency induction heating and magnetic pulse compaction (Allen et al, 1996;Kim and Khalil, 2006;Godlinski et al, 2002;Krell et al, 2003;Jiang et al, 2007).…”