Yoke Meng Tan

Effect of ZnO addition on the purity and densification of forsterite ceramic

Forsterite was found to the next potential candidate for bone implant application due to its superior mechanical properties as compared to the commonly used hydroxyapatite (HA). Various methods including two-step sintering and improvise synthesis method were introduced in hope to further improve the mechanical properties of forsterite. In this work, sintering additives, particularly zinc oxide (ZnO), was introduced into forsterite to provide enhancement on the densification of forsterite at lower sintering temperature. Forsterite powder was synthesized via solid-state reaction method with heat treatment at 1000°C for 2 hours with 10°C/min ramping rate. Addition of ZnO was conducted using milling process with composition of 0.5 wt% and 1.0 wt% ZnO. Green bulk samples were prepared prior to sintering process at 1200°C to 1500°C for 2 hours with 10°C/min ramping rate. Characterization was conducted in terms of phase stability and densification of forsterite with morphology examination to observe the grain surface of all samples. It was revealed that the addition of ZnO showed a more superior densification as compared to the undoped samples at all sintering regime studied with a maximum relative density obtained at 97.7% by 0.5 wt% ZnO doped sample sintered at 1500°C.

Rapid Densification of Forsterite Ceramic via Microwave Sintering

The effect of microwave sintering on the densification of forsterite ceramic was investigated. Forsterite powder was prepared via solid-state reaction method with the application of attrition milling and heat treatment. The forsterite compacts were microwave sintered at 1100 °C to 1250 °C with 30 min holding and a ramping rate of 50 °C/min. The samples were then characterized in terms of phase stability, relative density and microstructure evaluation. This work revealed that microwave sintering is beneficial in producing dense forsterite at lower sintering temperature with shorted operating hour (< 1 hr). Highest relative density of 87.9% was successfully obtained at 1250 °C with estimated grain size of lesser than 1 μm as compared to conventional sintering.

The effect of sintering ramp rate on the sinterability of forsterite ceramics

Abstract In the present work, pure forsterite (Mg2SiO4) powder was successfully synthesised via ball milling and subsequent heat treatment as an evident from X-ray diffraction analysis. The synthesised powder were formed by powder agglomerates that were made up of loosely packed fine particles. Then, the forsterite green bodies were sintered at 1200 and 1400°C with two different ramp rates (2 and 10°C per minute) via conventional pressureless sintering. No decomposition of forsterite phase was observed at both ramp rates. This study revealed that lower ramp rate (2°C per minute) possessed minor improvement on the mechanical properties only at lower sintering temperature (1200°C), whereas 10°C per minute ramp rate gave a significant enhancement on the mechanical properties of forsterite at 1400°C. A high fracture toughness of ∼4·9 MPa m1/2 and Vickers hardness of ∼7·1 GPa were obtained for forsterite samples sintered at 1400°C with a ramp rate of 10°C per minute.