Effects of sintering profile on the densification behaviour of forsterite ceramics

The sintering behaviour of forsterite prepared by mechanical activation and heat treatment has been studied. The green compacts were sintered using two different sintering profiles. The first was based on the conventional sintering (CS) profile in which the powder compact was sintered at the desired temperature, holding for 2 hours and then cooled to room temperature. The second was based on a two-step sintering (TSS) profile in which the samples were sintered at a temperature T1 = 1400 degrees C for 6 minutes and then continued sintering at a lower temperature T2 (i.e. 750 degrees C, 850 degrees C and 950 degrees C) for 15 hours before cooling to room temperature. It was found that a minimum ball milling time of 7 h was necessary to completely eliminate secondary phases from developing in the forsterite matrix after sintering at 1400 degrees C. The sintering study indicated that the CS profile was effective in enhancing the fracture toughness of the sintered body when sintered at 1400 degrees C but this was accompanied by exaggerated grain growth. In addition, it was found that sintering below 1400 degrees C was not effective in preventing the formation of secondary phases in the sintered body. On the other hand, the TSS profile (T1 = 1400 degrees C, T2 = 950 degrees C) was found to be most beneficial in promoting densification and more importantly, to suppress grain coarsening of the forsterite body

Effect of Copper Oxide and Manganese Oxide on Properties and Low Temperature Degradation of Sintered Y-TZP Ceramic

The effect of copper oxide (CuO) and manganese oxide (MnO2) co-dopant on the densification behavior of 3 mol% yttria-stabilized zirconia was investigated. Green samples were prepared and sintered in air at temperatures ranging from 1250 to 1500 °C with a short holding time of 12 min. Sintered bodies were characterized to determine the phase stability, bulk density, hardness, fracture toughness, Young’s modulus and grain size. In addition, the aging-induced tetragonal to monoclinic phase transformation of the sintered zirconia was evaluated. It was revealed that the addition of CuO-MnO2 co-dopant was beneficial in enhancing the densification and mechanical properties of the ceramic particularly at low temperatures. A high fracture toughness of 5.5 MPam1/2 coupled with high hardness of 14.5 GPa was obtained for co-doped samples sintered at 1350 °C. However, the undoped ceramic exhibited better properties when sintered above 1350 °C. The study also found that the dopants did not prevent grain coarsening and hence did not suppress the aging-induced phase transformation particularly for samples sintered above 1350 °C

Effects of two-step sintering on the properties of hydroxyapatite bioceramic

In the present study, the sintering behaviour of hydroxyapatite (HA) was investigated by employing the two-step and conventional sintering methods. Comparisons were made between different combinations of sintering temperatures to examine their influence on the sinterability of the samples. The sintered samples were examined in terms of phase stability, relative density, grain size, Vickers hardness, and fracture toughness. The results revealed that the two-step sintering cycle was effective in suppressing grain coarsening when compared to conventional sintering. The study also found that while employing the two-step sintering, the selected temperature (T-1) at which densification occurs plays a major role in determining the mechanical properties of HA samples

Comparison between microwave and conventional sintering on the properties and microstructural evolution of tetragonal zirconia

In this research, the comparison between microwave sintering and conventional sintering on the mechanical properties and microstructural evolution of 3 mol% yttria-stabilised zirconia were studied. Green bodies were compacted and sintered at various temperatures ranging from 1200 °C to 1500 °C. The results showed that microwave assisted sintering was beneficial in enhancing the densification and mechanical properties of zirconia, particularly when sintered at 1200 °C. It was revealed that as the sintering temperature was increased to 1400 °C and beyond, the grain size and mechanical properties for both microwave- and conventional-sintered ceramics were comparable thus suggesting that the sintering temperature where densification mechanism was activated, grain size was strongly influenced by the sintering temperature and not the sintering mode.Scopu