ผลของพารามิเตอร์ในการเผาผนึกต่อโครงสร้างจุลภาคและสมบัติของแมกนีเซียมอะลูมิเนตเซรามิก / ปรเมศวร์ ฉินทสงเคราะห์ = Effects of sintering parameters on microstructure and properties of magnesium aluminate ceramics / Poramate Chintasongkro
This study focuses on the influences of sintering conditions and sintering additives on the microstructures and properties of sintered magnesium aluminate ceramics. Two magnesium aluminate powders, S30CR and TSP-20, were isostatically pressed and then subsequently sintered in air or in other atmospheres (vacuum, nitrogen and hydrogen) at the temperature range from 1430˚C to 1650˚C. It was found that when sintered in air at 1650˚C, both pure magnesium aluminate ceramics gained fine-grain microstructure with the relative density over 99% and the Vickers hardness of 15 GPa. The addition of 1 wt.% lithium fluoride into magnesium aluminate powders showed the different results on the sintering behavior between these powders. For S30CR, the relative density of the sintered specimens improved when the specimens were soaked at 800-850˚C during sintering while no significant change was observed for TSP-20. Without soaking, the remaining lithium fluoride accelerated the grain growth in the lithium fluoride doped TSP-20 specimen to the size of 83 micron. The light transmittance of both sintered S30CR and TSP-20 specimens was low in the visible region. Furthermore, there was no improvement on the relative density of the sintered magnesium aluminate specimens when sintered in other atmospheres at the same temperature.