The low-temperature sinterability of TiO2-CuO systems was investigated using a solid solution of SnO2. Sample powders were prepared through conventional ball milling of mixed raw powders. With the SnO2 content, the compositions of the samples were Ti1-xSnxO2-CuO(2 wt.%) in the range of x 0.08. Compared with the samples without SnO2 addition, the densification was enhanced when the samples were sintered at 900oC. The dominant mass transport mechanism seemed to be grain-boundary diffusion during heat treatment at 900oC, where active grain-boundary diffusion was responsible for the improved densification. The rapid grain growth featured by activated sintering was also obstructed with the addition of SnO2. This suggested that both CuO as an activator and SnO2 dopant synergistically reduced the sintering temperature of TiO2.
Aluminum nitride (AlN) has excellent electrical insulation property, high thermal conductivity, and a low thermal expansion coefficient; therefore, it is widely used as a heat sink, heat-conductive filler, and heat dissipation substrate. However, it is well known that the AlN-based materials have disadvantages such as low sinterability and poor mechanical properties. In this study, the effects of addition of various amounts (1-6 wt.%) of sintering additives Y2O3 and Sm2O3 on the thermal and mechanical properties of AlN samples pressureless sintered at 1850oC in an N2 atmosphere for a holding time of 2 h are examined. All AlN samples exhibit relative densities of more than 97%. It showed that the higher thermal conductivity as the Y2O3 content increased than the Sm2O3 additive, whereas all AlN samples exhibited higher mechanical properties as Sm2O3 content increased. The formation of secondary phases by reaction of Y2O3, Sm2O3 with oxygen from AlN lattice influenced the thermal and mechanical properties of AlN samples due to the reaction of the oxygen contents in AlN lattice.
This paper reports the effect of sintering processes and additives on the microstructures and mechanical properties of -SiC composite ceramics. We fabricated sintered bodies of -20 vol.% SiC with or without sintering additive, such as C or , densified by spark plasma sintering as well as hot pressing. While almost full densification was achieved regardless of sintering processes or sintering additives, significant grain growth was observed in the case of spark plasma sintering, especially with . With sintered bodies, mechanical properties, such as flexural strength and Vickers hardness, were also examined.