Thermal conductivity of spark plasma sintered SiC ceramics with Alumina and Yttria

Low‐temperature Pr3Si2C2‐assisted liquid‐phase sintering of SiC with improved thermal conductivity

“…The thermal conductivity of the SiC samples measured in the present work is higher than that reported in the literature for SiC ceramics sintered at similar temperatures, 20,24,42–48 as shown in Figure 6. This is mainly caused by the fact that SiC ceramics usually cannot be well sintered at such low temperatures as 1400–1600°C using traditional liquid‐phase sintering additives, such as Al 2 O 3 and/or RE 2 O 3 .…”

“…However, the densification was limited due to a relatively small amount of the liquid formed at such temperatures. In the temperature range of 1400–1500°C, a large amount of the liquid was formed, which not only filled up the pores but also improved the atoms diffusion and promoted the grain growth of SiC 20,35 . Therefore, the porosity of the sample significantly decreased.…”

“…Therefore, the mean grain size of SiC significantly increased from 1.51 to 2.39 µm when the temperature increased from 1500 to 1600°C (Table 1). On the other hand, the amount of the liquid phase increased with the increasing content of sintering additive, which prolonged the average diffusion distance, resulting in the finer SiC grains 20 . Furthermore, a higher amount of the liquid was beneficial for the nuclei of the precipitated SiC, which would inhibit the grain growth of SiC 36,38 .…”

“…Thermal conductivity of SiC ceramics is a very important property for its application as a heat exchanger. SiC is a highly covalent material, which has limited free mobile electrons/holes; thus the heat is mainly transferred by phonons 20 . Therefore, the PMFPs in the SiC specimens were calculated.…”

“…), 42–47 usually possess a lower thermal conductivity when compared to SiC. Thus, a larger amount of sintering additives at the grain boundaries and/or grain junctions of SiC results in a greater phonon scattering, which leads to a decreased thermal conductivity 20 …”