Thermal and electrical properties of spark plasma sintered (Ti,Cr)B₂ ceramics

Abstract

Thermal and electrical properties were measured for TiB2 ceramics containing varying CrB2 contents up to 33 mol%. The room‐temperature thermal diffusivity decreased with increasing Cr content from 0.330 ± 0.003 cm2/s for pure TiB2 to 0.060 ± 0.003 cm2/s for (Ti0.66Cr0.33)B2. The amount of anisotropy in the coefficients of thermal expansion increased with increasing Cr content and the c‐axis had the greatest dependence on Cr addition, with an increase of more than 25% in the thermal expansion for 33 mol% CrB2 compared to TiB2, whereas the a‐axis only increased by about 8%. The electrical conductivity was the lowest for (Ti0.66Cr0.33)B2 at ∼8.5 × 103 S/cm compared to ∼106.1 × 103 S/cm for nominally pure TiB2. Overall, the addition of CrB2 as a sintering aid for TiB2 was shown to have a significant effect on the thermal and electrical properties of TiB2 for additions as small as 5 mol% CrB2.

Thermal conductivity of equiatomic high‐entropy diboride ceramics with 5–9 cations

“…The thermal conductivities at room temperature of the literature‐reported ceramics 15,25–29,34–36 and the high‐entropy ceramics prepared in this work are summarized in Figure 8B. It is clear that ceramics with more solid solution elements (larger configurational entropy) correspond to lower thermal conductivity.…”

“…Figure 8A shows the thermal conductivities of the HEBs calculated based on Equations ( 2) and (3). The thermal conductivities of constituent diboride and binary solid solution ceramics from literature [25][26][27][28][29] are also shown in this figure. The thermal conductivity of the HEBs is obviously lower than the corresponding constituent diboride ceramics.…”

Multi-phase (Zr,Ti,Cr)B 2 solid solutions: Preparation, multi-scale microstructure, and local properties

“…Specifically, the strong B rings, that are parallel to the a-direction, limit the amount that the a-parameter can change. On the other hand, along the c-direction, the bonds are not under such constraint and the weaker TM-B bonds allow the c-parameter to change by a greater amount [27].…”

Impact of TiB2 source on the microstructure and properties of TiB2–SiC–B4C ceramics

“…9,11 TiB 2 has a thermal conductivity of ∼95 W/m K, while B 4 C varies depending on stoichiometry but is typically <30 W/m K and SiC is typically <90 W/m K depending on the amount and type of sintering aids. 9,12,[13][14][15] The electrical resistivity of TiB 2 has been reported to be in the range of ∼7-40 µΩ cm, resulting in an electrical conductivity of ∼2.5-14 × 10 6 S/m. The values are reported to depend on the relative density, grain size, and extent of microcracking.…”