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

Abstract

A novel Pr 3 Si 2 C 2 additive was uniformly coated on SiC particles using a moltensalt method to fabricate a high-density SiC ceramics via liquid-phase spark plasma sintering at a relatively low temperature (1400 • C). According to the calculated Pr-Si-C-phase diagram, the liquid phase was formed at ∼1217 • C, which effectively improved the sintering rate of SiC by the solution-reprecipitation process. When the sintering temperature increased from 1400 to 1600 • C, the thermal conductivity of SiC increased from 84 to 126 W/(m K), as a consequence of the grain growth. However, an increasing amount of the sintering additive increased the interfacial thermal resistance, resulting in a decrease of thermal conductivity of the materials. The highest thermal conductivity of 141 W/(m K) was obtained for the material having the largest SiC grains and an optimized amount of the additive at the grain boundaries and triple junctions. The proposed Pr 3 Si 2 C 2assisted liquid-phase sintering of SiC can be potentially used for the fabrication of SiC-based ceramic composites, where a low sintering temperature would inhibit the grain growth of SiC fibers.

High‐strength SiC joints fabricated at a low‐temperature of 1400°C using a novel low activation filler of Praseodymium

“…A near fully consolidated interface was obtained when the joining temperature increased to 1400 and 1500°C, as the presence of the liquid phase promoted densification (sintering) of the precipitated SiC grains with the SiC matrix by the solution‐precipitation mechanism 53 . In addition, partially seamless joints were obtained (Figure 5c and d), which exhibited a very similar strength as the strength of the reference unjoined SiC matrix.…”

“…According to the Pr‐Si‐C ternary phase diagram, a liquid phase is formed at a relatively low temperature (∼1150°C) via eutectic reaction between Pr 3 Si 2 C 2 and SiC 52 . Furthermore, in our previous work, a highly dense SiC ceramics with a low residual open porosity of 0.5% was obtained using Pr 3 Si 2 C 2 as the sintering additive at such a low temperature as 1400°C 53 . In addition, SiC ceramics with the Pr 6 O 11 sintering additive was demonstrated to have a good radiation stability after irradiation at 750°C with 5 MeV Xe ions to the fluence of 9.5 × 10 15 ions/cm 2 54 .…”

In Situ Grown 1D/2D Structure of Dy3Si2C2 on SiCw for Enhanced Electromagnetic Wave Absorption

“…The formation process of the Dy3Si2C2 coating using the molten salt approach is similar to the formation mechanism of Y3Si2C2 and Pr3Si2C2 powders [45,48]. First, DyH2 decomposed to Dy and released H2 [49].…”

“…Rare earth silicide carbides (RE 3 Si 2 C 2 , where RE is a rare earth element) are a new group of ternary layered structure materials, which are similar to MAX phases (where M is an early transition metal, A is an A-group element, and X is either C or N) [37,38]. RE 3 Si 2 C 2 has been successfully used as the joining layer material and/or sintering additive for SiC-based ceramics and composites due to its ability to form a liquid phase by the eutectic reaction with SiC [39][40][41][42][43][44][45][46]. Furthermore, the addition of a second phase can significantly promote the EMW absorption properties of the resulting composites [47,48].…”

β→α Phase Transformation and Properties of Solid-State-Sintered SiC Ceramics with TaC Addition

“…Silicon carbide (SiC) ceramics have excellent properties, i.e., a high strength, high modulus, low thermal expansion, high thermal conductivity, and good corrosion resistance, enabling their widespread use in the nuclear, semiconductor and aerospace industries [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. Densification of SiC ceramics is extremely difficult due to their strong covalent bonds, leading to a low self-diffusion coefficient (~10 −11 cm 2 /s for C and ~10 −13 cm 2 /s for Si) [ 10 ].…”