Porous SiC ceramics were prepared based on precursor conversion method using liquid hyperbranched polycarbosilane (LHBPCS) as the preceramic polymer and expandable microsphere (EMS) as the pore foaming agent. By optimising the content of free radical initiator, the cross-linking process of LHBPCS is synchronised with the foaming process of EMS. The addition of EMS had no serious effect on the cross-linking reaction mechanism and rate of LHBPCS, and the cross-linking of LHBPCS did not significantly confine the foaming of EMS. After 1000°C pyrolysis, EMS decomposed, but its spherical shape with sizes of 20–30 μm homogeneously embedded in the pyrolysed LHBPCS. As a result, a highly porous SiC foam with density of 0.211 g cm–3 and porosity of 91.2% was obtained and its thermal conductivity at room temperature was as low as 0.05 W (m K)–1. In addition, with increasing test temperature, its thermal conductivity increased slowly, indicating a good thermal insulation property.
YamadaI, KumeS, NakanoH, Macro- and micro-scale thermal conductivities of SiC single crystal and ceramic. Key Eng Mater. 2009;403:179–183. doi: 10.4028/www.scientific.net/KEM.403.179
CuceE, CucePM, WoodCJ, Toward aerogel based thermal superinsulation in buildings: a comprehensive review. Renew Sust Energ Rev. 2014;34:273–299. doi: 10.1016/j.rser.2014.03.017
4.
JangBK, SakkaY.Thermophysical properties of porous SiC ceramics fabricated by pressureless sintering. Sci Technol Adv Mat. 2007;8:655–659. doi: 10.1016/j.stam.2007.08.003
5.
EomJH, KimYW, SongIH, Processing and properties of polysiloxane-derived porous silicon carbide ceramics using hollow microspheres as templates. J Eur Ceram Soc. 2008;28:1029–1035. doi: 10.1016/j.jeurceramsoc.2007.09.009
6.
WanP, WangJY.Highly porous nano-SiC with very low thermal conductivity and excellent high temperature behavior. J Eur Ceram Soc. 2018;38:463–467. doi: 10.1016/j.jeurceramsoc.2017.09.037
7.
KimYW, LimKY, SeoWS.Microstructure and thermal conductivity of silicon carbide with yttria and Scandia. J Am Ceram Soc. 2014;97:923–928. doi: 10.1111/jace.12737
8.
Gómez-MartínA, OrihuelaMP, Ramírez-RicoJ, Thermal conductivity of porous biomorphic SiC derived from wood precursors. Ceram Int. 2016;42:16220–16229. doi: 10.1016/j.ceramint.2016.07.151
9.
ChoTY, KimYW.Effect of grain growth on the thermal conductivity of liquid-phase sintered silicon carbide ceramics. J Eur Ceram Soc. 2017;37:3475–3481. doi: 10.1016/j.jeurceramsoc.2017.04.050
10.
FengW, ZhangLT, LiuYS, Increasing the thermal conductivity of 2D SiC/SiC composites by heat-treatment. Fusion Eng Des. 2015;90:110–118. doi: 10.1016/j.fusengdes.2014.12.005
11.
CollinsAK, PickeringMA, TaylorRL.Grain size dependence of the thermal conductivity of polycrystalline chemical vapor deposited -SiC at low temperatures. J Appl Phys. 1990;68:6510–6512. doi: 10.1063/1.346852
12.
LeeSG, FourcadeJ, LattaR, Polymer impregnation and pyrolysis process development for improving thermal conductivity of SiCp/SiC–PIP matrix fabrication. Fusion Eng Des. 2008;83:713–719. doi: 10.1016/j.fusengdes.2008.04.008
13.
VakifahmetogluC.Fabrication and properties of ceramic 1D nanostructures from preceramic polymers: a review. Adv Appl Ceram. 2011;110:188–204. doi: 10.1179/1743676111Y.0000000007
14.
ColomboP, MeraG, RiedelR, Polymer-derived ceramics: 40 years of research and innovation in advanced ceramics. J Am Ceram Soc. 2010;93:1805–1837.
15.
MieleP, BernardS, CornuD, Recent developments in polymer-derived ceramic fibers (PDCFs): preparation, properties and applications – a review. Soft Mater. 2007;4:249–286. doi: 10.1080/15394450701310228
LiS, DuanWY, ZhaoT, The fabrication of SiBCN ceramic components from preceramic polymers by digital light processing (DLP) 3D printing technology. J Eur Ceram Soc. 2018;38:4597–4603. doi: 10.1016/j.jeurceramsoc.2018.06.046
18.
BillJ, KamphoweTW, MüllerA, Precursor-derived Si-(B-)C-N ceramics: thermolysis, amorphous state and crystallization. Appl Organometal Chem. 2001;15:777–793. doi: 10.1002/aoc.242
19.
ZhongXQ, PeiXL, MiaoYL, Accelerating the crosslinking process of hyperbranched polycarbosilane by UV irradiation. J Eur Ceram Soc. 2017;37:3263–3270. doi: 10.1016/j.jeurceramsoc.2017.03.063
20.
JiP, PeiXL, MiaoYL, Effect of ultraviolet irradiation on the cross-linking process and ceramic yield of liquid hyperbranched polycarbosilane. Adv Appl Ceram. 2017;116:445–451. doi: 10.1080/17436753.2017.1352110
21.
EomJH, KimYW, RajuS.Processing and properties of macroporous silicon carbide ceramics: a review. J Asian Ceram Soc. 2013;1:220–242. doi: 10.1016/j.jascer.2013.07.003
22.
WangF, YinJW, YaoDX, Fabrication of porous SiC ceramics through a modified gelcasting and solid state sintering. Mater Sci Eng A. 2015;654:292–297. doi: 10.1016/j.msea.2015.12.061
23.
EomJH, KimYW, SongIH.Effects of the initial α-SiC content on the microstructure, mechanical properties, and permeability of macroporous silicon carbide ceramics. J Eur Ceram Soc. 2012;32:1283–1290. doi: 10.1016/j.jeurceramsoc.2011.11.040
24.
RoyS, SchellKG, BucharskyEC, Processing and elastic property characterization of porous SiC preform for interpenetrating metal/ceramic composites. J Am Ceram Soc. 2012;95:3078–3083. doi: 10.1111/j.1551-2916.2012.05347.x
25.
SongIH, KwonIM, KimHD, Processing of microcellular silicon carbide ceramics with a duplex pore structure. J Eur Ceram Soc. 2010;30:2671–2676. doi: 10.1016/j.jeurceramsoc.2010.04.027
26.
EomJH, JangDH, KimYW, Low temperature processing of porous silicon carbide ceramics by carbothermal reduction. J Korean Ceram Soc. 2006;43:552–557. doi: 10.4191/KCERS.2006.43.9.552
27.
JangDH, KimYW, SongIH, Processing of highly porous, open-cell, microcellular silicon carbide ceramics by expansion method using expandable microspheres. JCeram Soc Jpn. 2006;114:549–553. doi: 10.2109/jcersj.114.549
28.
EomJH, KimYW, SongIH.Effect of SiC filler content on microstructure and flexural strength of highly porous SiC ceramics fabricated from carbon-filled polysiloxane. J Korean Ceram Soc. 2012;49:625–630. doi: 10.4191/kcers.2012.49.6.625
29.
LiX, PeiXL, ZhongXQ, Highly effective free-radical-catalyzed curing of hyperbranched polycarbosilane for near stoichiometric SiC ceramics. J Am Ceram Soc. 2019;102:1041–1048. doi: 10.1111/jace.15966
30.
JobN, PanarielloF, CrineM, Rheological determination of the sol-gel transition during the aqueous synthesis of resorcinol-formaldehyde resins. Colloids Surf A. 2007;293:224–228. doi: 10.1016/j.colsurfa.2006.07.037
31.
ZhangJ, CaoYW, FengJC, Graphene-oxide-sheet-induced gelation of cellulose and promoted mechanical properties of composite aerogels. J Phys Chem C. 2012;116:8063–8068. doi: 10.1021/jp2109237
32.
LiHB, ZhangLT, ChengLF, Effect of the polycarbosilane structure on its final ceramic yield. J. Eur Ceram Soc. 2008;28:887–891. doi: 10.1016/j.jeurceramsoc.2007.07.020
33.
LiuQ, WuHJ, LewisR, Investigation of the pyrolytic conversion of poly(silylenemethylene) to silicon carbide. J Chem Mater. 1999;11:2038–2048. doi: 10.1021/cm981067c
34.
SuL, WangHJ, NiuM, Ultralight, recoverable, and high-temperature-resistant SiC nanowire aerogel. ACS Nano. 2018;12:3103–3111. doi: 10.1021/acsnano.7b08577
35.
LiBB, YuanXS, GaoY, A novel SiC nanowire aerogel consisted of ultra long SiC nanowires. Mater Res Express. 2019;6:045030. doi: 10.1088/2053-1591/aafaef
36.
PappacenaKE, FaberKT, WangH, Thermal conductivity of porous silicon carbide derived from wood precursors. J Am Ceram Soc. 2007;90:2855–2862. doi: 10.1111/j.1551-2916.2007.01777.x
37.
LiangCY, WangZF, WuLN, Light and strong hierarchical porous SiC foam for efficient electromagnetic interference shielding and thermal insulation at elevated temperatures. ACS Appl Mater Interfaces. 2017;9:29950–29957. doi: 10.1021/acsami.7b07735
38.
ShimizuT, MatsuuraK, FurueH, Thermal conductivity of high porosity alumina refractory bricks made by a slurry gelation and foaming method. J Eur Ceram Soc. 2013;33:3429–3435. doi: 10.1016/j.jeurceramsoc.2013.07.001
