We herein show that by integrating nano-scale phonon-scattering mechanisms

such as interfaces and stacking faults thermal resistances in porous nano-SiC

this outstanding material (with intrinsic very high thermal conductivity) could demonstrate promising thermal insulation property. Porous nano-SiC prepared at 1

500°C exhibits a specific balanced mechanical strength (compressive and flexural strength are 26 and 13 MPa

respectively

with 57% porosity) and extremely low thermal conductivity (2 W m

−1

 K

−1

at 300 K); and sample sintered at 1

800°C shows excellent mechanical strength but relatively high thermal conductivity. Our work reports the novel low thermal conductivity of porous nano-SiC for the first time.