[Composites Science and Technology] Flexible and insulating silicone rubber composites with sandwich structure for thermal management and electromagnetic interference shielding
writer：Yongqiang Guo, Hua Qiu*, Kunpeng Ruan, Shuangshuang Wang, Yali Zhang and Junwei Gu*
keywords：Thermally conductive composites
source：期刊
specific source：Composites Science and Technology
Issue time：2022年
High integration development of electronics requires materials possessing excellent thermal conductivity, electromagnetic interference (EMI) shielding, and electrical insulation. In this work, Fe2O3 particles are deposited on carbon fibers (CF) and then utilized as fillers (CF@Fe2O3) in boron nitride/silicone rubber (BN/SR) to fabricate sandwich structured CF@Fe2O3/(BN/SR) composites, herein, BN/SR as top & substrate layer, and CF@Fe2O3 as middle layer. Orientation of BN in CF@Fe2O3/(BN/SR) composites realizes excellent in-plane thermal conductivity coefficient (λ∥), and the core-sheath structure of CF@Fe2O3 achieves good EMI shielding performance by the “absorption-reflection (transmittance)-reabsorption” process of electromagnetic waves, insulation modification of CF and the sandwich structure strengthen the electrical insulation. When the amount of BN and CF@Fe2O3 are 20.6 wt% and 45.5 wt%, respectively, the λ∥, EMI shielding effectiveness, volume resistance and breakdown strength of CF@Fe2O3/(BN/SR) composites reach 3.86 W/(m·K), 37.7 dB, 6.2×1014 Ω·cm and 26.8 kV/mm, respectively, which are all higher than those of commonly fabricated CF/(BN/SR) composites with same amount of BN and CF (3.83 W/(m·K), 19.4 dB, 8.6×1013 Ω·cm and 21.4 kV/mm). CF@Fe2O3/(BN/SR) composites possess better cooling effect (5.6oC) than that of commercial silicon grease (QM850) on the testing platform of computer’s central processing unit, whose functions are more abundant and have wide application prospects in electronics.
電子產(chǎn)品高集成化的發(fā)展趨勢(shì)亟需兼具優(yōu)異導(dǎo)熱、電磁屏蔽且電絕緣的材料。本文以硅橡膠（SR）為基體，氮化硼（BN）為導(dǎo)熱填料，通過(guò)在碳纖維（CF）表面沉積Fe2O3制備CF@Fe2O3，再采用刮涂法制備上下層為BN/SR、中間層為CF@Fe2O3的三明治結(jié)構(gòu)CF@Fe2O3/(BN/SR)復(fù)合材料。BN在CF@Fe2O3/(BN/SR)復(fù)合材料面內(nèi)方向的取向排列賦予其優(yōu)異的面內(nèi)導(dǎo)熱性能；芯鞘結(jié)構(gòu)的CF@Fe2O3使電磁波能夠被“吸收-反射（透過(guò)）-再吸收”，實(shí)現(xiàn)其優(yōu)異的電磁屏蔽性能；CF表面絕緣化和上下層絕緣的三明治結(jié)構(gòu)保證其優(yōu)異的絕緣性能。當(dāng)BN和CF@Fe2O3用量分別為20.6 wt%和45.5 wt%時(shí)，CF@Fe2O3/(BN/SR)復(fù)合材料的面內(nèi)導(dǎo)熱系數(shù)、電磁屏蔽效能、體積電阻率和擊穿強(qiáng)度分別為3.86 W/(m·K)、37.7 dB、6.2×1014 Ω·cm 和26.8 kV/mm，其綜合性能明顯優(yōu)于同等BN和CF用量下制備的CF/(BN/SR)復(fù)合材料（3.83 W/(m·K)、19.4 dB、8.6×1013 Ω·cm 和21.4 kV/mm）。此外，CF@Fe2O3/(BN/SR)復(fù)合材料比市售的高導(dǎo)熱硅脂（QM850）更能有效降低實(shí)際工況下CPU的工作溫度（降幅約5.6oC），且功能更加豐富，在電子電氣等領(lǐng)域具有廣泛的應(yīng)用前景。