Polydimethylsiloxane as matrix, methyltrimethoxysilane JHN311 as coupling agent, Al2O3, ZnO, Si3N4, BN, AlN, carbon nanotubes, and homemade Al2O3-AlN as fillers, and each group was experimentally adjusted Parts blending ratio, screening fillers, and low-cost high-thermal-conducting and insulating low-viscosity silicone grease with excellent thermal and insulating properties. The main content of this article:
(1) Study the effect of the type of coupling agent and the amount of coupling agent on the surface treatment of thermally conductive fillers, the effect of filler treatment on the properties of thermally conductive silicone grease, and the effect of coupling agents. The results show that when using the silane coupling agent JHN311, the best dosage is 1.3% of the filler mass, the surface treatment effect is the best. After the filler is surface treated, the sedimentation rate of the thermally conductive silicone grease and the oil leakage condition are improved very well. Improved thermal conductivity of thermally conductive silicone grease.
(2) The effects of different thermally conductive fillers on the properties of thermally conductive silicone greases were studied, including Al2O3 and ZnO, Al2O3 and AlN mixed, irregular Al2O3, and spherical Al2O3. It is concluded that the filler addition ratio increases, and the viscosity and thermal conductivity of thermally conductive silicone grease also gradually increase. When the ratio of the random Al2O33μm and 10μm is 2: 8, the thermal conductivity of the silicone grease is the highest, 1.360 W / (m · k) ; When the spherical Al2O33μm and 10μm addition ratio is 4: 6, the thermal conductivity of thermally conductive silicone grease is the largest, 1.089 W / (mk).
(3) The thermal conductivity and viscosity of irregular Al2O3 filled with the same mass fraction are higher than spherical Al2O3, but it is difficult to achieve high filling with irregular Al2O3; the silicone grease system filled with 70 μm Al2O3 has a lower viscosity and heat than the silicone grease filled with small particle size Al2O3 The conductivity is large; when the filler is filled at 92%, the thermal conductivity reaches 3.98 W / (m · k). At this time, the viscosity of the thermal conductive silicone grease is 20,000 mPa · s and the volume resistivity reaches 9.13 × 1016Ω · cm.
(4) The self-made spherical Al2O3-AlN powder was filled to prepare thermally conductive silicone grease. As a result, the spherical Al2O3-AlN powder was successfully prepared with an average particle size of 14.153 μm; the prepared Al2O3-AlN powder replaced the spherical Al2O370 μm: 10 μm: 3 μm: 1 μm ZnO = 2.1: 2.94: 1.96: 3 The thermal conductivity of the thermally conductive silicone grease prepared after 10 μm Al2O3 is 4.35 W / (m · k), the viscosity is 35000 mPa · s, and the volume resistivity is 3.16 × 1015 Ω · cm.