Effect of diamond powder content on bonding and thermal conductivity of sodium silicate based thermal conductive adhesive

In order to find out the best range of diamond powder content for heat conductive adhesive, the influence of diamond powder content on the heat conductive adhesive was studied. The surface of diamond powder with different particle sizes was modified by silane coupling agent. In order to increase the specific surface area of diamond powder, a new type of inorganic thermal conductive adhesive was prepared by using 60 μm, 20 μm and 10 μm diamond powder as filler and water glass as matrix at the mass ratio of 6∶2∶1. The results show that the adhesive property of thermal conductive adhesive increases at first and then decreases, and that the adhesive property is best when the content of diamond is 60% and the tensile shear strength is 1.98 MPA. Besides, the thermal conductivity of the adhesive increases first and then decreases. The best thermal conductivity is 6.32 W/(m · K) when the content of diamond is 50%. Therefore, when the mass fraction of diamond is 50% ~ 60%, the adhesive and thermal conductivity of thermal conductive adhesive is the best.