Durable thermally conductive composition and the low de-oil grease

Both terminal vinyl high molecular weight silicone 0.5-10 volume% of a viscosity at 25 ℃ 10000~15000Pa · s, alkylalkoxysilane 1-10 vol%, an inorganic filler 40-65 vol%, the viscosity at rest is 25 ° C. There ruggedized thermally conductive composition comprising an addition reaction-type low molecular weight silicone 0.2~0.5Pa · s. Addition-reaction viscosity 0.2~0.5Pa · s at 25 ° C. Low molecular weight silicone 38 to 48 vol%, both terminal vinyl high molecular weight silicones 2-8 volumes of viscosity 10000~15000Pa · s at 25 ° C. %, the grease which comprises 50-60% by volume inorganic filler. It is preferable that the number of carbon atoms in the alkyl group of the alkyl alkoxysilane of the is triethoxysilane or trimethoxysilane of 6 to 10.