Thermally-conductive silicone elastomer for aerospace

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Master Bond MasterSil 323AO-LO is a two-component silicone elastomer with a self-priming feature, designed for bonding, sealing and gap filling applications.

This thermally-conductive, electrically-insulating compound meets NASA low outgassing specifications and can be used in the aerospace, electronics, opto-electronic and specialty OEM industries.


This system has a thermal conductivity of 1.15-1.30 W/(m*K). It is highly flexible with a low tensile modulus of 500-700 psi, an elongation of 50-60%, and a hardness of 70-75 Shore A. This combination of properties enables it to withstand aggressive thermal cycling and mechanical shock, according to Master Bond.


MasterSil 323AO-LO has a relatively high strength profile for a silicone with a tensile lap shear strength of 250-350 psi at room temperature. It bonds well to a wide variety of substrates, including metals, composites, glass, ceramics, plastics, and other silicones without imparting residual stress when heat cured. Serviceability is from -54°C to +204°C.


MasterSil 323AO-LO features a paste-like consistency, which allows it to also be used as a gap filling material where minimum flow after application is desired. This formulation offers a variety of cure schedule options, with the optimum being overnight at room temperature followed by 3-5 hours at 52-79125-175°C. It does not require exposure to air for complete cross-linking. MasterSil 323AO-LO has a 1:1 mix ratio and is available for purchase in standard containers or gun applicator kits.