Hermetic Compounds

materials based on various polymers, designed for application to bolt, rivet, and other junctions in metallic constructions, instruments, and unit assemblies and for solidification of joints between panels of exterior walls of buildings to ensure impermeability. In addition to polymers, hermetic compounds usually contain fillers, vulcanizing or hardening agents, and other components. Hermetic compounds are used in the form of a paste, a grease, or a solution in an organic solvent. The hermeticizing material is formed directly on the joining seam as a result of vulcanization (hardening) of the polymer base of the hermetic compound or the evaporation of the solvent.

The basic requirements for hermetic compounds are durability and elasticity, a high degree of adhesion to metals, stability under the action of working mediums (including kerosine, gasoline, oil, alcohol, acids, alkalis, and water), and heat-and frost-resistance; in addition, they must not cause the corrosion of metals. Hermetic compounds used for insulating radioelectronic devices must have high electroisolating properties.

The most widely used hermetic compounds are based on rubber polysulfides and organic silicone rubber. Hermetic compounds are widely used in industry and construction, including the making of airplanes, motor vehicles, and ships. They are also used in areas not connected with their primary purpose, as for example in criminology and in tooth prosthesis for making accurate molds and castings.