Chaff fiber comprising insulative coating thereon, and having an

Abstract

An article comprising a non-conductive substrate which is coated with a sub-micron thickness of an oxidizable metal and overcoated with a microporous layer of an inorganic electrically insulative material. Optionally, the oxidizable metal-coated substrate may be sulfurized and/or further coated with (i) a promoter metal which is galvanically effective to promote the corrosion of the oxidizable metal, discontinuously coated on the oxidizable metal coating, and/or (ii) a salt, to accelerate the galvanic corrosion reaction by which the oxidizable metal coating is oxidized, prior to overcoating with the microporous insulative layer. Also disclosed is a related method of forming such articles, comprising chemical vapor depositing the oxidizable metal coating on the substrate and contacting the metallized substrate with a sol gel dispersion of the inorganic electrically insulative material which then is dried under suitable conditions to form the microporous layer on the substrate. When utilized in a form comprising fine diameter substrate elements such as glass or ceramic filaments, the resulting product may usefully be employed as an evanescent chaff. In the presence of atmospheric moisture, such evanescent chaff undergoes oxidation of the oxidizable metal coating so that the radar signature of the chaff transiently decays.