High-temperature damping composite

A composite at least 1/2 meter in both width and length of a structural metal sheet and a viscoelastic layer, which composite can be formed to provide components of or facings for machines in order to provide effective damping of vibrations in such machines during prolonged high-temperature operation,

• said metal sheet having an average plastic strain ratio r of at least 1.3, a strain-hardening exponent n of at least 0.11 in the equation
• .sigma.=K.epsilon..sup.n
• where .sigma. is the true stress, K is a constant and .epsilon. is the true strain, and a thickness of at least 0.2 mm, and
• said viscoelastic layer having a thickness of at least 20 micrometers and being a cured polycyanurate polymer comprising the repeating unit ##STR7## wherein each R is the residue after removal of the hydroxyl radicals from one of
• (a) HO--Ar--OH
• (b) ##STR8## (c) HOCH.sub.2 --(CH.sub.2 CH.sub.2).sub.j (CF.sub.2 CFX).sub.k ].sub.m CH.sub.2 OH
• (d) HO--CH.sub.2 CF.sub.2 (CF.sub.2).sub.h CF.sub.2 CH.sub.2 OH
• wherein
• h is 0 or an integer of 1 to 6,
• j and k are integers whose ratio j/k is 1/1 to 10/1,
• m is an integer of 1 to 100,
• n is an integer of 1 to 20,
• X is fluorine or perfluoroalkyl,
• --Ar--represents ##STR9## wherein Z represents --S--, --SO.sub.2 --, --O--, ##STR10## wherein R.sub.1 and R.sub.2 represent hydrogen, lower alkyl or ##STR11## wherein .omega. is an integer from 2 to 6, ##STR12## and the polycyanurate polymer has sufficient crosslinks such that its cyanurate nitrogen comprises 0.5 to 2% of its total weight when the polymer comprises 60% fluorine and 1.0 to 3.5% of its total weight when it is free from fluorine.