The effects of processing variables on strength of carbon bonding between carbon/carbon composites

Bonding technique between carbon-carbon composites (C/Cs) was discussed using carbon as a bonding material. Carbon/carbon plates were first bonded using resin. The resin-bonded C/C composites were then heat-treated to carbonize the bonding layer under low pressure. The strength of the carbon bonding was evaluated at room temperature. Main focus was placed upon finding the effect of polymer precursor of the bonding layer, the thickness of the bonding layer, bonding pressure, bonding direction of substrate C/Cs on the bonding strength. The optimized bonding strength was shown to be equal to or higher than the interlaminar shear strength of substrate C/Cs. This high strength was obtained when bonding layer was thin and bonding precursor was phenolic resin even for flat-wise bonding. The effects of other parameters, including thermal residual stresses and cracks in the bonding layer, on the bonding strength were also discussed using the Kendall equation with an aid of finite element calculations.