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The aim of this work is to develop high‐performance adhesives to join carbon fiber reinforced composites (C/C) for use in aerospace applications; in order to guarantee sound mechanical strength, a low coefficient of thermal expansion, and ease of application on large components. Several different adhesive formulations, based on phenolic or cyanate‐ester resins (charged with the maximum experimentally feasible amount of carbon‐based fillers), are developed and tested. The measurements of the lap shear strength at room temperature of the C/C joined by means of one phenolic and one cyanate ester‐based resin demonstrates that these formulations are the most suitable for the given application. A complete characterization, by means of viscosimetry, dilatometry, and thermal gravimetric analysis, coupled with gas analysis by means of mass spectroscopy, confirms that the phenolic‐based formulation is the most promising joining material. A nano‐indenter is used to obtain its Young modulus and hardness, both inside the joint and as a bulk cured adhesive.

A high performance adhesive is used to join Zerodur to a carbon fiber reinforced polymers (CFRPs) honeycomb (HC) in a sandwich structure for aerospace applications. The main problem of finding an adhesive with suitable thermomechanical stability and ease of application for use in large components, together with a lower curing temperature than 160 °C, in order to avoid detrimental effects on the CFRPs is resolved. Two phenolic‐based and one cyanate ester‐based adhesives are considered. One phenolic‐based adhesive that is already proven effective in the joining of carbon/carbon composites (C/C) is used to join CFRP slabs and Zerodur–CFRP–Zerodur in a sandwich structure. Thermal analysis is conducted to characterize and compare the phenolic adhesive, cured at 150 °C and at 260 °C, with a cyanate ester‐based adhesive and a commercial phenolic‐based one. The phenolic adhesive cured at 150 °C results to be the most suitable joining material; the lap shear strength of the CFRP slabs joined at room temperature is measured after thermal cycling. Zerodur–CFRP–Zerodur sandwich structures, joined by the phenolic adhesive cured at 150 °C, are tested in tensile and lap shear modes.

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