CCT Surface Preparation & Bonding Flashcards

What is the primary purpose of abrading a composite surface before bonding?

Answer: To increase surface area and remove contaminants for better adhesion

Abrading removes surface contaminants and increases surface area, creating a stronger mechanical bond.

Which solvent is most commonly used for wiping composite surfaces prior to bonding?

Answer: Acetone or MEK (methyl ethyl ketone)

Acetone or MEK effectively removes oils, grease, and release agents without leaving residue harmful to bond integrity.

What does the term 'peel ply' refer to in composite surface preparation?

Answer: A sacrificial fabric layer left on a surface that, when removed, exposes a bondable surface

Peel ply is applied during layup and removed just before bonding to expose a clean, textured, bondable surface.

What is the maximum allowable time between surface preparation and adhesive application according to most aerospace bonding specifications?

Answer: 4 to 8 hours

Most bonding specs require adhesive application within 4–8 hours of surface prep to prevent recontamination.

Why is a water-break test performed on a composite surface before bonding?

Answer: To verify the surface is clean and free of oil contamination

A clean surface allows water to sheet evenly; if it beads, oil or release agent contamination is present.

Which primer is commonly applied to aluminum substrates before structural adhesive bonding in composite assemblies?

Answer: Corrosion-inhibiting epoxy primer (e.g., BR-127)

BR-127 or similar epoxy primers enhance adhesion and provide corrosion protection on metallic bond surfaces.