Surface treatment and adhesive bonding techniques for repair of high-temperature composite materials

Abstract

Adhesive bonding of structural aircraft materials depends upon a thorough understanding of factors that affect bond strength and durability. It is well known that surface preparation is critical to adhesive bond performance. However, little information is available regarding the effect of surface preparation procedures on adhesive bonding of high-temperature polyimide composites. Mechanical treatments such as hand sanding are commonly used for composite materials, and in general are known to improve the wettability of the surface as well as effect contaminant removal. Less is known about the influence of mechanical treatments on the surface chemistry. This article discusses the effects of mechanical surface preparation on the adhesive bond strength, durability, and failure mode of several high-temperature polyimide-based composites and adhesives.

Effect of surface treatment on the performance of composite‐composite and composite‐metal adhesive joints

“…It was observed that when the Al‐7075 surface was subjected to phosphoric anodizing, the hydrophilicity of the aluminum surface was increased remarkably as is observed in Figure 6C, due to the creation of a thin anodic porous layer of oxide on the surface. Similar findings were provided by Digby and Packham [ 24 ] and Dillingham et al [ 22 ]…”

“…A piece of non‐sticking, woven nylon fabric was used as a peel ply to impart a surface roughness on the composite surface during curing in the compression stage as suggested by Budhe et al [ 21 ] Sandblasting of the composite surface was carried out using 200‐μm silicon dioxide particles at an air blasting velocity of 2 mm/min for 1 min. The blasting angle was 75° and the nozzle to substrate surface distance was fixed at 450 mm while the blasting pressure was kept at 3 bars according to Dillingham et al [ 22 ]…”

“…A piece of non-sticking, woven nylon fabric was used as a peel ply to impart a surface roughness on the composite surface during curing in the compression stage as suggested by Budhe et al [21] Sandblasting of the composite surface was carried out using 200-μm silicon dioxide particles at an air blasting velocity of 2 mm/min for 1 min. The blasting angle was 75 and the nozzle to substrate surface distance was fixed at 450 mm while the blasting pressure was kept at 3 bars according to Dillingham et al [22] The composite surface was degreased for 3 min in an ethanol solution. An alkaline permanganate etchant was prepared using 70 g/L potassium permanganate (KMnO 4 ) and 60 g/L sodium hydroxide (NaOH), and then diluted with distilled water to obtain its 20% concentrated solution.…”

Design, fabrication, and construction of a freeform GFRP facade

“…The structural adhesive needed to satisfy the connection strength, as well as be able to fill the gap between panels. Scientific researches on structural adhesive connections are ongoing, and various structural adhesives are already available on the market (Mays and Hutchinson 1988;Dillingham et al 2014;Kumar, Patnaik, and Chaudhary 2017). For the actual projects, product maturity and construction convenience were also significant factors and thus, a commercially-available structural adhesive with a practical construction plan was required.…”

Prediction of Fracture Toughness and Durability of Adhesively Bonded Composite Joints with Undesirable Bonding Conditions

“…Although water interactions with polymer surfaces were studied earlier [93], very little has been researched on the effect of surface types on bond performance in ABCJ's. Dillingham et al investigated on abraded and non-abraded composite surfaces and correlated their surface free energy with the bond strength [94]. In another study, Dillingham et al…”