Effect of Nonwoven Carbon Tissue-Reinforced Epoxy Resin Adhesive Layer on the Single Lap Bonding Strength of Aluminum Alloy Joints

Abstract

The present paper provides a solution to enhance the reliability of bonding. The effect of the nonwoven carbon tissue (NWCT) composite adhesive layer on the bonding strength and reliability of aluminum alloy of single lap joints (SLJ) was investigated by embedding NWCT into the epoxy adhesive layer. The bonding strength, Weibull distribution, metallography of cross section, and fracture surface morphology of NWCT specimens were investigated. The results showed that the average bonding strength and Weibull characteristic strength (WCS) of NWCT-reinforced specimen were 16.78 and 17.17 MPa, which increased by 70.2 and 66.7%, respectively, compared with the neat specimen, and the Weibull modulus increased from 11.46 to 22.83, which indicated that NWCT specimens had higher bonding reliability. The mechanism of microcrack formation was obtained by analyzing the cross section of specimen loaded 95% WCS without macroscopic damage. The metallographic section showed that the microcrack of the neat specimen originated from the adhesive–aluminum interface, while the microcracks of the NWCT specimen originated from the interface between short carbon fibers (SCF) and adhesive. Typical failure modes were gained from visual observation and SEM. The failure mode of the neat specimen included more Al–adhesive interface failure, while the NWCT specimen included more internal failure of adhesive–SCFs with the fracture, pullout, peeling, and slippage of SCFs improving the toughness and bonding strength of the adhesive layer. The bridging effect of SCFs in the adhesive layer reinforced by NWCT can even the load and release the stress to improve the bonding reliability.

Effects of Chemistry of Silicon Surfaces on the Curing Process and Adhesive Strength for Epoxy Resin

“…Consequently, the reaction conversion decreases, resulting in a residue of unreacted substances at the interface, as evidenced by our previous study using X-ray photoelectron microscopy. 14,15 To improve the strength of epoxy adhesives to an adherend, reinforcement with fillers 16,17 and modification of the adherend surface 18−20 produce a hydroxy group, and the generated secondary amine further reacts with another epoxy group to form a tertiary amine, again producing a hydroxy group. This reaction mechanism indicates that the material becomes hydrophilic as the reaction proceeds.…”

“…To improve the strength of epoxy adhesives to an adherend, reinforcement with fillers , and modification of the adherend surface − by a chemical reaction and plasma treatment are effective. Considering amines as a curing agent, Figure shows the reaction scheme of epoxy and amine compounds.…”

P‐7.10: Investigations on the Mechanization and Key Factors for Strength Improvement of Display Panel†

“…What's more, in order to improve the result of Dupont test, the organic membrane, which can protect the single layer part from external force, was added in the process flow. Many reports indicated that resin may not only flatten the membrane but also protect from outer force because of its thickness and considerable elasticity [5]. The result of test was about twice higher than the samples without resin.…”

Preparation and Properties of Epoxy Adhesives with Fast Curing at Room Temperature and Low-Temperature Resistance

“…Epoxy adhesives have excellent mechanical properties, thermal properties, , adhesive properties, − and electrical insulation properties, which have been widely used in packaging, construction, automotive, electronics, plastics, wood, and other fields. However, the slow curing rate of epoxy adhesives at room temperature and poor low-temperature resistance still limits their application in the field of electronic and electrical sealing, especially during the winter season.…”