Stainless steel coupled with carbon nanotube-modified epoxy and carbon fibre composites: Electrochemical and mechanical study

Abstract

The aim of this work is the study of the electrochemical and mechanical behaviour of stainless steel (SS304) adhesively bonded with carbon nanotube (CNT)-reinforced epoxies to either SS304 or carbon-reinforced composites substrates. For metal to metal (MtM) joints, the shear strength of nano-reinforced adhesives was studied using single lap shear specimen geometries. The lap shear strength was improved by almost 50% and the highest shear strength appeared for 0.6% CNT weight content in the adhesive. The metal to composite joint performed altogether better compared to the MtM joint, although the CNT inclusion had an adverse effect on the lap shear strength attributed to the physical property change of the epoxy. Although the incorporation of CNTs was found to increase the galvanic effect, it also enhanced corrosion protection, as the modified adhesives exhibited increased resistance to uniform corrosion and localised corrosion and prevented the electrolyte from reaching the substrate.

The Role of Synergies of MWCNTs and Carbon Black in the Enhancement of the Electrical and Mechanical Response of Modified Epoxy Resins

“…% did not alter the electrical behavior of the system. Additionally, as previous studies have indicated [14,30], electrical percolation is reached at ca. 0.5 wt.…”

Galvanically Stimulated Degradation of Carbon-Fiber Reinforced Polymer Composites: A Critical Review

“…Arronche et al [ 277 ] studied galvanic corrosion between AISI 1018 carbon steel coupled to CFRPs modified with multi-walled carbon nanotubes and reported that the addition of MWCNTs do not have a statistically significant effect on the corrosion and mass loss rates compared to unmodified CFRP. Comparing their result [ 277 ] which is at variance with other works [ 275 , 276 ] that reported “CNT-induced” increase in galvanic corrosion of metals coupled to fiber reinforced polymer composites, they attributed their non-observance of an increase in metallic (AISI 1018 carbon steel) corrosion rates on galvanic coupling to MWCNTs modified CFRP to the already conductive nature of carbon fiber reinforcement with respect to the CNT fillers. This attribution in our opinion is most probably incorrect, because addition of CNTs above its percolation threshold in the polymer matrix is bound to increase the conductivity of the matrix phase of the composite so that the entire CFRP composite surface becomes conductive.…”

“…The effect of the introduction of CNTs and CNFs into CFRP as nano-fillers on the galvanic corrosion of technologically relevant metals/alloys coupled to CFRP is an area that require detailed study. However, there are just few reports in literature on galvanic corrosion of metals coupled to nano-filler modified fiber reinforced polymers [ 275 , 276 , 277 ] Ireland et al [ 275 ] investigated galvanic corrosion between aluminum 7075 and glass fiber reinforced polymer (GRFP) composites modified with carbon nanotubes and reported statistically significant increase (approximate doubling) of corrosion rate and mass loss rate on coupling MWCNT/GFRP samples with aluminum 7075 compared to baseline GFRP samples. It is important to note that in the MWCNT/GFRP - AA7075 galvanic couple studied by Ireland et al [ 275 ], the reinforcing fiber (glass fiber) in the GFRP is not electrically conductive in contrast to CFRP in which the reinforcing fiber (carbon fiber) is electrically conductive.…”

“…It is important to note that in the MWCNT/GFRP - AA7075 galvanic couple studied by Ireland et al [ 275 ], the reinforcing fiber (glass fiber) in the GFRP is not electrically conductive in contrast to CFRP in which the reinforcing fiber (carbon fiber) is electrically conductive. Baltzis et al [ 276 ] investigated the performance of austenitic stainless steel 304 (SS304) adhesively bonded to neat epoxy, CNT-modified epoxy and carbon fiber (CF)-reinforced epoxy (CFRRP), and reported that though the incorporation of CNTs increased the galvanic effects, it also retarded uniform corrosion and localized corrosion as the modified adhesives prevented the electrolyte from reaching the substrate. Arronche et al [ 277 ] studied galvanic corrosion between AISI 1018 carbon steel coupled to CFRPs modified with multi-walled carbon nanotubes and reported that the addition of MWCNTs do not have a statistically significant effect on the corrosion and mass loss rates compared to unmodified CFRP.…”

Acoustic Emission Feasibility Study for Carbon Epoxy Coated Aluminum Corrosion Monitoring

“…In order to further enhance adhesion and alleviate the mismatches, several studies have been conducted on nano-modified epoxies employing mainly graphitic structures like carbon nano tubes (CNTs) [4][5][6][7][8]. Apart from the improved adhesion, CNTs can also reduce the ingress of water in the epoxy due to their hydrophobic nature and the water affected specific area resulting in more tortuous paths for the absorption and diffusion of water, thus, further enhancing the performance of the joint structure [9][10][11].…”