Metal mesh-based special wettability materials for oil-water separation: A review of the recent development

This study presents a simple technique for positioning helical carbon nanotubes (CNTs) into chemically-etched vertical micro-channels on an aluminum (Al) substrate for strong adhesive bonding with carbon fiber composites. Helical CNTs with diameter up to 100 nm and length up to 10 μm were dispersed evenly in an acetone-diluted resin pre-coating (RPC) solution consisting of 90 wt% acetone + 10 wt% resin (without hardener), then applied onto the chemically etched Al substrate with vertical micro-channels. CNTs were dragged into those vertical micro-cavities through the capillary action during the evaporation process of acetone. The shear bond strength was more than doubled by the quasi-Z-directional CNTs, confirming the critical role of CNT bridging across the interface between the epoxy adhesive and Al substrate. Scanned electron microscope (SEM) and focused ion beam (FIB) were used to reveal micro-channels on the Al substrate. RPC on the surface of carbon fiber composites is also beneficial.

Directing helical CNT into chemically-etched micro-channels on aluminum substrate for strong adhesive bonding with carbon fiber composites

Optimized porous aluminum (Al) substrates chemically etched by three electrolytes have been prepared in this study. They are used to place multi-walled carbon nanotubes (CNTs) via resin pre-coating (RPC) technique for stronger adhesive bonding with carbon fiber reinforced polymers (CFRP). Shallower channels (~1–2 μm) were etched by 20 wt% H2SO4 solution, deeper channels (~5 μm) were etched by 20 wt% H2SO4 + 0.5 wt% C2H2O4 (or + 0.5 wt% FeSO4) solution. The former has less sub-surface void defect by directly adhesive bonding, its bonded composite has higher shear strength. Through RPC, the latter promotes effective interface behaviors including increasing contact area, reducing void defect and improving mechanical occlusion. Moreover, they have sufficient pore volumes to embed and form quasi-Z-directional CNTs, leading to around 135% improvements in shear strength. Therefore, Al substrate surface with deeper channels potentially contributes to improving adhesive interface and positioning vertical CNTs via RPC to further reinforce adhesive joint.

Adhesive bond strength enhancing between carbon fiber reinforced polymer and aluminum substrates with different surface morphologies created by three sulfuric acid solutions

Performance of the graphite felt flow-through electrode in hexavalent chromium reduction using a single-pass mode

This article provides a comprehensive review of the advancements made in the diffusion bonding of titanium and its alloys to other advanced materials such as aluminium, stainless steel, and magnesium. This combination of advanced alloys has received considerable attention in different industries, including aerospace, petrochemical, and nuclear applications due to high specific strength, lightweight, corrosion resistance, and moderate to high mechanical properties. The mechanisms of bond formation are discussed based on the type of microstructures formed and the mechanical properties achieved. The scientific literature identifies various methods/processes for controlling the volume of intermetallic compounds formed within the joint regions, as well as ways of maximising the strength of the weld/joints. This paper discusses the relationship between weld/bond properties and bonding parameters such as time, temperature, surface roughness, pressures, interlayer composition, and thickness. The scientific literature also shows that the bonding mechanisms and microstructural evolution of the bond zone can be significantly affected by suitable optimization of the bonding parameters. Additionally, this is a method of maximising bond strength.

https://www.mdpi.com/2504-4494/4/2/39/pdf

Current Trends in Dissimilar Diffusion Bonding of Titanium Alloys to Stainless Steels, Aluminium and Magnesium

Enhanced resistance-welding hybrid joints of titanium alloy/thermoplastic composites using a carbon-nanotube lamina

Effect of chemical etching of resistance wire surface on the strength and failure mechanism of the resistance‐welded joint of polyetherimide composites

The carbon nanotubes (CNTs)-grafted carbon fibers (CFs) were used as the interlayer heating element for resistance welding of glass fabric reinforced polyetherimide (GF/PEI) composite laminates to enhanced the strength of the joints of GF/PEI. The effects of CNTs on the wettability of PEI resin on the CF surface and the interfacial microstructure and mechanical properties of welded joints were investigated. The CNTs were in-situ grown on the surface of the CFs by flame method, and their structures and morphologies were characterized by Raman spectrum, scanning electron microscope (SEM) and transmission electron microscope (TEM). PEI resin solution exhibits better wettability on CNTs-grafted CF surface with the help of capillary action. Interfacial shear strength (IFSS) of CF/PEI resin and the SEM images of bonding interface shows a stronger binding effect between CNTs-grafted CFs and PEI resin. The mechanical property of the joints was evaluated by the tensile test of single lap shear strength (LSS). The LSS values increased first and then decreased with welding time (tw), and the optimum LSS of the joint with CNTs was increased by 23.6% to 32.5MPa in comparison with that of the joint without CNTs when tw was 60s.

https://iopscience.iop.org/article/10.1088/2053-1591/ab3b1f/pdf

Resistance welded thermoplastic composites joint strengthened via carbon nanotubes from flame: interface strength, mechanical properties and microstructure

The joining of composite parts with weight reduction and cost saving is being developed to improve aircraft performance. The high-efficiency resistance welding technology was hence explored for joining glass fabric reinforced polyetherimide (GF/PEI) laminates in this work and a composite PEI films reinforced with carbon fiber felt (CFF) reinforced laminae was embedded into the interface of the welding region to enhanced the strength of the joints of GF/PEI. The effects of CFF incorporation on the welding speed and the lap shear strength (LSS) of welded joints were investigated in comparison with those of the CFF-uncontained welded joints. The CFF-incorporated resistance welding speed was accelerated and its LSS was enhanced evidently, the maximum LSS value reached 32 MPa. The fracture mode and mechanism of welding implants, which varied with t w from the linear tearing to the annular tearing due to the coupling effect of the improvement of PEI molten state and the occurrence of PEI thermal degradation, were illuminated according to the test results from ultrasonic C-scan and SEM.

https://iopscience.iop.org/article/10.1088/2053-1591/ab226b/pdf

Resistance welded composite joints strengthened by carbon fiber felt: mechanical properties, failure modes and mechanism

Carbon nanotubes (CNTs) from the flame were used as interface enhancers for epoxy-bonded Al alloy joints. The structure characteristics of CNTs were investigated in detail by the combination of scanning electron microscopy (SEM), transmission electron microscope (TEM), and Raman spectroscopy. The effects of CNTs incorporation on the lap shear strength (LSS) of bonded joints were investigated in comparison with those of the CNTs-uncontained bonded joints. The CNTs-incorporated LSS was enhanced evidently, the maximum LSS value reached 20.1 MPa. The dependence of micromorphology of failure of the bonded joints was analyzed systematically based on the images from the SEM. The strengthening mechanism was also illuminated according to the fracture morphology of the bonded joints and evidently improved static contact angle of the surface of the Al alloy plates.

Zhongbao Zhang

Papers

Enhanced resistance-welding hybrid joints of titanium alloy/thermoplastic composites using a carbon-nanotube lamina

Effect of chemical etching of resistance wire surface on the strength and failure mechanism of the resistance‐welded joint of polyetherimide composites

Resistance welded thermoplastic composites joint strengthened via carbon nanotubes from flame: interface strength, mechanical properties and microstructure

Resistance welded composite joints strengthened by carbon fiber felt: mechanical properties, failure modes and mechanism

Improvement of mechanical properties in epoxy adhesive joints of Al alloy via carbon nanotubes from flame