Many 3D printing technologies are based on the development of inks and pastes to build objects through droplet or filament deposition (the latter also known as continuous extrusion, robocasting, or direct ink writing). Controlling and tuning rheological behavior is key for successful manufacturing using these techniques. Different formulations have been proposed, but the search continues for approaches that are clean, flexible, robust and that can be adapted to a wide range of materials. Here, we show how graphene oxide (GO) enables the formulation of water-based pastes to print a wide variety of materials (polymers, ceramics, and steel) using robocasting. This work combines flow and oscillatory rheology to provide further insights into the rheological behavior of suspensions combining GO with other materials. Graphene oxide can be used to manipulate the viscoelastic response, enabling the formulation of pastes with excellent printing behavior that combine shear thinning flow and a fast recovery of their elastic properties. These inks do not contain other additives, only GO and the material of interest. As a proof of concept, we demonstrate the 3D printing of additive-free graphene oxide structures as well as polymers, ceramics, and steel. Due to its amphiphilic nature and 2D structure, graphene oxide plays multiple roles, behaving as a dispersant, viscosifier, and binder. It stabilizes suspensions of different powders, modifies the flow and viscoelasticity of materials with different chemistries, particle sizes and shapes, and binds the particles together, providing green strength for manual handling. This approach enables printing complex 3D ceramic structures using robocasting with similar properties to alternative formulations, thus demonstrating the potential of using 2D colloids in materials manufacturing.

Basalt fiber is an emerging alternative reinforcement to glass or carbon depending upon the application. An important contributing parameter to ultimate performance of any composite is the fiber–‐matrix interface, to which toughness and compressive strength are intimately related. To better understand this matrix fiber interaction in controlling properties, we compared different modification strategies and the impact upon the properties of composites. Strategies focussing upon mechanical interlocking through increased surface roughness and covalent chemical bonding using sol/get methods were explored. Combined methods were also used to explore synergistic behavior as well as the use of aliphatic triethylenetetramine (TETA) to react with any covalently attached epoxy groups. Results from single ply composites showed that when the properties were fiber or fiber/matrix dominated, the sol/gel or epoxy silane method gave the largest improvement in ultimate tensile strength increasing 66% and 27% for uni‐weave 0° and 45° laminas. The combined surface modification methods exhibited increases of 45% and 13% for the same laminas. When properties were matrix dominated, the combined strategies produced the highest improvements in ultimate tensile strength of about 55% compared with 37% for sol/gel modification. For 16‐ply plain weave laminates, epoxy silane surface treatments produced the greatest improvements in compressive and interlaminar shear strengths, increasing 52% and 21%, respectively. This correlated with fiber‐ and fiber/matrix‐dominated results from single ply laminas. The combined treatment using TETA however decreased shear and compressive strength by about 20%, while scanning electron microscopy (SEM) evaluation and dynamic mechanical thermal analysis (DMTA) attributed this to increased resin ductility and plasticization. © 2013 Society of Plastics Engineers

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A novel method of repairing leaking or otherwise damaged metallic pipelines using composites is presented. The method uses a uniquely designed resin-infused composite clamp. This is a significant improvement over commercially available metal clamps, providing lightweight and corrosion-resistant benefits. The design, analyses and testing presented here show that these benefits are in addition to providing uncompromising strength and reliability to the repaired structure. The design includes a combination of calculations and design of experiment optimisation with Finite Element models. The developed design methodology is shown to be robust for designing different clamp sizes. Testing involved short-and long-term survival tests of the clamps as per industrial standards, as well as hot-wet conditioning followed by mechanical testing of the composite material. Finally, a case study field deployment of the clamp on a 4-in propane pipeline with internal corrosion is presented.

A new glass/epoxy prepreg system has been developed as a solution to a long-standing challenge of corrosion and other damage, such as gouging and denting, sustained by piping, pipelines, and risers. The system has been designed to be applicable in the majority of operational conditions encountered in the oil and gas sector, encompassing onshore as well as offshore environments. This paper discusses the comprehensive qualification process undertaken to enable the repair of wall-thinning defects (Type A) and through-wall defects (Type B). The results show that the composite system meets the requirements of ISO/TS 24817 and so also concurrently complies with ASME PCC-2.