Using Additive Processing to Harness and Implement Graphene Technology for Wear and Corrosion Protection

NPS NRP Executive SummaryGraphene emerged as new wonder material in 2004 when it was isolated and resulted in the awarding of a Nobel Prize. In the nearly two decades since its discovery research has advanced graphene technology to the point of technological maturation for numerous applications, including as a promising structural reinforcement, anti-wear and low friction material, and as a diffusion barrier. Graphene has been shown to be biocompatible and poses no cytotoxicity hazards, thus making it a green and eco-friendly additive. Being a purely carbonaceous material makes it biodegradable, so that long term issues with waste generation and disposal should not exist. It is imperative that the Navy evaluate this promising and maturing technology for use in naval applications. The time is ripe to transition graphene technology to naval applications that could benefit from enhanced resistance to wear and corrosion. Additive manufacturing is a converging technology that could enable graphene materials to be quickly transitioned and implemented into the Navy fleet as either new coatings or components. The additive processes of fused deposition modeling and cold spraying will be evaluated here to determine whether graphene infused polymer and metallic materials can be implemented to provide protection from wear and corrosion. Graphene infused materials will be 3D printed and deposited as coatings to evaluate wear resistance and resistance to salt fog and UV exposure. The source of graphene will be graphene nanoplatelets, which are commercially available at less than $1000/kg. Salt fog chamber testing, humidity and UV exposure testing, and wear tests will be conducted and analyzed to evaluate the efficacy of graphene infused materials for provided wear and corrosion protection. Analysis will be used to provide recommendations on the viability of harnessing and implemented graphene technology in the field for protection of ground vehicles and naval vessels from wear and corrosion.N9 - Warfare SystemsThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Using Additive Processing to Harness and Implement Graphene Technology for Wear and Corrosion Protection

NPS NRP Project PosterGraphene emerged as new wonder material in 2004 when it was isolated and resulted in the awarding of a Nobel Prize. In the nearly two decades since its discovery research has advanced graphene technology to the point of technological maturation for numerous applications, including as a promising structural reinforcement, anti-wear and low friction material, and as a diffusion barrier. Graphene has been shown to be biocompatible and poses no cytotoxicity hazards, thus making it a green and eco-friendly additive. Being a purely carbonaceous material makes it biodegradable, so that long term issues with waste generation and disposal should not exist. It is imperative that the Navy evaluate this promising and maturing technology for use in naval applications. The time is ripe to transition graphene technology to naval applications that could benefit from enhanced resistance to wear and corrosion. Additive manufacturing is a converging technology that could enable graphene materials to be quickly transitioned and implemented into the Navy fleet as either new coatings or components. The additive processes of fused deposition modeling and cold spraying will be evaluated here to determine whether graphene infused polymer and metallic materials can be implemented to provide protection from wear and corrosion. Graphene infused materials will be 3D printed and deposited as coatings to evaluate wear resistance and resistance to salt fog and UV exposure. The source of graphene will be graphene nanoplatelets, which are commercially available at less than $1000/kg. Salt fog chamber testing, humidity and UV exposure testing, and wear tests will be conducted and analyzed to evaluate the efficacy of graphene infused materials for provided wear and corrosion protection. Analysis will be used to provide recommendations on the viability of harnessing and implemented graphene technology in the field for protection of ground vehicles and naval vessels from wear and corrosion.N9 - Warfare SystemsThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Using Additive Processing to Harness and Implement Graphene Technology for Wear and Corrosion Protection

NPS NRP Technical ReportGraphene emerged as new wonder material in 2004 when it was isolated and resulted in the awarding of a Nobel Prize. In the nearly two decades since its discovery research has advanced graphene technology to the point of technological maturation for numerous applications, including as a promising structural reinforcement, anti-wear and low friction material, and as a diffusion barrier. Graphene has been shown to be biocompatible and poses no cytotoxicity hazards, thus making it a green and eco-friendly additive. Being a purely carbonaceous material makes it biodegradable, so that long term issues with waste generation and disposal should not exist. It is imperative that the Navy evaluate this promising and maturing technology for use in naval applications. The time is ripe to transition graphene technology to naval applications that could benefit from enhanced resistance to wear and corrosion. Additive manufacturing is a converging technology that could enable graphene materials to be quickly transitioned and implemented into the Navy fleet as either new coatings or components. The additive processes of fused deposition modeling and cold spraying will be evaluated here to determine whether graphene infused polymer and metallic materials can be implemented to provide protection from wear and corrosion. Graphene infused materials will be 3D printed and deposited as coatings to evaluate wear resistance and resistance to salt fog and UV exposure. The source of graphene will be graphene nanoplatelets, which are commercially available at less than $1000/kg. Salt fog chamber testing, humidity and UV exposure testing, and wear tests will be conducted and analyzed to evaluate the efficacy of graphene infused materials for provided wear and corrosion protection. Analysis will be used to provide recommendations on the viability of harnessing and implemented graphene technology in the field for protection of ground vehicles and naval vessels from wear and corrosion.N9 - Warfare SystemsThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Graphene NanoPlatelets Reinforced Tantalum Carbide consolidated by Spark Plasma Sintering

Hypersonic aerospace vehicles are severely limited by the lack of adequate high temperature materials that can withstand the harsh hypersonic environment. Tantalum carbide (TaC), with a melting point of 3880°C, is an ultrahigh temperature ceramic (UHTC) with potential applications such as scramjet engines, leading edges, and zero erosion nozzles. However, consolidation of TaC to a dense structure and its low fracture toughness are major challenges that make it currently unviable for hypersonic applications. In this study, Graphene NanoPlatelets (GNP) reinforced TaC composites are synthesized by spark plasma sintering (SPS) at extreme conditions of 1850˚C and 80-100 MPa. The addition of GNP improves densification and enhances fracture toughness of TaC by up to ~100% through mechanisms such as GNP bending, sliding, pull-out, grain wrapping, crack bridging, and crack deflection. Also, TaC-GNP composites display improved oxidation behavior over TaC when exposed to a high temperature plasma flow exceeding 2500 ˚C

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Effects of Cold Spray Repairs on the Mechanical Properties of a Component

NPS NRP Project PosterCold dynamic gas spray, better known as cold spray, has generated much interest for repairing metallic components and depositing protective metal coatings. Naval shipyards recognize the potential of this technology to provide rapid repair and manufacturing capability and to replace welding as the state-of-the-art for metal joining and repairs. As cold spray evolves into a mature technology, there is a need to understand the mechanical behavior of widely used engineering alloys such as the cupronickel alloys. This study investigates the mechanical behavior of Cu-38Ni coatings cold sprayed onto Cu-10Ni substrates with and without an annealing heat treatment. The cold sprayed coated specimens undergo uniaxial tensile tests to study the durability of the cold sprayed coating layer and its effects on the overall mechanical behavior of the coated substrate. Annealing at 650 °C is found to enhance both the ductility and strength of the coating material. The annealed coating specimen experiences an elongation to failure of ~13.7%, while the as-sprayed specimen only experienced ~3.9% elongation. Adhesion tests show that annealing leads to a large increase in adhesion strength of the coating to the substrate due to solid state diffusion across the interface during the heat treatment. Annealing further leads to a reduction in pores, intersplat cracks and porosity, and a more ductile and tough material due to recrystallized grains. Nanoindentation reveals that the cold as-sprayed material is the hardest, but also the most brittle, exhibiting plasticity of only 81%, as compared to 89-90% for the annealed coating and the substrates.Naval Sea Systems Command (NAVSEA)ASN(RDA) - Research, Development, and AcquisitionThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Effects of Cold Spray Repairs on the Mechanical Properties of a Component

NPS NRP Executive SummaryCold dynamic gas spray, better known as cold spray, has generated much interest for repairing metallic components and depositing protective metal coatings. Naval shipyards recognize the potential of this technology to provide rapid repair and manufacturing capability and to replace welding as the state-of-the-art for metal joining and repairs. As cold spray evolves into a mature technology, there is a need to understand the mechanical behavior of widely used engineering alloys such as the cupronickel alloys. This study investigates the mechanical behavior of Cu-38Ni coatings cold sprayed onto Cu-10Ni substrates with and without an annealing heat treatment. The cold sprayed coated specimens undergo uniaxial tensile tests to study the durability of the cold sprayed coating layer and its effects on the overall mechanical behavior of the coated substrate. Annealing at 650 °C is found to enhance both the ductility and strength of the coating material. The annealed coating specimen experiences an elongation to failure of ~13.7%, while the as-sprayed specimen only experienced ~3.9% elongation. Adhesion tests show that annealing leads to a large increase in adhesion strength of the coating to the substrate due to solid state diffusion across the interface during the heat treatment. Annealing further leads to a reduction in pores, intersplat cracks and porosity, and a more ductile and tough material due to recrystallized grains. Nanoindentation reveals that the cold as-sprayed material is the hardest, but also the most brittle, exhibiting plasticity of only 81%, as compared to 89-90% for the annealed coating and the substrates.Naval Sea Systems Command (NAVSEA)ASN(RDA) - Research, Development, and AcquisitionThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

From High-Entropy Ceramics to Compositionally-Complex Ceramics: A Case Study of Fluorite Oxides

Using fluorite oxides as an example, this study broadens high-entropy ceramics (HECs) to compositionally-complex ceramics (CCCs) or multi-principal cation ceramics (MPCCs) to include medium-entropy and/or non-equimolar compositions. Nine compositions of compositionally-complex fluorite oxides (CCFOs) with the general formula of (Hf1/3Zr1/3Ce1/3)1-x(Y1/2X1/2)xO2-delta (X = Yb, Ca, and Gd; x = 0.4, 0.148, and 0.058) are fabricated. The phase stability, mechanical properties, and thermal conductivities are measured. Compared with yttria-stabilized zirconia, these CCFOs exhibit increased cubic phase stability and reduced thermal conductivity, while retaining high Young's modulus (~210 GPa) and nanohardness (~18 GPa). Moreover, the temperature-dependent thermal conductivity in the non-equimolar CCFOs shows an amorphous-like behavior. In comparison with their equimolar high-entropy counterparts, the medium-entropy non-equimolar CCFOs exhibit even lower thermal conductivity (k) while maintaining high modulus (E), thereby achieving higher E/k ratios. These results suggest a new direction to achieve thermally-insulative yet stiff CCCs (MPCCs) via exploring non-equimolar and/or medium-entropy compositions.Comment: 39 pages; 8 + 5 figures; Accepted for publications in Journal of the European Ceramic Society (1/7/2020

Experimental Analysis and Material Characterization of Ultra High Temperature Composites

Proceedings of ASME Turbo Expo 2021 Turbomachinery Technical Conference and Exposition GT2021Ultra high temperature ceramic (UHTC) materials have attracted attention for hypersonic applications. Currently there is significant interest in possible gas turbine engine applications of UHTC composites as well. However, many of these materials, such as hafnium carbide, zirconium carbide, and zirconium diboride, have significant oxidation resistance and toughness limitations. In addition, these materials are very difficult to manufacture because of their high melting points. In many cases, SiC powder is incorporated into UHTCs to aid in processing and to enhance fracture toughness. This can also improve the materials’ oxidation resistance at moderately high temperatures due to a crack-healing borosilicate phase. ZrB₂-SiC composites show very good oxidation resistance up to 1700 °C, due to the formation of SiO₂ and ZrO₂ scales in numerous prior studies. While this may limit its application to hypersonic applications (due to reduced thermal conductivity and oxidation resistance at higher temperatures), these UHTC-SiC composites may find applications in turbomachinery, as either stand-alone parts or as a component in a multi-layer system.This research was supported in part by an appointment to the Postdoctoral Research Participation Program at the U.S. Army Research Laboratory administered by the Oak Ridge Associated Universities through an interagency agreement between the U.S. Department of Energy and DEVCOM ARL. Research was sponsored by the Army Research Laboratory and was accomplished under Cooperative Agreement Number W911NF-16-2-0008. The first author would like to acknowledge the support of DoD Laboratory University Collaborative Initiative (LUCI) Fellowship [2016-2019]. The UHTC specimen fabrication via Spark Plasma Sintering processing was done at UCSD by UCSD and DEVCOM ARL. The ablation experimental testing was conducted at DEVCOM ARL. The microstructure analysis and characterization were performed at NPS.W911NF-16-2-000