ENDURANCE: Graphene based coatings for durable wear resistance low cost position sensors

由Choy教授开发的气溶胶辅助离子沉积（AAID）是一种新颖，非真空，成本效益和环保的方法，用于非视线沉积薄涂层和厚涂层到3D结构（非保形基板），并在纳米尺度上控制结构和成分。均匀石墨烯基纳米复合涂层的制造涉及化学前体的配方，可以是溶液或悬浮液，并将前体雾化以产生精细带电的气溶胶。这允许控制液滴的动力学和它们的蒸发形成由聚合物离子组成的液滴，导致聚合物薄膜的沉积，结合石墨烯基纳米材料，形成在开放气氛中具有均匀和良好控制结构的纳米复合涂层。在ENDURANCE项目中，我们将把这项技术应用于电位器雨刷头的石墨烯基纳米复合涂层的开发，目标是获得1至300欧姆/平方之间的优异导电性和耐磨性。在我们的研究中需要解决的主要挑战包括：(1)石墨烯界面：对石墨烯与石墨烯材料接触磨损性能的了解有限——我们将探索石墨烯涂层配方、化学/物理性能与石墨烯与石墨烯界面磨损性能之间的关系；(2)涂层稳定性：在固化过程中实现完全聚合，从而实现长期涂层稳定性——我们将探索石墨烯油墨配方与固化性能之间的关系，从而优化快速稳定的固化；(3)涂层表面：确保石墨烯在涂层表面集中，使表面性能得以实现——我们将评估利用静电（斥力）和配方密度促进石墨烯表面聚集的可行性；(4)涂层附着力：石墨烯传统上与材料表面的附着力较差，从而限制了涂层的磨损稳定性——我们将探索涂层配方、基材表面处理和层厚，以提高附着力和磨损性能；(5)导电性：高导电性要求石墨烯层之间具有良好的连通性，这可能很难实现——我们将探索添加导电添加剂和表面处理来提高涂层的导电性。我们的研究方法将遵循三个关键阶段（任务）：配方筛选：将使用标准配方筛选纳米复合成分（石墨烯、纳米管、表面活性剂、粘合剂、交联剂、溶剂、润滑剂等），以了解配方、AAID加工和涂层性能（粘附、导电、磨损和固化）之间的关系。涂层配方：将研究不同的涂层配方，以在材料和加工要求的约束下实现目标性能。将选择有限数量的系统进行进一步研究。任务3。第一代油墨开发：选定的涂料配方将经历多个开发周期，以优化一致性，可靠性，磨损，流变学，固化等。将考虑基材化学（蚀刻）和物理表面改性策略来提高涂层的附着力。将使用摩擦计测试装置来评估磨损和涂层附着力。我们还将支持使用统计分析方法（性能分析）和磨损样品分析来研究石墨烯与石墨烯界面的磨损特性，以了解磨损机制。

Developed by Prof. Choy, Aerosol Assisted Ion Deposition (AAID) is a novel, non-vacuum, cost effective and eco-friendly method for the non-line-of-sight deposition of both thin and thick coatings to 3D structure (non-conformal substrates) with control of structure and composition at the nanoscale. The fabrication of uniform graphene based nano-composite coatings, involves formulation of chemical precursors, which can be a solution or a suspension, and atomisation of the precursor to generate a finely charged aerosol. This allows control of the dynamics of droplets and their evaporation to form droplets consisting of polymeric ions, leading to the deposition of polymeric films incorporating with graphene based nanomaterials to form nanocomposite coatings with uniform and well-controlled structures in an open atmosphere. Within the ENDURANCE project we will apply this technique for the development graphene based nanocomposite coatings on potentiometer wiper heads targeting excellent conductivity between 1 and 300 ohm/square and wear resistance. Key challenges to be addressed in our research include: (1) Graphene interfaces: Limited knowledge of wear properties for graphene to graphene material contacts - we will explore the relationships between graphene coating formulation, chemical / physical properties and the wear properties at graphene to graphene interfaces; (2) Coating stability: Achieving complete polymerisation during cure thereby enabling long term coating stability - we will explore the relationships between graphene ink formulation and cure properties enabling optimisation of rapid and stable cure; (3) Coating surfaces: Ensuring graphene is concentrated at the coating surface to enable the surface properties to be realized- we will assess the feasibility to utilise electrostatic (repulsion) and formulation density to promote surface aggregation of graphene; (4) Coating adhesion: Graphene traditionally has poor adhesion to material surfaces thereby limited coating wear stability - we will explore coating formulations, substrate surface treatments and layer thickness to improve adhesion and wear performance; and (5) Conductivity: High conductivity requires excellent connectivity between graphene layers which may be difficult to achieve - we will explore the addition of both conductive additives and surface treatments to promote coating conductivity. Our research approach will follow three key phases (tasks): Task 1. Formulation Screening: nano-composite ingredients will be screened (graphene, nano-tubes, surfactants, binders, cross linkers, solvents, lubricants etc...) using standard formulations to understand relationships between formulation, AAID processing, and coating properties and performance (adhesion, conduction, wear and cure) Task 2. Coating formulation: different coating formulations will be investigated to achieve the target properties within the constraints of the material and processing requirements. A limited number of systems will be selected for further study. Task 3. First generation ink development: selected coating formulations will undergo a number of development cycles to optimise consistency, reliability, wear, rheology, cure etc. Substrate chemical (etching) & physical surface modification strategies will be considered to improve coating adhesion. A tribometer test rig will be used to assess wear and coating adhesion. We will also support investigation of graphene to graphene interface wear properties using statistical analysis methods (performance analysis) and analysis of wear samples to understand the wear mechanisms.