Development of tungsten diamond composites for nuclear fusion applications

该项目将专注于聚变应用的钨金刚石复合材料的分析和开发。技术背景ITER偏滤器等离子体面对组件(PFC)的设计能够承受10 mW m-2的稳态表面加热。作为比较，航天器再入过程中的隔热罩约为1 mW m-2，弧焊机约为10-80 mW m-2，低温冷却火箭发动机喷管约为50-150 mW m-2。在过去的25年里，聚变方面的进展在很大程度上依赖于在高热流密度地区使用细粒石墨和碳纤维复合材料，那里的碳技术是从裂变和航空航天工业中改编而来的。最近，碳表面被高性能的钨薄膜(10-200微米)增强，以提高耐腐蚀性。在类似的时间范围内，来自CVD的钻石已经变得容易获得。英国能源署从2007年到2010年的一项研究计划包括：(I)暴露在高热流电子束测试下的5毫米厚的掺硼平板原型，以及(Ii)暴露在几个聚变设备中的等离子体中的薄膜。CVD钻石之所以令人感兴趣，是因为与所有其他材料相比，钻石具有许多通常是同类中最好的相关特性：-在室温下各向同性导热系数比铜高5倍，-非常低的热膨胀，-以上结合在一起提供了无与伦比的抗热震性，-升华而不是熔化，-在气体环境中与氢的低化学反应活性，-与许多金属形成牢固的碳化物化学键，包括钨，-高抗拉强度，-良好的抗中子辐射损害。目标是致力于开发和分析钨钻石复合材料。这将有助于开发多层复合钨金刚石材料，以：a)降低化学反应活性，b)增加对物理溅射的耐蚀性，c)在高温下略微改善延展性，以及d)准自修复，因为如果表面膜丢失，钻石将被侵蚀直到形成新的钨层。该项目将致力于开发钨钻石复合材料和潜在的多层复合材料，并在与熔化相关的条件下对它们进行测试。实验分析技术将被用来评估新材料的质量。

This project will focus on the analysis and development of tungsten diamond composites for fusion applicationsTechnical ContextITER divertor plasma facing components (PFCs) are engineered to withstand 10 MW m-2 of steady-state surface heating. For comparison, the value is approximately 1 MW m-2 for a spacecraft heat shield during re-entry, 10-80 MW m-2 for an arc welder, and 50-150 MW m-2 for a cryogenically cooled rocket engine nozzle. For the last 25 years, progress in fusion has largely relied on the use of fine grain graphite and carbon fiber composites in the high heat-flux regions, where the carbon technology was adapted from the fission and aerospace industries. More recently, the carbon surface has been enhanced with high performance tungsten thin films (10-200 microns) in order to increase erosion resistance. Over a similar timeframe, diamond from CVD has become readily available. A UKAEA led research programme from 2007-2010 included: (i) a 5 mm thick boron-doped plate prototype exposed to high heat-flux electron beam testing, and (ii) thin films exposed to plasma in several fusion devices.CVD diamond is of interest because diamond has many relevant properties that are often best-in-class compared to all other materials: -isotropic thermal conductivity 5 times higher than copper at room temperature,-very low thermal expansion,-the above combine to give diamond unparalleled thermal shock resistance,-sublimates instead of melting,-low chemical reactivity with hydrogen in a gas environment,-forms strong carbide chemical bonds with many metals, including tungsten,-high tensile strength, and-good resistance to neutron radiation damage.Objective The goal is to work on developing and analysing tungsten diamond composites. This will contribute to the development of a multi layered composite tungsten diamond material in order to:a) reduce chemical reactivity, b) increase the erosion resistance to physical sputtering,c) marginal improved ductility at elevated temperatures, andd) quasi-self-repairing, since the diamond erodes until a new tungsten layer if the surface film is lost.This project will work on developing tungsten diamond composites and potentially a multi-layer composite and test them under fusion relevant conditions. Experimental analysis techniques will be used to assess the quality of the novel material.