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Structural integrity characterisation of nuclear materials via nano additive manufacturing

通过纳米增材制造对核材料进行结构完整性表征

基本信息

批准号：
EP/P034446/1
负责人：
ANTON SHTERENLIKHT
金额：
$ 25.71万
依托单位：
University of Bristol
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FP034446%2F1
关键词：
Structural integrity characterisation nuclear materials

项目摘要

We need to know the behaviour of novel materials in the presence of high irradiation and high temperature before we could embark on building advanced Generation IV and fusion nuclear systems. However, health and safety issues prevent us from testing macromechanical irradiated coupons in the laboratory. The solution is to test very small volumes of irradiated material, i.e. micromechanical coupons, and use multi-scale modelling to extrapolate the measured behaviour to macromechanical components. Because of their very low volume such specimens can be lab tested, even when irradiated to low or medium level of activity. This offers a possibility of testing multiple specimens to investigate stochastic effects, e.g. effects of irradiation on the shift of the ductile to brittle transition. The manufacturing technology is fast moving from subtractive methods to additive methods. Additive manufacturing can produce geometries which so far have not been possible using the traditional subtraction (e.g. milling) methods. The advances of additive manufacturing, so far, have not been replicated in micromechanical testing. Currently the common method for fabricating micromechanical coupons is to use Gallium or Helium Focused Ion Beam (FIB) micro-milling. In FIB milling, charged ions of helium or gallium are focused on the sample, sputtering the parent material in a pre-defined geometry until the desired shape is milled. The subtractive FIB milling method not only is not representative of additive manufacturing foreseen to be used in future nuclear complete fabrication, it leaves damages such as helium bubbles or gallium implantation in the milled micromechanical samples. It is therefore highly desirable to develop a new method to fabricate micro-scale micromechanical testing coupons that do not suffer from FIB damage (i.e. helium or gallium implantation or in severe cases, parent material amorphisation).In this feasibility study, we will investigate the applicability of a novel nano-additive manufacturing methodology, originally developed for tuneable optical systems, to fabricate micromechanical specimens. We will be using three-dimensional direct laser method to produce a 3D polymer scaffolding of the negative desired structure, we will then deposit the parent material (tungsten, iron or carbon) on the polymer scaffolding using electron beam induced deposition. We then remove the polymer by inductively coupled oxygen plasma, and finally fill out the scaffolding with parent material using thermal evaporation, electron beam induced deposition or chemical vapour deposition depending on the material. This method allows us to produce a micromechanical test coupon with desired geometry with an accuracy of at least one order of magnitude better than FIB milling. This is especially important for fabricating specimens that contain cracks as the natural cracks occurring in service components, for example due to corrosion, are very sharp which are hard to replicate using FIB milling. We will investigate the fracture behaviour of nanometre cracks in our micro-scale specimens by X-ray nano-tomography. Using X-ray nano-tomography will allow us to observe, in real time, the interaction of the crack with the surrounding microstructure. The information obtained from micro-fracture tests will validate our cellular automata finite element model which we then use to extrapolate the results to a macro-scale component.If successful, in future we will neutron irradiate the nano-additively manufactured specimens to investigate the effects of irradiation damage on the structural integrity of components with complex geometries. Complex geometry specimens irradiated with a high dose are important for fusion plants as the geometry of many structural components is complex and dictated by physics. Thus in the follow-on research we will be working with Culham Centre for Fusion Energy, National Nuclear Laboratory and Nuclear Advanced Manufacturing Research Centre.

在我们着手建造先进的第四代核聚变系统之前，我们需要知道新材料在高辐射和高温下的行为。然而，健康和安全问题阻止我们在实验室测试宏观机械辐照券。解决方案是测试非常小体积的辐照材料，即微力学材料，并使用多尺度建模来推断宏观力学部件的测量行为。由于它们的体积非常小，即使辐照到低或中等水平的活动，也可以进行实验室测试。这提供了测试多个试样来研究随机效应的可能性，例如辐照对韧脆性转变的影响。制造技术正迅速从减法向增法发展。增材制造可以产生迄今为止使用传统减法（例如铣削）方法无法实现的几何形状。到目前为止，增材制造的进步还没有在微机械测试中得到复制。目前制造微机械薄片的常用方法是镓或氦聚焦离子束（FIB）微铣削。在FIB铣削中，氦或镓的带电离子聚焦在样品上，以预先定义的几何形状溅射母材，直到所需的形状被铣削。减法FIB铣削方法不仅不能代表未来核完整制造中预期使用的增材制造，而且会在铣削的微机械样品中留下氦气泡或镓植入等损伤。因此，非常需要开发一种新方法来制造不会遭受FIB损伤的微尺度微机械测试片（即氦或镓植入，或者在严重的情况下，母材变形）。在这项可行性研究中，我们将研究一种新型纳米增材制造方法的适用性，这种方法最初是为可调谐光学系统开发的，用于制造微机械样品。我们将使用三维直接激光方法生产负期望结构的3D聚合物脚手架，然后我们将使用电子束诱导沉积将母材（钨，铁或碳）沉积在聚合物脚手架上。然后，我们通过电感耦合氧等离子体去除聚合物，最后根据材料的不同，使用热蒸发、电子束诱导沉积或化学气相沉积的方法填充母体材料。这种方法使我们能够生产出具有所需几何形状的微力学测试片，其精度至少比FIB铣削好一个数量级。这对于制造含有裂纹的试样尤其重要，因为服务部件中发生的自然裂纹（例如由于腐蚀）非常尖锐，很难用FIB铣削来复制。我们将通过x射线纳米断层扫描研究我们的微尺度样品中纳米裂纹的断裂行为。利用x射线纳米层析成像技术，我们可以实时观察到裂纹与周围微观结构的相互作用。从微断裂试验中获得的信息将验证我们的元胞自动机有限元模型，然后我们使用该模型将结果外推到宏观尺度组件。如果成功，未来我们将对纳米增材制造的样品进行中子辐照，以研究辐照损伤对复杂几何形状部件结构完整性的影响。由于许多结构部件的几何形状复杂且受物理特性的制约，因此高剂量辐照的复杂几何样品对核聚变电站非常重要。因此，在后续研究中，我们将与Culham聚变能中心、国家核实验室和核先进制造研究中心合作。