Functional Surfaces via Electrical Discharge Methods

通过放电方法的功能表面

• 批准号: EP/L017482/1
• 负责人: Adam Clare
• 金额: $ 25.29万
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FL017482%2F1
• 关键词: Functional; Surfaces; via; Electrical; Discharge

Electrical discharge machining (EDM) is an excellent process of realising complex features in tough materials. EDM makes use of repeated electrical discharges to remove material from a workpiece. Each discharge constitutes a plasma channel which results in removal of a small amount of material from both the EDM machine's electrode ('the tool') and the work piece. Machine parameters and spark conditions are optimised such that under typical conditions more material is removed from the work piece when compared to the tool per discharge. When the plasma arc strikes a localised region is rapidly heated and liberated from the bulk. This 'debris' is then normally evacuated from the spark gap by the so called flushing mechanism. The spark gap is in an incredibly tempestuous place and hence very difficult to understand. However, knowledge of this behaviour is crucial to advancing our understanding of ED techniques for industrial applications.It has been shown that under the correct physical conditions in the spark gap the debris created by these discharges can be used to apply a coating and build low aspect ratio surface structures. This presents an interesting opportunity to high value manufacturers who are often tasked with machining precision features and then applying precision coatings or, perhaps, repairing worn regions in high value components. However, the physics of this process is not yet fully understood and there remains a requirement to advance this technology significantly from fundamental principles.This project will explore the technology from a new, multidisciplinary perspective which will incorporate both experimental and modelling activities. The investigators will present a solid understanding of the debris dynamics electrical discharge coating techniques to the community and will use this new knowledge to create complex multi-layer coatings which will have applications in the aerospace, biomedical and tool making industries. Companies operating in these industries thrive on the technological advantage their products possess over competitors. For example all of these products require advanced tribological properties amongst other complex surface characteristics. There is an array of surface modification techniques available to manufactures such as laser cladding, cold/plasma spray, PVD amongst others which have developed rapidly in the last 20 years. However, none of these have been directly integrated into a process which can also remove material. The rapid adoption of all of these coating techniques has been borne out of a solid understanding of the process mechanics, materials science and optimisation for application. In all of the high value applications for these coating techniques surface integrity is critical since failures which occur as a result of corrosion, fatigue or high temperature effects emanate from the surface or near surface. Enhancing surface integrity is the core rationale for surface treatment although coatings are also often applied for aesthetic purposes also.EDM itself has developed significantly in recent years with modern machine makers claiming to have developed processes capable of the so called 'near zero' recast layer. This is in response to the extensive studies which have been undertaken on the surface damage that results from EDM and is known to induce deleterious tensile stresses. However, no solid solution to this has been developed which means the confidence in EDM surface layers is currently low. However, the application of consolidated coatings may be able to tackle this problem and will be investigated in this project. The ability to remove material and apply a coating within the same process presents significant advantages. Therefore the use of ED coating methods has great potential to enhance high value manufacturing in terms of enhanced product performance but also through process efficiency savings.

电火花加工(EDM)是一种在韧性材料中实现复杂特征的优良工艺。电火花加工利用重复放电从工件上去除材料。每一次放电都构成一个等离子体通道，导致从电火花机床的电极(刀具)和工件上去除少量的材料。优化了机床参数和火花条件，使得在典型条件下，与每次卸料时刀具相比，从工件上去除的材料更多。当等离子弧击中局部区域时，该区域被迅速加热并从块体中释放出来。然后，这些“碎片”通常通过所谓的冲刷机制从火花隙中排出。火花隙位于一个令人难以置信的狂风暴雨的地方，因此非常难以理解。然而，对这种行为的了解对于促进我们对工业应用的电火花技术的理解是至关重要的。已经表明，在正确的物理条件下，在火花隙中，由这些放电产生的碎片可以用于涂覆涂层和建立低长宽比的表面结构。这为高价值制造商提供了一个有趣的机会，他们的任务通常是加工精密特征，然后应用精密涂层，或者修复高价值部件的磨损区域。然而，这一过程的物理学还没有完全理解，仍然需要从基本原理上大幅推进这项技术。这个项目将从一个新的、多学科的角度来探索这项技术，其中将包括实验和建模活动。研究人员将向社会介绍对碎片动力学电火花涂层技术的坚实理解，并将利用这一新知识创建复杂的多层涂层，这些涂层将在航空航天、生物医学和工具制造行业中应用。经营这些行业的公司依靠其产品相对于竞争对手拥有的技术优势而蓬勃发展。例如，所有这些产品都需要先进的摩擦学性能，以及其他复杂的表面特性。有一系列表面改性技术可供制造商使用，如激光熔覆、冷/等离子喷涂、PVD等，这些技术在过去20年中发展迅速。然而，这些都没有直接集成到也可以去除材料的过程中。所有这些涂层技术的迅速采用都是基于对工艺机械、材料科学和应用优化的扎实理解。在所有这些涂层技术的高价值应用中，表面完整性是至关重要的，因为由于腐蚀、疲劳或高温效应导致的失效是从表面或近表面发出的。提高表面完整性是表面处理的核心原理，尽管涂层也经常用于美学目的。近年来，电火花加工本身也有了很大的发展，现代机械制造商声称已经开发出了能够实现所谓的近零重铸层的工艺。这是对电火花加工引起的表面损伤进行的广泛研究的回应，众所周知，电火花加工会导致有害的拉应力。然而，还没有开发出解决这一问题的固体解决方案，这意味着目前对电火花加工表面层的置信度很低。然而，固结涂层的应用可能能够解决这一问题，并将在该项目中进行研究。在同一工艺中去除材料并涂覆涂层的能力显示出显著的优点。因此，使用电火花镀膜方法在提高产品性能的同时，也通过节省工艺效率，在提高高价值制造方面具有巨大的潜力。

项目成果

Electrical discharge coating of nanostructured TiC-Fe cermets on 304 stainless steel

• DOI: 10.1016/j.surfcoat.2016.09.062
• 发表时间: 2016-12-15
• 期刊: SURFACE & COATINGS TECHNOLOGY
• 影响因子: 5.4
• 作者: Algodi, Samer J.;Murray, James W.;Brown, Paul D.
• 通讯作者: Brown, Paul D.

Heat-treatment and mechanical properties of cold-sprayed high strength Al alloys from satellited feedstocks

• DOI: 10.1016/j.surfcoat.2019.05.043
• 发表时间: 2019-09-25
• 期刊: SURFACE & COATINGS TECHNOLOGY
• 影响因子: 5.4
• 作者: Al-Hamdani, Kamaal S.;Murray, James W.;Clare, Adam T.
• 通讯作者: Clare, Adam T.

Formation mechanism of electrical discharge TiC-Fe composite coatings

• DOI: 10.1016/j.jmatprotec.2016.12.011
• 发表时间: 2017-05-01
• 期刊: JOURNAL OF MATERIALS PROCESSING TECHNOLOGY
• 影响因子: 6.3
• 作者: Murray, J. W.;Algodi, S. J.;Clare, A. T.
• 通讯作者: Clare, A. T.

Defect-free TiC/Si multi-layer electrical discharge coatings

• DOI: 10.1016/j.matdes.2018.06.019
• 发表时间: 2018-10
• 期刊: Materials & Design
• 影响因子: 8.4
• 作者: J. Murray;R. Cook;N. Senin;S. J. Algodi;A. Clare

Characterisation of TiC layers deposited using an electrical discharge coating process

使用放电涂层工艺沉积的 TiC 层的表征

• DOI: 10.1088/1742-6596/644/1/012008
• 发表时间: 2015
• 期刊: Conference Series
• 作者: Algodi S