Contactless Ultrasonic Processing for Liquid Metals

液态金属的非接触式超声波加工

• 批准号: EP/P034411/1
• 负责人: Koulis Pericleous
• 金额: $ 46.38万
• 依托单位: University of Greenwich
• 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%2FP034411%2F1
• 关键词: Contactless; Ultrasonic; Processing; Liquid; Metals

In the quest for lighter, stronger metals for the transport and aerospace industry we aim in this research to develop and evaluate a contactless electromagnetic excitation device producing vibration in liquid metal melts, for the purpose of Ultrasonic treatment (UST). UST of light alloy metals (aluminium or magnesium) at the liquid state, has been shown to improve their final mechanical properties, leading to finer microstructure, removal of dissolved gases, or dispersion of strengthening particles. A 'sonotrode' probe immersed in the melt is commonly used for this UST process, vibrating at ultrasonic frequency (~20-100 kHz) and generating intense sound waves in the molten metal. These pressure waves cause dissolved gas to come out of solution in the form of micro-bubbles (think of champagne), then oscillate in size and either implode generating high speed jets and shock waves or enlarge to the point where they float to the surface and out of the melt. This cavitation phenomenon assists crystal nucleation and/or breaks up emerging dendritic crystals to reduce grain size and so improve material properties. Strengthening particles in the form of oxides are used in metal composites to improve their properties. However, it is difficult to disperse these particles evenly, ensuring homogeneous performance in the final component. Furthermore, very small particles tend to cluster together becoming defects. The action of shock waves produced by collapsing bubbles is known to break up particle clusters, but then strong stirring is also needed to disperse them evenly. The same particle dispersion requirement is needed in aluminium recycling, to disperse unwanted inclusions, such as oxides or ferritic intermetallic particles. So UST is a very useful process but even in low temperature melts (Al, Mg), there are problems preventing widespread use by industry: the immersed probe is consumed contaminating the melt; the mass treated is restricted to a small volume surrounding the sonotrode horn, and further mechanical stirring is then necessary to spread the effect. Contactless UST as proposed here will avoid contamination and the cost of exotic probe materials, transferring the potential benefits of UST to a wider range of alloys, avoiding most of the drawbacks: (a) Bulk stirring is automatically generated by the electromagnetic 'Lorentz' force, (b) Scale-up is easy, since the induction coil can be designed to fit the application, provided the supply frequency is tuned to promote resonance, (c) Since there is no contact, there is no contamination of the melt, or need for a frequent probe replacement and finally (d) high temperature or reactive metals used in power or aeroengine applications can be treated in the same way (viz. nuclear steels, nickel and titanium alloy blades) The patented 'Contactless Sonotrode' concept originated from theoretical work and computer simulations carried out in Greenwich; but to translate its immense theoretical potential into a useful manufacturing technique, careful practical validation is needed through the proposed experimental programme at Birmingham and Oxford Universities. A prototype installation at Birmingham will investigate light alloys, steel and nickel in crucible melts, whilst Oxford will test the idea in the Direct Chill (DC) continuous casting process for aluminium ingot production.

为了寻求更轻、更坚固的金属，用于运输和航空航天工业，我们在这项研究中的目标是开发和评估一种在液态金属熔体中产生振动的非接触式电磁激励装置，用于超声波处理(UST)。已证明，轻合金金属(铝或镁)在液态下的UST可以改善其最终的机械性能，导致更细小的组织、溶解气体的去除或强化颗粒的分散。在这种UST过程中，通常使用浸入熔体中的“声电极”探头，以超声波频率(~20-100 kHz)振动，并在熔融金属中产生强烈的声波。这些压力波导致溶解的气体以微泡的形式从溶液中出来(想想香槟)，然后在大小上振荡，要么内爆，产生高速射流和冲击波，要么放大到漂浮到表面并从熔体中出来。这种空化现象有助于晶体形核和/或分解新出现的树枝晶，从而减小晶粒尺寸，从而改善材料的性能。在金属复合材料中使用氧化物形式的强化颗粒来改善其性能。然而，很难将这些颗粒均匀分散，以确保最终组件具有均匀的性能。此外，非常小的颗粒往往聚集在一起成为缺陷。众所周知，气泡坍塌产生的冲击波作用会分解粒子团，但随后还需要强有力的搅拌才能使它们均匀分散。在铝回收中需要同样的颗粒分散要求，以分散不需要的夹杂物，如氧化物或铁素体金属间化合物颗粒。因此，UST是一个非常有用的过程，但即使在低温熔体(铝、镁)中，也有一些问题阻碍了工业的广泛使用：浸入的探头被消耗掉，污染了熔体；处理的质量被限制在声极喇叭周围的小体积内，然后需要进一步的机械搅拌来传播效果。这里提出的非接触式UST将避免污染和外来探头材料的成本，将UST的潜在好处转移到更广泛的合金中，避免了大多数缺点：(A)由电磁‘洛伦兹’力自动产生主体搅拌，(B)放大容易，因为感应线圈可以被设计成适合应用，只要电源频率被调节以促进谐振，(C)由于没有接触，所以不会污染熔体，或需要频繁更换探头，最后(D)在动力或航空发动机应用中使用的高温或活性金属可以同样的方式处理(即。核钢、镍和钛合金叶片)获得专利的“非接触式声电极”概念源于格林威治的理论工作和计算机模拟；但要将其巨大的理论潜力转化为有用的制造技术，需要通过伯明翰和牛津大学拟议的实验计划进行仔细的实践验证。伯明翰的一个原型装置将研究坩埚熔体中的轻合金、钢和镍，而牛津大学将在用于生产铝锭的直接冷却(DC)连铸工艺中测试这一想法。

项目成果

Light Metals 2023

轻金属 2023

• DOI: 10.1007/978-3-031-22532-1_131
• 发表时间: 2023
• 作者: Beckwith C

Liquid Metal Flow Studied by Positron Emission Tracking

通过正电子发射跟踪研究液态金属流动

• DOI: 10.1007/s11663-020-01897-7
• 发表时间: 2020
• 期刊: Metallurgical and Materials Transactions B
• 作者: Dybalska A

Comparison of frequency domain and time domain methods for the numerical simulation of contactless ultrasonic cavitation.

• DOI: 10.1016/j.ultsonch.2022.106138
• 发表时间: 2022-09
• 期刊: ULTRASONICS SONOCHEMISTRY
• 影响因子: 8.4
• 作者: Beckwith, Christopher;Djambazov, Georgi;Pericleous, Koulis;Tonry, Catherine
• 通讯作者: Tonry, Catherine

Electromagnetic particle separation in the cold crucible melting with novel type bottom pouring nozzle

• DOI: 10.1088/1757-899x/424/1/012029
• 发表时间: 2018-10
• 期刊: IOP Conference Series: Materials Science and Engineering
• 作者: V. Bojarevics;K. Pericleous

Patent: Manufacturing of a metal component or a metal matrix composite component involving contactless induction of high - frequency vibrations

专利：涉及非接触式高频振动感应的金属部件或金属基复合材料部件的制造

• 发表时间: 2019
• 作者: Jarvis DJ