RUI: Field-Induced Phase Transitions in Monodisperse Ferrofluid Emulsions

RUI：单分散铁磁流体乳液中的场诱导相变

• 批准号: 9321201
• 负责人: Jing Liu
• 金额: --
• 依托单位: California State University-Long Beach Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-02-15 至 1998-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9321201&HistoricalAwards=false
• 关键词: RUI; Field; Induced; Phase; Transitions

9321201 Liu The proposal is to explore experimentally the rich phase behavior exhibited in a confined colloidal suspension, a monodisperse ferrofluid (oil-in-water) emulsion. An externally applied magnetic field induces a large magnetic moment in each droplet, leading to a transition of the suspension from a fluid-like phase to a more ordered phase. The various phases can consist of separated chains, ordered columns, or a complex labyrinthine pattern. The evolution of the structure that forms, and its dependence on various key parameters will be investigated. These field induced structures dramatically modify the viscosity of the fluid, making this system an ideal model for a magnetorheological fluid. Thus the results are expected to lead to new insight into the fascinating phase behavior of these systems and provide guidelines for making technologically important materials with fundamentally new properties. %%% The proposal is to experimentally explore the phase behavior of a suspension of small droplets of oil immersed in water. Each oil droplet is uniform in size and contains thousands of tiny floating magnets. An externally applied magnetic field reorients the tiny magnets so that each droplet acts like a big magnet. This causes the droplets to line up into chains such that the suspension undergoes a phase transition. These field-induced new phases modify the viscosity of the fluid dramatically, turning the liquid into a solid which may lead to the development of actively controlled shock absorbers and clutches for cars or robotic joint controls. This research is to study the field-induced structural change of these systems and to provide guidelines for making technologically important materials with fundamentally new properties. ***

9321201 LIU该提案是在实验中探索在密闭胶体悬浮液中表现出的丰富相行为，该悬浮液（一种单分散的铁氟烷（水中）乳液）。 外部施加的磁场会在每个液滴中诱导一个较大的磁矩，从而导致悬浮液从流体样相转变为更有序的相。 各个阶段可以由分离的链，有序的柱或复杂的迷宫模式组成。 将研究形成的结构的演变及其对各种关键参数的依赖。 这些场诱导的结构大大改变了流体的粘度，使该系统成为磁性流体的理想模型。 因此，结果有望导致对这些系统的迷人阶段行为的新见解，并为使具有从根本上新属性的技术重要材料提供指南。 该建议是实验探索浸入水中的小滴油的悬浮液的相行为。 每个油滴的尺寸均匀，包含数千个微小的浮动磁铁。 外部施加的磁场对微小的磁铁进行了重新定制，使每个液滴的作用像大磁铁。 这会导致液滴排成链，使悬架发生相变。 这些场引起的新阶段会急剧改变流体的粘度，使液体变成固体，这可能导致汽车或机器人关节控制的积极控制的减震器和离合器的发展。 这项研究是研究这些系统的现场引起的结构变化，并提供了使具有从根本上新属性的技术重要材料制造的指南。 ***