Composite Nanoparticle Materials for Electromagnetics

This thesis summarizes the work done toward the fabrication of a novel composite material that is projected as a viable replacement for conventionally used magnetic core materials in various electromagnetic applications. Conventional linear and rotary electric motors, generators and actuators are too bulky to be used in lightweight applications. The major component of weight in electromagnetic devices is the magnetic core, usually made of soft iron. Further, losses due to eddy currents and magnetic remnance occur in soft iron cores. This thesis discusses the different materials suitable that might be to replace soft iron in electromagnetic devices, Methods developed to fabricate different composite cores and their characterization is presented. The composite cores consist of one or more nanoparticle materials consolidated into a polymer or elastomer matrix material. Nanoparticles such as Carbon Nanosphere Chains, Carbon Nano Fibers and Superparamagnetic Iron Oxide nanoparticles were used to fabricate the cores. Superparamagnetic iron oxide nanoparticles were selected as the best among the available materials to achieve optimal core properties needed for electromagnetic applications. As described in this thesis, the ability to control the properties of the cores by varying the types and quantities of the materials used in the process of fabrication is an important advantage over soft iron. A permanent magnet is used to lift the cores to approximately measure the Relative magnetic permeability of the fabricated cores. A Digital Multimeter is used for the measurement of Resistivity of the cores. An Instron Tensile Testing machine is used to determine the strength of the cores. The specific permeability of the superparamagnetic iron oxide powder nanocomposite cores relative to soft iron was measured and the percentage of nanoparticles in the matrix material was increased to increase the magnetic permeability. Superparamagnetic nanoparticles may exhibit higher overall Magnetic Moment compared to paramagnetic materials, and lower core losses compared to ferromagnetic materials, of similar volume fraction. The work documented in this thesis details a process that involves: (i) Nanomaterial Selection, (ii) Matrix Material Selection, (iii) Magnetic Core Fabrication, (iv) Core Material Characterization, and (v) Results Comparison with soft iron. The specific permeability’s of the fabricated nanocomposite material and soft iron were found to be similar when measured using a permanent magnet. The electrical resistivity of the nanocomposite material when compared to soft iron is very high resulting in lower eddy current losses making it suitable for high frequency operations. Future work would consist of testing for superparamagnetic behavior over the entire sample, accurate measurement of the magnetic permeability using a Superconducting Quantum Interference Device (SQUID) or a Vibrating Sample Magnetometer (VSM) and finding ways to improve dispersion of the nanoparticles such as coating the surfaces of individual particles to prevent agglomeration. The nanocomposite core material can then be tested in low and high frequency applications including electric motors, generators, electromagnetic shielding, smart materials, biomedical devices, morphing air foils, switches, sensors and many of the other possibly hundreds of applications that use electromagnetics.

Name thesis:degree_name

MS

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Engineering and Applied Science: Mechanical Engineering

Grantor dc:publisher

University of Cincinnati

Year dc:date

2012

Author dc:creator

• Venkatasubramanian, Rajiv

Contributors dc:contributor

• Schulz, Mark

• Engineering
• Mechanical Engineering
• Nanotechnology
• Magnetism
• Electromagnetics
• Composites
• Nanoparticles

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=ucin1352993374

OAI identifier oai:identifier

oai:etd.ohiolink.edu:ucin1352993374