Temperature-dependent dynamic response in epoxy-free and epoxy-bonded ME composite: a comparative study

Abstract

This work presents an experimental comparative study of the frequency-dependent response of the epoxy-free magnetoelectric (ME) composite against epoxy-bonded two-phase and threephase ME composites of various configurations at varying operating temperatures. Conventionally, ME composites are prepared by bonding the piezoelectric and magnetostrictive material phases by means of an epoxy material. Therefore, the response of the composite becomes a function of the properties of the epoxy used. Since the epoxy properties degrade significantly with increase in temperature, the ME response of the ME composite becomes poor at elevated temperatures. In this work, two-phase and three-phase epoxy-free ME composite has been fabricated by employing a press-fit embedded structure and compared with similar epoxybonded embedded structure as well as conventional layered ME composite. Frequencydependent experiments have been conducted at various temperatures and the responses from the two types of composites have been compared. Magnetostriction measurements at different temperatures have been conducted on individual magnetostrictive constituents to observe the effect of piezomagnetic coefficient on the ME response. It is observed that the ME responses of the epoxy-free composites at room temperature are nearly equivalent to their epoxy-bonded counterparts, whereas at higher temperatures the epoxy-free ring composite offers a much better response. The effect of demagnetizing field on the response of composites of various configurations is studied at different temperatures and a similar result is obtained. The resonant frequency of the ME composite is seen to decrease with an increase in temperature owing to the decrease in the effective Young's modulus of the composite.

Epoxy-free fabrication techniques for layered/2-2 magnetoelectric composite: a review

“…A self-biased ME output of 35 mV cm −1 Oe was observed in the case of FeNi/PZT/Ni composite. The efficacy of epoxy-free composites over their epoxy-bonded counterparts was visible in temperature-dependent quasi-static ME measurements, wherein the former showed appreciable response even for temperatures in excess of 150 • C, whereas epoxy-bonded composites displayed poor ME output for temperatures around 100 • C. Similar behavior was also observed under resonant conditions, wherein the press-fit fabricated composites performed reliably at aggravated temperatures when compared to the epoxy-bonded ones [153,154]. Quasistatic and resonant ME models have been formulated in literature which predict the response of these press-fitted disc/ring composites at any thermal operating conditions with good accuracy.…”

Thermally stable multi-directional magnetoelectric based embedded magnetic sensor

“…Additionally, the usage of temperature for fabrication might lead to potential depoling of the piezoelectric material. Thus, an alternative yet simpler method was proposed in the form of the press-fit method, wherein the outer diameter of the disc constituent was slightly higher than that of the slot in the ring constituent leading to the formation of interference fit [38][39][40]. Recently, a novel ME distributed disc structured configuration was proposed, which employed the press-fit fabrication technique to enhance the ME response [41,42].…”