Particle orientation and bulk properties of magnetoactive elastomers fabricated with aligned barium hexaferrite
- PDF / 576,840 Bytes
- 10 Pages / 584.957 x 782.986 pts Page_size
- 109 Downloads / 205 Views
Particle orientation and bulk properties of magnetoactive elastomers fabricated with aligned barium hexaferrite Corey Breznak1,a)
Paris von Lockette1
1
Department of Mechanical Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA Address all correspondence to this author. e-mail: [email protected]
a)
Received: 15 October 2018; accepted: 17 December 2018
This work studied the relationship between embedded particle volume fraction and magnetic particle orientation distribution in aligned 325 mesh barium hexaferrite (BHF) and polydimethylsiloxane (Sylgard 184; Dow Corning) magnetoactive elastomer (MAE) composites. BHF particles were aligned within the elastomer in the out-of-plane direction, as the material cured. Particle orientation distribution was defined herein by observations of the population of directions at which particle magnetizations resided; magnetization coincides with the physical crystallographic c-axis of BHF. The work used results of vibrating sample magnetometry experiments on MAEs with increasing volume concentrations of embedded ferromagnetic particles (10–30 v/v%) to determine changing widths of analytical particle distribution functions used to describe the range of particle orientations. With over 80% confidence, results showed that MAE composites having the intermediate 15 v/v% had the highest degree of magnetic (and thereby physical) alignment as well as magnetic remanence.
Background and motivation This work studies the relationship between embedded particle volume fraction and magnetic particle orientation distribution in ferromagnetic–elastomer composites by mathematically characterizing experimental results of vibrating sample magnetometry (VSM). The work is novel in that while much research has been performed on the process, structure, and properties relationships of soft-magnetic ferromagnetic–elastomer composites, much less study has been directed at hardmagnetic ferromagnetic–elastomer composites, the focus of this work. For clarity, soft-magnetic ferromagnetic–elastomer composites will be referred to by the more familiar term magneto-rheological elastomers (MREs), while hard-magnetic ferromagnetic–elastomer composites will be referred to as magnetoactive elastomers (MAEs). For more on this distinction, see Lockette et al. [1]. Furthermore, particle orientation distribution, the metric of this work, is defined herein as observations of the population of directions at which particle magnetizations reside across the aggregate of particles embedded within the matrix. For the magnetic particles studied, the magnetization axes and the crystallographic c-axis coincide. MAEs are fabricated by embedding ferromagnetic particles with high remanence in an elastomer matrix [1, 2, 3, 4]. Typical
ª Materials Research Society 2019
sizes range from particles on the nanoscale to particles with diameters in the tens of microns [4, 5, 6, 7]. The particles can be oriented as-mixed, nominally randomly, or aligned in a specific orientation by applying an external magnetic
Data Loading...
