3.5.8 Product examples
Magnetic Nanoparticles Developer Kit
Ferrotec Corporation introduces the Ferrotec Magnetic Nano Particles (MNP) Developer's Kit, a special collection of biomedical ferrofluid evaluation samples for in-vitro diagnostic researchers and engineers. With over 30 years of experience in producing nano-scale ferrofluids, Ferrotec is recognised for high-quality particle suspensions.
The MNP Developer's Kit offers a set of solutions that are specially suited for synthesis of microbeads used for in-vitro diagnostic applications. The MNP Developer's Kit includes samples of four types of surface-treated dry particles, two types of water-based ferrofluids and bare particles in aqueous suspensions. All particles in the kit are very small, typically 10 nm, chemically iron oxide, and superparamagnetic in nature. With the capability of significantly increasing the micro-bead surface area, Ferrotec's MNP products enable better assay responsiveness and the potential for enhanced receptor attachment on bead surfaces. This is useful for improved specific bio-separations and molecular diagnostics.
The MNP Developer's Kit offers an excellent entry point for the bio-medical application developer. While the MNP Developer's Kit contains evaluation quantities of Ferrotec's nano-scale ferrofluids, the company works closely with application developers to optimise particle formulations, and Ferrotec has an established history of adapting ferrofluid solutions to unique application demands.
Nanocrystalline softmagnetics like Fe73,5Cu1Nb3Si15,5B7 are best characterised by a unique combination of extraordinary properties, a reliable and cheap production process based on low cost raw materials. They are superior to permalloys, ferrites or even amorphous cobalt based alloys in a rapidly growing range of applications.
Independent from the application, the benefits gained from the use of nanocrystalline cores instead of ferrites or permalloys are: significant reduction of build volume of inductive components; less heat dissipation due to reduced number of turns; stable operation in a temperature range from -25 ... + 120°C; bigger safety margins and variable toroidal geometries without tool costs.
The main application for the new material so far is common mode chokes for EMI (Electromagnetic Interference) mains filters for any kind of switched mode power converters. Here, the most significant reduction of build volume is achieved because both relevant material parameters namely permeability and flux swing are factors higher compared to the so far commonly used ferrite toroids.
Nanocrystalline alloys VITROPERM® are materials on the basis of Fe, Si and B with additions of Nb and Cu. They are produced via a rapid solidification technology as a thin ribbon, initially in the amorphous state and then crystallised in a subsequent heat treatment around 500 to 600°C. This produces an extremely fine grained microstructure with grain sizes of 10 nm - hence the term nanocrystalline. These nanocrystalline alloys combine low magnetic anisotropy and low magnetostriction, both prerequisites for high magnetic permeability, with a high magnetic flux density and good thermal stability.
Like Amorphous materials, the nanocrystalline VITROPERM® alloys are manufactured using rapid solidification technology. VITROPERM® is an amorphous material in the beginning stages of the manufacturing process. In order to produce the nanocrystalline two-phase structure, the amorphous circular tape cores are annealed at about 550°C.The two-phase structure is characterised by a fine crystalline grain (mean diameter 10-20 nm), which is embedded in an amorphous residual phase. This structural feature is responsible for the VITROPERM® material achieving highest permeabilities and lowest coercivity field strengths.
In addition, low tape thickness of about 20 µm and relatively high electrical resistance of 1.1-1.2 µΩm ensure the lowest eddy current losses and an excellent write-read response in the permeability of the alloy. The combination of these properties together with a saturation induction of 1.2 T and favourable thermal properties, results in VITROPERM® being a state-of-the-art material. This alloy is equal or superior to ferrites, permalloys and amorphous materials based on Cobalt.
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