Soft Materials and Applications

Transcription

1 Soft Materials and Applications O. Geoffroy Grenoble Electrical Engineering (G2Elab)

2 Materials Application Fields Transformation of Energy Actuation Recording Magnetic Properties Soft Hard Coupling properties Sensors and EAS Magneto-Mechanic Magneto-caloric Magneto-optic

3 Soft Materials : Some General points * The wold of soft materials : a Schematic view * Basic properties and application fields * How does it work? (Static) * The different permeabilities * How does it work? (Dynamical) Massive, Stacked laminated sheets, wounded ribbons, compacted composites The different frequency ranges * f < 1000 Hz : Classical laminated SiFe, CoFe and futur challenges * 400 Hz < f < 100 khz : Iron based amorphous ribbons * 1000 Hz < f < 100 GHz : Soft ferrites The Vanishing anisotropies alloys * What does it mean? * How do we do? * How tayloring the shape of the loop : The induced anisotropies K u * Transverse K u, flat loops and coherent rotation magnetization mechanism The Very low permeabilities and Energy storage * The classical way : Soft ferrite + Air Gap * The Soft Composites Ribbons, wires and microwires for sensors * The Giant Magneto-Impedance * Electronic Article Surveillance ( harmonic systems, Acousto-magnetic labels )

4 Metrology K 1, λ s Vanishing anisotropies highest permeabilities Taylorded loops Unipolar electronics Protection Filtering Energy Actuation Power Electronics Special Properties T C Elasticity Thermal expansion Macroscopic : e > 50 µm Massive, laminated Particles + compaction Staked or wounded ribbons Dynamical behaviour frequency range Soft Materials Low dimensions : e 20 µm Particles, Wires, Ribbons Individually Wires Ribbons Sensors K 1, λ s

5 Soft Materials Materials and Applications transformers drive the magnetic flux i 1 e 1 n 1 φ n 2 S l e 2 Magnetic Shields Flux detection Concentration in air gaps Electromagnets Magnetic forces Machines Actuators Sensors, fault circuits breakers H - F Β e I stator rotor

6 Soft Materials : the mirror effect Magnetic inductor Soft yoke : µ H yoke = 0 σ yoke ~ J H out = 0 (shielding ) Air gap : B r 0, B θ 0 B r 0, -B θ 0 2 B r 0 The ideal soft Material : µ J s Iron based alloys : µ rfe 8000 J s Fe = 2.2 T

7 Soft Materials : the different permeabilities µ a, µ i, µ dyn apparent intrinsic B = µ i H Counter field due to eddy currents B = µ a H a = µ i ( H a H j ) applied 1/µ a = H / B + H j / B 1/µ a = 1/µ i + 1/µ dyn static dynamic µ a inf(µ i, µ dyn )

8 Soft Materials under dynamical regime : Transformation of energy, actuation, power Electronics Classical eddt-currents conductivity e < δ = ( µ i σ π f ) -1/2 skin depth thickness P vclas = σ B m 2 e 2 π 2 f 2 Main mechanism : Domain Walls e H a F J S 4 l F a <F> = F a µ dyn = v j π 2 16 l e σ 1 f P v = 1,628 P vclas 2l / e σ (material) e (Process) l (treatments)

9 Soft Materials under dynamical regime : f < 1000 Hz σ e l 800 ( C) kj/ m l (treatments) J s T C K 1 λ % Si (weight) Laminated SiFe alloys ρ ρ Fe = 10 µωcm ρ FeSi3% = 48 µωcm 2.2 (T) µω cm CVD enrichment after lamination Lamination : e min ~ µm Stacked or wounded magnetic circuits Laser irradiation, Plasma etchching

10 Soft Materials under dynamical regime : f < 1000 Hz Challenges for the next years : the in-board machines Until now : Electromagnetic ; Hydraulic In the next future : All Electromagnetic Specific power Electrical generation (alternators) Ω Mechanical stress Tensile Strenght : GPa alternators directly set in the jet engine : Operating temperature T : C Transformers J f (400 Hz 900 Hz) Acoustic noise Vanishing λ 100 New CoFe alloys CoFe alloys ; new dedicated insulation 6% SiFe alloys

11 Soft Materials under dynamical regime : 400 Hz < f < 100 khz magnetism Glass former Iron based amorphous ribbons : Fe 81 B 13.5 Si 3.5 C 2 resistivity A T Liquid dt dt > 10 6 K / s Planar flow casting C B Amorphou s Cristal D t n t Thickness e ~20-40 µm ρ ~ 140 µω cm (ρ FeSi ~ 48 µω cm) J S ~1.6 T Operating Temperature : 150 C Medium frequency range

12 Soft Materials under dynamical regime : f > 100 khz Soft Ferrites Very cheap, ρ J S (J S MnZn ~ 0.4 T) Powder compaction sintering massive cores Spinels : Garnets : ρ MnZn ~ 1 Ω m fmax ~ 1 MHz R F ρ NiZn ~ 10 5 Ω m fmax ~ 100 MHz ρ YIG ~ Ω m fmax ~ 100 GHz (microwaves)

13 Soft Materials : vanishing anisotropies alloys : highest permeabilities and taylored loops µ i : static magnetic shielding, low voltage circuits breakers, filtering inhomogeneities µ i = J S / ( b + K 1 + K u + 3/2 λσ ) 1/2 magnetocristallne induced magnetoelastic About inhomogeneities : bubbles H = ε B H B H b Vanishing K 1 Vanishing λ

14 Soft Materials : vanishing anisotropies alloys : b Vanishing K 1 process disordered structure : Amorphous, Nanocristalline solid solution (NiFe alloys) 100 K 1, 100 Ku Ni % Vanishing λ composition evolution of K 1, Ku for NiFe alloys λ λ111 λ Ni % evolution of λ 100 and λ 111 for NiFe alloys λs evolution of λ in Nanophy with the cristaline fraction Annealing temperatures 490 C fc The winners : Co based Amorphous Fe based Amorphous Nanocristalline (Finemet, Nanoperm, Hitperm ) Ni 80 Fe 15 Mo 5 Permalloy

15 Soft Materials vanishing anisotropies alloys : taylored loops and induced K u Heat treatment diffusivity Materials and Applications Vanishing λ, K 1 isotropy effect of a stress applied during the cristallisation flash annealing on a soft nanocristalline alloy K u > 200 J/m 3 mechanical stress magnetic field B (T) induced K u H (A/m) σ = 0, 10, 40, 120, 270 MPa Rectangular loops : magnetic amplifiers, fluxgate sensors Flat loops : µ r = J S2 / (2 µ 0 K u ) ground fault circuits breakers, Unipolar electronics (pulse transformers ) K u < 200 J/m 3 different shapes (rectangular, flat, round) obtained on Nanophy applying a magnetic field during annealing B / B m H an Long. H an nul H an Transv. H anl H a / H am H ant

16 Soft Materials Flat loops Materials and Applications Energy storage K u Vanishing K 1, λ, alloys : Permalloys, Co based amorphous, soft nanocristalline < µ r < Field annealing 500 < µ r < Stress annealing u u if 0 t E = ½ L I 2 f = ½u 2 t 2 / L L µ µ 0 ra E µ ra 10 < µ r < 500 Classical : soft Ferrite + Airgap e CR : DW : θ H a µ dyn = 1 e µ dyn = 1 e J S 2 µ σπ π 2 16 l σ 1 f 1 f Coherent rotation mechanism Dynamical properties B µ 0 µ r H µ r B µ 0 µ ra µ ra H a

17 Soft Materials Soft Magnetic Composite materials : 10 < µ r < 500 Energy storage : High induction Ni Fe Co alloys suitable for high frequency range (10 khz < f < 100 MHz) homogeneous Distributed air gap Enclosed eddy-currents H a Damaging leakage flux at high f No Damaging leakage flux R 20 µm f < 1000 Hz : Moulding possibility 3D geometries µ r 800 Mechanical strengh

18 Soft Materials Soft Magnetic Composites: Manufacturing process Materials and Applications B ( T ) Fe powder H ( A / m ) B ( T ) H ( A / m ) Fe powder No lubricant : isolating layer destroyed lubricant : isolating layer preserved 1024 µ 512 rm mean field theory 256 (µ Cluj r = 1000) 128 (mechanical 64 alloying) f

19 Soft Materials : Ribbons, Wires and Microwires for sensors RF heating coil rotating copper wheel as quenched ribbon melt spinning Process 1 mm Amorphous wire µm (Unitika) Microwire CoFeNi(SiB) glass coated Rotating wheel : Amorphous (Fe or Co based), Nanocristalline Water Cooled Microwires : Amorphous (Fe or Co based) Classical Wire drawing : Cristalline NiFe mumetal

20 Soft Materials : Materials and Applications Ribbons, Wires and Microwires for Giant Magneto-Impedance Principle : Complex Domain Structure depending on λ s B = H / µ c circular µ Inhomogeneous stress j M.I. E = ρ j + E' Inhomogeneous cooling rate Quenching process Domains in a microwire: λ s > 0 (a), λ s < 0 (b) j H H 0 f Z = Lω ~ µ C DW H 0 = 0 DW + rotation µ C = f(h 0 ) Field sensor f Z = R ~ δ ~ µ C -1/2 Z/Z (%) = f(h 0 ) microwire CO Fe 4.5 Si B 15

21 Soft Materials : Ribbons, Wires and Microwires for Electronic Article Surveillance Principle : Basic R.F. labels transmitter receiver Rewritable labels Harmonic labels label Magneto Acoustic labels

22 Soft Materials : Materials and Applications Ribbons, Wires and Microwires for Electronic Article Surveillance Harmonic labels Harmonic response content = shape dependent B / J S u flat loop rectangular loop flat loop rectangular loop H a / H am flat loop rectangular loop t f / f Semi Hard FeCo : 160 A/m < Hc < 800 A/m Co based amorphous ribbon rectangular loop Hc < 1 A/m J = 0 40 mm 1 mm 30 µm

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