Soft Materials and Applications O. Geoffroy Grenoble Electrical Engineering (G2Elab) ESM 2007, Cluj-Napoca, Romania
Materials and Applications Materials Magnetic Application Fields Properties Transformation of Soft Energy Hard Actuation Coupling Recording properties Magneto-Mechanic Sensors and EAS Magneto-caloric Magneto-optic … ESM 2007, Cluj-Napoca, Romania
Materials and Applications 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 ) ESM 2007, Cluj-Napoca, Romania
Materials and Applications Unipolar electronics K 1 � , λ s � Protection ➙ Vanishing anisotropies Metrology Energy Filtering ➙ highest permeabilities Actuation … ➙ Taylorded loops Power Electronics Special Properties Dynamical Macroscopic : e > 50 µ m T C behaviour Massive, laminated Elasticity ➙ frequency range Particles + compaction Thermal expansion Staked or wounded ribbons Sensors Soft Materials Individually Low dimensions : K 1 � , λ s � e ≤ 20 µ m Wires Particles, Wires, Ribbons Ribbons ESM 2007, Cluj-Napoca, Romania
i 1 Materials and Applications φ Soft Materials S n 1 n 2 e 2 e 1 transformers ℓ drive the magnetic flux Magnetic Shields Sensors, � Flux detection fault circuits breakers � Concentration in air gaps I stator Electromagnets F Magnetic forces - - Β Machines - rotor H � - - Actuators - e ESM 2007, Cluj-Napoca, Romania
Materials and Applications Soft Materials : the mirror effect Soft yoke : µ ∞ H yoke = 0 Magnetic inductor σ yoke ~ J H out = 0 (shielding ) Air gap : B r 0 , B θ 0 2 B r 0 B r 0 , - B θ 0 J s � � The ideal soft Material : µ � � Iron based alloys : µ r Fe ≈ 8000 J s Fe = 2.2 T ESM 2007, Cluj-Napoca, Romania
Materials and Applications Soft Materials : the different permeabilities µ a , µ i , µ dyn apparent B = µ a H a intrinsic � 1/ µ a = H / B + H j / B = µ i ( H a – H j ) B = µ i H applied Counter field 1/ µ a = 1/ µ i + 1/ µ dyn � due to eddy static currents dynamic � µ a ≈ inf( µ i , µ dyn ) ESM 2007, Cluj-Napoca, Romania
Materials and Applications Soft Materials under dynamical regime : Transformation of energy, actuation, power Electronics… Main mechanism : Domain Walls Classical eddt-currents conductivity H a J S v e < δ = ( µ i σ π f ) -1/2 F a j e skin depth F thickness 4 ℓ π 2 16 ℓ e σ 1 µ dyn = f <F> = F a P vclas = 0.167 σ B m 2 e 2 π 2 f 2 P v = 1,628 P vclas 2 ℓ / e ℓ � � σ � � e � � (Process) (material) (treatments) ESM 2007, Cluj-Napoca, Romania
Materials and Applications Soft Materials under dynamical regime : f < 1000 Hz ℓ � � σ � � � e � Lamination : Laser irradiation, SiFe alloys � e min ~ 50-100 µ m Plasma etchching… ℓ ➘ � 2.2 (T) 800 (°C) (treatments) Stacked or J s 2.0 760 T C wounded magnetic 1.8 720 circuits 60 680 K 1 µΩ cm ρ 40 40 kJ/ m 3 20 10 -6 20 λ 100 0 0 0 2 4 6 % Si (weight) CVD enrichment Laminated after lamination ρ Fe = 10 µΩ cm ρ FeSi3% = 48 µΩ cm ESM 2007, Cluj-Napoca, Romania
Materials and Applications Soft Materials under dynamical regime : f < 1000 Hz Challenges for the next years : the in-board machines Until now : In the next future : Specific power �� Electromagnetic ; All Electromagnetic Hydraulic Electrical generation (alternators) New CoFe alloys Ω � � Mechanical stress � Tensile Strenght : 500 � 700 GPa alternators directly set in the jet engine : T : 220 � 400 °C Operating temperature � CoFe alloys ; new dedicated insulation Transformers Acoustic J � Vanishing λ 100 noise �� f � (400 Hz � 900 Hz) 6% SiFe alloys ESM 2007, Cluj-Napoca, Romania
Materials and Applications Soft Materials under dynamical regime : 400 Hz < f < 100 kHz Glass former magnetism Iron based amorphous ribbons : Fe 81 B 13.5 Si 3.5 C 2 resistivity T Liquid A dT C dt > 10 6 K / s Cristal � Planar flow Amorphou D casting B s t n t Thickness e ~20-40 µ m ρ ~ 140 µΩ cm Medium ( ρ FeSi ~ 48 µΩ cm) frequency range J S ~1.6 T Operating Temperature : 150 °C ESM 2007, Cluj-Napoca, Romania
Materials and Applications Soft Materials under dynamical regime : f > 100 kHz Soft Ferrites ☺ J S � (J S MnZn ~ 0.4 T) � Very cheap, ρ �� Powder � compaction � sintering � massive cores Spinels : ρ MnZn ~ 1 Ω m � fmax ~ 1 MHz R F ρ NiZn ~ 10 5 Ω m � fmax ~ 100 MHz Garnets : ρ YIG ~ 10 10 Ω m � fmax ~ 100 GHz (microwaves) ESM 2007, Cluj-Napoca, Romania
Materials and Applications Soft Materials : vanishing anisotropies alloys : highest permeabilities and taylored loops µ i �� : static magnetic shielding, low voltage circuits breakers, filtering… inhomogeneities magnetoelastic µ i = J S / ( b + K 1 + K u + 3/2 λσ ) 1/2 magnetocristallne induced About inhomogeneities : bubbles B B H H H = ε Vanishing λ b �� Vanishing K 1 ESM 2007, Cluj-Napoca, Romania
Materials and Applications Soft Materials : vanishing anisotropies alloys : process �� b �� disordered structure : 100 K 1 , 100 Ku Amorphous, Nanocristalline Vanishing K 1 solid solution (NiFe alloys) Ni % Vanishing λ composition evolution of K 1 , Ku for NiFe alloys … The winners : 22 evolution of λ in Nanophy with 10 6 λ λ 111 20 the cristaline fraction 40 18 16 14 20 6 λ s Co based Amorphous 12 10 10 Fe based Amorphous 0 8 λ 100 Annealing temperatures 6 490 °C 4 510 550 Nanocristalline (Finemet, 530 570 2 40 50 60 70 80 Ni % 0 fc Nanoperm, Hitperm…) evolution of λ 100 and λ 111 for -2 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 NiFe alloys Ni 80 Fe 15 Mo 5 Permalloy ESM 2007, Cluj-Napoca, Romania
Materials and Applications Soft Materials vanishing anisotropies alloys : taylored loops and induced K u B (T) 1 effect of a stress applied during 0.5 the cristallisation H (A/m) flash annealing on a soft 0 3000 nanocristalline σ = 0, 10, 40, alloy 120, 270 MPa K u > 200 J/m 3 Vanishing λ , K 1 Heat treatment mechanical stress induced K u � isotropy � diffusivity magnetic field K u < 200 J/m 3 1.0 B / B m H anT different shapes H an Long. 0.5 H an nul (rectangular, flat, H an Transv. round) obtained on Nanophy 0.0 Rectangular loops : H anL applying a magnetic field -0.5 magnetic amplifiers, fluxgate sensors… during annealing H a / H am -1.0 -1.0 -0.5 0.0 0.5 1.0 2 / (2 µ 0 K u ) µ r = J S Flat loops : ground fault circuits breakers, Unipolar electronics (pulse transformers…) ESM 2007, Cluj-Napoca, Romania
Soft Materials Materials and Applications Flat loops Energy storage K u � Vanishing K 1 , λ , alloys : E = ½ L I f 2 = u ½ u 2 ∆ t 2 / L if Permalloys, Co based amorphous, u L ≈ µ 0 µ ra soft nanocristalline E � � µ ra � ∆ t 0 500 < µ r < 2 000 2 000 < µ r < 200 000 10 < µ r < 500 Field annealing Stress annealing Classical : soft Ferrite + Airgap → Coherent J S θ rotation e → mechanism H a B B 2 µ µ dyn = 1 σπ 1 CR : e f µ 0 µ r µ 0 µ ra Dynamical H H a properties �� π 2 µ dyn = 1 16 ℓ σ 1 µ r ≈ 10000 µ ra �� DW : e f ESM 2007, Cluj-Napoca, Romania
Materials and Applications Soft Materials Soft Magnetic Composite materials : 10 < µ r < 500 High induction Ni Fe Co alloys suitable for high frequency range Energy storage : (10 kHz < f < 100 MHz) Enclosed eddy-currents homogeneous Distributed air gap H a No Damaging � Damaging R ≤ 20 µ m leakage flux leakage flux at high f f < 1000 Hz : Moulding possibility � 3D geometries µ r ≈ 800 Mechanical strengh � � ESM 2007, Cluj-Napoca, Romania
Soft Materials Materials and Applications Soft Magnetic B ( T ) B ( T ) Fe powder Composites: Manufacturing process H ( A / m ) H ( A / m ) Fe powder No lubricant : isolating lubricant : isolating layer layer destroyed preserved 1024 µ rm 512 mean field theory ( µ r = 1000) 256 Cluj 128 (mechanical 64 alloying) 32 16 8 f 4 0.4 0.6 0.8 1.0 ESM 2007, Cluj-Napoca, Romania
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