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Accredited laboratory in line with DIN EN ISO / IEC 17025, to qualify and validate new non-destructive testing (NDT) processes for industrial applications

Accelerated time-to-market and opportunity for qualifi ed, norm-compliant deployment in industrial applications as well as for complete new in-house developments or custom adaptation of innovative NDT technologies, even in fi elds where norms have not been established

Certifi cation of the corresponding quality management system in accordance with DIN EN ISO 9001

Fraunhofer-Institut für Zerstörungsfreie Prüfverfahren IZFP

Campus E3 166123 Saarbrücken

+49 681 9302 0

info@izfp.fraunhofer.dewww.izfp.fraunhofer.de

F R A U N H O F E R I N S T I T U T E F O R N O N D E S T R U C T I V E T E S T I N G I Z F P

BARKHAUSEN NOISE AND EDDY CURRENT MICROSCOPE BEMI

MICROMAGNETIC INSPECTION OF METALLIC MATERIALS AND LAYERED SYSTEMS WITH HIGH SPATIAL RESOLUTION

Local residual stress in a steel sample

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Above all, after a single calibration using samples with defi ned characteristics, BEMI can deter mine material and layer properties quantitatively and show their distribution as an image. It is possible to determine several target values simultaneously.

Frequently used target values of the calibration:

Residual stress Hardness, hardness depth (near surface, e.g. NHD) Layer thickness and layer properties Microstructure

Possible Applications

Materials characterization and optimization with high spatial resolution for all materials or layered systems containing at least one metallic component

Examination of the homogeneity of microstructure or layers Imaging of stress distribution Determination of the thickness of a metallic and/or ferromagnetic top layer on any substrate Determination of the thickness of a non-ferromagnetic top layer on a ferromagnetic substrate Characterization of multilayers

System Features

Lateral resolution of probe and scanner: approximately 20 µm, depending on material Maximum scan range 10×10 mm2 (larger areas on demand) Measurement time per measuring position ≤ 1 s Measuring range for layer thickness 5 nm to 100 µm, depending on material

BEMI was developed in cooperation with Matesy GmbH.

Knowledge of material properties and their local distribution is of great importance for the develop-ment and optimization of metallic materials or layered systems. The application of the multiparameter micromagnetic testing method BEMI provides the capability to characterize the material properties or layered systems with high spatial resolution.

Components of the BEMI (Barkhausen Noise and Eddy Current Microscope)

3MA inspection device (3MA: Micromagnetic Multiparameter Microstructure and Stress Analysis):A powerful testing device for micromagnetic characterization of materials and layered systems

Special probe with high spatial resolution: Acquisition of electromagnetic properties with a spatial resolution of about 20 µm

Scanning machine: Stepwise scanning of sample surfaces in defi ned x and y positions Computer: Control of the scanner, acquisition of data, visualization of the results and evaluation

Principle

The 3MA inspection device combines the four micromagnetic methods:

Harmonic analysis of the tangential magnetic fi eld strength Barkhausen noise signal analysis Incremental permeability analysis Multi-frequency eddy current impedance analysis

The application of these methods with several testing frequencies provides more than forty micromagnetic characteristics, which correlate to the properties of the material structure and layered systems. The combination of the micromagnetic characteristics in a multiparameter approach enables the separation of overlapped infl uences, for example stress and layer thickness. The image of the distribution of these micromagnetic characteristics provides primary information on material homo-geneity. Furthermore, the comparison of the characteristics of several samples allows for a qualitative estimation of the differences in material or layer properties.

Thickness of Fe coating on Cu substrate Microstructure: cementite needles in austenitic matrixBarkhausen Noise and Eddy Current Microscope BEMI Special probe with high spatial resolution

1 mm

0,022

0,017

Vpeak [V]