Barkhausen Noise and Eddy Current Microscope BEMI for Nondestructive Testing & Measuring

Situation of material properties testing

Knowledge of material properties and their local distribution is of great importance for the development 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)

■ Inspection main device based on 3MA technique (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;

Special NDT Technique and Principle

The Inspection main device based on 3MA technique, 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 homogeneity. Furthermore, the comparison of the characteristics of several samples allows for a qualitative estimation of the differences in material or layer properties.

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

Possible Applications of Barkhausen Noise and Eddy Current Microscope BEMI

? 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.

For more details, please contact LAB GAGES directly.

Frequently used target values to be tested:

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

BEMI 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.

For more details, please contact LAB GAGES directly.