1. Cover Story – Probes – Karl Deutsch Ultrasonic Probes – Still Made in Germany 2. Special – Angle Probes – Special 35º & 70º 3. News – News from Foerster 4. Application – Application – PERMEABILITY MEASUREMENT
The New MAGNETOSCOP 1.070 from Institute Dr Foerster offers the high-precision measurement of magnetic flux density as an absolute or gradient value as well as the determination of the relative permeability μr for feebly magnetic materials.
A variety of sensors provide the best possible adaptation to your measuring tasks.
High sampling rates, pre-configured measuring procedures, application optimized visualization and multiple data interfaces – support your work.
A comprehensive application software- for data processing and analysis on your PC – complements the user-friendly scope of supply.
MAGNETOSCOP 1.070 and sensors are calibrated traceable to national standards of the PTB Braunschweig-Germany.
Foerster is recently observing an increase in applications with the highly alloyed material “zircaloy”.
This material is used, amongst others, for the production of nozzles, pump components or valves. Furthermore, it can be also used for fuel rods in water-cooled nuclear reactors. Especially in this application, the requirements for processing and handling as well as defect detectability are extremely high.
As a consequence, the demands on our test electronics are also increasing since the zircaloy material requires a high test frequency of 3 MHz.
Our CIRCOGRAPH DS can meet these increased demands, but with the CIRCOGRAPH CI/DI, we reach the limits of the test electronics.
Therefore, this specific test application of 3 MHz will be only offered in combination with the CIRCOGRAPH DS.
MAGNETOSCOP 1.070 – PERMEABILITY MEASUREMENT
Theoretical Background
The magnetic induction of material is described by: B = μ * H
The permeability μ corresponds to the steepness of the hysteresis and describes how good ferromagnetic material can be magnetized by an external field H. To characterize material, it is common to refer to the steepness of the so called initial magnetizing curve starting from the demagnetized state of the material.
The permeability μ can also be described as multiple of the physical constant μ0 which is the permeability of vacuum. The factor μr is called relative permeability.
B = μ0 * μr * H μ0 = 4π*10-7
μr = 1.0 describes non-magnetic material
μr > 1.0 describes feebly magnetic material
μr >> 1.0 describes material, easy to magnetize
From the shape of the initial magnetization curve it is obvious, that the permeability is not a material constant, it is strongly depending on the magnetic field H.
This circumstance is most important when referencing a measurement or comparing measuring results and will be explained over leaf.
Applications
Practical industrial applications for permeability measurement are:
Proof quality and non-magnetic property of austenitic steel and special alloys (Cu, Al, …)
Proof non magnetic property of austenitic drill collars for directional drilling
Proof non-magnetic property of components for integration into:
– MRI systems
– Particle accelerators
– Electron beam devices
– Controlled magnetic environment
Proof non-magnetic property of implants
Measurement Method
Permeability Meter Method – Flux Distortion Method This method is using the FOERSTER Permeability Probe. It is an appropriate measurement technique for the permeability measurement of feebly magnetic material. It is based a correlation between relative permeability μr and the flux distortion of a permanent magnet caused by the test material. It is a suitable method for industrial test applications of different sample geometries and sizes.
Traceability to National Standards
The Solenoid/Magnetic Moment Method is the “master-method” used by the national institutes to define national reference standards. These “primary reference standards” are used by FOERSTER to reference the Permeability Meter Method when operating the FOERSTER Permeability Probe. They are also used to reference the “secondary reference standards” which are distributed as part of the MAGNETOSCOP Permeability Measuring Kit.
The measurement with MAGNETOSCOP 1.070 and permeability probe PP-2-5 including the 1.070 Reference Standards is traceable to National German Standards of the PTB Braunschweig.
Optional Permeability probes;
For further inspection purposes like, the detection of smaller in-homogeneities & for comparison procedures the smaller Permeability Probe PP-2-2 may sometimes be more suitable.
