Work package 7: Magnetic Arrays

The approach is the integration of high electron mobility, high magnetic sensitivity 2DEG structures with on board analogue and digital electronics to deliver scanning magnetic imaging systems for Non Destructive Testing of metallic and composite materials.

Lead

Prof M.Missous (m.missous@Manchester.ac.uk)

Overview

The overarching theme of WP7 is magnetic imaging of ferrous and non-ferrous materials. The work follows a vertically integrated approach starting from epitaxial growth of advanced 2DEG structures with tailored magnetic sensitivities to device fabrication of integrated arrays and passives, packaging and finally system integration for imaging of flaws, defects and microstructures (See Figure 1 below).

Figure 1 Vertical integration of magnetic imaging of defects, flaws and microstructures

Progress and Challenges

During the period magnetic imaging modality using Quantum Well Hall Effect sensors (QWHE) for both ferrous and non-ferrous materials were
developed. The work to date has led to ~ 10 journal publications and 24 conference presentations spanning from epitaxial growth to full system demonstrations with key challenges being imaging and classifications of flaws and defects in metals.

Impact has been very strong. Impact as demonstrated in 6, separate, fully funded collaborative INNOVATEUK projects with [Renishaw, TWI, EtherNDT, FarUk, Wright, Home office, BAESystems] in imaging micron size flaws in high value steel to decimeter concealed threats (knives and guns) as shown in Figure 2 below.

Figure 2. Left – metallic imaging and Right – micron size flaws in high value steel and concealed threats (guns).

The work to date in WP7 has concentrated on both ferromagnetic (and non-ferromagnetic) materials mainly using flux leakage as the means to detects flaws and microstructures using low frequency (below 10kHz) illumination
techniques. We have now started looking at composite materials using conductivity as the imaging modality which has necessitated the use of very high frequency (MHz) interrogation techniques. The high frequency techniques also result in much more compact imaging systems that are ideal for aerospace applications.

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