Detection of Defects in Ferromagnetic Materials by Nanofluid as a Sensor

摘要

Nanotechnology provides wide range of applications in medicine, electronics, energy production and biomaterial fields. One of the applications used in this project is magnetic flux leakage sensor to detect the defects in ferromagnetic material. Magnetic Flux Leakage is one of the most widely used electromagnetic non-destructive techniques to locate and asses discontinuities such as fatigue, cracks, corrosion, erosion, non-metallic inclusion and abrasive wear in magnetic components. The gradient in the magnetic flux lines around the defective region induces the formation of one-dimensional array of nano-particles along the field direction in the Nano fluid, which produces a discernible grey level contrast in the Ferro fluid. The grey level contrast produced by the leaked magnetic flux is used to detect the defects buried inside the sample. Small defects provide shape information on the defects because of its high sensitivity and spatial resolution. Different metal oxide (Nickel oxide, Iron oxide and Ferrofluid) nanofluids were prepared and characterized using SEM, AFM and FTIR. Using VSM technique, the magnetization, coercivity and paramagnetic nature of nanofluids are studied. Ferrofluid shows super-paramagnetic behavior with enhanced coercivity and magnetization when compared to other fluids.