Magnetic hysteresis and Barkhausen noise emission analysis of magnetic materials and composites.

摘要

specialchapt{ABSTRACT}.;Barkhausen emission studies have been used to analyze the effect of residual stresses in ferromagnetic materials. The stresses generated due to mechanical wear and tear, abrasion and prolonged use can also lead to phase changes within the material. These phase changes can cause damage to the structural parts and should be prevented. In this study we analyze the magnetic hysteresis and Barkhausen noise profile of materials with more than one ferromagnetic phase. The correlation between the hysteresis and Barkhausen noise profiles for such materials is studied. Secondary Barkhausen emission peaks can be simulated for such materials. Experimental observations are compared with simulation measurements. Drawing a correlation between the secondary emergent peaks and the composition of each secondary phase should lead to an improved technique for non-destructive characterization of ferromagnetic materials.;par.;Improved sensor-to-specimen coupling is also essential for conducting Barkhausen noise measurements of multiphase materials which may also have different surface geometries. A finite element study was conducted to optimize the design parameters of the magnetizing core in a Barkhausen noise sensor. Several sensor parameters inclusive of core material, core-tip curvature, core length and pole spacing were studied.;A procedure for developing a high sensitivity Barkhausen noise sensor by design optimization based on finite element simulations has been demonstrated. The study also shows the applicability of Barkhausen emission and magnetic hysteresis analysis as advanced tools of non-destructive characterization of ferromagnetic materials.