Magnetostriction of Fe-Ga coatings and their application in ultrasonic guided wave sensing

摘要

Fe83Ga17 (at. %) coatings with a thickness of 270-500 mu m were prepared on 316L stainless steel by high velocity oxy-fuel spraying technology. The coatings exhibited a lamellar structure, and the magnetostriction reached 34.5 ppm. The magnetostrictive coatings were applied to electromagnetic acoustic transducers (EMATs), where the different bias magnetic fields and coating thicknesses were considered to examine the ultrasonic guided wave sensing capability and the detection sensitivity. The 180-kHz ultrasonic guided waves were captured from artificial defects and the pipe end under different bias magnetic fields. Among them, the EMATs exhibited the best sensing performance under a bias magnetic field of 255.7 Oe. Meanwhile, magnetostrictive stress induced the decrease of the magnetic permeability and the rearranged magnetic moment, resulting in a large strain sensitivity (d lambda/dH). Because of the relatively good field sensitivities in magnetization and magnetostriction, the EMATs using Fe83Ga17 coating with a thickness of 500 mu m exhibited better detection sensitivity than that of 300 mu m. This work provides a good prospect of Fe-Ga alloy coatings applied in non-destructive testing. Published under license by AIP Publishing