Abstract:
Mechanical properties of glass-coated metal fiber with different metal compositions (Co_{68.15}Fe_{4.35}Si_{12.5}B_{15}, Co_{68.15-x}Fe_{4.35}Ni_{x}Si_{12.5}B_{15}, and Fe_{77.5}Si_{7.5}B_{15}), diameters and glass thicknesses were analyzed. Tensile strengths and elastic modulus were measured with and without the glass coating present. Strengths on the order of 1 to 1.5 GPa have been found for as-received (A-R) GCAF and strengths on the order of 2.5 to 4 GPa have been found for the glass-removed (G-R) fibers. Elastic moduli of the composite fibers fall between 68 and 98 GPa which is 10 to 20% lower than the values calculated from a composite model. Elastic moduli of the G-R fibers range from 120GPa to 180 GPa and depend on composition and thickness of the metal fiber. The failure mode of GCAF is dependent on fiber composition and the thickness of the glass coating. Some composite fibers fail catastrophically while others exhibit high toughness in that the glass coating fails before the metal core. The influence of crystallization on the metal core was also studied. The tensile strength of GCAF decreased 10 to 40% after crystallization. A sensor was made to observe the waveform and the harmonic components that each GCAF produced under a magnetic field. The magnetic permeability of the Co_{68.15}Fe_{4.35}Si_{12.5}B_{15} and CoFeNiSiB compositions is influenced by the stress placed on them by the glass coating as well as any tension or torsion forces. This change in permeability allowed the GCAF to be used in conjunction with a sensing device to function as a load cell or torsion cell. From these measurements the axial stress relieved on the metal core from the removal of the glass cladding was calculated and found to be between 180 and 250MPa depending on the fiber. The effects of fiber length and the multiple fibers were also observed for future reference and possible device applications.
