Effects of silicon content on properties of gas-atomized Fe-Si-Cr powders
Fe-Si soft magnetic composites, SMC have some advantages such as excellent dc current superimposed permeability and low core loss over ferrite and Fe-Si bulk cores.
The magnetic properties and microstructure of phosphated amorphous FeSiCr/silane soft magnetic composite
Abstract Herein, amorphous FeSiCr phosphating powders were prepared using two phosphating methods and were further formed into soft magnetic composites (SMCs). The effects of phosphating treatment on the morphology and composition of phosphate layers of amorphous FeSiCr particles and mechanisms of the phosphating process were investigated via scanning electron microscopy, X-ray diffraction (XRD), Fourier transform infrared spectra, and X-ray photoelectron spectroscopy. The magnetic properties of amorphous FeSiCr phosphating powders were determined via the Quantum Design vibrating sample magnetometer. The effects of heat and phosphating treatments on AC magnetic properties of SMCs were investigated using a B-H curve analyzer. Results showed that both phosphating treatments significantly increase the resistivity of amorphous FeSiCr and do not deteriorate its magnetic properties. However, owing to the thick phosphating layer of amorphous FeSiCr phosphate on the zinc phosphate solution, its compressibility deteriorated. The magnetic permeability of the SMC was very stable in the frequency range of 10–500 kHz. Following heat treatment at 500 °C in an argon atmosphere, the magnetic permeability of the SMC significantly increased, whereas the magnetic loss significantly reduced.
Measuring Sheet Resistances of Dielectrics Using Co‐Planar Hydrogel Electrochemical Cells with Practical Applications to Characterize the Protective Quality of Paints on Sculptures
Electrical properties of thin dielectric films at the solid-liquid phase boundary are an important performance characteristic of many devices, coatings and sensors. In this paper, co-polymeric hydrogels of polyacrylic acid co-sulfonic acid, swollen with a salt solution to act as the solid electrolyte, were used to assess interfaces using electrochemical impedance spectroscopy (EIS) in a co-planar geometry. Silane-modified glasses were characterized by the co-planar hydrogel EIS cell and found to be distinguishable based on their surface monolayer chemistry. EIS measurements were also made on primed and painted metal substrates, using both test panels and an outdoor sculpture, Tony Smith's Stinger. The panels were then exposed to accelerated and outdoor weathering and showed degradation on the surface paint layers, which was observable electrochemically using EIS and confirmed visually by SEM. Electrochemical spectral features were compared between data from a standard paint-test cell versus this co-planar hydrogel cell; both cell types were able to measure coating capacitance, providing useful information about the condition of the bulk coating. Yet, sheet resistance (Rs) was a spectral feature seen only by the co-planar hydrogel cell. Thus, it can be concluded that the use of such co-planar hydrogel cells can provide an earlier warning sign to coating degradation and such cells provide a new type of spectral information that is not assessable by the standard geometry.