Electroless Deposition Of Fe-Me-P Alloys And Their Performance Characteristics

Iron alloy films are widely used in magnetic devices, computer, aviation materials and memory alloys due to its excellent soft magnetism, good resistance to corrosion and excellent catalytic performance. Investigation on iron alloy films has been attracted increasing interest. In this work, Fe-Me(Co, Ni,La,W)-P films were prepared by electroless deposition from a sulfate stable bath. The influence of bath composition and parameters on the deposition process, film structure, composition, magnetic and anticorrosion performance were systematically investigated by scanning electron microscopy(SEM), X-ray diffraction (XRD), microhardness tester, vibrating sample magnetometers (VSM), gravimetric and electrochemical measurement.Fe-Co-P films were successfully prepared on brass substrates by electroless deposition. The deposition rates derived from polarization curves show a similar trend to that determined from the gravimetric method, indicating that electroless deposition proceeds along electrochemical mechanism. Increase of Ms and remanent magnetization'(Mr) as well as decrease of He are observed for the Fe-Co-P films with bath pH and temperature increasing. Fe-Co-P films with good soft magnetic properties were obtained from high pH bath and thereafter heat treatment. The film is found to be suitable as soft magnetic materials for core materials. It is also found that Fe-Co-P films shows good anticorrosion behavior in base medium.Fe-Ni-La-P films were also successfully prepared. The effects of lanthanum on the deposition rate, composition, structure, hardness, magnetic and anticorrosion behaviors of Fe-Ni-La-P films were investigated. The results show that the deposition rate decreases, the coercivity of the film increases, while its saturation magnetization decreases with the increasing LaCl3·7H2O concentration in the bath. When the LaCl3·7H2O concentration ranges from 0.4 to 0.8 g L-1, the films show good anticorrosion behavior in base and salt medium. The moderate addition of lanthanum in the bath will increase the hardness of the deposits evidently as a result of the change of composition and structure of films.In addition, the Fe-W-P films deposition process was investigated by electrochemical method. It is found that deposition rate depends on the deposition potential, electroless deposition is difficult to proceed as the deposition potential is too high, the deposition rate increases as the deposition potential shifts negatively. The coupled aluminum shifts the potential negatively, and decreases the anodic and cathodic reaction resistance, thus provides an active surface and induces the iron based alloys deposition.