Magnetic properties of silicon-iron laminations Si-enriched by a SiH₄ based CVD process

Abstract
Grain-oriented Fe-Si laminations have been Si enriched up to 6.5 wt% by means of Chemical Vapour Deposition processes, using either SiCl₄ or SiH₄ as reacting gaseous phases. The chloride based process has been applied to conventional 0.33 mm thick laminations, while the silane method has been investigated using thinned sheets (0.10 mm). In the latter case, the decomposition of SiH₄ produces Si coating over a strip shaped sample. Joule heated at a temperature of 1000 °C- 1100°C. Coating is followed by Si diffusion in the bulk, up to the optimal concentration of 6.5 wt%. An important reproducible improvement of the d.c. and a.c. magnetic properties is observed after the SiCl₄ treatment, which is not, however, comparably matched by the properties of the SiH₄ treated samples, likely due to structural inhomogeneities residual to the deposition process. A rationale to the loss behavior in the investigated materials, based on the analysis of the loss components, is provided in this paper.