MAGNETIC-PROPERTIES OF SILICON-IRON LAMINATIONS SI-ENRICHED BY A SIH4BASED CVD PROCESS

Grain-oriented Fe-Si laminations have been Si enriched up to 6.5 wt% b y 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 me thod has been investigated using thinned sheets (0.10 mm). In the latt er case, the decomposition of SiH4 produces Si coating over a strip sh aped sample, Joule heated at a temperature of 1000 degrees C-1100 degr ees C. Coating is followed by Si diffusion in the bulk, up to the opti mal concentration of 6.5 wt%. An important reproducible improvement of the d.c. and a.c. magnetic properties is observed after the SiCl4 tre atment, which is not, however, comparably matched by the properties of the SiH4 treated samples, likely due to structural inhomogeneities re sidual to the deposition process. A rationale to the loss behavior in the investigated materials, based on the analysis of the loss componen ts, is provided in this paper.