1995 Volume 59 Issue 3 Pages 347-355
In order to clarify the mechanism responsible for the ultra-low iron loss in TiN-coated grain oriented silicon steel sheet, direct observations were made of the domain structure obtained by coating a thin TiN film, which had been produced by ion plating on polished silicon steel sheets.
The results obtained are summarized as follows.
(1) After making distinct chemically polished and TiN-coated areas inside a single giant secondary Goss grain of a silicon steel sheet, the domain structure of the chemically polished area showed an original main domain with large black and white 180° domain wall spacings elongated in the rolling direction, while that of the TiN-coated area showed marked domain refinement due to the induced strong tensile stress by the TiN film.
(2) At the borderline between the chemically polished area and the TiN-coated area, the domain wall spacings changed drastically, showing four to six narrow wall spacings in the coated area for each wall spacing in the polished area, and lens-like refined-domains also formed at the beginning of the TiN coating area from the large black and white 180° main domains.
(3) In the chemically polished side of these line between the two areas, longitudinally striped domains formed distinctively within regions about ±45° to the rolling direction due to local strain arising from the strong surface tension in the TiN film.
(4) By causing a slight deviation in the orientation of the secondary Goss grains in the silicon steel sheet, both the main domain and its refined domain in the chemically polished and TiN-coated area became less pronounced.
(5) It is considered that the ultra-low iron loss in TiN-coated silicon steel sheet was obtained due to the reduced eddy current loss arising from the strong surface tension of the TiN coating on the silicon steel sheet, which induced radical domain refinement.
