Yukio Inokuti, Kazuhiro Suzuki and Yasuhiro Kobayashi
Research Laboratories, Kawasaki Steel Corp., Chiba
In order to investigate the influence of magnetic properties of TiN-coated silicon steel sheet due to the difference of PVD coating methods, which were the hollow cathode discharge(HCD) and electron beam(EB)+radio frequency(RF) methods, TiN coating has been done inside the PVD apparatus. The magnetic properties of the TiN-coated silicon steel sheets after ceramic coating were evaluated. Measurements by thin-film X-ray diffraction, color monitoring, Ti/N analysis and observations of the three-dimensional scanning electron microscope and magnetic domain were also carried out.
The experimental results obtained are summarized as follows.
(1) The magnetic flux density [B8(T)] and iron loss [W17/50(W/kg)] of the TiN-coated silicon steel sheets deposited by the PVD method were improved dramatically in good agreement with the previous experimental results, but the degree of improvement of B8(T) and W17/50(W/kg) by the HCD method was about twice as large as that by the EB+RF method.
(2) This improvement in magnetic properties in both HCD and EB+RF methods was most marked in silicon steel sheets with the highest magnetic flux density.
(3) For example, in the silicon steel sheet with B8=1.93 T, the changes in {Δ}B8(T) and {Δ}W17/50(W/kg) after TiN ceramic coating by the HCD method were 0.007 T and 0.15 W/kg, respectively, while those by the EB+RF method were 0.003 T and 0.08 W/kg.
(4) Thin-film X-ray diffraction inspection by the HCD method indicated a strong peak of (111) of TiN, while that by the EB+RF method indicated comparatively strong (200), (111) and (110) peaks and weak (311) and (222) peaks.
(5) It is considered that, due to a higher ionization of the HCD method than that of the EB+RF method, it is possible to give a strong surface tension to the near-surface of the TiN-coated silicon steel sheet, to which a fine, smooth TiN film with good adhesion has been coated, and thereby it can improve the iron loss drastically.
(Received October 13, 1994)
grain oriented silicon steel, ceramic coating, TiN, ultra-low iron loss, magnetic flux density, polished surface, hollow cathode discharge method, electron beam+radio frequency method, ionization, titanium/nitrogen analysis
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