Effect of Difference in Ion Plating Method on the Magnetic Properties of TiN-coated Grain Oriented Silicon Steel Sheet

Abstract

The hollow cathode discharge (HCD) and electron beam (EB)+ radio frequency (RF) ion plating methods were, respectively, applied to investigate the influence on the magnetic properties of TiN- coated silicon steel sheet, and to clarify the difference in the properties of the TiN film and ionization resulting from the HCD and EB+RF methods. The TiN ceramic coating and measurement of the ionization by using these two kinds of ion plating methods were both performed inside an ion plating apparatus. The experimental results obtained are summarized as following items. (1) The magnetic flux density [B 8 (T)] and the iron loss [W 17/50 (W/kg)] of the silicon steel sheets TiN-coated by the two ion plating methods were both dramatically improved, in good agreement with our previous experimental results, but the degree of improvement by the HCD method was about twice that by the EB+RF method. This improvement in magnetic properties by both methods was most marked in the silicon steel sheets with the magnetic flux density of B 8 =1.93 T. (2) The surface appearance of the silicon steel sheet TiN-coated by the HCD method showed a gold color, whereas that by the EB+RF method showed a brown color. A thin-film X-ray diffraction inspection after HCD indicated a strong (111) peak of TiN, while that after EB+RF indicated comparatively strong (200), (111) and (220) peaks, and weak (311) and (222) peaks. Scanning electron microscopic observation of the TiN film deposited by the HCD method showed a fine and smooth surface, whereas that by the EB+RF method showed a rougher surface. (3) The ionization level by the HCD method was 43%, whereas that by EB+RF was 6%. (4) The silicon steel sheet TiN-coated by HCD method had a stronger compressive stress dependence than that coated by the EB+RF method. (5) The adhesion of the TiN film deposited by the HCD method was stronger than that deposited by the EB+RF method. (6) It is considered that, due to the higher ionization by the HCD method than that by EB+RF, it was possible to apply a strong surface tension to the near-surface of the TiN-coated silicon steel sheet, resulting in a fine and smooth TiN film with good adhesion, thereby endowing the TiN-coated silicon steel sheet with a reduced iron loss.