Comparison of the Crystallization Behavior of Silica Between Mg- and Al-Phosphate Used in Tension Coatings of Grain-Oriented Electrical Steel
The effect of the phosphate component on the thermal stability of tension coatings was investigated with a focus on the crystallization behavior of amorphous silica in the tension coating. After stress-relief annealing, core loss of samples coated with a Mg-phosphate was improved, while that coated with an Al-phosphate was deteriorated. The domain wall spacing of the samples coated with Mg- and Al-phosphates was respectively increased and decreased after stress relief annealing. This means that the stress relief annealing did not much diminish the tensile stress for Mg-phosphate coating but much diminished the tensile stress for Al-phosphate coating. Based on FTIR and XRD results, we found that the crystallization temperature of silica with Al-phosphate was lower than that of silica with Mg-phosphate. The crystallization of silica was accompanied by an abrupt volume change, which formed cracks in the tension coating and deteriorated the tensile stress.
KeywordsGrain-oriented electrical steel Tension coating Silica Crystallization Phosphate
The authors gratefully acknowledge POSCO Technical Research Laboratories for financially and technically supporting this research.
- 2.H. Honda, S. Kaya, On magnetization of single crystals of iron. Sci. Rep. Tohoku Imp. Univ. 15, 721–727 (1926)Google Scholar
- 6.P.J. Banks, E. Rawlinson, Dynamic magnetostriction and mechanical strain in oriented 3% silicon-iron sheet subject to combined longitudinal and transverse stresses. IEE Proc. 114, 1537–1546 (1967)Google Scholar
- 18.A.C. Adams, Plasma deposition of inorganic films. Solid State Technol. 26, 135–139 (1983)Google Scholar