Effect of residual internal stresses in TiN coatings On specific losses in anisotropic electrical steel

Methods of X ray diffraction analysis, mass spectrometry, and atomic force microscopy have been used to perform a comparative analysis of factors that cause the appearance of residual stresses in TiN coatings deposited by reactive magnetron sputtering and to study their effect on specific magnetic losses in electrical sheet steel. Physical and mechanical parameters of coatings, such as hardness, elastic modulus, residual stress, microstructure, and surface morphology, have been studied. It has been shown that the level of internal stresses in a coating depends on its thickness and increases with increasing quantity and energy of ions in the deposited beam. The maximum magnitudes of compressive stresses in coatings (13 GPa) were obtained when using an unbalanced working regime of the magnetron and a negative bias at the substrate. The hardness of coatings produced under such conditions reaches 29 GPa. There has been demonstrated a possi-bility of reducing losses in electrical sheet steels by about 15% by depositing surface coatings with high compressive stresses.