STEEL WITH ELECTRICALLY INSULATING HEMATITE LAYER

摘要

THE PRESENT INVENTION IS DIRECTED TO A METHOD OF FORMING AN ELECTRICALLY INSULATING LAYER ON A STEEL ARTICLE SUCH AS OF ELECTRICAL STELL LAMINTIONS OR AN INDIVIDUAL, UNSTACKED ELECTRICAL STEEL LAMINATION , COMPRISING EXPOSING THE ARTICLE TO AN OXIDATION ATMOSPHERE, AND TO A TEMPERATURE (SUCH AS AT LEAST ABOUT 427°C (800°F)) FOR A TIME SUFFICIENT TO FORM ON THE ARTICLE AN ELECTRICALLY INSULATING LAYER COMPRISING HEMATITE . THE HEMATITE LAYER IS EFFECTIVE TO PROVIDE THE ARTICLE WITH A SURFACE RESISTIVITY CHARACTERIZED BY AN F-AMP VALUE OF NOT GREATER THAN ABOUT 0.85 AT A TEST PRESSURE OF 3.5 KG/CM2 (50 PSL) AND TRANSFER SURFACE ROUGHNESS OF ABOUT25.4X10¯⁶ CENTIMETERS (10 MICROINCHES) (RA).ALSO FEATURED IS A STEEL ARTICLE HAVING THE ELECTRICALLY INSULATING LAYER FORMED THEREON .(FIGURE 7)