Patent ID: 7964044
Filing Date: 2011-06-21
Classification: C23C

Abstract:
1. A process for forming a magnetite coating on ferrous metal substrates, the process comprising: removing oxides from the surface of the ferrous metal substrate without formation of an intermediate conversion coating by contacting the substrate with an aqueous acidic solution comprising sulfamic acid and alkyl naphthalene sodium sulfonate; and forming a magnetite coating on the surface of the ferrous metal substrate after removing the oxides and without forming an intermediate conversion coating by contacting the surface of the ferrous metal substrate with an aqueous oxidizing solution, the ferrous metal substrate lacking an intermediate conversion coating, to directly oxidize iron on the surface of the ferrous metal substrate to form a magnetite coating, the aqueous oxidizing solution comprising from about 0.2 g/L to about 2 g/L of SnCl