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Various oxide sealing processes have been proposed and promoted over the past decades. Among them cold sealing having a sealing time of approximately 1 minute per micron and hot sealing having a sealing time of approximately 3 minutes per micron.
During the last years some nickel based medium temperature sealing have been promoted having a sealing time of approximately 1 to 2 minutes per micron.
However recently, due to restrictions in the use of heavy metals, in particular nickel, it is important to find valid alternatives to cold sealing and nickel based medium temperature sealing.
Taking into considerations these new limitations, the Authors conducted research to propose innovative high-speed sealing methods having immersion times between 1 to 2 minutes per micron of oxide thickness and a temperature variable within 80 – 90 °C.
A product without any heavy metals for medium temperature sealing has been developed, tested industrially and then approved by Qualanod. |