Process and apparatus for in situ electroforming a structural layer of metal bonded to an internal wall of a metal tube

摘要

A process for repairing degraded sections of metal tubes, such as heat exchanger tubes, by in situ electroforming utilizes a probe containing an electrode. The probe is movable through the tube to the site of degradation and is sealed in place, thereby creating an electrochemical cell. Electrolyte flows from a reservoir through the cell and a structural layer of metal is deposited on the tube using a pulsed direct current and a duty cycle of 10-60%. The metal layer so formed possesses an ultrafine grain size preferably with a highly twinned microcrystalline structure giving the layer excellent mechanical properties.