Patent DE-102009013467-A1 (DE)
Title: Wet treatment and electrochemical treatment of the electrically conductive products, comprises flowing electrochemical treatment current to the product fixed at an electrically conductive frame as second electrode of the electrolytic cells
Inventor: HUEBEL EGON
IPC: C25D17/06
Filed: 2009-03-07
Abstract: The process for wet treatment and electrochemical treatment of the electrically conductive products (1) such as for partial pretreatment e.g. pickling, electropolishing, cleaning, degreasing or etching of the products and for partial metallization of the products by galvanizing in electrolytic cells (18) and electrolytic galvanizing cells (20) with corresponding treatment liquids or galvanizing electrolytes (17), comprises flowing an electrochemical treatment current to the product fixed at an electrically conductive frame as second electrode of the electrolytic cells. The process for wet treatment and electrochemical treatment of the electrically conductive products (1) such as for partial pretreatment e.g. pickling, electropolishing, cleaning, degreasing or etching of the products and for partial metallization of the products by galvanizing in electrolytic cells (18) and electrolytic galvanizing cells (20) with corresponding treatment liquids or galvanizing electrolytes (17), comprises flowing an electrochemical treatment current to the product fixed at an electrically conductive frame as second electrode of the electrolytic cells during the pretreatments of a counter electrode of the electrolytic cells, where the galvanizing cells are assigned to a bath current source (21) and the counter electrode with one pole of the bath current source and the frame with the other pole of the bath current source are electrically connected, and flowing the electrochemical bath current to the same product at the same frame as anode during subsequent galvanization of an electrode of the electrolytic galvanizing cells and then reflowing as cathode from electrically non-contacting frame to a second electrode of the electrolytic galvanizing cells, where the anode and the cathode are electrically connected with a negative pole of the bath current source. The bath current or the treatment current flows from the product to the frame over current-transmitting clamping jaws (3). During galvanization, the treatment current flows from the anode to an area of the product electrically not connected to the bath current source where the product is metallized and then the treatment current reflows from the outer surface of the frame to the cathode. The treatment liquid and the galvanizing electrolyte flow from the frame through the openings, slits and/or channels and/or through inclined position of the products during the excavation from an immersion bath. The flat anodes and flat cathodes and/or the frame are cyclically or vibratably moved in any direction for electrolytic exchange and/or gas separation from the surfaces, and are plane-parallelly arranged to each other. The galvanization of the products takes place in the galvanizing electrolyte, in which the surfaces of the unprotected area of the frame anodically do not dissolve. During galvanization, a metallization of the cathode of the electrolytic galvanizing cells is avoided by placing the frame nearer to the cathode and by an electrically conductive metal layer at the surface of the cathode, which is cathodically constant in the galvanizing electrolyte and at which no metallization takes place in the galvanizing electrolyte, where minimum cathodic current density occurs through an active surface of the cathode, which is larger than the effective anodic surface of the frame, so that the metallization of the cathode is avoided. A metal deposition on the cathode is avoided by cooling the cathode at a surface temperature below a working temperature of the galvanizing electrolyte. The metallization of the surface of the cathode is avoided by using an electrolyte as catholyte in the area of the cathode, which does not contain metal ions that are deposited on the cathode. For avoiding the metal deposition on the cathode, an ion-selective and liquid-tight membrane of the electrolyte in the area of the cathode as catholyte, which does not contain metal ions, is separately kept from the galvanizing electrolyte, which contains metal ions that are present in the product and the anode. The requirement of energy for cooling the cathode is reduced by an ion-permeable and heat-insulating layer as heat insulator against the electrolytes present at the working temperature. The electrolytic cells or the galvanizing cells are operated with the bath current source, direct current source, unipolar pulse current source, bipolar pulse current source or technical alternating current. The product is electrochemically partially treated or galvanized by protective layers and/or covers of areas of the frame against the anode of the electrolytic cell or galvanizing cell. An independent claim is included for a device for wet treatment and electrochemical treatment of the electrically conductive products such as for partial pretreatment e.g. pickling, electropolishing, cleaning, degreasing or etching of the electrically conductive products and for partial metallization of the electrically conductive products by galvanizing in electrolytic cells and electrolytic galvanizing cells with corresponding treatment liquids or galvanizing electrolytes.