Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/04—Electroplating with moving electrodes
  • C25D5/06—Brush or pad plating
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
  • C25D17/10—Electrodes, e.g. composition, counter electrode
  • C25D17/14—Electrodes, e.g. composition, counter electrode for pad-plating
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/22—Electroplating: Baths therefor from solutions of zinc

Definitions

• the present invention relates to a method and associated devices for the electrolytic deposition of adherent and opaque coatings of metallic zinc on metals, in particular on iron or on zinc and on galvanized iron, here briefly called galvanizing.
• the main purpose of galvanizing on iron is to protect it against corrosion from atmospheric influences.
• the galvanizing then excludes the deposition and impure or alloyed zinc.
• electrolytes for short, which serve as a bath in which the objects with the negative polarity, to be galvanized and the positive electrodes with zinc are immersed.
• hand electrodes for bath-free galvanizing by hand g electrodes were suggested, so-called hand electrodes, in which brushes, sponges, felts and paste-forming agents serve as carriers for the aqueous electrolyte.
• Alien known electrolytes are the use of non-volatile acids or the non-volatile alkali bases and electrolytically particularly conductive salts, so-called conductive salts.
• the tendency of the zinc to acicular deposition is due to the special recipe (material composition of many components, distance and area ratio of the electrodes, electrical voltage and current density, acid strength temperature, etc.) and the movement of the bath or the electrodes bath-free galvanizing counteracted by rubbing the hand electrodes (so-called friction electrodes) on the surface to be galvanized.
• electrolytes and hand electrodes have been recommended for the repair of damaged areas on galvanized or painted iron sheets, in particular a motor vehicle.
• the strongly acidic or alkaline electrolytes quickly attack any zinc that is still present and, like the tiniest residues of the salts, lead to rust formation in unprotected areas, where the electrolyte runs in an uncontrolled manner.
• the known hand electrodes are not suitable for every surface contour and spatial position and not for narrow parts, they mechanically damage the paintwork in the vicinity of the repair point and decimate the galvanization produced.
• the electrolytes attack the zinc electrode when de-energized.
• the object of the present invention is to find a corrosion-free electrolyte, in particular a bath-free priming galvanizing, which the aforementioned should be found for repair purposes
• Electrolyte when using zinc as a positively polarized electrode, or positive for short, is suitable and the described shortcomings can be overcome.
• a perpendicular iron wire negative of 3 mm in diameter at a distance of 2 mm is compared with a zinc wire positive made of a pair of wires each 3 mm in diameter and electrolyzed at about 1 volt with 6 mA corresponding to an electrical current density of 0.3 A / dm 2 longitudinal zinc cut surface, so after a start-up time of a few seconds, which is associated with a clear hydrogen development on the negatives, a light gray zinc coating is formed on the negatives.
• finely divided zinc oxide for example zinc white, or salt-free zinc hydroxide
• these compounds slowly dissolve moderately in aqueous ammonia to form the zinc aminohydroxides.
• Powdered zinc can also be mixed in, since it also reacts with aqueous ammonia with evolution of hydrogen to form zinc aminohydroxides.
• Another possibility of enriching the electrolyte with zinc aminohydroxides is, according to the invention, prior electrolysis of the aqueous ammonia solution between zinc electrodes b, the greatest possible current density, which entails a large hydrogen evolution on the negatives and repeated polarity reversal of the electrodes. In each period, as a result of the simultaneous formation of hydrogen, more zinc is dissolved than is deposited.
• the electrolyte according to the invention can also be produced by reacting zinc nitride with water or aqueous ammonia.
• the process according to the invention requires no conductive salts and no alkali bases.
• traces of ammonium carbonate or other reaction products of aqueous ammonia with the carbon dioxide in the air are not to be mentioned as a lead acid content.
• the above-mentioned salt-free zinc hydroxide can only be produced approximately by laboriously washing zinc hydroxide precipitated from zinc salt solution.
• the solubility of the same in aqueous ammonia increases with the residual salt content.
• the electrolyte according to the invention can contain soluble zinc phosphates which are added or originate from a coating of the iron materials to be galvanized with zinc phosphates.
• Zin phosphate is not a salt that leads to corrosion, but is known as an anti-corrosion pigment.
• the additives mentioned all increase the electrolytic conductivity of the aqueous ammonia and, under otherwise identical circumstances, enable higher current densities.
• Zinc phosphate is more soluble in aqueous ammonia and can significantly increase the viscosity of the electrolyte.
• the admixture of the zinc oxide and / or zinc hydroxide can go as far as paste formation, in particular to prevent the electrolyte from draining off from the damaged area during bath-free galvanizing.
• zinc is used according to the invention in granular form, in particular from roundish granules produced from the melt flow or in the form of a large number of small wire sections.
• Grains made of fine zinc (99.99% Zn), which are larger than 0.5 mm, are not attacked by aqueous ammonia at room temperature or below, as long as no external electrical current flows.
• the low electrolytic conductivity of the electrolytes according to the invention is taken into account by the fact that, in contrast to previous practice, b
• Hand electrodes - preferably no electrolyte carriers, which take up the entire cross-section of the power line and have a considerable thickness.
• electrolytes there are only in certain cases thin fabrics, knitted fabrics, nets, sieves, perforated foils, nonwovens or the like made from as largely as possible permeable to electrolytes, compatible with electrolytes, wettable by the electrolyte, electrically non-conductive, possibly abrasion-resistant and soft-elastic materials, here abbreviated separators, used, which do not significantly restrict the electrolytic conductivity between positive and negative, because they also allow a particularly small electrode spacing. If wicks are used as the electrolyte carrier, they may not cover the main current-conducting cross-section between the electrodes. It has been found that the known particularly strong tendency of zinc, in the electrolytic
• Galvanizing from ammonical solutions does not grow firmly and does not form a layer, but forms loose dendrites or a black sponge, and the tendency towards poiarization until the current comes to a standstill, which can otherwise only be remedied by a strong voltage surge for a limited time, is therefore the easiest and safest way can be countered that friction bodies slide over the separating surface, the necessary speed of movement of which generally increases with the current density.
• a prerequisite for the current flow and the area-wide deposition is that the electrolyte wets the negative base. It has an advantageous effect that aqueous ammonia can saponify and wash away greasy soiling.
• Aqueous ammonia is a good wetting agent. It can e.g. To wet polyethylene so that we can use this material for the manufacture of hand electrodes.
• the rubbing movement can do the rest. In principle, the iron surface must also be metallically clean in order to achieve a firmly adhering, uniform and area-wide galvanizing. Without the rubbing movement, a strong hydrogen evolution spontaneously sets in on the black zinc that is immediately deposited at a higher current density. Adequate movement completely or almost completely dissolves black zinc.
• a hydrogen evolution means loss of electricity yield and danger of hydrogen embrittlement of a steel base. Rapid movement prevents or at least minimizes the development of hydrogen.
• a moving bulk material to be galvanized e.g. iron wire pins, work yourself.
• the mouthpieces of the same are preferably used as rubbing elements, which consist of electrically non-conductive material.
• the current density is limited to approximately 3 A / dm 2 zinc end face of the positive, it can be galvanized for a long time without movement.
• the hand electrode can be fixed in the correct position with an iron binding wire and with the help of a permanent magnet.
• the hand electrode is guided so quickly in the frictional contact over the surface to be galvanized that the black zinc does not form or at least largely dissolves again immediately after the electrical current is switched on.
• the electrolyte vessels of the hand electrodes are designed so that they are airtight - apart from the open mouthpiece. So you have the general form
• the width of the cup mouthpiece is limited to approximately 8 mm, it is possible with such hand electrodes to use the same in every room, i.e. Also galvanize the undersides and vertical side surfaces, because the electrolyte runs out when handling the filling or after the flush fitting, because it passes through the top
• the electrolyte vessel includes not only the space between the electrodes, but also a resume that can also receive and release electrolyte.
• This reserve space is - also without the use of carrier substances for the electrolyte - mainly gap-shaped and the gaps are up to 3 mm wide.
• the loss of electrolyte in the hand electrodes is limited to the amount that remains on the entire surface to be galvanized and is more or less evaporated on it as a wetting layer, as well as the mostly very small amount that results from the electrolyte being displaced by the usually very low hydrogen evolution .
• the hydrogen bubbles leave the mouthpiece laterally outwards.
• the current-carrying cross-section is correspondingly reduced by gas accumulation, and it is only necessary to replenish it in the event of larger gas accumulation, which prevents the flow of electricity or reduces it too much.
• the galvanizing of vertical surfaces is advantageous for the galvanizing of vertical surfaces to bevel the mouth piece and put it on in such a way that the gas bubbles can withdraw upwards into the open or into the spare compartment from the mouthpiece space.
• the evolution of hydrogen can be achieved by moving the hand electrode faster and by reducing the current, e.g. by increasing the electrode gap, who minimized the. It was found that a strong intermixing in the electrolyte space, which preferably has no flow resistance in the form of the known electrolyte carrier but is free, is caused by the rubbing movement, which serves the zinc ion transport and thus counteracts the competing hydrogen separation.
• the electrolyte will not leak, even if the mouthpiece is a few cm in diameter, regardless of the spacing, even if the mouthpiece is placed on the surface to be galvanized and then moved.
• a knitted nylon stocking stretched over the edge of a cylindrical cup can carry a hanging column of 10% aqueous ammonia with a diameter of over 9 c of the cup rim.
• Such large diameters are, however, forbidden in practice due to the power supply and the dissipation of the current heat and because of the shock sensitivity.
• the separators can at the same time ensure that the granular zinc filled in does not fall out, as does the electrolyte.
• the separators must be made of non-conductive material if they come into contact with the positive and the negative at the same time.
• the zinc positive has the shape of a cup, e.g. are known from dry cell batteries then it can serve directly as an electrolyte vessel. So that the open side of the cup can serve as a mouthpiece, all that is required is a border made of electrically non-conductive material, which projects somewhat. At least from a mouthpiece width of about 8 mm, the coverage by a Se
• REPLACEMENT LEAF parator necessary, which can also represent the electrically insulating border itself.
• the cup may then contain granular zinc without losing it.
• the cup - also to enlarge the zinc solution area - can also contain other loose or solid zinc internals that are in electrical contact with the cup.
• the electrolyte space is not only open at the bottom, but also open at the top, slit-shaped, free and so closely formed that, due to its capillarity, the electrolyte fills up to a considerable height when the electrolyte is soaked in, the electrolyte will run downwards when the wetting contact is flush directed mouthpiece on the surface to be galvanized, but the split pillarity ensures restraint.
• Such electrodes can be made very narrow and are therefore suitable for galvanizing in narrow places. Gas bubbles can escape upwards into the open. Since wetting and outgassing losses occur during the movement, they are refilled every few minutes by briefly soaking them up.
• mouthpieces made of soft, elastic and abrasion-resistant material give very good galvanizing results when used as the rubbing electrode.
• the paint in the vicinity of the damaged area is not damaged.
• Zinc that has already been deposited will not be abrasively removed.
• the mouthpiece of this type consists of a tube made of ammonia-resistant and abrasion-resistant soft rubber. Rubber glides smoothly and effortlessly on the wetted surfaces. no porous materials are used in the manufacture of the mouthpiece edges because they are not sufficiently abrasion-resistant and too blunt when moving and because they promote ammonia outgassing.
• the simplest, most cost-effective and most widely applicable hand electrode of the present invention consists of a section of a zinc wire which, on the one hand, forms a gap-like reserve storage space for the electrolyte with a soft-elastic sheathed tube and protrudes somewhat beyond the wire and forms the mouthpiece here, and the cavity on the other hand , ie is closed between the hose and the zinc wire, and the other end of the zinc wire is connected to the electrical line and the positive pole of the direct current source.
• the closure and sealing of the gap space is preferably carried out in the simplest manner by a second hose on which the hose and in which the zinc wire are difficult to move.
• This second hose in addition to its extension, can provide the contacting of the clamped, stripped end of the lead wire with the zinc wire and can further serve to support the lead.
• the tightness and an adjustable The electrode gap can be ensured by additional means such as a screw hose clamp or a rubber band, which can be easily loosened or tightened as required.
• the two hoses can also be combined in a uniform molded rubber body, which can be equipped, for example, with sealing lips against the zinc wire.
• the zinc cup electrode can also contain granular zinc or zinc wire or zinc tube sections of the same length, which are arranged so as to be loosely movable parallel to the casing wall, and which are in electrically conductive contact with the cup.
• a resilient material placed on the inner cup base for example high density polyurethane foam, ensures that the end faces of the inserts on the mouthpiece press against the mouthpiece separator so that this automatically follows the contour of the surface to be galvanized.
• the separator fabric In order to avoid damage to the Separato drawn over the sharp edge of the zinc cup electrode by this edge, the latter can be covered by an aluminum foil of e.g. 0, mm thickness can be defused. It has been found that in the case of empty, i.e. only electrolytically filled zinc cup electrode there is no wear on the separator fabric if its protruding edge is squeezed between the outer wall of the zinc cup and the mouthpiece hose and the latter jumps little.
• the electrolyte vessel consists of a soft rubber or soft plastic body, which not only contains a zinc wire positive and the lead, but also has space for granular zinc or longer zinc wire sections that are in electrical contact with the lead, the latter being movable parallel to one another are and can follow the surface contour via a separator
• An advantage over the cylindrical zinc cup electrode is that the electrolyte vessel can be reversibly deformed to form a gap in the case of zinc grain filling, so that narrow throats or gaps to be galvanized can also be achieved, and that special external insulation is unnecessary.
• the elastic vessel can also take over the function of the spring insert. A coarser sieve tray is sufficient as separator for this filling. The one for a finer
• the finely meshed separator required for zinc grain filling can be used with the more wear-resistant sieve bottom, e.g. perforated vessel bottom, can be combined, the fine-meshed separator is preferably arranged on the inside.
• the fine-meshed separator can also be at the bottom of a bag which contains the granular zinc and in which the feed line, preferably a zinc wire, is inserted and the bag has plat in the electrolyte vessel.
• the feed line is inserted airtight into the vessel.
• the vessel can be composed of several parts.
• Mouthpiece is advantageously made from a piece of zinc sheet as a positive, which is partially surrounded by an electrically insulating sheath that forms capillary wetting gaps with the sheet.
• the shell slightly protrudes below the sheet and forms the narrow, gap-shaped mouthpiece.
• the cover is preferably made of hard polyvinyl chloride and is made airtight against the outstanding sheet metal preferably by air-self-vulcanizing silicone material. With this seal, it becomes
• German patent 34400 describes a brush electrode which consists of a narrowly wound zinc sheet, the gap distance being determined by inserted bristles, d emerging from the winding roller in a brush-like manner. By installing it in a zinc cup, it is made usable for lower teeth.
• the electrolyte vessel preferably a zinc cup, zinc in the form of parallel displaceable Zinrschreibchen
• the mouthpiece-side openings carry slightly projecting Isolierkö by, so they can serve as spacers and as rubbing elements against the surface to be galvanized, so that a separator is unnecessary.
• wick-like materials adapt to the shape of the surface and supply the annular space between the zinc cup rim as a positive and the surface to be galvanized as a negative with electrolyte.
• the mainly current-conducting annulus is essentially not used by these carrier materials.
• the overall height of the foam can be very large, and thus the electrolyte absorption capacity as well as softness and conformability can be very large without the electrolytic conductivity and the leic activity of the rubbing movement of the mouthpiece being appreciably impaired.
• the galvanizing according to the invention is not dependent on compliance with certain formulations and narrow working conditions.
• the ammonia content of the aqueous solution can vary within wide limits.
• the maximum electrolytic conductivity is approximately 10% by weight of ammonia. Handling with aqueous ammonia of this concentration can be done without odor.
• the current densities that can be used are also not critical and within a wide range variable current densities from 5 to 50 A / dm 2 of active zinc surface are practicable with moving electrodes. At higher current densities there are problems with the dissipation of the current heat.
• the electrode spacing results from the separator thickness and, in the case of the uncovered hand electrodes, from the fact that short circuit v should be avoided.
• REPLACEMENT LEAF In order to limit the current at a given voltage of the motor vehicle battery, ma can replace the long lead wire, which is necessary in order to be able to reach all points of the vehicle, in whole or in part by a resistance wire in order to save a special series resistor
• An environmentally friendly simplification is that the galvanizing does not have to be washed a after the end of the electrolysis, but it suffices to wipe dry or to dry in the air.
• copper can also be used with an oxidized surface.
• the particularly ductile and wetting-friendly zinc coatings obtained by the present process are suitable as lubricant carriers for mechanical deformations of the metal base.
• the hand electrode according to Fig. 1 consists of a wire section (1) made of fine zinc (99.99%) with a diameter and 40 mm length, a soft and elastic one and transparent molded body (2, 3) and a stranded wire (4).
• the molded body on the one hand protrudes from one end of the zinc wire by an adjustable length (d) and forms the open and 5 mm wide mouthpiece through which commercially available ammonia is filled as a starting electrolyte with an ammonia content of 10% by weight and that of the zinc wire and filled the shaped body cylindrical and slit-cylindrical cavity
• the molded body encloses the zinc wire tightly and airtight, and its extension (4 'presses the stripped end of the strand against the zinc wire.
• the extension supports the insulated strand further elastically and prevents it from kinking.
• the molded body can also be fitted with two matching hose sections (2 and 3) of ⁇ 2.8 x 1, 3 x 25 and ⁇ 5 x 0.4 x 35 mm. Surface tension and air pressure as well as capillarity ensure that the electrolyte does not leak in any position of the electrode when handling, except in the case of sudden acceleration, very strong deformation of the electrolyte vessel or when vacuuming with, for example, absorbent paper.
• the electrode which is filled to the brim and air-free, is applied vertically and flush to the damaged area (5) of an ia kized (7) steel sheet, which has been removed from rust and paint residues by scratching with a steel nail, with a slight pressure by hand and flush with the mouthpiece sets on, whereby the electrolyte wets the bare area.
• a molded iron wire (8) and a permanent magnet (9) hold the electrode in this position.
• the small amount of electrolyte corresponding to the amount of hydrogen formed flows out at the edge of the mouthpiece.
• the electrolyte is not refilled. Apart from this small amount of runoff, there is no loss of electrolyte. Since the mouthpiece closes quite tightly, no appreciable amount of ammonia evaporates. There is therefore no odor pollution.
• the galvanizing is light gray, matt, when viewed under a microscope, fine-grained-metallic-crystalline and fully opaque and glittering, it is ductile and after rubbing with a rounded steel tool, it is fully shiny,
• Fig. 2 illustrates the application on a lower view throat (5), the mouthpiece adjusts from 2 and allows galvanizing down to the depth of the throat. In this F, however, it must be carefully placed air-free. Gas bubbles can leave the mouthpiece and the kehie laterally outwards. If the zinc wire is pushed back further, so that d becomes larger, which is favorable with the Geomet, the current flow and the gas development as well as the current loss decrease.
• the existing 12 volt battery power source can be used with the advantage that each damaged area is connected to the negative pole.
• the current can be limited to 1.2 mA.
• Galvanizing iron with moving, smaller. Hand-held rubbing electrode and 10% aqueous ammonia Amperages greater than approximately 2 mA, corresponding to 3 A / dm 2 of zinc end face, cannot be achieved with the hand-held electrode, which is described in detail in Example 1, because it deposits spongy black or dendritic zinc and the evolution of hydrogen becomes significant.
• Much higher currents and separating capacities are possible if the hand electrode b is moved, the mouthpiece of the electrode being rubbed lightly over the surface to be galvanized when it is used by the electrolyte as flush as possible back and forth or rotating.
• a beveling of the mouthpiece is practical.
• the Glasbläs Chen can be made to disappear from the mouthpiece in this position, in which this can be derived outwards (strand end directed downwards) or - preferably - inwards upwards (strand connection nac directed upwards).
• Table 1 provides guide data on the achievable currents I as a function of the electrode distance d at 12 volts, using an aqueous ammonia as a starting electrolyte with an ammonia content of approximately 10% by weight, and at a temperature of 15 ° C.
• the time t is given in minutes after which a refill of the aqueous ammonia is necessary or opportune.
• REPLACEMENT LEAF can be brought back to solution by - if necessary only temporarily - increasing the speed of movement.
• the mouthpiece does not cause any damage to the intact paint around the galvanizing when moving.
• the 10% ammonia synthetic resin varnish does not attack at all and an existing galvanizing only to the extent that it is favorable for the adhesion of the new deposition.
• the galvanizing achieved can be easily painted after drying.
• the minimum electrolysis time should be about one minute per cm 2 .
• an approximately 8 mm long, thin, flexible strand is used, which is connected to the positive pole of the vehicle battery by clamping the stripped bare end between the iron pole clamp and an applied holding magnet.
• Fig. 3 four electrodes are shown in plan and in side view, which are loosely bundled by the rubber block (10) and placed on the curved surface (5). If a slight pressure is exerted on the electrodes by hand, the electrodes adapt to the curvature by placing the Mun pieces of the electrodes 2 and 2 'lower than that of 2 "and 2". The mouthpieces deform somewhat on the one hand, on the other hand they form wetting gussets (11) with the filled electrolyte.
• a spherical surface can be galvanized with 3 bundled electrodes, the mouthpieces of which lie on a smooth surface; they can therefore be bundled together so that they cannot move.
• Such bundles make galvanizing faster than with individual electrodes and are advantageous when galvanizing larger areas.
• a zinc wire section (1) of 3 mm in diameter is airtight and tight in a molded body (2, 3) made of soft polyvinyl chloride.
• the 16 mm wide circular mouthpiece of the molded body is covered with 2 layers of polyester fabric (6) as a separator, which is attached to the outside of the molded body with adhesive tape and has a layer thickness of 2 times 0.125 mm.
• the interior of the molded body is filled with zinc granules (1 ') made of fine zinc (99.99% Zn) with a grain size of 0.5 to 2 mm.
• the electrode can be used in any position. Under current flow, it must be moved quickly who the. The current density at 12 volts is approx. 50 A / dm 2 mouthpiece area. Cover a 3 x 3 cm 2 area i with 3 ⁇ m zinc coating in 3 minutes. There is no refill. The thin sheet iron underlay heats up considerably. After use, the electrode is placed on the absorbent paper with the mouthpiece, since the remaining electrolyte sucks off. The electrode can be used again at any time. However, the fabric is a wear spare part.
• the molded body on the mouthpiece can be pressed into a gap with your fingers, see longitudinal section and plan in the lower part of Fig. 4.
• the separator and granules emerge in a bead-like manner.
• the loosely clamped fabric adapts easily to any mountainous and tired surface contours, and the large scatter also ensures the galvanizing in the depth of threads, into which no electrode fits.
• 100 A / dm 2 is sufficient. Then the heating by the current is so strong that the galvanizing must be interrupted after 1 minute.
• the thin-walled, slightly conical, cup-shaped rubber container (2) together with the soft, matching rubber stopper (3) forms the electrolyte container, inner diameter 26 mm.
• the bottom of the rubber cup is perforated.
• the textile fabric (6) is on the inside, which is fixed by the rubber plug.
• the zinc wire (1) is passed airtight through the plug, which is in electrical contact with the granule filling (1 ') and has a positive polarity.
• the electrolyte is applied with the polyethylene bottle pipette to a bottom hole up to the edge.
• the cup When galvanizing from below, the cup is pressed together a little to make good wetting contact between the electrodes.
• the movement of the cup base as a mouthpiece is flush with the negatives, the mouthpiece can follow the surface contour and is most easily guided in a spirally rotating manner with changes in direction.
• 150 mA at 12 V corresponding to 105 A / dm 2 total area of the hole cross sections, are achieved with a floor thickness of almost 2 mm and a fabric thickness of 0.13 mm.
• the separators are wear-free.
• FIG. 6 ge An electrode that brings 1.5 amps at 12 V with 10% aqueous ammonia is shown in Fig. 6 ge. It consists of a rubber tube (2) ⁇ 28 mm by 2 mm wall thickness, which, together with the two-layer tissue separator (6) and the rubber stopper (3), forms the electrolyte container in which the granules (1 ') and the zinc wire (1 ) are located.
• the tissue separator is clamped between the hose 2 and a rubber hose (6 ') ⁇ 28 times 0.5 mm.
• Flat textiles can be used as a separator, diameter 95 mm.
• the electrode has a good grip and is also suitable for rough hands.
• the separator (6) is made of strong, soft elastic, coarse mesh polyamide (Lycra fibers) with a layer thickness of 0.6 mm using the rubber tube (4 ', 6') over the mouthpiece of a zinc alloy cup (0, 3% bei and cadmium) of 13 mm diameter and 48 mm length g.
• the hose is also used for the external electrical insulation and for contacting the cable (4).
• the sharp edge of the mouthpiece is covered with aluminum foil 0.1 mm thick so that the knitted separator (6) cannot be injured.
• On the bottom of the cup there is a tight polyurethane foam pad (12), which removes 10 zinc wire sections ⁇ 3 mm (V) against the separator, so that it can follow the surface contours (5.5 ', 5 ").
• (13) is an insulating adhesive film .
• zinc bite tubes can also be used, in particular those in whose mouthpiece sides plastic wedges are crimped, which, like the enveloping hose (4 ', 6'), protrude beyond the zinc end faces and the distance to the surface to be galvanized (5) guarantee and make a separator obsolete.
• Handle serves, and especially forms the edge of the mouthpiece by the hose protruding from the cup edge u almost 1 mm.
• the soft, elastic, open-pore foam (12, 14) is flexibly fitted into the cup, which in the decompressed state protrudes over the edge of the mouthpiece.
• the foam soaks up the electrolyte.
• the foam of this surface adapts to its contours by receding accordingly, Fig. 8 below flat surface (5).
• the foam soaked in the electrolyte wets the surface to be galvanized and the zinc wall, in particular the edge of the zinc cup, and ensures electrolytic conduction between the cup positions and the negatives (5).
• Foam here is much less stressed by the rubbing movement, that the current path through the foam in the edge area is not covered at all and less so inside that di
• Foam thickness is not equal to the electrode spacing, and that fasteners are omitted.
• the electrode is suitable in every room. With 10% aqueous ammonia, 125 mA at 15 ° C are achieved.
• a wick made of textile fibers especially in the shape of a rectangular piece of woven fabric made of cotton, which is tightly wound into a matching cylindrical wick.
• Such a wick has an unsurpassed absorption and holding capacity for the electrolyte.
• Such a wick is not just a particularly long galvanizing process with a filling of 4 m
• the adhesive strength of such galvanizing is lower on such surfaces that are not completely pure metal.
• Textile fabric (polyester, polyamide) covered, the protruding edge of which is clamped between the outer wall of the cup and the inner wall of the tube by means of slipping over the lower 17 mm high tube section.
• Hose protrusion d 0.2 mm, textile fabric thickness 0.1 mm.
• the cup is expediently filled with electrolyte beforehand. It was surprisingly found that such a separator shows no signs of wear after a long period of use and has not been damaged by the unprocessed edge of the zinc cup produced by the extrusion process.
• the zinc wire (1) is passed airtight through the bottom (3) of a soft rubber cup (2,6 ').
• the cup contains a stiffer soft PVC hose (2 ', 6 ") of 20 cm inner diameter, 2 mm wall thickness and 20 mm height, the mouthpiece of which is somewhat opposite the rubber rim, and the one with the foam rubber perforated disc (12)
• the electrode delivers 0.8 A. After A cooling break must be taken every 1 minute of electrolysis.
• the electrolyte hold is good and galvanizing is equally possible in any position.
• a second rubber cup similar to the outer one can also be used as the inner cup.
• a piece of hard polyvinyl pipe with a height and diameter of 15 mm and a wall thickness of 0.8 m is compressed in the heat to a gap of 1 mm in width and fixed in this shape by cooling, Fig. 11 (2).
• Zinc sheet titanium zinc 40 mm long, 17 mm wide and 0 mm thick (1) is tightly inserted into the gap, so that free gaps of 0.2 mm in width are created on both sides of the zinc sheet Zinc sheet are stabilized.
• the protruding end of the positively polarized sheet, which is electrically insulated by adhesive film (4 ', 13), is sealed against the casing by self-vulcanizing silicone compound (3).
• the shell, together with the silicone seal, represents the cup-shaped electrolyte vessel, which has to be refilled approximately every 2 minutes by inclined soaking and air vents with the mouthpiece pointing upwards.
• Fig. 11 shows a cross section through the electrode.
• the maximum current when filled with 25% aqueous ammonia is 150 mA.
• This electrode is particularly suitable for galvanizing in narrow throats and gaps and for every position g.
• Bathroom ginGes A negatively polarized horizontal iron axis carries a perforated drum made of non-conductive
• the drum rotates in an iron trough that contains the electrolyte. Zinc sheets are arranged around the trough as fixed positives. The encapsulation has a gas vent.
• the drum is filled 3/4 with iron wire pins (Nägein) freshly pickled in hydrochloric acid and washed with water. Galvanizing with 10% ammonia as the starting electrolyte proceeds with a moderate current density almost without gas evolution and very evenly. The galvanizing is matt light gray. The dried ones
• REPLACEMENT LEAF Wire sticks are dipped in mineral oil and centrifuged. They are served so that they are permanently rust-proof.
• a test tube contains 10% aqueous ammonia, into which 2 zinc electrodes in the form of a wire double, wire diameter 3 mm, are inserted vertically and parallel to each other. is initially electrolyzed with 12 volts. The current increases from 75 to 230 mA in 7 minutes. Zinc is deposited on the negatives as a black sponge. The voltage is reduced to 10 volts and after 5 minutes to 5 volts as the temperature rises. After another 10 minutes, d
• the invention has shown that in the electrolytic galvanizing on corrosive Sal alkali bases and acids can be completely dispensed with, in the simplest way.
• electrolytic galvanizing has only become practical for iron parts that border on Mauerwe masonry mortar, concrete and other porous materials, since it is inevitable that these will be wetted by the electrolyte and soak it up.
• An electrolyte that contains corrosive non-volatile constituents - and this applies to all known galvanizing electrolytes - would then be the source of a bottom rust that cannot be switched off.
• Electrolyte for galvanizing has been described which contains only volatile (water and ammonia) and inert (zinc oxide, zinc hydroxide) as well as anti-rust (zinc phosphate) components.
• a short circuit is prevented by a built-in series resistor, which, however, limits the usable current strength to approximately 100 mA when using the motor vehicle battery with a 12 volt terminal voltage.
• the electrode is quite large for this performance (outer diameter 15 mm, carbon diameter 6.5 mm, length 110 mm) and not suitable for narrow spaces. Since there is no zinc solution electrode, the small amount of electrolyte between the electrodes is electrolyzed extremely quickly, and care must always be taken to get fresh electrolytes under the carbon positive. The passage of electricity is hampered by the strong gas formation (hydrogen and chlorine), a viscous foam quickly forms. The zinc chloride is the most corrosive of all zinc salts. A fresh portion of electrolyte is required after just 1 minute.
• the electrode according to the invention preferably works with a soft-elastic mouthpiece that does not grind off zinc and does not damage the paint environment of the repair site.
• the new electrolyte is not only free of salt and corrosion, it does not develop toxic chlorine, but at most a little hydrogen.
• the electrolyte is hardly used up and in principle only a very thin electrolyte layer is required as a vehicle for the absorption and release of zinc ions.
• a series resistor is not necessary.
• the electricity yield is over 90%.
• the refill times are usually longer than the galvanizing times.
• the process according to the invention achieves perfect galvanizing without the need to contain a specific recipe, and this even with the commercially available ammonia and the simplest electrodes available in every drugstore.
• An approximately 10% aqueous ammonia is optimal, but it can also be much more concentrated or weaker, so that the process is inefficient.
• T reacts to outgassing of ammonia. Outgassing is also very limited due to the flush-fitting mouthpiece designs.
• the electrode spacing, the current density, the voltage, the temperature, the area ratio from positive to negative are also variable, all parameters that are otherwise precisely prescribed.
• Galvanizing without the use of corrosive substances brings advantages not only for repair galvanizing, but also for bath galvanizing. Because the galvanized goods do not have to be washed until the smallest traces of these substances have been removed. The method according to the invention is therefore more environmentally friendly and less expensive. There is also no danger, since corrosive substances are trapped in the galvanizing and later wreak havoc. In many cases, it is sufficient to simply drain the galvanized material and let it air dry.
• the new devices are adaptable and unsuitable for other electrolytes. Just as aqueous ammonia does not attack the fine zinc solution electrode in the de-energized idle state, it does not attack existing and already generated zinc coatings, while the known electrolytes are all aggressive.
• the aqueous ammonia dissolves the weathering products of zinc, copper and nickel and therefore exposes the metal base necessary for the electroplating. Since copper and nickel form metal amminohydroxides just like zinc, these metals are deposited analogously to zinc. Without additional oxidizing agents such as Air, hydrogen peroxide, etc. but copper and nickel are not attacked by ammonia, and in contrast to zinc also not with electrolytic current flow. in general, it is not necessary to rinse out the electrodes according to the invention after use. When the zinc oxide and hydroxide which precipitate out and, if appropriate, zinc phosphate dry out, they re-dissolve with the filled-in aqueous ammonia when used again.
• the service life of the electrodes is determined either only by the consumption of zinc parts for the galvanizing itself or by the service life of the separator, which is, however, easily replaceable.
• the plastic or rubber mouthpieces according to the invention slide very easily and comfortably on the wetted, wet surface. With the densest and thus the most capillary-active pack, the evenly thick
• REPLACEMENT LEAF Round bristles cover this geometrically 91% of the free cross-section, which the present invention does not restrict or only as little as possible.
• impure and alloyed zinc can also be used.
• a preliminary test can quickly determine whether a zinc alloy is suitable for the present process.
• tampon electrodes are the advantages of the electrodes according to the invention the unimpeded or only slightly hindered current passage, the abrasion resistance and the avoidance of short-circuit bridges, as they occur due to zinc deposition in the pore passages of the tampon electrodes.
• the design of the hand electrode according to claim 32 it has compared to d
• Hand electrode according to German PS 673 190 the advantages that the electrolyte carrier does not cover all the positives in a thick layer, the electrolyte carrier is nevertheless much thicker and more adaptable, the distance between the electrodes is smaller and the storage capacity for the electrolyte is greater because the electrolyte vessel - apart from that Mouthpiece - is sealed airtight, and that no short-circuit bridges made of zinc form in the carrier, probably because it does not cover the annular main flow path and the soft-elastic foam carrier in the mouthpiece area is in strong movement.
• the electrode according to claim 26 is suitable for galvanizing in any spatial position, which is not the case with the known because its - Similar to painting a ceiling with a brush - the electrolyte can flow out on the handling side because the brush is not encapsulated.
• the known electrode is only suitable for larger flat surfaces, while the inventive both for narrow gaps and - bundled according to claim 38 - can be used for contoured surfaces.
• the claim 27 includes an improvement of the electrode according to the aforementioned DE PS 3 400 by encapsulating it with a zinc cup, so that it can be used in any position. Few bristles are sufficient as a gap width holder and the bristle protrusions are unnecessary when using the protruding insulator border of the zinc cup rim as a means of maintaining the electrode spacing and as friction elements.
• Hand electrodes that can be adapted to any surface contour.
• Thin separators allow a very small electrode gap and the use of granular zinc, which has a high dissolving activity. 8. Very good current spreading, so that galvanizing e.g. Thread recesses is possible.
• REPLACEMENT LEAF 21 Flexible bundling of hand electrodes for processing larger, even curved surfaces.

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• Chemical & Material Sciences (AREA)
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• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electroplating Methods And Accessories (AREA)
• Prevention Of Electric Corrosion (AREA)

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• 1990
  • 1990-06-11 DE DE19904018649 patent/DE4018649A1/de active Granted
• 1991
  • 1991-04-19 WO PCT/DE1991/000326 patent/WO1991019833A2/de not_active Ceased
  • 1991-04-19 EP EP19910907528 patent/EP0489875A1/de not_active Withdrawn

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