US3259562A - Method of adhering an electrophoretically deposited metal coating to a metal substrate - Google Patents

Method of adhering an electrophoretically deposited metal coating to a metal substrate Download PDF

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US3259562A
US3259562A US403408A US40340864A US3259562A US 3259562 A US3259562 A US 3259562A US 403408 A US403408 A US 403408A US 40340864 A US40340864 A US 40340864A US 3259562 A US3259562 A US 3259562A
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coating
substrate
metal
coated
strip
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Salt Frederick William
Lewis Kenneth Gill
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British Iron and Steel Research Association BISRA
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C24/00—Coating starting from inorganic powder
    • C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
    • C23C24/082—Coating starting from inorganic powder by application of heat or pressure and heat without intermediate formation of a liquid in the layer
    • C23C24/085—Coating with metallic material, i.e. metals or metal alloys, optionally comprising hard particles, e.g. oxides, carbides or nitrides
    • C23C24/087—Coating with metal alloys or metal elements only
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
    • B22F7/02—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers
    • B22F7/04—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite layers with one or more layers not made from powder, e.g. made from solid metal
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D13/00—Electrophoretic coating characterised by the process
    • C25D13/02—Electrophoretic coating characterised by the process with inorganic material

Definitions

  • This invention is concerned with a method of forming a metal coating on a metallic substrate and, more particularly, on metallic substrates in elongated form, that is a form which can be subjected to rolling, such as sheet, strip, wire or rod.
  • a base metal By coating a base metal with another metal, it is frequently possible to obtain an advantageous combination of properties, for example various types of steel can be coated with metals which have a better corrosion and/ or heat resistance than steel, while .the composite material retains the advantageous mechanical and metallurgical properties of the steel. Where such a combination of properties can be obtained by the addition of alloying elements to the base steel, it is often the case that the alloy steel is more expensive to produce than a coated steel having the same properties.
  • coating metals which can impart useful properties to steel substrates are, for example, aluminium, nickel, zinc, copper, brass, stainless steel, cadmium, titanium and zirconium.
  • Aluminium coated steel is a very useful material for applications where strength coupled with corrosion and heat resistant properties are required.
  • the self-healing oxide film of the aluminium ensures good resistance to corrosion and this coating, under certain conditions, particularly in sulphurous industrial atmospheres, provides superior protection to that obtained with a zinc coating.
  • the oxide film together with the iron-aluminum alloy formed on heating, provide excellent resistance to scaling at high temperatures.
  • the composite material thus provides a perfectly satisfactory substitute for an expensive alloy steel in some applications.
  • Aluminium may be applied to steel by a variety of methods, the principal methods available being spraying, cladding, vacuum deposition, vapour plating, electro deposition or hot dipping.
  • the processes of spraying and cladding are well known, the former resulting in a rather porous deposit lacking in ductility; vacuum deposition has been used to produce extremely thin and highly refleeting surfaces for particular applications, and thermal deposition of such compounds as tri-isobutyl aluminium has been used to produce deposits 0.005 inch thick. It is not possible to deposit aluminium electrolytically from an aqueous bath and although various organic plating baths have been described, this method is not economic on an industrial scale.
  • Hot-dipping processes are used on a commercial scale; hot dipped aluminium-coated steel, by reason of the temperature involved in its production, always has a layer of iron-aluminium alloy at the interface between the steel substrate and the coating and while this layer provides 3,259,562 Patented July 5, 1966 the composite material with good heat resistance, its brittleness limits the useful applications of the material, when, for example it is desired to take advantage of the aluminium coating mainly for its corrosion resistance properties.
  • Cladding essentially involves rolling an aluminium foil onto the steel substrate in a plurality of passes so as to obtain a heavy reduction, this being required to obtain good bonding between the substrate and the coating metal.
  • nickel and copper can be conveniently deposited by electrolysis.
  • the only methods which are suitable for the production of tonnage quantities of coated material having coatings some thousandths of an inch thick are cladding and hot-clipping.
  • Zinc and cadmium coatings can be .formed on steel by bot-dipping and brass, stainless steel, titanium and zirconium coatings can be formed on steel by cladding.
  • cladding gives rise to the same disadvantages as already mentioned in the case of cladding with aluminium, that is heavy reduction is required which substantially reduces the formability of the substrate.
  • Cladding is also subject to the inherent disadvantage that it necessitates the use of relatively thin toils of the coating metal which may be considerably more expensive than the same metal in ingot or powder form. All hot-dipping processes have the inherent disadvantages that a considerable heat input is required to maintain the bath of coating metal molten and that the molten metal is subject to drossing.
  • Metal coatings are formed, according to the present invention, by a process which essentially comprises the steps of electrophoretically depositing finely divided coating metal on the substrate, heating the coated substrate so that it is thoroughly dried and raised to .a temperature adapted to promote adhesion of the coating to the substrate, rolling the coated substrate while still hot with a pressure suflicient to bring the coating metal particles into intimate contact with one another, and then heating the coated substrate to effect sintering of the coating metal until, but only until, the coating becomes so firmly bonded to the substrate as to prevent delamination upon subsequent deformation of the coated substrate.
  • Scheible is primarily concerned with the use of prolamines, such as zein, as activators for the electrophoretic deposition; a typical coating process described by Scheible comprises an electrophoretic deposition step (in the presence of a prolamine as just mentioned), air drying to remove the electrophoresis solvents, placing the coated article in a rubber envelope, evacuating the envelope to remove air, compressing the envelope isotatically in a glycerine medium at pressures from 20 to 50 tons/sq. inch to density the coating, and then sintering the coating in a hydrogen'atmosphere at temperatures of from lO0-l200 C. for from 1 to 3 hours.
  • prolamines such as zein
  • a continuous process for the formation of aluminium oxide or titanium oxide insulating coatings on heater filaments for use in thermionic valves is described by Thomson in US. Patent No. 2,956,937.
  • This is a continuous process suitable for the large-scale production of coated wire in which, following electrophoretic deposition of the coating material, the coated wire is first dried at a relatively low temperature and is then heated to a much higher temperature to effect sintering of the oxide coating, a temperature of from 1300 C. to 1700 C. being mentioned as suitable for the sintering treatment. If such a sintering temperature were used in the case of an aluminium-coated substrate, the aluminium would be com pletely alloyed with the substrate metal and the mechanical properties of the substrate metal would be very deleteriously affected.
  • the process of the present application is essentially characterised by the use of conditions in the after-treatment of the coating when it has been formed by electrophoresis, which are such that the final product can be deformed without risk of damaging the coating.
  • FIGURE 1 shows diagrammatically apparatus suitable for carrying out the present process on relatively narrow strip substrates, that is having a width of, say, 5 inches;
  • FIGURES 2 and 3 are photomicrographs of sections through samples of coated strip metal which will be described in detail in a subsequent portion of this application.
  • FIGURE 4 shows curves of temperature against time for the sintering of aluminium coatings.
  • the apparatus comprises an uncoiler for the strip 11, deflector rolls 12 and 13, the latter being a contact roll which serves to polarise the strip as the cathode during operation, a narrow, vertically elongated electrophoresis tank 14, the top of which is surrounded by a header 15 which collectselectrophoresis suspension flowing over the top edge of the tank 14 (which constitutes a weir).
  • the tank 14 contains two sheet anodes (not shown) arranged parallel to and on either side of the path of the strip.
  • a delivery pipe 16 leads from the header 15 to a suspension reservoir 17 from the bottom of which leads a valved pipe 18 which delivers the suspension via a pump 19 to the bottom of the electrophoresis tank 14.
  • a pair of inclined rolls 20 which are arranged to deflect the strip and pass it downwards through a drying duct 21, the rolls 20 being so arranged that they contact only the edges of the strip.
  • the strip On leaving the duct 21, the strip is passed under a further pair of inclined deflecting rolls 22 and into a pre-heating furnace 23 from which the strip passes directly to a compacting mill 24 and from the latter to a coiler 25.
  • the drying duct 21 and the preheating furnace 23 are provided with heaters capable of raising the coated strip to the desired temperatures (which are more fully described below); any conventional heat ing means can be used for this purpose.
  • the pie-heating furnace 24 is also suitably provided with means for maintaining a reducing atmosphere therein.
  • the apparatus illustrated and described above is suitable, as stated, for the coating of relatively narrow strip and for the case where the final heat treatment is carried out in coil. If the final heat treatment is to be carried out continuously, that is, in line, the strip is passed from the compacting mill 24 to a sintering furnace arranged in line with the mill and from the latter to the coiler.
  • a suitable arrangement is for a drying and pre-heating furnace to be located vertically above the tank 14 and for the compacting mill to be located vertically above the pre-heating furnace.
  • the coated strip can, in fact, be passed over a suitably surfaced roll without damaging the coating, chromium plated and tetrafiuoroethylene surfaced rolls being suitable for this purpose.
  • a suitably surfaced roll as a deflector roll vertically above the drying and pre-heating furnace in the arrangement just described, the compacting mill can be located at ground level instead of vertically above the furnace as described, and this arrangement may be considerably more convenient.
  • Electrophoretic deposition step of the present process can be carried out in a generally similar manner to electrophoretic deposition processes previously described. Electrophoresis can be effected in a polar organic medium, suitable organic liquids being, for example, methyl alcohol, ethyl alcohol, for example in the form of industrial methylated spirit (denatured ethyl alcohol), isopropanol and acetone.
  • suitable organic liquids being, for example, methyl alcohol, ethyl alcohol, for example in the form of industrial methylated spirit (denatured ethyl alcohol), isopropanol and acetone.
  • suitable organic liquids being, for example, methyl alcohol, ethyl alcohol, for example in the form of industrial methylated spirit (denatured ethyl alcohol), isopropanol and acetone.
  • suitable organic liquids being, for example, methyl alcohol, ethyl alcohol, for example in the form of industrial methylated spirit (denatured ethyl alcohol
  • a wholly organic medium can be used, it is much preferred to use a medium consisting of a mixture of a major proportion of one or more organic liquids and a minor proportion of water.
  • a partially aqueous bath By using a partially aqueous bath, the electrophoresis yield in terms of grams deposited per coulomb, is considerably increased as compared with deposition under identical conditions but using a wholly organic medium.
  • Suitable proportions of water are from 0.2% to 30% by volume of the mixture, from 2 to 20% being preferred. Within these ranges, it is found that optimum deposits of different coating metals are obtained with different proportions of water in the bath.
  • a bath containing v./v. of water when depositing nickel and a bath containing 2% v./v. of water when depositing aluminium.
  • the limiting current density for the formation of acceptable coatings is dependent upon other conditions of the electrophoresis and, more particularly, upon the relative velocity between the suspension and the metallic surface. The lower this relative velocity, the lower the limiting current density for the formation of acceptable coatings, and vice versa. In practice this means that if the process is carried out discontinuously, that is the metallic surface is held stationary within the bath and the latter is agitated just sufficiently to maintain the coating metal particles in suspension, the maximum current density which can be used is about 2 amps/ square foot.
  • Suitable panticle sizes for the coating metal in the suspension are up to 50 microns in diameter, the upper limit of size being governed by the difiiculty of maintaining particles having a diameter greater than 50 microns in suspension. Aluminium powder having particle sizes in the range 5 to 50 microns has been successfully used.
  • the amount of finely divided coated metal in the electrophoresis bath is not critical, but since the electrophoresis yield has been found to increase approximately linearly with increasing powder content, it is preferred to use as high a powder content as is compatible with obtaining sufiicient wet adhesion for the powder coating to withstand the vibration of the compacting roll. Suitable proportions are, for example, from 10 to 30% by weight.
  • the electrophoresis suspension should also contain a soluble salt of a multivalent metal in order to give good electrophoresis yields (i.e. in terms of weight of deposit per coulomb) and to provide adequate adhesion of the wet powder to the substrate to allow rapid removal from the bath and of the dried powder to permit in-line rolling; rolling in-line is not practical unless the powder stays in position despite inevitable rolling mill vibraton.
  • a variety of multivalent metal salts have been proved to be satisfactory in this respect, for example, salts of nickel, aluminum, manganese, magnesium, zinc, chromium, iron and calcium with monovalent anions, such as nitrate, chloride, iodide or bromide, may be used.
  • All multivalent metals which can form insoluble hydroxides can be recommended as giving good physical properties after heat treatment. There is usually a residual contaminant in the coating from the electrolyte and some electrolytes would be better than others in applications involving the long term corrosion resistance of the product.
  • the minimum amount of multivalent metal salt which should be used is that which will just give an adherent continuous coating from the bath at maximum line speed and pumping velocity of the suspension. The maximum amount is determined by the fact that above a certain concentration there is a reduction in electrolysis yield. Providing the electrolyte concentration is sufficient to produce a uniform layer from the bath, the amount and nature of the electrolyte is not important since it has been shown that a coating with good wet adhesion also has good dry adhesion and rolls well. In general a concentration of electrolyte of about 1 millimole per litre has been found to be very satisfactory.
  • the coated substrate is subjected to a drying and pre-heating step which should be effected in such a Way that the substrate is not contacted by any roll or guide prior to completion of this step since the powder coating would otherwise be dislodged to an undesirable extent.
  • a drying and pre-heating step which should be effected in such a Way that the substrate is not contacted by any roll or guide prior to completion of this step since the powder coating would otherwise be dislodged to an undesirable extent.
  • this is effected by passing the coated elongated substrate upwards from the electrophoresis bath through a heating zone, provided for example, with radiant electric heaters, which is located in the path of the upwardly moving substrate, there being no contact between the coated substrate and any part of the heating apparatus.
  • pre-heating temperatures depend upon the nature of the coating metal and the substrate metal. In the case of steel substrates, suitable pre-heating temperatures are as'follows: for aluminium coatings, from 200 to 350 C.; and for the other coating metals from 100 to 350 C. In the case of these other coating metals, pre-hea-ting should be carried out in a reducing atmosphere, for example hydrogen or the mixture of nitrogen and hydrogen obtained by cracking ammonia, if a temperature above 200 C.
  • the pre-heated coated substrate is then subjected to rolling.
  • the purpose of this rolling step is to bring the individual particles of the powder coating into intimate contact with one another and for any particular substrate and coating metal, a suitable minimum rolling load is relatively critical, in that unsatisfactory coatings are obtained in the final product if the rolling load is too low.
  • adhesion of an electrophoretically deposited coating to the substrate is obtained by heating alone (as taught, for example, by Thomson, US, Patent No. 2,956,937), the heat treatment must be longer or at a higher temperature or both, to achieve a coherent and adherent coating.
  • the minimum rolling load required to obtain satisfactory compaction depends upon the hardness of the coating metal and of the substrate metal, and to a lesser extent, as will be more fully described below, on the roll diameter. The greater the hardness of the substrate, the higher will be the rolling load required. As a result of numerous experiments, we have developed a formula for determining the minimum rolling load in tons per inch width required to obtain adequate compaction; this formula is as follows:
  • Annealed low carbon steel 82 40% cold reduced low carbon steel 160170
  • the Brinell hardness of other coating metals and other substrate materials can be readily ascertained from the literature by those skilled in the art.
  • the minimum rolling load given by the above formula gives satisfactory results.
  • the above formula gives the minimum rolling load using 7 inch diameter work rolls and the rolling load should be increased with larger diameter work rolls.
  • the rolling load given by the above formula should be increased by about 25%.
  • suitable minimum rolling loads are as follows- Annealed and temper rolled low carbon steel strip having a Brinell hardness of 82, 0.025 inch thick, and coated with aluminium:
  • Copper (Brinell hardness 42) About 6 tons/inch width. Brass (Brinell hardness 66) 810 tons/inch width. Stainless steel (Brinell hardness 15-20 tons/inch width.
  • under-compacted coatings do not have the characteristic appearance of a solid sample of the coating metal, whereas properly compact coatings do.
  • under-compacted aluminium coatings exhibit characteristic white powdery flecks and under-compacted nickel coatings exhibit an off-white bloom; similar phenomena are observed with the other coating metals.
  • Rolling is preferably effected with a load which is just suflicient to prevent the appearance of the visual characteristics of undercompaction.
  • insufiicient compaction leads to a product with poor corrosion resistance and poor formability, that is the coating will crack and/or delaminate when the product is bent or drawn, since the adhesion of the coating is poor and the relatively high temperatures required to effect sintering of the under-compacted coating lead to the formation of an alloy interlayer.
  • Rolling loads in excess of the minima described can be used, but when rolling loads greatly in excess of the minimum for a particular substrate and coating metal are used, blisters are occasionally formed in the product during sintering.
  • the effect of rolling loads substantially in excess of the minimum is, in general, to cause deterioration of the mechanical properties of the substrate and, in particular, to reduce its formability. This is of little or no importance where the coating metal is such that the conditions of temperature and time required to sinter it are also such as to effect complete or partial annealing of the substrate since, in these cases, the subsequent sintering step restores all or most of the formability Which was lost in the compaction step.
  • the final step of the present process consists of a second heat treatment to eflect sintering of the compacted coating; for any coating metal sintering may be carried out at a relatively ⁇ low temperature for a relatively long time or at a. relatively high temperature for a relatively short time. In general the least severe conditions compatible with obtaining complete sintering should be employed. If the sintering temperature chosen is such that the time required is more than, say, 30 seconds, the coated substrate is advantageously coiled (if in the form of strip or wire) or stacked (if in the form of sheets) after rolling and sintering effected in the coil or stack as the case may be. If the sintering time is sufiiciently short, on the other hand, sintering can be carried out in line with the sintering furnace located after the compacting rolls.
  • Suitable sintering conditions for aluminium are as follows:
  • FIGURE 4 of the drawings which shows two curves, AB and AC, obtained by plotting sintering temperature, in C., against log sintering time in seconds. Any combination of temperature and time lying between the curves AB and AC gives a satisfactory, i.e.
  • Example I Annealed and temper rolled steel strip was coated with aluminium in apparatus of the kind illustrated in FIG URE 1.
  • the strip had a width of 5 inches and thickness of 0.025 inch and had been degreased by cathodic treatment in hot alkali, lightly pickled in cold 50% v./v. hydrochloric acid, and then washed.
  • the strip was passed continuou'sly into the electrophoresis cell through the bottom of the cell and passed vertically upwards through the bath contained therein, the path length of the strip in the bath being 30 inches.
  • the bath was continuously circulated through the cell, being pumped in at the bottom of the cell and allowed to flow over a weir at the top before being recirculated to the pump.
  • a steel anode 30 inches long and 5 inches wide was arranged parallel to each side of the strip, the spacing between the surface of the strip, which was connected as the cathode, and the surface of the anodes being 1 inch.
  • the bath consisted of a 10% W./v. suspension of aluminium powder of which passed through a 300 mesh sieve) in a mixture of 80% by weight of industrial methylated spirit and 20% by weight of water and contained 1.0 millimole/ litre of aluminium nitrate.
  • the strip speed was 10 feet/minute, the bath velocity in the cell was 75 feet/ minute, the applied voltage 75 volts and the cathode current density 2.4 amps./ square foot.
  • the coated strip was dried by passing it through an electrically heated drying chamber which raised the temperature of the coated strip to 200 C. and then passed through a rolling mill having 7 inch diameter work rolls and giving a load of 4 tons/inch width of strip.
  • the thickness of the coating after rolling was 0.001 inch.
  • the rolled strip was then coiled and heated in the coil to 500 C. over a period of 3 hours, the rate of heating being such that its temperature was below 300 for 2 hours.
  • the coiled strip was then allowed to cool in air.
  • the resulting coating was tightly bonded to the strip and the coated strip could be bent round a mandrel having a diameter equal to the thickness of the coated strip without delamination occurring.
  • Example 2 Coating of annealed and temper rolled mild steel strip similar to that of Example 1 was carried out substantially as described in that example, except that the anodes were formed of pure nickel and were 36 inches long, their spacing from the strip being as before.
  • the suspension contained 10% w./v. of aluminium powder having a particle size range of 5 to 50 microns in a mixture of 98% by weight of industrial methylated spirit and 2% by weight of water which also contained 1 millimole/ litre of nickel chloride.
  • the strip was passed through the electrophoresis cell at 10 feet/minute, a current of 1.5 amps was applied to each side of the strip and the applied voltage was volts; the finished thickness of the coating was 25 microns.
  • the coated strip was subjected to different combinations of after-treatments, rolling being effected in each case with 12 inch diameter work rolls.
  • the results obtained are summarised below; in these results, satisfactory coating means that the coated strip
  • the suspension consisted of 30% by weight of nickel powder in a mixture of 90% by volume of industrial methylated spirit and 10% by volume of water which also contained 1 millimole of nickel chloride per litre.
  • the strip was passed through the electrophoresis cell could be bent round a inch mandrel without damagat feet/mlnute, a current of 1.5 amps was applied to ing or delamlnatmg the coating and unsatisfactory coateach side of the strip and the applied voltage was 60 mg means that the coating was damaged and/ or devolts.
  • the finished thickness of the coating was laminated on being sub ected to this test. microns.
  • 250 4 u-.. o Satisfactory coating 250 4 520 for2hours... Unsatisfactory coating (brittle alloy). 250 4 620 for 10 minutes Unsatisfactory coating (see Figure 3 (a)). 250 4 620 for 15 minutes Unsatisfactory coating (see Figure 3 (12)). 250 4 620 for 60 minutes Unsatisfactory coating (see Figure 3 (0)).
  • FIGURE 2 of the accompanying drawings comprises photomicrographs at a magnification of X500 of a section through (a) an undistorted sample of the product obtained in run 2a and (b) a sample of the same product which had been bent round a inch mandrel, the latter photomicrograph being of a portion of the sample near the apex of the bend.
  • 26 is the steel substrate and 27 the compacted and sintered aluminium coating. It will be seen from.
  • FIGURE In a number of runs, the coated strip was subjected to different combinations of after-treatments, rolling being effected in each case with 12 inch diameter work rolls.
  • FIGURE 3(a) thicker from FIGURE 3(a) to FIGURE 3(a), showing the increasing formation of this alloy on holding at a high sintering temperature.
  • the products of runs 211, 2i and 2j all failed the deformation test because of the presence of the layer of brittle iron-aluminium alloy shown in FIGURE 3, the formation of which was avoided by the process followed with runs 2a, 2b and 2f.
  • Example 3 Coating of hard unannealed mild steel strip 5 inches wide and 0.025 inch thick with nickel was carried out in apparatus as described in Example 2.
  • Example 4 Steel strip of the type used in Example 1 was coated with zinc by a procedure substantially as described in that example, except that the aluminium powder in the suspension was replaced by zinc powder (10% w./v.) and the aluminium nitrate electrolyte was replaced by Zinc nitrate (1 millirnole per litre).
  • the coated substrate was heated to 200 0., passed through a rolling mill having 7 inch diameter work rolls and giving a load of 4 tons/inch width of strip and coiled.
  • the coiled strip was heated for 1 hour at 250 C. to give a tightly adherent zinc coating.
  • the metallic substrate should, of course, be free of grease and other contaminants prior to effecting electrophoretic deposition thereon.
  • Suitable metal cleaning procedures are well known to those skilled in the art and one suitable cleaning procedure has been described in the above examples. Degreasing by cathodic treatment in hot alkali followed by washing in water is in many cases quite sufficient.
  • a more thorough cleaning schedule comprises (a) immersion of the substrate in a aqueous caustic soda solution at 60 C., (b) cathodic electrocleaning in an aqueous solution containing caustic soda and 5% sodium carbonate using a current density of 100 amps/square foot, and (c) fiash pickling in hydrochloric acid.
  • treatment (a) is effected for 20 seconds, and the substrate is then washed in water
  • treatment (b) is effected for 30 seconds and the substrate is then washed in water
  • treatment (c) is effected for seconds and the susbtrate is again washed before being passed into the electrophoresis tank.
  • Another suitable cleaning procedure comprises subjecting the substrate to vapour blasting; this gives a clean matt surface.
  • a hollow-cylindrical anode is preferably employed, the wire to be coated being aligned along its axis.
  • Rolling of the coated wire after the preheating step is preferably carried out by two passes between shaped rolls which are designed so that 60% of the wire surface is compacted at each pass, the axes of the rolls for the second pass being at right angles to the axes of the rolls used for the first pass. In this way the coating is uniformly compacted around the wire.
  • the degree of pressure applied by the rolls is preferably such as to cause a 1% reduction in cross-sectional area in the case of a mild steel wire; a suitable rolling load is, for example, approximately 0.2 ton per stand for hard drawn 01120 inch mild steel wire. In the case of harder, i.e. less deformable, wires the reduction in area can be less, but should be at least 0.2%.
  • the second stand may, if desired, be rotated with respect to the first stand to allow for any twisting of the wire as .a result of induced stresses.
  • the rolls should be kept clean, i.e. free from metal powder, suitably by means of rotating brushes.
  • two fourroll Turks head rolling units can be used for compacting the powder coating, but this offers no advantages over the simpler and cheaper double roll units already described.
  • the powder can also be compacted by rolls describing a helical path around the wire.
  • the method of electrophoretically depositing a metal coating on a metal substrate in elongated form comprises the step of continuously passing the substrate through an electrophoresis cell containing a suspension of finely divided coating metal in its metallic form in a polar organic solvent said suspension also con taining from 2% to 30% water by volume and a minor proportion of a soluble rnultivalent metal salt, said substrate being connected as cathode and said suspension being continuously agitated, whereby said coating metal is electrophoretically deposited on said substrate.
  • the method of causing an electrophoretically deposited coating of aluminium to adhere to a steel substrate sufficiently to prevent delamination when said coated substrate is subsequently bent about a A inch mandrel comprises the steps of preheating said coated substrate to a temperature between 200 and 350 C., compacting said coated substrate while still hot with a rolling load of at least three tons per inch of subtrate width, and then sintering the coated substrate under conditions of temperature and time insufiicient to cause the formation of an alloy layer at the interface between the coating and substrate, said time and temperature lying between curves AB and AC of FIGURE 4 of the drawings.
  • the method of causing an electrophoretically deposited coating of aluminium to adhere to a steel wire comprises the steps of preheating said coated wire to a temperature between 200 and 350 C., compacting said coating by compressing said heated and coated wire along at least two diameters positioned at right angles to each other sufficiently to reduce the crosssectional diameter of the wire between 0.2% and 1%, and then heating said coated wire to a temperature and for a length of time suflicient to sinter the coating but insufiicient to cause the formation of a layer of alloy at the interface between the coating and substrate said time and temperature lying between curves AB and AC of FIG. 4 of the drawings.

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US403408A 1959-05-22 1964-10-12 Method of adhering an electrophoretically deposited metal coating to a metal substrate Expired - Lifetime US3259562A (en)

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GB17501/59A GB884797A (en) 1959-05-22 1959-05-22 Improvements in or relating to the formation of metal coatings

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DE (1) DE1295307B (de)
GB (1) GB884797A (de)
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NL (2) NL124362C (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3395088A (en) * 1964-05-15 1968-07-30 British Iron Steel Research Method for improving the adhesion of electrodeposited metal coatings
US3859426A (en) * 1972-01-17 1975-01-07 Gte Sylvania Inc Method of purifying refractory oxides of aluminum and zirconium
US5125213A (en) * 1990-07-30 1992-06-30 Focke & Co. Process and apparatus for packing bulk materials
US20040104047A1 (en) * 2002-12-02 2004-06-03 Andreas Peter Insulative gap sub assembly and methods

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3331762A (en) * 1961-11-15 1967-07-18 British Iron Steel Research Process of forming metal coatings on metal strip by electrophoretic deposition
JPS5278228A (en) * 1975-12-17 1977-07-01 Mitsubishi Electric Corp Method of forming glass protective film

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2372607A (en) * 1940-11-23 1945-03-27 American Electro Metal Corp Method of making layered armors
US2442863A (en) * 1944-11-23 1948-06-08 Sylvania Electric Prod Electrophoresis coating of electron tube parts
US2878140A (en) * 1957-05-01 1959-03-17 Vitro Corp Of America Densification of coating by use of isostatic hydraulic pressure
US2935402A (en) * 1954-04-15 1960-05-03 Mannesmann Ag Hot rolling of metal powder
US2982707A (en) * 1958-07-30 1961-05-02 Vitro Corp Of America Electrophoretic dispersion
US3142560A (en) * 1960-11-17 1964-07-28 Vitre Teja Ind Co De Process for strip cladding by hot rolling of particulate material

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB650753A (de) * 1900-01-01
DE539162C (de) * 1927-03-14 1931-11-21 Eugen Harsanyi Dipl Ing Verfahren zum UEberziehen von festen metallischen Strahlungskoerpern elektrischer Vakuumgefaesse mit schwer Schmelzbaren Metallen oder Metallverbindungen
GB444723A (en) * 1934-08-08 1936-03-26 Philips Nv Improvements in or relating to methods of applying a top layer to an article, more particularly to the surface of an electric device
DE625217C (de) * 1934-08-09 1936-02-06 Philips Patentverwaltung Verfahren zum UEberziehen von Koerpern mit einer Deckschicht
NL81831C (de) * 1952-04-23

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2372607A (en) * 1940-11-23 1945-03-27 American Electro Metal Corp Method of making layered armors
US2442863A (en) * 1944-11-23 1948-06-08 Sylvania Electric Prod Electrophoresis coating of electron tube parts
US2935402A (en) * 1954-04-15 1960-05-03 Mannesmann Ag Hot rolling of metal powder
US2878140A (en) * 1957-05-01 1959-03-17 Vitro Corp Of America Densification of coating by use of isostatic hydraulic pressure
US2982707A (en) * 1958-07-30 1961-05-02 Vitro Corp Of America Electrophoretic dispersion
US3142560A (en) * 1960-11-17 1964-07-28 Vitre Teja Ind Co De Process for strip cladding by hot rolling of particulate material

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3395088A (en) * 1964-05-15 1968-07-30 British Iron Steel Research Method for improving the adhesion of electrodeposited metal coatings
US3859426A (en) * 1972-01-17 1975-01-07 Gte Sylvania Inc Method of purifying refractory oxides of aluminum and zirconium
US5125213A (en) * 1990-07-30 1992-06-30 Focke & Co. Process and apparatus for packing bulk materials
US20040104047A1 (en) * 2002-12-02 2004-06-03 Andreas Peter Insulative gap sub assembly and methods
WO2004051050A1 (en) * 2002-12-02 2004-06-17 Baker Hughes Incorporated Insulative gap sub assembly and methods
US6926098B2 (en) 2002-12-02 2005-08-09 Baker Hughes Incorporated Insulative gap sub assembly and methods
GB2411682A (en) * 2002-12-02 2005-09-07 Baker Hughes Inc Insulative gap sub assembly and methods
GB2411682B (en) * 2002-12-02 2006-11-08 Baker Hughes Inc Insulative gap sub assembly and methods

Also Published As

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DE1295307B (de) 1969-05-14
NL251859A (de)
GB884797A (en) 1961-12-20
LU38691A1 (de)
NL124362C (de)

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