DE1916446A1 - Method for the electrolytic treatment of a surface side of an object - Google Patents

Description

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29 ¹ . ■ ■ '<·; 1916448

5044 / kr

Patent application

John Lysaght Limited, 50 Young Street, Sydney

Process for electrolyte treatment of a surface side of an object .

The invention relates to a method for the electrolyte treatment of a surface side of a Object.

The invention can be mainly, but not exclusively, apply to a method of electrolytically applying a coating to one side of a base, while the other side remains essentially uncoated. The basis can be a sheet metal or a Be stripes or, accordingly, other material «.

While this process can be used to make one-sided coated material, it is possible, with further training, coatings on both sides of the basis in the normal sense of the invention create to produce different coatings, these are coatings of unequal thickness on the respective sides the basis.

In conventional electroplating practice, the

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article immersed in an electrolyte bath, so that the to be coated Surface of the article arranged opposite an electrode or one or more sets of electrodes is; either continuously, as is the case with the coating of strip material and similar processes, or interrupted, as is the case with the coating of bushings and similar structures for a large number of objects is ο said electrodes are anodic, while the surface is cathodic when an electrical is applied Potential is »Coating material is deposited on the two cathodic surfaces as it degrades the anode, and on adjacent surfaces of the article from “To a To avoid depletion of the electrolytic bath, it is necessary to make the solution either by using more soluble ones Top up anodes or by adding independent chemical additives.

The known methods of creating one-sided coated material had several disadvantages:

In the equipment of the plant that is used to apply a coating to both sides of a sheet or strip which eliminates or electrically separates the anode set opposite one side of the base, was inadequate in that an inadvertent coating was deposited on the side of the foundation that was more distant,

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of the active anode set is also above that Side of the base usually unintentional "coating of uneven thickness, stronger near the edges and sometimes of insignificant thickness in the Center. If you bring two sheets or strips that come with each one side against each other, into the electrolyte bath and then separates them to two sheets or strips with only one coated Page to create - a method as disclosed in British Patent Specification 939 9 ^ -9 - is shown the complexity of handling two sheets or strips at the same time in the electroplating work chain. In addition, solution can become trapped between the sheets or strips due to contamination of the subsequent ones Treatment steps in the electroplating work chain; it also causes difficulties in the rapid drying of the surfaces in order to prevent undesirable chemical reactions and besides that there is still the big story that some of the coating gets onto the uncoated sides.

If you dip the. Sheet metal or the strip only with little Depth into the electrolyte - a method such as that disclosed in U.S. Pat. No. 3,350,000 - is shown to be essential Ilortrollprobleme, making it actually impossible In de "_ · practice, the immersion if e is sufficient to be kept small in order to achieve a flame-like

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bath

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to avoid a coating «

If you run a strip through an electrolytic Bath, by arranging the strip around the circumference of a rotating part, -a technique like the Australian one Patent application 1 7181/67 disclosed7 shows that the required equipment complicated and expensive in the Acquisition and entertainment is. Besides- it would be costly to match the existing equipment to remodel.

The present invention is characterized in that a coating is deposited electrolytically by immersion in an electrolyte on one side of a base, in that the surface of the base to be coated is arranged essentially opposite at least one electrode to which an electrical potential is applied electrode is positive or anodically in relation to the workpiece so that a second electrode or a second electrode set with respect to the not to be coated side of the base or of the article is arranged, ₀ is cathodic with a to be applied electric potential which or negative in relation to the coated workpiece.

Both electrodes or electrode sets are on separate Power sources connected. The applicant is known that in many plants in which galvanic coatings are produced

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is usually provided with two sets of anodic electrodes to be arranged on both sides of the base or the workpiece. So far it had not been recognized that at Reversing the electrical potentials on a set of electrodes so that the electrodes are in fact a more cathodic one Have potential as the basis or the workpiece to be coated, and that the surface of the basis remains essentially free of coating material in relation to said set of electrodes.

The be _s Agte a set of electrodes is referred to as "reverse electrode set"; it is clear that the so-called electrode set may include only one electrode, as well as a number of electrodes, and the surface of the base facing the inverted anode set is hereinafter referred to as the "inverted surface of the base"

The method of the invention makes the conventional equipment for the production of sheets or strips coated on both sides or other articles unnecessary.

Often, coating material builds up slowly on the reverse Electrode set onο This is advantageous because in the following electrolytic operations for plating this material by alternating the potentials of both sets of electrodes can be used to just cover the surface of the

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Base to coat the set of electrodes on which the coating material has built up beforehand, is opposite »

If so desired, it is possible to use one of these various methods to achieve the Prevent build-up of coating material on the inverted electrode set. In accordance with one of these procedural options the inverted electrode set is either designed accordingly or in close contact with a metal that has something in the electrical series above the hydrogen. Materials slightly above hydrogen in the electrical voltage series are described in: Reference Electrodes by Ives and Janz (1969), Academic Press, New York, page 116.

Other electrolytic processes, such as electrical plating, can also be used, if desired In accordance with the invention, such as the one-sided electrolytic removal of material »

In other methods, the electrical potential applied to the first set of electrodes is opposite depending on the surface to be electrolytically coated according to the method negative or positive, and the electrical potential which is applied to the reversed electrode set is the reverse of the former.

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The application of the invention is not limited by a "certain shape, geometry or position of the inverted set of electrodes. According to a further development of the Er-. It is characterized by the fact that the set of electrodes is reversed compared to the entire set of electrodes The surface of the foundation is arranged where it is protected against the coating material at all times ο That is advantageous in many cases because similar positioning of the electrodes is widely used in manufacture double-sided coated material. The minimum "distance of the inverted electrode set can be approximated, but not necessarily exactly, equal to the width of the surface of the base, which remains uncoated, be} general this width is about 250 mm, and sometimes about 125 mm; these widths also agree with practice in the manufacture of double-sided coated material match. It is not necessary to specify a limit on the size and breadth of the reverse electrode set with which As a result, there is no difficulty in positioning the electrodes.

According to another development of the invention, drawing-r It is characterized by the fact that the reverse set of electrodes is mainly opposite the areas of the surface

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the basis of the _s • to be left uncoated in the vicinity of the outer areas is arranged. This development requires less inverted electrodes and still results in an uncoated surface _e

It is emphasized that the invention does not apply the above execution is limited, and that other possible embodiments are within the scope of the invention.

The voltage difference between the base and the reverse electrode set can be over a wide range can be varied. This tension will be referred to as "reverse tension" hereinafter.

If the value of the reverse tension is increased, the amount of the coating material that is attached decreases The surface of the inverted basis is deposited and is deposited on a narrow band at the edges of the surface reduced.

It has been found that when working according to the above-described procedure, the increased build-up of coating material on the edges of the coated side is significantly reduced. -

For a further and more detailed description of the The following specific examples should serve the procedure:

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example 1

Cold rolled steel plates, 200 mm format χ 280 mm, are * cleaned 1 5 seconds at 70 ⁰ C by sprayed alkali. After unwinding, the panels are anodically cleaned in alkali cleaners, immersed for 10 seconds, rinsed again and etched in dilute hydrochloric acid for 10 seconds and rinsed again.

The plates are plated ^{with zinc} in a bath of 35 g / liter of ZnSO ^ · TH ₂ O and 30 g / liter of (NH ^) ₂ ^so zj.>. The ^B has ad a pH of 3.5 and a temperature of 5O ⁰ O.

A pair of electrodes measuring 200 mm x 280 mm is cast from zinc with a degree of purity of 99 »995 ° / °. Each electrode is carefully positioned opposite the two surfaces facing the electrodes, parallel and now removed from the steel plates.

The etched steel plates are connected to earth potential, and the * zinc electrode is connected to an anode voltage of approximately 10 "volts, so that there is a current density of 0.215 amps / cm at the cathode surface. A reverse Controlled magnitude potential is applied to the remaining zinc electrode. The plating time is so one

regulated to a one-sided coating of 0.0305 kg / m to produce.

The other side of the steel plate is essentially uncoated, except for a zinc bath on the edges of

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negligible thickness and width remained. The strength of the Zinc tape is greatest at the edges, sloping at an angle not to be present at a short distance from the corners.

The table shows the maximum strengths and

at

approaching latitudes of the / various zinc potentials occurring Zinc tape.

reverse tension zinc strip on the not loading

layered side

- 6 volt

- 4 volt

- 2 volt

- 1 volt

broad mm Max. strength 0.76 mm 0.3 mm 4.75 τητη 0.28 mm 15.2 τητη 0.33 τητη 19.0 R ans 0.23 mm Tiannim celeet is. will

coated all over the reverse side; the one that runs along the edges, is 0.23 mm thick and extends over 19mm expanding tape, and 0.025mm thick on the remaining area.

Example 2

A steel plate is cleaned and etched like it's im Example 1 is illustrated.

The plate is copper coated in one of the following ways Components of existing electrolyte:

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5OgA

CON 90g / l

KOH
Sochell Sa ^ ze "

Temperature 58 ⁰ G

The Eupfer electrodes are positioned in the same way as the zinc electrodes in the previous example,

An anode voltage of applied approximately 6 volts, so that on the cathode surface

a current density of 0.0215 amps / cm. The other way round A voltage of 2 volts is applied to the other copper electrode.

The plating time is controlled to be one

to produce one-sided coating of 0.0015 kg / m. the the other side of the steel plate is mostly without coating, apart from the non-measurable coating on the outer ones Edge.

Example $

An otahlplatte is cleaned and etched as in the examples described above.

The steel plate is plated with cadmium in an electrolyte which is commercially available under the name "Kadamax"; the bathroom consists of the following components:

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cadmium 22 g / l NaCN 125 g / l NaOH 34 g / l temperature 27 ⁰ O

The cadmium electrodes are made in the same way as the zinc and copper electrodes in the previous ones P examples positioned.

An anode voltage is applied to one of the cadmium electrodes

of approximately 10 volts applied so that at the cathode

2 surface has a current density of 0.1J amp / cm «, An A reverse voltage of 4 volts is applied to the remaining cadmium electrode.

The plating time is adjusted so as to

side coating of 0.0244 kg / m. The other side of the steel plate is essentially uncoated ,apart from. a 2.5 µm wide band with a thickness 0.005 mm at the outer edges.

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Claims (1)

1916U6 5044 / ot - 13 - Claims; Λ_ ± Process for one-sided electrolytic treatment of parts by immersion in an electrolytic bath,. . · characterized , that the surface of the part to be "treated" is essentially opposite a first electrode or a Electrode set is arranged that an electrical potential applied to said first electrode or the Electrode set is present, positive or anodic relative to the potential of the part to be coated is that one second. Electrode or set of electrodes essentially opposite the remaining surface that is not to be treated of the part is arranged, and that an electrical potential at said second electrode or the second Electrode set is present, which is negative or cathodic relative to / the part to be treated. 2_ * "Method according to claim 1, characterized in that that the electrolytic treatment consists of electrolytic Heinigen and electrolytic pickling or electrolytic etching. _x electrolytic process for one-sided treatment of T _e iien by immersion in an electrolytic 909846/094 1 - 14 - Bath, characterized in that the surface of the part to be treated is essentially opposite one another first electrode or a set of electrodes is arranged that an electrical potential which at said Electrode or the electrode set is applied, negative or cathodic relative to the potential of the to be coated Part of it is that a second electrode or set of electrodes is essentially not opposite to the remaining one the surface of the part to be treated is arranged, and that an electrical potential is applied to said second electrode or the second set of electrodes, the to
is positive or »anodic relative to the / treated part. 4_. Method according to claim 3, characterized in that that the electrolytic treatment from electrolyte ' cleaning, electrolytic pickling or anodizing of metallic parts. ° A method for electrolytic plating of a metal plate on one side of a base layer of a part in an electrolyte, characterized in that the surface of the base plate to be coated is arranged essentially opposite a first electrode or a set of electrodes, that an electrical potential is applied to said first Electrode or said first set of electrodes is applied, which is positive in relation to the part to be plated 909846/0941 -15 - 5044 / ot - 15 - tive or anodic. is that a second electrode "resp. a second set of electrodes essentially the opposite of the remaining -uiiplafctierten surface of the Part is arranged, and that there is an electrical potential applied to the second electrode or second set of electrodes is negative, the part plating in relation to zram su or is cathodic. € u method according to one of the preceding claims, characterized in that the applied electrical potential is 0.6 volts to 20 YoIt »