DE1521382A1 - Metal plating - Google Patents

Description

The invention relates to the application of metal plating to electrically conductive carriers or »underlay-

materials, "In particular, the invention relates to a novel and valuable metal plating, the more convenient and less costly than the plating current, provides the thicker coatings than can be obtained by displacement plating, and is as easy as mechanical plating ₀

Two applied on a large scale methods by which resistant coatings on other metals can be · apply are the G-alvanisieren and mechanical plating ,, In the electroplating an external DC voltage is applied to two electrodes ₉ are immersed in an electrolyte ion of the metal to be plated,

Q09845 / 13Q7

BATH

where the cathode represents the object to be plated »

In mechanical plating, the is brought to be plated objects together with particles deo plating metal and promoter chemicals, preferably contains in an aqueous solution, the impact media in a plating barrel ₀ Ünn the plating barrel rotated or moved to other Vfeise that Plattierungsmetallteilchen by the hammers effect are the Impact media and the objects to be plated are flattened and cold-welded to one another and to the surface of the objects to be plated. These objects have a visually coherent coating; Plating metal "

According to the invention is now a simple, effective; Method for applying a metal coating to a electrically conductive material suggested » The inventive method is gekennaeicunei ;, that you can remove the underlay material with a free-flowing Liquid, the ions of a dissolved salt of a plating metal contains, and a "driving" or «, the plating-inducing metal, which is both less noble than the base material as well as less noble than the plating; metal is, brings in contact «The pH value of the liquid and the potential difference between the driving metal and the plating metal are such that the

909845/130?

SAD ORIGINAL

driving metal loosens. The parts of the base material to be plated are then mixed with the liquid in Brought into contact with the driving metal, the base material on practically all surfaces that come with the Liquid in contact, touches, causing these surfaces with a metallic coating of the plating metal be provided.

To carry out the process according to the invention, the use of a stable product has proven to be desirable which, in combination, is a water-soluble salt of a plating metal, a powdered metal which is both less noble than the base material to be plated and less noble than the plating metal, and agents which prevent intimate contact between the salt and the powdered metal in the absence of water ; when this product is placed in water, the constituents are released and a plating bath is obtained,

The metal plating process of the present invention has the rich benefits of electroplating without it the high investment costs for the electrical and other systems required by this process «Simultaneously it preserves the simplicity, convenience and urgency aer mechanical plating process. According to the invention will induce a "driving" or plating

9098-5 / 1307

Rende metal and an ionizable salt of a metal to be deposited by plating are introduced into a free flowing liquid medium in which the salt is soluble, the pH of the liquid and the potential difference between the floating metal and the plating metal being such that the floating metal dissolves . An electrically conductive base material to be plated is then - such as _o B "by stirring, rotating or otherwise moving - contacted with the liquid medium and the driving metal to be plated surfaces in contact, whereby the plating metal from the solution onto the substrate material and forms a smooth, even coating layer of the desired thickness.

Since no external power source is required, and since it is easier to use in the method according to the invention mechanical working methods an equally uniform coating is obtained as with electroplating, it is in other words, a completely new and advantageous method for applying metal coatings or plating «

In carrying out the process that can be a solid metal object to be plated rnterlagematerial, or it can be small parts such "B _e washers, SchlauchkleffiEen, 3chraube" closures etc, "acting ₀ The backing material can also provide your own metal

909845/1307

BATH ORIGINAL

be in powder whose flakes are -Be or _o grains plated "In any case, the driving must metal less noble, DOHC in the solution in which it or suspended" with which it -is brought into contact electrochemically active than both the plating metal (this is incorporated into the solution in the form of a metal salt) and the metal base to be plated must be ₀

In many cases, with the aid of the method according to the invention, a superior protective or decorative metal coating can be obtained directly on a conductive substrate these metal parts with zinc, cadmium or other corrosion-resistant metal the invention proposes a u _o "a novel storage-stable product which can be used to apply a uniform, smooth metal plating on the electrically conductive parts ₀

With the aid of the method according to the invention, long-standing problems with the application of Pre-plating coatings for anchoring subsequently applied metal plating on ferrous metal substrates, A common pre-cladding material for ferrous metal parts was previously copper, either

909845/130?

by electroplating or displacement plating. Prior to mechanical plating, displacement plating has generally been applied to
apply extremely thin coatings; for practical reasons these coatings were limited to copper »

Although copper is used for pre-plating metal particles prior to the application of a metal coating by mechanical means Plating is generally satisfactory, copper plating (even copper primers) are for certain

the .

Purposes where plated metal objects come into contact with certain substances, v / ie z "B" with certain gases,
undesirable because of the catalytic effect of copper which induces polymerizations. Copper also has the disadvantage that its reddish color and the black color of the
Contrast the copper oxide with the color of the last metal coating applied over the primer. Occasionally, the copper "shows through" through a subsequently applied plating, which then becomes stained
or may appear inherited, although it is still able to fully fulfill its functions. Silvery Vorplattierungsmetalle such "B _e tin, cadmium, lead, nickel, mercury, silver and thallium, these disadvantages would not have
and the appearance of the finished plated article does not
affect »

Tin is an excellent pre-plating material

909845/1307

has been recognized and is sometimes applied by electroplating, but displacement plating is much more difficult to apply than copper. If the tin plating bath is acidic, satisfactory coatings can hardly be obtained unless extremely high temperatures are used; even then, the plating is slow If the tin plating bath is alkaline, either the normally acidic cleaning bath (which precedes the plating) must be neutralized or the parts must be removed from the bath; in addition, alkaline tin plating baths * require an excessively high concentration of tin salt.

As already stated above, according to the invention, metal substrates or other electrically conductive substrates are plated by bringing the substrate into contact with a free-flowing liquid containing ions of a dissolved salt of the plating metal, in the presence of a plating-inducing ("driving") Metal is worked that is both less noble than the base material and less noble than the plating metal. Preferably, the floating metal is used in finely divided form and the liquid is kept in motion during the fluttering , so that the particles of the floating metal are practically all of them surface to be plated touch the method according to the invention simply and

909845/130 7

easily carried out in almost all available containers that have an electrically insulating liner cladding drums are particularly suitable, especially when the drum is rotated and axially at the same time is moved back and forth "

The mechanism of the method according to the invention appears to be electromechanical. A simple one is formed Galvanic cell, when the plating inducing, driving metal with the surface of the conductive base material is brought into mechanical contact. Plating is easier when the pH of the solution is so adjusted so that the floating metal becomes more soluble »The potential difference between the floating metal and the Plating metal also promotes the dissolution of the floating metal. While the floating metal goes into solution, it gives off electrons that reduce the positively charged ions of the plating metal, thereby breaking the plating metal deposited on the base material "

If the floating metal is in the form of solid metal powder particles in the plating solution, the metal particles touch all surfaces of the base material exposed to the liquid when the solution is moved, even if the surface geometry is quite complicated coherent as in displacement plating, but the process of the invention is

909845/130 7

BATH ORIGINAL

Ug other than the extrusion cladding not on utterly thin coatings limited with the aid of the invention The Innemv andungen of pipes over the process can the entire length of the pipe can be clad practically at the same time »

The following examples serve to further illustrate the invention without limiting it. Unless otherwise stated, all parts are weighted parts ₀

example 1

The following ingredients were placed in a 4 liter plating drum given with open ends:

Glass balls (size approx. 1 mm to 4 mm) 3500 g

SnOl ₂ 3.0 g

Aluminum powder (5- 4Ou.) 6g

Disodium salt of ethylenediamine tetra

acetic acid 2 g

.! TaHSO, in sufficient quantity to lower the pH- ^T .- / ert to about 2

Previously cleaned _t cold-rolled 10 mm

Steel T-washers 5000 g

• 1.5 liter barrel

ras aluminum powder serves as the driving metal _β Although the disodium salt of ethylenediaminetetraacetic acid is not absolutely necessary, it appears to improve the adhesive strength of the subsequently applied plating. The glass spheres serve as impact media ₀

The plating drum (which is made by the with the help of steam cleaning of the metal parts was still hot) was then about 10 minutes with 50 revolutions per minute

9 0 9 8 4 5/1307 _8AD original.

rotated, after which the liquid was poured out of the drum and the washers rinsed and examined « It was found that they had a thin, uniform tin plating, the adhesive strength of which was satisfactory it can be seen therefrom that the adhesive surface of a pressure-sensitive adhesive strip coincides with the surface brought into uniform contact and then peeled off without any of the plated Metal was torn off with, upon subsequent mechanical zinc plating, the washers exhibited significant greater corrosion resistance than washers, which are zinc plated over in an identical manner a conventional one applied by displacement plating Copper plating had been applied "

7 / enn the procedure of example 1 under '.. "admission of the aluminum powder repeatedly found no coating formation at all

In general, the smaller the particles of the floating metal, the lower the total weight required of the floating metal, on the other hand, small aluminum particles are particularly sensitive to oxidation and can, Based on a given weight of powder, a smaller amount of aluminum will provide, large particles of the floating Metal can be used, but if the particles are too large, they cannot turn into fine indentations intricate metal particles penetrate «continues to form

909845/1307

15213 * 32

A layer of the plating metal is more easily formed on the larger particles by displacement plating than with smaller particles. Ideally, the composition of the plating bath should be adjusted so that the amount of metal powder is just sufficient to reduce all of the metal ions in the metal salt to provide electrons available 'Senn a present to large excess of the metal powder, there is a tendency that the powder itself is plated with the metal of the metal salt by displacement plating. It has been found that efficient work is possible when about 4 to 8 g (0.15-0.30 g-mol) aluminum particles of size 10 µm per 3 g of SnCl ₂ (corresponding to about 1.9 or 0.016 g -Mol tin) can be used «,

The optimum composition of the plating bath for a particular job depends on the specific materials used, the molecular weights, the desired thickness of the plating, etc. «. If φ having the metal salt used to Yorplattieren token ", a smaller molecular weight than SnCl _2, or if the metal ertigkeit greater // aufweist- p.1.3 Z, nehr Aluminiiunpulver is required '.! Hen ÖIN driving metal powder used is , which has a less viscous oxide layer than aluminum powder, the amount of metal powder can be reduced. On the other hand, if the quality of the powdered metal is less than that of the

909845/1307

BATH ORIGINAL

15213Ü2

Aluminum, more metal atoms are required to make the to deliver equal number of electrons. It has been found empirically that when using zinc powder with a Particle size of 2 - 5 U as a floating metal instead of aluminum powder with a particle size of 10 ρ only about half the weight of metal powder is required.

When using NaOH instead of FaEKXK to get a alkaline solution with a pH value of about 11-13, and when replacing the SnCIp with KgSnO ^ in the corresponding Amount to obtain the same amount of available tin, results similar to those above were obtained results described are generally similar · While aluminum requires a plating bath that either quite strongly acidic odejj but is quite strongly alkaline to to be able to act as a driving metal according to the invention, Metals with less viscous oxide layers do not require such drastic pH conditions. Numerous others Metals in the electrochemical voltage series above both tin and iron can also be used as the driving metal, such as the following Explain examples «

example 2

The following ingredients were mixed together in a 400 cc glass jar:

909845/1307

BATH ORIGINAL

SnSO ₄ 2 g

- Manganese powder (\ 0.074 mm) 1 g glass balls (4 mm) 200 g

H-PO, (85 ^c / i) 1 ecm

(65 ⁰ C) 50 ecm

A previously purified lO-mm steel washer "was added to the above mixture, which then about 1 minute -was vigorously stirred _o! Laughing removing has been found that the washer having a uniform, thin Zlnnplattierung" When using in the experiment an otherwise identical mixture, but which did not contain any manganese powder, was used, no coating at all was obtained

Example 3

The procedure of Example 2 was repeated, but instead of the manganese powder 1 g of powdered magnesium (<C'0.15 mm) and instead of the SnSO * SnGl _{2 was} used. Practically the same results were obtained »

Example 4

The procedure was as in Example 3, but instead of the magnesium powder using 1 g Titanium powder (<0.044mm) worked, and there were some a few drops of HF are added to facilitate the removal of the oxide layer from the titanium powder particles. There were obtained practically identical results "

909845/130 7 _ _{ΜΛ |}

D ORIGINAL

Vl 4-

Example 5

The procedure was as in Example 2 , but 1 g of zinc powder (<0.044 mm) was used instead of the manganese powder. Virtually identical results were obtained »

Example 6

In a 400 cc beaker were the following Components given:

CdO 2 g

Aluminum parts (<^ 0.074 mm) 1 g

Hydrochloric acid (12 n) 2 ecm

Water (65 ⁰ C) 50 ecm

Glass balls (4 mm) 200 ecm

A 10mm otaxil washer made by cold rolling was added to the mixture, which was then stirred vigorously for 1 minute. It became a thin, more even Received cadmium coating,

Example 7

A 10 mm cold rolled Ütahl washer was made Purified in 50 ecm of a solution consisting essentially of phosphoric acid and a mixture of surface-active substances The means consisted of “In a beaker containing the solution and the washer, 2 g of lead fluorate and 1 g zinc powder (<^ 0.044 mm) given. The mix was Stirred for 1 kinute, after which it was found that a lead coating had formed on the washer »

909845/1307

BAD ORiQINAL

Example 8

The procedure was as in Example 7, but 1 g of HgGl _{2 was} used instead of the lead fluoroborate. A coating of mercury formed on the surface of the washer.

Example 9

The procedure was as in Example 7, but was 1 g of silver nitrate was used instead of the lead fluoroborate. A silver coating formed on the washer.

Example 10

The procedure was as in Example 7, but 1 g of thallium chloride was used instead of the lead fluoborate « A thallium coating formed on the washer

Example 11

The following ingredients were put into a 400 cc beaker given:

SnCl ₂ 1 g,

HaHiJO ₄ £ 7

Water, 65 ^° C. 50 g

Zinc powder (<0.044 mm) Ic

Glass balls (2.4 mm) 200 g

A 5 cm 2: 10 cm 1.6 mm copper stencil was then used used to stir the solution vigorously for 1 minute. A tin smear formed on the template.

909845/1307

15213 ^ 2

Example 12

The procedure was as in Example 11, but instead of the copper template, a 5 cm × 10 cm × 1.6 mm was used large molybdenum template used * Virtually identical results were obtained

Example 15

The procedure was as in Example 11, but a brass template was used instead of the copper template Virtually identical results were obtained.

Example 14 became into a 400cc The following components Beaker given: 1 G NiCl ₂ 2 G Aluminum powder 1 , 5 ecm H ₃ PO ₄ (85 ^c / o) 50 ecm H ₀ O (65 ⁰ C)

A previously cleaned 10 mm steel washer was added to the mixture, which then was stirred vigorously for about 1 minute ₀ After removal has been found that a uniform nickel coating was formed on the washer.

The above examples illustrate the results obtained using a powdery floating metal can be obtained in the process according to the invention. Metal powders have the advantage that they can be divided into small corners and 3-inch

909845/130 7

ORIGINAL BATHROOM

penetrate indentations and ensure a practically even coverage and contact with the surface to be plated »A large roll of sheet steel can, however, be plated continuously - like Z ₁₁ Bo can be plated with tin by being attached to a roller made of the drifting metal, such as ZoBo to an aluminum roller, is passed while the surface is flooded with a solution of the salt of the plating metal _{or the like}

When aqueous treatment solutions are used, the driving metal such _e B is preferably selected from a group other than the groups IA and HA of the Periodic Table, in particular from a group other than the group IA, although even these alkali metals may be used, _c in an ionizing solvent with which they will not react violently.

The relative position of the metal of the object to be plated to the metal of the metal salt used for plating in the electrochemical series does not seem to be of particularly decisive importance, but both the metal of the object to be plated and the metal of the plating salt must be more noble (or less active As the driving metal The difference in the oxidation potential between the driving metal and the base material apparently only needs to be so great that the resistance of the electrical circuit is overcome _e

909845/130 7

1 52 Γ3ϋ2

If either the substrate or the driving metal are electrochemically significantly more active than iron, the pH of the plating bath should be controlled to minimize the dissolution of the metal object and / or the plating being plated, If Z ₀ B ₀ iron is to be plated with zinc using magnesium powder as the floating metal, the pH of the plating bath should probably be at least 2.

The method according to the invention can be modified in many different ways and adapted to specific applications other than those described above. "Z" B, an object provided with a porous zinc coating applied by mechanical plating can be "sealed" by treating it in a plating drum containing an acidified solution of a tin salt and dispersed aluminum particles. The driving metal can advantageously be an alloy (such as Z “E _e AlrMn, Al: Zn, Sn: Al: Zn, numerous other alloys are also suitable) instead of a single metal The presence of even small amounts of other metals obviously reduces the toughness with which the oxide layers normally adhere to metals such as aluminum »

909845/1307

ßAD ORIGINAL

15213Ü2

Although the floating metal particles and the plating metal salt can be added separately to the liquid, it is also preferable to combine these materials in solid form in a predetermined ratio in order to achieve the most effective coverage for the surface to be plated. For example, the particles of the floating metal can be premixed with an inhibitor (such as, for example, 1 or 2 drops of diethanolamine or n-tallow-1,3-propylenediamine per g of aluminum powder of 10μ particle size) and then compressed into tablets with the salt of the plating metal. According to another embodiment, the metal powder can be dispersed in a solution of a water-soluble rubber (for example, 5 e zinc particles with a particle size of 2-5μ can be dispersed in 10 ecm of a 5% aqueous solution of hydroxyethylcellulose), after which the water is evaporated and zerkTsinert the cake obtained in this V, ^r else v / ground the Met allteil cn s with a thin, water-soluble rubber coating provided "the one with the rubber coating comparable ÄK provided metal, salt and optionally other ingredients used can then tablets or the like, compressed or incorporated into a textile or abrasive product in order to be shipped later in the presence of water.

- patent claims -

90 9 845/130 7

BATH

Claims (1)

Patent claims: 1, a method for applying a metal coating to a conductive base material, characterized in that, that you can the underlay material with a free-flowing Liquid, especially water, the ions of a dissolved oil salt of a plating metal, especially a silver-colored metal, and a driving metal that is both less noble as the backing material and less noble than the plating metal, the pH of the liquid and the ^ Potential difference between the driving metal and the plating metal are such that the driving metal is dissolved, and wherein the floating metal the backing material on practically all surfaces of the backing material touches that are in contact with the liquid, whereby these surfaces with a coating of the Plating metal are provided « 2. The method according to claim 1, characterized in that that the floating metal is used in the form of fine particles and the liquid is kept in motion mechanically will move the particles of the floating metal with the entire surface of the backing material that is with the liquid is in touch, to bring in touch » 3β method according to claim 1 or 2, characterized in that αε, ί; All I-lating metal. silver applied wire. 909845/130 7 BATH ORIGINAL ~ 152 * i3ü2 4o method according to claim 1 or 2, characterized in that as _y nickel plating is applied ο 5p method according to claim 1 or 2, characterized in that that thallium is applied as the plating metal ο 6 "Method according to claim 1 or 2, characterized in that that mercury is applied as the plating metal ο 7o method according to claim 1 or 2, characterized in that that cadmium is applied as the plating metal. So method according to claim 1 or 2, characterized in that that tin is applied as the plating metal * 9o "method according to claim 1 or 2, characterized in that that lead is applied as the plating metal » 10 «The method according to claim 8, characterized in that that one clad a support material made of a ferrous metal consists ", 11c method according to claim 1, 2, 8 or 10, characterized characterized in that aluminum is used as the driving metal will ο 12. 909845/130 7 _BATH 1 5 2 i 3 b 2 12o method according to claim 1, 2, 8 or 10, characterized characterized in that zinc is used as the driving metal o 13ο method according to one of the preceding claims, characterized in that the plating is carried out in a plating drum in the presence of impact media » 14-β resistant product for use in carrying out the method according to claim 1, characterized in that it is in combination a water-soluble salt of a plating metal, a powdered metal which is both less noble than the base material to be plated and less noble than the plating metal, and contains an agent which prevents intimate contact between the zbIz and the powdered metal in the absence of water 15o product according to claim 14, characterized in, that there is in combination a water-soluble tin salt, a powdery metal, which is less noble than iron, and a "Contains a water-soluble substance that prevents intimate contact between the salt and the powdery metal", 16 _O product according to claim 15, characterized in that the powdery metal is aluminum _a 17 »Product according to claim 15, characterized in that that the powdered metal is zinc » 909845/1307, _n ORIGlNAL BATHROOM 18 · Conductive underlay material with a metal coating has, characterized in that the metal coating by contacting the base material with a free flowing liquid, in particular water, the ions of a dissolved salt of a plating metal, in particular a silver-colored metal, and a floating metal, which is both less noble than the base - material is also less noble than the plating metal, where the pH of the liquid and the potential difference between the driving metal and the plating metal are such that the driving metal is dissolved, and wherein the drifting metal touches the base material on practically all surfaces of the base material with the liquid in contact has been made, whereby these surfaces with a coating of the plating metal have been provided. 19 »Product according to claim 1, characterized in that that the base material is made of a ferrous metal consists. 20. Product according to claim 18 or 19, characterized in that that the plating metal is tin. H 1755 909845/1307