DE1090482B - Method of gas plating with nickel carbonyl - Google Patents

Description

GERMAN

Gas plating with nickel carbonyl is known made in such a way that the nickel carbonyl over the object to be coated conducts, which is heated to the decomposition temperature of the nickel carbonyl. This is where it arises Problem, a good adhesion between the metal coating and the surface of the to be coated Object, i.e. · the base metal. Closely related to this is the difficulty which opposes the achievement of a completely coherent coating.

To solve the above-mentioned problem, one has the action of various carrier gases, the influence the flow velocities, the temperature, the plating pressure and the impurities examines the plating process. However, there were no indications for this a satisfactory solution to the problem.

It is now known that careful cleaning of the surface of the object to be coated is an absolute prerequisite for the production of a well-adhering coating. The cleaning of the base metal of fats and the like has been done with acid, alkali and the like. It is also the removal of the oxide films often adhering to the surface of the base metal is necessary. To this Purpose has been proposed to the object to be plated with a reducing gas, e.g. hydrogen, prior to performing the plating process. Completely satisfactory Results relating to the improvement in the adhesion of the nickel coating to the substrate were obtained but also not achieved by these measures.

It is true that the object to be plated has already been reached at higher temperatures (400 to 500 ° C) exposed to a reducing atmosphere. However, this treatment took place only after it was already had formed a thin coating layer on the base metal and for the purpose of desorbing the in gases trapped in the thin coating layer. It is clear that these measures are not in the spirit can have the effect of improving the adhesion of the coating metal to the base metal; because this it is necessary that the surface be suitably pretreated before plating at all begins, which is not the case with the known methods.

The invention relates to such a pretreatment with the aim of solving the problem described. It suggests that the surface of the object to be plated and heated is pretreated with a carbon monoxide, which is achieved by prior passing over an oxide-free process at a temperature above about 650 ° C., preferably between 650 and 830 ° C., for gas plating
with nickel carbonyl

Applicant:

The Commonwealth

Engineering Company of Ohio,

Dayton, Ohio (V. St. A.)

Representative: Dipl.-Chem. Dr. pfa.il. E. Sturm, patent attorney, Munich 23, Leopoldstr. 20th

Herman Nack, Dayton, Ohio (V. St. A.),
has been named as the inventor

heated nickel is catalyzed. The one following the pretreatment of the base metal according to the invention on this nickel plating produced by way of gas plating shows an excellent one Liability on the document. This can be done on a thin sheet of iron or hot or cold rolled steel are shown, the surface of which is pretreated in the manner according to the invention and then plated became. When the panel is bent, there is no bulging or peeling of the coating from the panel Observe pad. This suggests that the coating and base metal are intimately connected are.

How the catalyzed carbon monoxide is used in the pretreatment of the object to be coated acts on its surface has not yet been clarified. In any case, it is certain that the Surface a good receptivity for the deposited metal from the nickel carbonyl at the the pretreatment is given to subsequent plating.

The freedom from oxides of the catalytic converter seems essential for the action of the carbon monoxide used to be nickel. Namely, it was observed that a deposit of nickel lasted for some time exposed to air, no catalysis

009 610/234.

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of the carbon monoxide that is then passed over, before the nickel is completely absorbed so that this also occurs when passing over the below the decomposition temperature of the nickel surface of the object to be plated has not cooled down any carbonyls. The nickel for kata improvement the adhesion between coating and lysing of the monoxide can be on the inner wall Base metal causes. 5 one equipped with a hollow steel cylinder

It was found, however, that the we plating chamber was precipitated,

kung of the oxide-free used according to the invention After completion of the "pretreatment is not

Nickel does not have any apparent loss of effectiveness only the nickel, but also the one to be plated and

with regard to the catalyzing of the transferred to higher temperatures (260 to 430 ° C)

Carbon monoxide suffers. This should, among other things, cool the heated object to about

be due to the fact that the nickel through the 120 to 230 ° C. In this temperature range

Carbon monoxide treatment at high temperature affects the gaseous used for plating

the reducing effect of the carbon monoxide nickel carbonyl results in decomposition with separation

is always kept in the active state. In that- from nickel.

The same sense also affects the fact that 15 According to a special feature of the invention When the nickel carbonyl is later passed over, the material to be plated will be cooled before it has cooled down about the active nickel, corresponding to a below item and the nickel on or below special decomposition temperature of the nickel carbonyl described in detail according to the form of delivery of the invention, always somewhat virgin end of the pretreatment a very slow flow Nickel deposits. 20 of nickel carbonyl, to which carbon monoxide can be added as a carrier gas to maintain the effectiveness of the nickel, over the nickel and the with regard to the catalyzing of the carbon monoxide with the metal coating to be provided workpiece also the temperature of the nickel at which it conducts. As already mentioned, this is not just something Carbon monoxide is passed over, a carbonyl influence on the nickel decomposes, which is more beneficial. Nickel has a tendency, the implementation of 25 wise always leads to the renewal of the same, but To promote carbon monoxide into carbon dioxide. It is already forming on the material carbon is formed, which is deposited on the nickel as a thin layer of nickel. It was observed that suggests what is of course undesirable. Now with this thin coating, which is practically a primer low temperatures represents the equilibrium on the front side for the subsequent plating the formation of carbon dioxide and carbon, the temperature of the nickel must be correspondingly high on the base metal for optimal adhesion of the coating. If, on the other hand, the to get voted. It has been found that in the case of Er plating, heating is required only after the cooling of the plating the nickel starts to a temperature above the object's decomposition temperature, 650 ° C satisfactory results can be achieved. coatings with less adhesion are applied

It is also of importance that carbon monoxide is retained in the substrate.

Temperatures below 830 ° C a strong re- The temperature of the nickel should, however, fall below

is duktionsmittel, stronger z. B. as hydrogen. From half the decomposition temperature of nickel carbonyl

For this reason, the nickel is used for the catalysis, if with the introduction of the strong carbonyl

of nickel is preferably started below this temperature current in order to prevent excessive

maintained temperature so that the temperature interval in between 40 to avoid decomposition,

see 650 and 830 ° C is particularly favorable. With reference to the

A device for carrying out the requested

the temperature should also be on the base metal;

which the object to be coated will be refined during the preliminary refining.

Treatment with catalyzed carbon monoxide 45 Referring to the drawing, in FIG. 1 a is heated. It has been found that particularly glass containers shown, a movable stopper 3, good results are obtained when these ER- _e i _n through a valve 7 controlled inlet 5 and an overheating takes place to 260 to 430 ° C. In this case, the starter 9 controlled by valve 11 should have. It is the temperature of the softening point of the base metal of an auxiliary gas inlet 13, which naturally cannot be exceeded by a valve 15. It is present at through-50, which is not provided as a bypass device of the method according to the invention, in order to allow the introduction of nickel to allow the object to be plated by carbon monoxide carrying carbonyl gas to allow particular heat supply at these temperatures.

is brought because the in the container on the right side is conducted over the hot nickel Carbon monoxide heat is placed on the 55 narrow platform to be covered, on which the basic object gives away. It is therefore advantageous if metal can be attached, and it is in advance In a particular embodiment of the present case, a cold-rolled steel plate 16. An finding, the pretreatment, but also, as after the left end of the container is a tubular one standing still will be explained in detail, the plate part 17 is arranged, the internally with active nickel tation is carried out in a vessel in which 60 19 is coated, the tube in the container in both the object to be coated and any suitable type, such as. B. through the part the oxide-free nickel is located, the temperature of which is fixed after 21.

Completion of the pretreatment on below the A first water-bearing jacket 23 surrounds the Decomposition temperature of the right part of the tube in the vessel and is appropriate introduced nickel carbonyl is lowered, which is also provided 65 with inlet 24 and outlet 25. A second the oxide-free nickel is painted over. This creates a water-bearing jacket 27 with an inlet 29 and an outlet also achieved the advantage that the 31 abuts the jacket 23 from the left and around-catalysis The nickel used in the carbon monoxide is the container 1, insofar as it is adjacent to the part 17 can always renew, especially when it is already with. Separate water wraps are in front Introduction of nickel carbonyl into the vessel admitted to a rapid cooling of the part 17 from the

5 6

applied high temperature allow; drop by 120 to 230 ° C at any time. The temperature of the

however, a single sheath can also be used. Cylinder 17 is at approximately the same time

it is then necessary to open the inlet to the 38 ° C, i.e. H. below the decomposition point of the

Induction heating coil 33 to control the carbonyls lowered.

To keep workpiece 16 at a suitable temperature. 5 However, while this temperature is falling,

For similar control reasons, a separate nickel carbonyl preferably surrounds with carbon monoxide as

Induction heating coil 35 the left side of the loading carrier gas in a concentration of about 35%

1. carbonyl into the container through the valve 40

A feed line 37 with valve at 38 for out; when the carbonyl evaporates in the heat the supply of carbon monoxide is at the io, carbon monoxide will beckon through the valve 38 Side of the figure along with a feed to deal with the carbonyl in about the To mix guide line 39 with valve 40 for the passage of the same concentration. The flow of the Nickel carbonyls arranged. In practice it is speed, like all other volumes in general, it is desirable to maintain the normally liquid room temperature, i. H. 24.5 ° C and atmospheric Nickel carbonyl (bp 44 ° C) measured by means of a current of 15 pressure is very slow - approx warm carbon monoxide to vaporize, however, 10 to 20 ecm per minute. The initial flow any other method of vaporization of this gas mixture can begin while still Carbonyls are used. high temperatures prevail, and the results of the

At the right end of the container 1 ends the tests show that for optimal plating the

Outlet 9 into a U-shaped part 41, which must be used by dry flow 20 while the temperature

ice or another coolant 43 and the workpiece is still above 260 ° C. Although in

is contained in the container 45. The outlet of part 41 cylinder 17 some decomposition of the nickel in er-

is connected to a vacuum pump 45, which can appear suitable, this is not detrimental because

is, the removal of gases from the container 1 to this is done by the deposition of nickel

accelerate. 25 to renew the nickel content of the cylinder. It has to be

Before the workpiece 16 made of cold rolled steel is attached to a sufficient amount of carbonyl passed through it, the same is preferably cleaned by rubbing a dense adhesive film on the rub and a trichlorethylene treatment to precipitate base metal 16,
and the dry and cleaned object is then afterwards and while the workpiece is annealing, the container 1 is inserted and the stopper 3 has a temperature of 120 to 230 ° C, the flow stopper is, the speed of the carbonyl-carbon monoxide

Then with the valve 7 closed, research is carried out at approximately the same concentration open valve 11 increased with the action of the vacuum pump about 1 1 per minute. The carbonyl zer-45 Heat through the heating coils 33 and 35 to which then settles on the workpiece under the influence Container supplied while it is evacuated. 35 the heat of it, so that any desired Although such precautionary measures cannot always be maintained on nickel. on are necessary and the air of the container through this way will be a lower following in about 30 minutes Stream of carbon monoxide flushed out a blow of 3 miis by means of the aforementioned method, it is assumed that evacuation measures are achieved. The nickel deposit that is on is desired in the manner described, to be obtained in the same way, is firmly adherent and has moderate way to achieve optimal results. a high gloss.

The temperature of the part 17 is then set to an- The above procedure can be varied by

approximately 705 to 730 ° C and the temperature of the plant that the plating current, i. H. the weaker ones

Piece 16 to about 345 ° C by means of induction «- gas flow through the auxiliary inlet 13 and valve 15,

heating coils 35 and 33 increased; whereupon the valves 7 45 instead of the inlet 5 leads. In this procedure

and 38 are opened to a stream of coal- it is then not necessary to change the temperature of the

monoxide from any suitable source, e.g. B. from nickel-containing cylinder with each approach up

a steel bottle, or in some cases off in a circle- to drop to 38 ° C, and the production will

to enable running from other procedures. accelerated this way. The exact temperature

The carbon monoxide flow is comparatively long - a reduction then necessarily becomes natural

sam, preferably about 0.11 per minute. _VO n the physical conditions of the apparatus

The carbon monoxide flowing in this way will hang, but because the vacuum pump will normally

will be in action at its passage through the nickel, will have a slight tendency for suffices

a high temperature and, when touched, shows the plating gas persist from the cylinder

to migrate out with the workpiece 16 a strongly reducing We- 55 17.

The following examples illustrate suitable hydrogenation under the same conditions for the practical implementation of the test. The nickel also tends to find the activity,
of the gas, since less effective results

nits, assessed according to the adhesion characteristics 60 Example 1
of the end product, can be achieved if only heated workpiece (metal body) hot rolled steel gas under the same conditions to the work strip
piece is led. Previous cleaning abrasion

Under the conditions set out is a time plus acid and

of about 10 minutes is sufficient to drink alcohol

necessary activation of the surface of the cold rolled heating time 10 minutes

16 steel to ensure. The heating is then reached workpiece temperature 425 ° C

either decreased or stopped, and the temp. Cylinder temperature reached 675 ° C

The temperature of the workpiece is left on the normal flow of carbon monoxide for 10 minutes at V101

rich for plating for nickel carbonyl, d. H. to un- 70 per minute

Workpiece temperature (during the carbon monoxide flow) '

445 to 475 ° C (range over three points on the piece) cylinder temperature (during

of the carbon monoxide stream) 675 ° C (maximum) cooling of the workpiece

a temperature of 165 to 175 ° C

Cooling down of the cylinder

a temperature of less than 38 ° C

Carbon monoxide and nickel carbonyl (35%) during the

Cooling 10 to 15 ecm per

Minute for 10 minutes

Workpiece temperature 455 to 175 ° C

Cylinder temperature 650 to 38 ° C

Cooling of the cylinder to less than the plating

temperature maximum 38 ° C

Hold the workpiece at .. 165 to 175 ° C carbon monoxide and nickel car-

bonyl (35%) 11 per minute

Example 2

Workpiece (metal body) .... Cold rolled steel strip

Prior cleaning, rubbing plus degreasing by hot trichlorethylene treatment

Heating time 10 minutes

Reached workpiece temperature Maximum 355 ° C Reached cylinder temperature 790 ° C

Carbon monoxide flow for 10 minutes at ¹ Ao

per minute workpiece temperature (during

of the carbon monoxide stream) 333 to 363 ° C (range over three points at the Piece) cooling of the workpiece

a temperature of 165 to 175 ° C

Cooling down of the cylinder

a temperature of less than 38 ° C

Carbon monoxide and nickel car-onyl (35%) during the

Cooling 10 to 15 ecm per

Minute for 10 minutes

Workpiece temperature 363 to 170 ° C

Cylinder temperature 790 to 38 ° C

Cooling of the cylinder to less than the plating

temperature maximum 38 ° C

Hold the workpiece at .. 165 to 175 ° C carbon monoxide and nickel car-

bonyl (35%) 11 per minute

In connection with the preceding description it should be noted that a preferred practical implementation to achieve optimal adhesion the touch of the activated Base metal surface with the initial carbon monoxide stream, while the base is above the normal plating range.es from 120 to 230 ° C for nickel carbonyl. Apparently, such a touch allows that to be completely Always obtain repeatable results as far as adhesion is concerned. On the other hand, in one of those Case where the! Carbonyl has not been added to the workpiece until it has reached a temperature was brought to the lower end of the plating area, the coating was unusual Standard features.

It should also, with regard to the special data of the cylinder and workpiece temperature, be recorded that such measurements are carried out

ίο Thermocouples are carried out, their supply lines are passed through the container walls; the slight variations in the maximum temperature between the workpiece and the cylinder were the same, and touch with respect to them Thermocouples are caused by the sheathing of the heating coil. As already stated, that Temperatures are measured at three points on each surface, and the items treated are complete comparable to real conditions

ao strive.

It should be noted that the particular physical shape of the active nickel is not is critical and that the active nickel is conveniently placed on a sieve, wire mesh or on Balls made of a material that can withstand the temperatures used can be applied, or it may itself be in the form of a wire, and it may be any suitable means that does the Nickel holds on to treatment with the gas, inequivalent Manner to be used for the practice of the invention.

It should also be understood that the present invention can be modified to provide them adapt to a wide variety of uses and conditions, and accordingly, such modifications are intended to be encompassed by the invention.

Claims (6)

PATENT CLAIMS: 1. A method for gas plating with nickel by passing nickel carbonyl over the object to be coated, which is heated to the decomposition temperature of the nickel carbonyl, wherein the object is previously brought into contact with a reducing gas for the purpose of cleaning its surface, characterized in that the surface of the heated object is pretreated with a carbon monoxide which by previously passing over and oxide-free to a temperature above about ¹ 650 ° C, preferably between ^650! and 830 ° C, heated nickel is catalyzed. 2. The method according to claim 1, characterized in that the object to be coated when Passing the catalyzed carbon monoxide to a temperature between about 260 ° to 430 ° C and in any case is heated below its softening point. 3. The method according to one or both of the preceding claims, characterized in that the temperature of the object to be coated after the pretreatment with the catalyzed Carbon monoxide is lowered to around 120 to 230 ° C. 4. The method according to one or more of the preceding claims, characterized in, that the pretreatment and the plating of the object to be coated are carried out in one vessel in which both the pulling object as well as the oxide-free nickel, whose temperature after the end of the Pretreatment to below the decomposition temperature of the subsequently introduced into the vessel Nickel carbonyl is lowered, which also coats the oxide-free nickel. 5. The method according to claim 4, characterized in that even before the cooling of the Nickel and the object to be coated after completion of the pretreatment a very iq slow stream of nickel carbonyl is initiated. 6. The method according to one or more of the preceding claims, characterized in that that carbon monoxide is used as a carrier gas for the Nickelkarbonflj. References considered: U.S. Patent No. 2,653,879. 1 sheet of drawings ©, 009 610/234 9.60