Europaisches Patentamt J) European Patent Office Qv Publication number: 0 234 738 Office europeen des brevets A1
EUROPEAN PATENT APPLICATION
Qy Application number: 87300675.3 © intci.3: C 25 D 5/34 C 25 D 7/10 @ Date of filing: 27.01.87
(30) Priority: 27.01.86 IL 77709 QJ) Applicant: TECHNO INSTRUMENTS INVESTMENTS 1983 LTD. P.O.B. 1233 Bat-Yam 591 128, Metzudat-Beitar Street (43) Date of publication of application : Bat-Yam 59592IIL) 02.09.87 Bulletin 87/36 @ Inventor: Relis, Joseph © Designated Contracting States: 80 Krinrtzi Street AT BE CH DE ES FR GB GR IT LI LU NL SE RamatGan(IL)
@ Inventor: Holtzman, Abraham Moshe 23 Usishkin Street Rehovot(IL)
@ Representative: Bizley, Richard Edward et al, BOULT, WADE & TENNANT27 Furnival Street London EC4A1PQIGB)
(54) Nickel immersion solution and process for electroplating of a bimetal bearing utilizing the same. © The invention provides an immersion solution for the pretreatment of a bimetal bearing, having one portion thereof composed of an aluminum base metal and another portion of the surface thereof composed of a ferrous base metal, com- prising nickel and halogen ions, the solution having an acidic pH. The invention also provides a process for the electroplat- ing of a bimetal bearing having one portion thereof com- posed of an aluminum base metal and another portion of the surface thereof composed of a ferrous base metal, compris- ing the pretreatment step of immersing the bearing, prior to the electroplating thereof, in a solution having an acidic pH and containing nickel and halogen ions, whereby the bearing is provided with a coating from the solution without the use of an external source of electricity, which coating can then be coated with an electroplated deposit without any further in- 00 termediary steps. M
M M
0. LU Croydon Printing Company Ltd. 0234738
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NICKEL IMMERSION SOLUTION AND PROCESS FOR ELECTROPLATING OF A BIMETAL BEARING UTILIZING THE SAME
The present invention relates to the electroplating of bimetal bearings containing aluminum alloys. More particularly, the present invention relates to an immersion bath solution for pretreatment of a composite bearing structure which has on& surface* composed of an aluminum base metal (i.e., aluminum or an alloy of aluminum) and another surface composed of a ferrous base metal) (i.e., iron or an alloy of iron) prior to the electroplating thereof and to an improved process for electroplating; utilizing said immersion hath solution.
As described in U.S. Patent 4,170,525 the deposition of a thin coating or plating on the surface of bearings composed of aluminum or aluminum alloys in order to impart a pleasing appearance thereto or to provide corrosion protection therefor, or to provide a "run-in" surface thereon is well known in the art.
Specifically, it is common practice to apply a thin coating to the surface of a bearing by means of electrodeposition to achieve such results. While this technique has met with success, there are certain inherent disadvantages associated therewith. For example, an elec- trical power source must be provided and the parts must be properly oriented in the plating bath in order to obtain a satisfactory deposit thereon. In addition, an electrodepusition technique also suffers from the fact that it is difficult to apply thin layers of metal to a structure having a complicated surface configuration. Accordingly, while this technique finds use as a means of applying a thin layer to the surface of a bearing structure it suffers from certain inherent limitations. U^Of / OO
- 2 ~
Another well known technique for coalincj the surface of a bearing is the so-called immersion plating process. In this process, metal is deposited from its salt on the surface of the bearing without the aid of an outside source of electrical current or of chemical reducing agents. This process is especially appealing in that thin coatings of uniform thickness can be readily appied to a structure having a complicated surface configuration. Immersion plating baths are either alkaline or acidic. While both types of baths can be used to deposit on the surface of aluminum or aluminum alluy, mmt; of the heretofore
known baths can be used to satisfactorily apply a thin coating to a
composite structure having one surface composed of an aluminum base
metal and another surface composed of a ferrous base metal. Speci-
fically, alkaline immersion baths do not coat both the aluminum and
ferrous base metals, but only the aluminum base metal.
Today the most popular commercial system employed in the electro-
plating of aluminum and its alloys and bi-metal bearings of iron/
aluminum alloys involves the immersion of parts in an alkaline
solution containing Zinc, known as ZINCATE. This process for bearings
is described as involving the following steps:
(1) alkaline clean 1
(2) alkaline clean 2
(3) Activation 1
(4) Activation 2
(5) Picking
(6) Chemical dip in Zincate solution, containing zinc and nickel
salts 0234738
(7) Immersion in c. 50% Nitric acid solution
(8) Immersion in same Zincate solution as in (6), but with
current applied
(9) Activate and neutralize in mild acidic solution
(10) Electrolytic nickel or copper plat* to produce
about 1 micron
(11) Electrolytic lead-tin plate in fluoborate solution to
achieve required thickness.
It is to be noted that with rinses after each of the above process steps the complete cycle above contains about twenty-two baths.
It has now been found that contrary to the teaching of the prior art, it is possible to avoid such a tedious and expensive time and chemical consuming multistage process and to obtain bearings having an adherent and uniform electroplated coating by using the novel process and immersion solution of the present invention.
Thus, according to the present invention, there is now provided a for the process electroplating of a bimetal bearing having one portion thereof composed of an aluminum base metal and another portion of the surface thereof composed of ferrous a base metal, comprising the pre- treatment step of immersing said bearing, prior to the electroplating thereof, in solution a having an acidic pH and containing nickel and halogen ions, whereby said bearing is provided with a coating from said solution without the use of an external source of electricity, 0234738 - 4 -
which coating can then be coated with an electroplated deposit without any further intermediary steps.
In the process of the present invention said electroplated deposit is obtained from the lead f luoborate/tin fluoborate/copper
fluoborate baths typically used in the bearing industry and which are
collectively known as 'Babit1 solutions.
Alternatively, said electroplated deposit is obtained from lead,
lead-tin, tin-lead, nickel, copper, brass, silver, tin, zinc, cadmium,
or chromium plating solutions typically used in the metal finishing
industry.
U.S. Patent 3,672,964 discloses a process for plating aluminum
with an adherent nickel coating by contact with an aqueous solution of
hydrofluoric acid and a soluble metal salt such as nickel salt;
U.S. Patent 2,746,136 discloses treatment of aluminum and its
alloys prior to electro-plating, wherein aluminum or aluminum base
alloys are initially treated by pickling and subsequently coated with
a nickel layer by treating in a solution containing a nickel salt and
finally electroplated with lead coating;
U.S. Patent 2,580,773 discloses immersing cleaned aluminum or
aluminum alloy articles in an aqueous bath containing a water soluble
zinc salt and a water soluble fluoride'. The electroless metal coating
provides a base for receiving a subsequently deposited electrolytic
metal layer; 0234738
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U.S. Patent 2,694,017 discloses nickel plating of aluminum or
aluminum alloy materials by immersion in an acetic solution including
nickel ions, fluoride ions, phosphite ions and nitrate ions; and
U.S. Patent 3,726,771 discloses a process for chemical nickel
plating of aluminum and aluminum alloys wherein the base is electro-
lessly plated with nickel without extensive pretreatments wherein the
nickel is characterized by good adhesion to the aluminum base and
which is sufficiently active to allow for direct electrolytic plating without extensive chemical treatments to activate the nickel. The electroless plating solution has an acetic pH and includes nickel ions and fluoride ions.
It is to be noted, however, that none of said patents teaches the nickel coating of an aluminum/iron or aluminum alloy/iron composite bimetal bearing utilizing an immersion bath solution containing Ni+2 ions and free of reducing agents.
In U.S. Patent 4.170.525 there is described and claimed a method of concurrently coating the surface of a composite bearing structure having one portion of the surface area thereof composed of an aluminum base metal and another portion of the surfce area thereof composed of a ferrous base metal with an adherent layer of tin base metal, comprising:
contacting said composite structure with a mineral acid containing ions selected from the group consisting of fluoride
ions, fluoride containing ions or mixtures thereof to activate the surface of said aluminum base metal; and 0234738
structure in an aqueous plating bath immersing said composite of ions selected from the containing a mineral acid, a source ions or of fluoride ions, fluoride containing group consisting of stannous ions with said mixtures thereof and a source 1 in an amount ranging from about stannous ions being present liter, for a period of time sufficient to about 75 grams per aluminum deposited concurrently on said to cause tin to be exchange of alumnum ions for tin base metal surface by the base metal surface by means of a ions and on said ferrous and between said aluminum base metal galvanic couple formed
said ferrous base metal.
limited to the use of an immersion Said patent, however, is
which are also considered to be solution containing stannous ions for teach suggest a method or solution reducing agents and does not or 1 of with nickel. Further-more, when example coating bimetal bearings nickel ions instead of stannous ions, said patent was repeated using
obtained. no nickel coating was
suggest the immersion Thus, said patent also does not teach or
invention. solution and method of the present
of the present invention said In a preferred expanded process
cleaning and etching followed by bearing is subjected to alkaline in said solution as neutralization and desmutting prior to immersion
described hereinafter. 0234738 -7-
The present invention also provides an immersion solution for the pretreatment of a bimetal bearing having one portion thereof composed of an aluminum base metal and another portion of the surface thereof composed of a ferrous base metal, comprising the pretreatment step of immersing said bearing, prior to the electroplating thereof, com- prising nickel and halogen ions, said solution having an acidic pH.
Said solution preferably comprises an acid, such as HC1 or H«SO- 2 4 to bring the pH of the solution within a range of about 6 to about
-0.2 and a solution having a pH range of about 3 to about 0 is especially preferred.
As indicated said solution contains halogen ions, such as F~, Cl , BR , I , either individually or in combination, and in individual concentrations up to 160 g/L, and solutions containing chloride or fluorideions and especially solutions containing both fluoride and chloride are preferred.
Said halogen ions are obtained in the solution from readily soluble salts such NaCl, KC1, LiCl. as RbCCl, N^Cl, KF. KHF2t NH4HF HF, NaF and especially preferred are solutions, wherein said halogen ions are derived from an ammonium salt thereof.
Another preferred source of halogen atoms and or the acidic of nature the solution can be the nickel salt which serves as the 0234738 - 8 -
solution and thus a solution source of the nickel Ions in the about 600 g/1 comprising about 10 to 800 g/1 especially 150 to
NiCl2.6Hp0, NiS046H20 or a combination thereof, is preferred.
Alternatively the solution can* contain between about 0.2 g/1 and
180 g/1 of nickel ions that are provided from nickel salts other than
those mentioned above and produced by dissolving nickel metal in an
acid or other solution.
An additional preferred component of the solutions of the present
invention is an aluminum oxidizing material. Said oxidising materials
are typically from the following groups: F , MnO4« I03 , I04 , N03 ,
C10~, etc. They can be in the form of simple ions, such as FeCl^, or
complex ions, such as K, Fe(CN)g, especially preferred is an aluminum
oxidizing material selected from the group consisting of ferric and
permanganate salts.
It is believed that said oxidizing material acts as a promoter to
achieve an effective replacement of the aluminum alloy with nickel,
thus providing an adherent conversion coating, that is primarily
nickel-based and on which an effective and adherent lead-tin coating
can be deposited to the required thickness.
As indicated the preferred expanded process of the present
invention involves the following process sequence for electroplating
of a bi-metal bearing:
(1) cleaning and activating in an alkaline solution; 0234738 - 9 -
(2) Neutralisation and desmutting in an acid solution, typically
containing nitric add;
(3) Immersion 1n the claimed solution without external current.
(4) Electroplating with an electrolytic lead-tin plate fluoborate
solution to achieve the required thickness.
Thus the innovative method of coating bi-metal bearing materials of iron/aluminum alloys and aluminum and its alloys prior to further or nickel electrolytic plating in lead-tin/ solutions also Includes the pretereatment steps of cleaning and etching the parts, which produces a smut on the aluminum alloy surface. This smut is then removed in the acid solution, which typically contains nitric acid, with or without additives depending on the aluminum alloy being employed.
The alkaline solution used for cleaning and etching includes up
to 150 g/L of NaOH and up to 200 g/L of proprietary additives and
complexors from the groups of EDTA, NTA, DTPA, AGPTA, ethylene
diamines, methylene diamines and their derivatives, and also organic
acids or their derivatives such as citric acid, tartaric acid, amino
acids, gluconic acids, oxalic acids, mallic acids, etc. and salts of
acids that are the products of oxidation of carbohydrides, especially
the oxidation of the end groups of carbohydrides, such as the aldehyde
group and the alcohol group. These organic acid salts are contained in
concentrations up to 250 g/L and preferably in concentrations up to
100 g/1. The cleaning and etching solution also contains a wetting
agent or surfactant, which 1s typically non-ionic or anionic and in
concentration up to 5Z, with a preferred range up to 1.5Z. -10- 0234738
The neutralisation and desmutting solution typically contains nitric acid 1n concentrations of between 5Z and 100Z, with a preferred
limited by the time range of 50Z to 100Z, the lower range being only
required to remove the resultant smut from the alkaline cleaning and
etching solution. This process is designed to leave the aluminum
surface clean and active prior to processing in the innovating
immersion solution of the present inventions. If the aluminum alloy
contains silicon, it is preferable to also add to the acid
neutralisation and desmutting solution salts of the halogen groups,
such as F~, Cl"", Br~, I", either individually or in combination, and
in individual concentrations up to 160 g/L, preferably 2 to 60 g/1.
It will be noted that the improved process of the present
invention even with rinses after each process step requires only eight
baths.
Advantages of the process of the present invention could be
summarized as follows:-
(1) As already mentioned above, a much shorter process cycle is
required.
(2) There does not exist a normal electrolytic plating requirement in
the pre-treatment stages prior to final electrolytic lead-tin
plate.
(3) As the immersion solution is acid-based, there is no requirement
for a neutralisation step prior to the electrolytic lead-tin
plating solution, which is also acid-based.
(4) Excellent adhesion properties of the lead-tin deposit on the
aluminum alloy 1s achieved. - 11- 0234738
50 and (5) An adherent and uniform deposit thickness up to microns
more 1s achievable.
The solution also preferably can contain all the metal salts of the metals contained in the bimetals being processed, such as iron salt, aluminum salt, nickel salt, tin salt, copper salt, etc. The
which showed the purpose of this was found from experiments clearly
solution, which did not Initially contain these metal salts, performed
better after ageing due to the replacement process.
Thus said solution preferably contains bivalent iron salts,
bivalent ion salts and combinations thereof such as FeCl^, Fe^CSO^),.
FeSO., FeCl3 etc, preferably in amounts of up to about 150 g/1 iron
ions.
The solution preferably also contains a non-ionic wetting agent
or surfactant.
While the invention will now be described in connection with
certain preferred embodiments in the following examples so that
aspects thereof may be more fully understood and appreciated, it is
not intended to limit the invention to these particular embodiments.
On the contrary, it is intended to cover all alternatives,
modifications and equivalents as may be included within the scope of
the invention as defined by the appended claims. Thus, the following
examples which include preferred embodiments will serve to illustrate
the practice of this invention, it being understood that the
particulars shown are by way of example and for purposes of
illustrative discussion of preferred embodiments of the present 0234738 . 12 .
invention only and ere presented in the cause of providing what is believed to be the most useful and readily understood description of formulation procedures as well as of the principles and conceptual aspects of the invention.
The following examples set forth solutions prepared and tested according to the present invention.
While the solution of Example 1 gave acceptable results,
uniformity of coating and grain structure improved with the addition
of ingredients 1n each subsequent example with the solution of example
2 being preferred over the solution of example 1 etc. and the solution
of example 6 being most preferred.
EXAMPLE 1
1) NiCl26H20 500 g/lit
EXAMPLE 2
1) NiCl26H20 400 g/lit
2) HC1 10 cc/lit
EXAMPLE 3
1) NiC126H20 300 g/lit
2) HC1 20 cc/lit
3) NH4C1 30 g/lit
4) NH4HF 15 g/lit 02347J -13-
EXAMPLE 4
400 g/Ht 1) NiCl26H2O
2) HC1 20 cc/lit
3) NH4HF2 10 g/lit
4) FeC13 20 g/lit
5) CuCl2 2 g/lit
EXAMPLE 5
1) N1C126H2O 450 g/lit
2) HC1 30 cc/lit
3) NH4HF2 15 g/lit
4) FeCl3 15 g/lit
5) CuCl2 1 g/lit
6) FeS04 100 g/lit
EXAMPLE 6
1) NiCl26H20 450 g/lit
2) HC1 40 g/lit
3) NH4HF2 15 g/lit
4) FeCl3 20 g/lit
5) CuCl2 1 g/lit
6) FeS04 100 g/lit
7) WETTING AGENT 0.1 g/lit
While the composition of example 6 represents an especially
preferred and commercial immersion solution according to the present
Invention further components can be added thereto to meet customer
specifications and to further improve the properties thereof. 0234738 -14 "
Thus said solution can also preferably contain metallic brighteners from the group, such Zn, Cd, Pb, and Thalium in the form of one of their salts of complexes, and in concentration up to 5 grams of metal per liter.
The solution can also preferably contain organic brighteners
which can also be included to provide stress-relieving, said
brighteners including imide derivatives such as ortho-benzole
sulphonimide, benzene sulphonimide, bi-dibenzene sulfonimide,
heterocyclic sulphonic acids such as thiophen-2- sulphonic acid,
aromatic sulphinic acids such as benzene sulphinic acid, ethylenic
aliphatic sulphonic acids such as ally! sulphonic acid, aromatic
sulphonic acids such as benzene suphonic acid, aromatic sulphonamides
such as paratoluene sulphonamide, in concentrations up to 10 g/L.
The following further solutions according to the present
invention were also prepared each solution incorporating several of
the following 20 possible components, set forth hereinafter in amounts of g/1.
Of the following compositions, that of Example 13, is especially preferred. 0234738 - 15 -
Ex.7 Ex.8 Ex.9 Ex.10 Ex. 11 Ex.12 Ex. 13
100 50 - 150 1) N1SO4 200 - -
500 - 250 650 2) NiCL2 - 400 28 10 3) NH4S04 - 15 32
4) FeCl 15 1 3 5 1 -
150 90 5) FeS04 100 100 120 10 - 12 5 6) FeCl3 - 15 13 - 3 - 7) Fe2(S04)3 5 3 5 6 2.5 8) CuS04 1 1.5 2 2.5 3 4
9) CuCl2 - 2 1.5 2.5 5 - 10) NH4HF2 10 10 10 6 17 8
11) HF - 13 - 2 1 -
7 12) KHF2 3 8 1
13) KMnO4 1 1 0.8 -
14) KI03 - 1.5
15) KBr 0.1 - " 0.2 0.5
16) ORTO-BENZOIC
SULPHONIMIDE 0.5 0.3 - - 0.3 0-3
17) BENZENE SULPHONATE - - 0.2 0.5 -
18) A12(SO4)3 3 6 4 0.3 - 15 19) SnS04 10 0.2 0.1 15 - - 20) WEtttng AGENT 2 3 1 2.5 0.2 in 3
The following example describes an electroplating process
according to the present invention. w a- w -i- I w VI " 16 -
EXAMPLE H
An aluminum alloy bearing conforming to SAE standard J460e and containing 78. 3Z aluminum and 20Z tin is first placed in an alkaline bath for 1 to 3 minutes at a temperature of between 25 to 50°C for cleaning and surface activation. The bearing is then removed and washed with water.
After rinsing the bearing is placed in a nitric acid bath for 20 to 90 seconds at room temperature (20 - 30°C). The nitric acid bath desmutes the surface of the bearing and leaves it clean and active.
The bearing is then once again rinsed in a water bath for 1-2 minutes.
The rinsed bearing is then placed in a solution according to the present invention for 1 to 3 minutes at room temperature.
The bearing is then rinsed in again water and placed in an
electroplating bath containing lead fluoborate. tin fluoborate. copper fluoborate and fluoboric acid having a preferred ratio of 90Z lead fluoborate : 92 tin fluoborate : 1 Z copper fluoborate.
The current density of the electroplating bath is up to about 6 amper/dm2 and the voltage is about 0.4-6 volts. The electroplating is carried out at 20 - 60 °C for 30 up to minutes using a lead tin anode (90% Pb : 10Z Sn) direct using or preferably pulsed current. 0234738
- 17 -
The resulting bearing has a uniform plating of about 12-50 microns.
After the pretreatment step of the present invention, the bearing can alternatively be plated with nickel from a Wattes Nickel bath containing 300-330 g/1 nickel sulphate, 60-80 g/1 nickel chloride and
35-45 g/1 Boric acid, or other nickel bathes.
In this nickel plating process the current density used is up to
10 ampers/dm , the voltage is about 6-8 volts, the temperature 1s preferably about 40°-60°C and the anode is made of nickel.
It will be evident to those skilled in the art that the invention
is not limited to the details of the foregoing illustrative examples
and that the present invention may be embodied in other specific forms without departing from the essential attributes thereof, and 1t is
therefore desired that the present embodiments and examples be considered in all respects as illustrative and not restrictive,
reference being made to the appended claims, rather than to the
foregoing description, and all changes which come within the meaning
and range of equivalency of the claims are therefore intended to be
embraced therein. - IB - 0234738
CLAIMS;
1. An immersion solution for the pretreatment of
a bimetal bearing, having one portion thereof 5 composed of an aluminum base metal and another portion of the surface thereof composed of a ferrous base metal, comprising nickel and halogen ions, said solution having an acidic pH.
10 2. An immersion solution according to claim 1, further comprising an acid to bring the pH of the solution within a range of about 6 to about -0.2.
3. An immersion solution according to claim 1, 15 having a pH of about 3 to about 0.
4. An immersion solution according to any one of claims 1 to 3, wherein said halogen ions are chloride ions or fluoride ions or a combination of chloride 20 and fluoride ions.
5. An immersion solution according to any one of claims 1 to 4, wherein said halogen ions are derived from an ammonium salt thereof or from a potassium or 25 sodium salt thereof.
6. An immersion solution according to any one of claims 1 to 5, further comprising an aluminum oxidizing material, e.g. a ferric and/or permanganate 30 salt.
7. An immersion solution according to any one of claims 1 to 6, further comprising bivalent iron salts, trivalent iron salts and combinations thereof, 35 and/or copper ions. 0234738 - 19 -
8. An immersion solution according to claim 7, comprising up to about 150 g/1 of said iron ions.
9. An immersion solution according to any one of 5 claims 1 to 8, comprising about 10 to about 800 g/1 NiCl2.6H20, NiS046H20 or a combination thereof.
10. An immersion solution according to any one 10 of claims 1 to 9, comprising up to about 260 g/1 halogen ions.
11. An immersion solution according to any one of claims 1 to 10, further comprising up to about 30 15 g/1 of a wetting agent or surfactant.
12. An immersion solution according to any one of claims 1 to 11, further comprising metallic brighteners selected from the salts and complexes of 20 zinc, cadmium, lead and thallium.
13. An immersion solution according to any one of claims 1 to 12, further comprising soluble metal salts corresponding to the metal components of said 25 bimetal bearing.
14. A process for the electroplating of a bimetal bearing having one portion thereof composed of an aluminum base metal and another portion of the 30 surface thereof composed of a ferrous base metal, comprising the pretreatment step of immersing said bearing, prior to the electroplating thereof, in a solution having an acidic pH and containing nickel and halogen ions, whereby said bearing is provided 35 with a coating from said solution without the use of an external source of electricity, which coating can - 20 - 0234738
then be coated with an electroplated deposit without any further intermediary steps.
15. A process according to claim 14, wherein 5 said electroplated deposit is provided by a lead fluoborate, tin fluoborate or copper fluoborate solution.
16% A process according to claim 14, wherein 10 said electroplated deposit is provided by a lead, lead-tin, tin-lead, nickel, copper, brass silver, tin, zinc, cadmium or chromium plating solution.
17. A process according to any one of claims 14 15 to 16, wherein said bearing is subjected to alkaline cleaning and etching following by neutralization and desmutting prior to immersion in said solution.
20
25
30
35 European Patent /Q,2a3 AZ3 8 J> EUROPEAN SEARCH REPORT Office EP 87 30 0675
DOCUMENTS CONSIDERED TO BE RELEVANT Citation of document with indication, whert appropriate, Relevant CLASSIFICATION OF THE Category of relevant passages to claim APPLICATION (In! CM)
X CHEMICAL ABSTRACTS, vol. 98, no. 1-4,9 26, 27th June 1983, page 547, 10,14 C 25 D 5/34 abstract no. 224260w, Columbus, 16 C 25 D 7/10 Ohio, US; & HU-A-23 661 (K. TIHANYI et al.) 28-09-1982
US-A-2 734 024 (SCHULTZ) 1,14- 17 * Column 2, lines 40-62; column 3, lines 1-28 *
GB-A-2 107 741 (MOBIL TYCO 1-5,9, SOLAR ENERGY CO . ) 10,14 * Page 2, lines 59-90 *
FR-A-1 040 250 (PECHINEY) 1-4,9, 10,14, 16,17 TECHNICAL FIELDS * Page 1, right-hand column, SEARCHED (Int Cl'j lines 14-39; page 2, left-hand column, lines 1-19 * C 23 C 18/32 C 25 D 5/34 C 25 D 5/36 US-A-4 013 492 (E.A. RAGER et C 25 D 5/42 al.) C 25 D 5/44 C 25 D 7/10
METALLOBERFLACHE, vol. 37, no. 6-8, 12 7, July 1983, pages 300-305, ,13 Munich, DE; J. BIELINSKI et al.: "Untersuchungen zur Optimierung von Losungen zur chemischen Vernicklung"
The present search report has been drawn up for all claims Place of search Date of completion of the search Examiner THE HAGUE 25-05-1987 VAN LEEUWEN R.H.
8 CATEGORY OF CITED DOCUMENTS T : theory or principle underlying the invention 8 E : earlier patent document, but published on, or X : particularly relevant if taken alone after the filing date Y : particularly relevant if combined with another D : document cited in the application document of the same category L : document cited for other reasons A : technological background O : non-written disclosure & : member of the same patent family, corresponding P : intermediate document document