DE3809139A1 - USE OF A PALLADIUM / NICKEL ALLOY LAYER AS AN INTERMEDIATE LAYER BETWEEN A NON-CORROSION-RESISTANT OR LESS-CORROSION-RESISTANT METAL BASE MATERIAL AND A COATING APPLIED BY THE PVD PROCESS - Google Patents

Abstract

An interlayer between a metallic substrate material of little or no corrosion resistance and a coating applied by the PVD process comprises palladium-nickel alloy containing 30-90 wt.% preferably 60-85 wt.% of palladium deposited from an aqueous electrolyte containing palladium and nickel ammines at a palladium concentration in thge range 2-20 g/l and a nickel concentration in the range 5-30 g/l, together with optional conductivity salts and organic additives which can contain sulphur, wherein the electrolyte components are selected so that any sulphur precipitated with the alloy has a valency exceeding two. The presence of the Pd-Ni alloy improves the corrosion reisitance and mechanical tenacity of PVD coatings in finishes where the substrate has little or no corrosion resistance, by avoiding a single PVD layer which would commonly be in the thickness range of .3-1 micron, and the coating defects of porosity characteristic therewith. The coating applied by PVD may be a boride, carbide, nitride, oxide or a silicide of elements in subgroups 4 to 6 of the periodic system, eg TiN, TiC optionally containing aluminium, cobalt, gold, carbon, copper, nickel, palladium, titanium, zirconium or tantalum. The substrate may be aluminium, lead, copper, magnesium, nickel, silver, steel, zinc or an alloy material based thereon which may further by provided with a layer of copper, copper alloy, nickel, nickel alloy, silver or tin alloy. The metallic substrate may itself be an electroplate coating on a galvanisable material such as coatings of copper, copper alloy, nickel, nickel alloy, silver or tin alloy.

Description

The invention relates to the application of coatings that generated by the PVD process on metallic base material. It is both technical and decorative coatings. PVD stands for physical vapor deposition. Common coating materials are metal borides, carbides, nitrides, oxides, silicides of the elements of the 4th to 6th subgroup of Periodic table titanium, zircon, hafnium or vanadium, niobium, tantalum or chrome, molybdenum, tungsten individually or in combinations. From The carbides, nitrides and oxides are of particular interest Elements of the 4th subgroup, aside from the large Hardness and wear resistance of such coating materials that Hard chrome covers can surpass several times, even attractive ones decorative colors such as TiN - gold colored - or TiC - anthracite - can be reached. Such coating materials appropriate additions of other elements such as Contain aluminum, cobalt, gold, carbon, copper, nickel, palladium, so that even decorative bluish, brownish, greenish, reddish or silvery colors can be achieved. In addition, you can with the PVD technology but also metallic materials such as aluminum, Titanium, zircon, platinum or gold are deposited, so that in corresponding systems with several sputter sources also layer combinations are producible. Titan can be retrofitted, for example Surface oxidise chemically or electrochemically, so that colorations can be reached in all possibilities of the spectrum. But it is also possible, using amorphous and / or diamond-like processes using PVD Separate carbon, for example in order to and produce low-wear surfaces.  

The PVD process has proven itself in many areas of technology (cf. GB 21 23 039) and leads to considerable improvements in quality of the coated products, the prerequisite is that the base material even with corrosive stress on the coated objects is sufficiently corrosion-resistant. This applies to the PVD process applied coatings such as titanium carbide or titanium nitride for example for austenitic chrome / nickel steel or titanium itself as basic material. If the basic material depends on the respective corrosion conditions not corrosion resistant or is not very corrosion-resistant, will interfere with later practical use Corrosion phenomena. This applies, for example, to metal Basic material such as aluminum, lead, copper, magnesium, nickel, silver, Steel, zinc or many alloy materials based on it such as Brass, bronze, nickel silver, monel, alpaca, zinc die-cast alloy, Lead centrifugal casting alloy etc. Corrosion also occurs a, if such basic materials additionally with a galvanically or currentlessly deposited matt, glossy, semi-glossy or matt gloss underlay as chrome, copper, Copper alloy, nickel, nickel alloy, silver or tin alloy layer or layer systems of the same are provided. Under Nickel or nickel alloy layers are made of dispersion nickel, Understand Ni-P and Ni-B coatings. The same applies to galvanized Plastic such as ABS (acrylonitrile-butadiene-styrene) or copolymers made of polycarbonate / ABS (e.g. Bayblend - Fa. Bayer, Leverkusen), polypropylene, etc., which are usually based on the electroless metallization using electrolessly deposited copper or Nickel phosphorus or nickel boron first with a bright copper and shiny or matt glossy nickel layer and possibly a Be polished chrome.  

The corrosion phenomena are based on that of the PVD process applied coatings, especially at low coating temperatures and under non-clean room conditions in the usual way Layer thickness range 0.3. . . 1 µm are porous or micro-cracked and have a high pinhole density and a very noble electrochemical Can have potential. The cause of the high pinhole Density lies in a preferred stem-like growth of the medium PVD process produced coating perpendicular to the substrate surface, without the stems growing sufficiently thick at the same time and thus result in a closed, homogeneous surface. These Shift defects can decrease with increasing layer thickness, however would be such a procedure because of the very slow separation speed the PVD process alone in terms of plant technology already too expensive. Add to that in many cases how special the galvanized plastic only very low PVD process temperatures in the range of 100-120 ° C so that the Vicat softening temperature of the plastic is not reached. In such extremely low process temperatures can therefore in most In cases no self-contained layers are deposited using the PVD process will.

You could think of the annoying corrosion phenomenon due to it an intermediate layer made of a very noble metal such as gold or platinum to counteract, of course, with conventional electroplating processes at least not adherable to chrome-plated surfaces would. On the one hand, this is costly, on the other hand such intermediate layers as especially gold very soft, which is very light damage in the further process of applying the coatings after the PVD process. In many cases there is also a Intermediate layer of low micro hardness under a hard material top layer  particularly disadvantageous. Experiments have also shown that such Intermediate layers like gold often cause adhesion problems when mechanically apply the coating applied using the PVD process Thrust is claimed.

The invention is therefore based on the object in an assembly from a non-corrosion-resistant or little corrosion-resistant Base material and one applied according to the PVD process Coating the corrosion resistance as well as the mechanical adhesion to improve the PVD coating.

To achieve this object, the object of the invention is the use a palladium / nickel alloy layer, which consists of an aqueous Palladium and nickel amine electrolytes with a palladium content in the range of 2 to 20 g / l, a nickel content in the range of 5 to 30 g / l and optionally conductive salts and organic additives, which may have sulfur, is deposited and at which electrolyte sets the palladium / nickel ratio so is that the electrodeposited alloy has a palladium content from 30 to 90% by weight, preferably 60 to 85% by weight, as Intermediate layer between a non-corrosion resistant or little corrosion-resistant metallic base material and one after the PVD process applied coating with the proviso that the Electrolyte components are selected so that when Sulfur this is higher than divalent.

The electrolyte can add aliphatic, unsaturated and / or heterocyclic sulfonic acid salts and optionally conductive salts, selected aromatic sulfonimides as tension reducers or Corrosion protection additive and also non-ionic and / or anion-active Have wetting agents, with the proviso that the  Addition of aliphatic unsaturated and / or heterocyclic sulfonic acid salts from an alkali salt (especially a sodium salt) of Vinyl, allyl, propyne, methallyl, N-benzylpyridinium-2-ethylsulfonic acid, N-pyridinium propyl sulfobetaine, N-pyridinium methyl sulfobetaine or more of these substances.

The metallic base material can be aluminum, lead, Copper, magnesium, nickel, silver, steel, zinc and based thereon Alloy materials such as brass, bronze, nickel silver, Monel, Trade alpaca, zinc die casting alloy or lead centrifugal casting alloy, as they are common in technical practice. These can ever according to basic material or desired optical effect or technical Specification additionally with a galvanic or currentless matt, glossy, semi-glossy or matt glossy underlay as copper, Copper alloy, nickel, nickel alloy, silver or tin alloy layer or layer system of the same. The Definition of nickel and nickel alloy layer should also include dispersion nickel as well as Ni-P or Ni-B coatings. With the metallic The basic material can also be an electroplated one Surface layer on electroplatable plastic components, especially matt, glossy, semi-glossy or matt glossy Copper, copper alloy, nickel, nickel alloy, silver or Tin alloy layers, individually or in combinations of layers, act. It is understood that the palladium / nickel alloy with usual galvanotechnical processes at least not adherent chrome-plated lower layers is separable.

Surprisingly, within the scope of the measures according to the invention the one constructed and produced in the manner described Palladium / nickel alloy layer no damage, and indeed  not if this intermediate layer is applied very thinly. The much greater micro hardness of the palladium / nickel layer resists possible damage to the subsequent PVD coating better than comparable pure gold intermediate layers. Self for a base material that is usually considerable in use Shows corrosion problems, these disappear when the Measures according to the invention. The palladium / nickel alloy layer, which is used in a special way according to the invention is in itself known (DE-31 08 508 and DE 32 32 735). There are also no liability problems more when the PVD applied Coating is mechanically stressed on thrust.

The invention relates to a preferred embodiment and in other words, a method for applying a PVD coating to a non-corrosion-resistant or less corrosion-resistant Basic material, with a first on the basic material Intermediate layer made of a palladium / nickel alloy is made from an aqueous electrolyte of palladium and nickel amines with a palladium content of 2 to 20 g / l, a nickel content from 5 to 30 g / l and additives of aliphatic, unsaturated and / or heterocyclic sulfonic acid salts and optionally conductive salts, selected, aromatic sulfonimides as tension reducers or Corrosion protection additive (benzenesulfonimide or benzenesulfonylurea) and also nonionic and / or anionic wetting agents which electrolyte the palladium / Nickel ratio is set so that the electrodeposited Alloy preferably a palladium content of 30 to 90 wt .-% 60 to 85 wt .-%, and wherein the addition of an aliphatic, unsaturated and / or heterocyclic sulfonic acid salt as  Alkali salt such as, in particular, sodium salt of vinyl, allyl, propyne, Methallyl-, N-benzylpyridinium-2-ethylsulfonic acid, N-pyridiniumpropylsulfobetaine, N-pyridinium methylsulfobetaine or more of these Fabrics.

In the beginning, well-known ones that could be applied using the PVD process were introduced Called coatings. In the context of the invention it can for the coatings applied by the PVD process by one such as metal borides, carbides, nitrides, oxides, silicides Elements of the 4th to 6th subgroup of the periodic table individually or act in combination. In particular, they can be carbides, nitrides and oxides of elements of subgroup 4 such as TiN or TiC or mixtures of different substances, which continue to be admixtures of aluminum, cobalt, gold, carbon, copper, nickel, Can contain palladium. The coatings using the PVD process can also be of a metallic nature such as aluminum, titanium, zirconium, Gold, platinum, etc. It can also be amorphous and / or be diamond-like carbon.

It is understood that depending on the type of base material before application the palladium / nickel intermediate layer another galvanically sub-layer to be applied may be necessary, for example to improve the roughness depth of the base material by leveling layers, to ensure the perfect adhesion of the palladium / nickel layer, to achieve special matt glossy surface effects or in the case of plastics, the copper underlayer is as thick as possible Resistance to temperature changes in the composite plastic coating to reach. This also includes dispersion nickel, Ni-P or Ni-B coatings, for example to make particularly hard sub-layers  produce. It is further understood that when using galvanized Plastic the material type with regard to its Vicat softening temperature adjust the process temperature of the PVD process is. - The palladium / nickel layer can be used with conventional galvanotechnical Procedure at least due to lack of liability not on chrome-plated Lower layers are applied.

According to the invention for the purpose of producing a non-porous or at least largely low-pore palladium / nickel intermediate layer these in their layer thickness, the roughness depth of the base material and / or be adapted to the galvanically deposited lower layer and have a minimum thickness of 0.1 µm. The layer thickness is that Roughness depth of the base material or the lower layer deposited on it adapt. In other words, the palladium / nickel The thicker the intermediate layer is deposited, the larger the Roughness of the base material is. Average layer thicknesses are in the range of 0.5 to 5 µm. The one applied by means of the PVD process Coating should have a thickness in the range 0.1 to 5 μm, in particular 0.3 to 1 µm. It goes without saying that the process Parameters of the PVD coating are advantageously to be set up in such a way that the coating has the lowest possible layer defect density (porosity, Micro cracks and pinholes).

In the following the invention and advantages achieved with reference to Exemplary embodiments explained.  

Example 1

Brass sheets also MS 58 are made according to known rules of electroplating pre-cleaned, electrolytically degreased, pickled, approx. 1 µm in copper-plated cyanide copper electrolytes, then approx. 7 µm nickel-plated and approx. 0.3 µm in sulfuric acid chrome electrolyte chrome-plated.

For the subsequent PVD coating, these sheets are made of emulsifier Freon (product TWD 602 from Du Pont) using ultrasound pre-cleaned and then in Freon TF and Ultrasound cleaned, before using a PVD process an approx. 0.5 µm thick TiN layer is applied. Cleaning in Freon products before PVD coating is therefore recommended, so that everyone Dirt and finger stains when fixed on special transport frames be removed for PVD coating.

Such test sheets are then subjected to various corrosion tests how

A condensation-changing climate with a SO₂-containing atmosphere
SFW 2.0 S DIN 50 018 or
Acetic acid salt spray test
ESS DIN 50 021

subject to 72 h each. There is heavy pitting on the test panels visible with approx. 2 to 3 pores / cm². Such test sheets can sometimes be used are literally eaten up.  

Example 2

Only the bright chrome coating is applied to test sheets according to Example 1 by a palladium / nickel alloy intermediate layer according to the invention from 1 to 1.5 µm thick with otherwise unchanged layer structure replaced. The specified corrosion tests over 72 hours each passed successfully now.

The palladium / nickel electrolytes of the present invention can do the following Compositions have:

6 g of palladium as [Pd (NH₃) ₄] Cl₂
9 g of nickel as [Ni (NH₃) ₆] SO₄
100 g of conductive salt as (NH₄) ₂SO₄
2.5 g sodium allyl sulfonate

possibly additionally:

1 g of benzoic acid sulfonimide, sodium salt

or

2 g benzenesulfonylurea

also as a wetting agent

0.5 g nonylphenol ethoxylate (23 EO)
NH₄OH for pH 8-8.5 adjustment
Water for 1 l bath
Electrolyte temperature 25 to 30 ° C
slight movement of goods
cathodic current density 1 A / dm²
Exposure time 4 to 6 min
Anodes: platinized titanium or graphite.

Instead of the non-ionic wetting agent, selected ones can also be used anionic surfactants based on alkyl and alkylaryl ether sulfonates can be used like:

1 g / l H₃C- (CH₂) _12/14 -O- (CH₂-CH₂-O) _n -CH₂-CH₂-CH₂-SO₃K

n = 11

Since such wetting agents have no cloud point, can now Electrolyte temperatures of, for example, 40 to 50 ° C applied will. At the same time, the degree of gloss of the deposition is improved.

Example 3

The base material according to Examples 1 and 2 is made of steel C 45 WN 1 0503 replaced. The same results are obtained, i. H. a Pd / Ni intermediate layer is required for corrosion reasons.  

Example 4

An additional 0.1 is applied to the titanium nitride layer applied by means of PVD 23 ct gold / nickel sputtered on. The corrosion sensitivity after Example 1 is even reinforced, while according to Example 2 with a Pd / Ni intermediate layer instead of the bright chrome plating Signs of corrosion appear.

Example 5

The titanium nitride can be replaced by titanium carbide, titanium aluminum carbonitride, metallic titanium, etc. to be replaced. Again they are the same Corrosion differences can be seen according to Examples 1 and 2.

Example 6

A test plate made of Bayblend T 45 MN is made according to the usual galvanotechnical Measures initially electroless nickel-plated, the electrolessly deposited Ni-P layer electrolytically in a Watt electrolyte preamplified, then 20 to 30 µm in a sulfuric acid electrolyte copper-plated and then 10 µm nickel-plated. Becomes a top layer immediately on this matt, shiny nickel layer Applied using PVD technology, there is no corrosion resistance achieved according to the tests according to Example 1. The corrosion resistance is immediately given again, however, if an intermediate layer is made Palladium / nickel according to Example 2 is applied.  

Example 7

Instead of the 0.3 µm thick chrome plating according to Example 1 now electrolytically 0.1 µm pure gold from commercially available electrolytes applied and then the top layer applied by means of PVD process. Apart from the poor corrosion resistance results when examining abrasion behavior using the drum grinding method and commercially available grinding wheels that the hard material top layer pushed down from the gold interlayer becomes. If the palladium / nickel intermediate layer according to the invention is used, the PVD top layer adheres excellently, d. H. the The gold intermediate layer is too sensitive to shear stress.

Example 8

For applications without special demands on you high decorative gloss level of the palladium / nickel intermediate layer, especially for many technical applications, palladium / Nickel electrolytes without aliphatic, unsaturated and / or heterocyclic Sulphonic acid salts as well as without aromatic sulphonimides applicable. The palladium / nickel intermediate layer also works the required corrosion resistance and causes at the same time good adhesion of the subsequently applied PVD coating, if it is ensured that if sulfur is co-deposited, this Electrolyte composition is higher than divalent:

6 g of palladium as [Pd (NH₃) ₄] Cl₂
10 g of nickel as [Ni (NH₃) ₆] SO₄ or CH₂NSO₃) ₂Ni · 4H₂O
50-100 g of conductive salt as (NH₄) ₂SO₄ or H₂NSO₃NH₄

possibly additionally as a wetting agent:

1 g of H₃C- (CH ₂ ) _12/14 -O- (CH₂-CH₂-O) _n -CH₂-CH₂-CH₂-SO₃K

n = 11

NH₄OH for pH 8-8.5 adjustment
Water for 1 l bath
Electrolyte temperature 40-50 ° C
slight movement of goods
cathodic current density 1 A / dm²
Exposure time 4 to 6 min
Anodes: platinized titanium or graphite.

Carrying out the experiment as in Example 2. The ones given in Example 2 Corrosion tests are passed.

Claims (12)

1. Use of a palladium / nickel alloy layer, which consists of a aqueous electrolytes of palladium and nickel amines with one Palladium content in the range of 2 to 20 g / l, a nickel content in the  Range from 5 to 30 g / l and optionally conductive salts and organic additives, which may have sulfur, is deposited and at which electrolyte the palladium / nickel ratio is set is that the electrodeposited alloy has a palladium content from 30 to 90% by weight, preferably 60 to 85% by weight, as an intermediate layer between a non-corrosion resistant or little corrosion-resistant metallic base material and one after the coating applied to the PVD process with the proviso that the electrolyte components are selected so that with co-deposition of sulfur which is higher than divalent. 2. Use according to claim 1 with the proviso that the electrolyte Additions of aliphatic, unsaturated and / or heterocyclic sulfonic acid salts and optionally conductive salts, selected aromatic Sulphonimides as tension reducers or corrosion protection additives and further comprises nonionic and / or anionic wetting agents and that the addition of aliphatic unsaturated and / or heterocyclic Sulfonic acid salts from an alkali salt (especially one Sodium salt) of vinyl, allyl, propyne, methallyl, N-benzylpyridinium 2-ethyl sulfonic acid, N-pyridinium propyl sulfobetaine, N-pyridinium methyl sulfobetaine or more of these substances. 3. Use according to one of claims 1 or 2 with the proviso that that the metallic base material is aluminum, lead, Copper, magnesium, nickel, silver, steel, zinc or based thereon Alloy materials that are additionally galvanic or currentless with a matt, glossy, semi-glossy or matt glossy Underlayer as copper, copper alloy, nickel, Nickel alloy, silver or tin alloy layer or layer systems the same can be provided.   4. Use according to one of claims 1 or 2 with the proviso that the metallic base material is galvanic applied surface layer on a galvanizable plastic component, especially matt, glossy, semi-glossy or matt glossy copper, copper alloy, nickel, nickel alloy, Silver or tin alloy layers individually or in combinations of layers acts. 5. Use according to one of claims 1 to 4 with the proviso that it is in the coating applied by the PVD process to such a one from a material of metal borides, carbides, -nitride, -oxide- -silicide of the elements of the 4th to 6th subgroup of Periodic table individually or in combinations. 6. Use according to claim 5, with the proviso that the after Additional coating applied to the PVD process Admixtures of aluminum, cobalt, gold, carbon, copper, nickel, Palladium can contain. 7. Use according to one of claims 1 to 4 with the proviso that it is in the coating applied by the PVD process to be made of metallic aluminum, titanium, zirconium or Tantalum deals, which subsequently oxidizes surface chemically or electrochemically can be. 8. Use according to one of claims 1 to 4 with the proviso that it is in the coating applied by the PVD process around an amorphous and / or diamond-like carbon acts.   9. Use according to one of claims 1 to 8 with the proviso that that for the purpose of making a non-porous or at least largely low-pore palladium / nickel intermediate layer in their Layer thickness of the roughness of the base material and / or on it galvanically deposited lower layer is adapted and a Has a minimum thickness of 0.1 µm. 10. Use according to claim 9 with the proviso that the average Layer thickness of the palladium / nickel intermediate layer in the Range is 0.5 to 5 microns. 11. Use according to one of claims 1 to 10 with the proviso that that the coating applied by the PVD method has a thickness in the range 0.1 to 5 µm, in particular in the range 0.3 to 1 µm. 12. Use in particular of technically functional layer systems according to claims 1 to 11 with the proviso that the Combination of palladium / nickel intermediate layer and that using PVD Process applied top layer hard chrome coatings substituted.