WO2010046392A2

WO2010046392A2 - Electrochemical coating method

Info

Publication number: WO2010046392A2
Application number: PCT/EP2009/063793
Authority: WO
Inventors: Selma Hansal; Martina Halmdienst; Wolfgang Hansal
Original assignee: Happy Plating Gmbh
Priority date: 2008-10-23
Filing date: 2009-10-21
Publication date: 2010-04-29
Also published as: WO2010046392A3; AT506583B1; EP2342371A2; AT506583B9; AT506583A4

Abstract

The invention relates to an electrochemical coating method for depositing at least one layer on at least one work piece in a deposition bath, comprising at least one deposition sequence (P) that is repeated at least once, wherein provided within the at least one deposition sequence (P) are at least two individual sequences (A, B, C), and each individual sequence (A, B, C) comprises a specific deposition method, and the at least two individual sequences (A, B, C) comprise different deposition methods within a deposition sequence (P).

Description

14518

Electrochemical coating process

The invention relates to an electrochemical coating method for the deposition of at least one layer on at least one workpiece in a deposition bath, comprising at least one deposition sequence that is repeated at least once, wherein at least two individual sequences are provided within the at least one deposition sequence, and each individual sequence is a specific deposition method and its use.

A method of the type mentioned in the opening paragraph is disclosed in CA 2 365 749 A. It relates to a method for producing in particular a gold-tin alloy, in which in a first step, a first component of the alloy and in a second step, the second component of the alloy is deposited. The deposition method used in both steps is a classical pulse separation (Unipolar Pulse Plating). The different constituents of the alloy are preferably deposited according to the selected current density, always using the same deposition method.

DE 40 09 914 A1 discloses a method in which a three-layer system is applied to a workpiece, wherein a second layer in the form of a zinc-nickel alloy is connected to a first layer of cobalt. Both layers are deposited by means of DC methods. This is followed by an electrolessly deposited chromate layer. EP 1 122 989 B1 describes the combination of direct current with a reverse pulse method for depositing two layers. A similar method for depositing several layers can also be found in JP 2000-173 949 A.

In particular, the following methods are generally known:

• Unipolar Pulse Plating: cathodic pulses only (Fig. 1)

Reverse Pulse Plating: cathodic and anodic pulses (Fig. 2)

• Superimposed Pulse Plating: cathodic pulses on a base current, optionally also anodic pulses (Fig. 3)

• Pulsed Pulse Plating: multipulse system with cathodic and anodic phase, a sequence consists of up to 500 single pulses (Fig. 4)

Spike Current Pulse Plating: Using ramps and triangular coils (Figure 5) Pulse method or pulse separation is generally understood to mean the use of a modulated current for the electrolytic metal deposition in contrast to the DC separation. Most frequently, rectangular pulses, which are interrupted by so-called pulse pauses, are generated by suitable pulse rectifiers. These cathodic pulses (metal deposition) are supplemented by one or more, regularly spaced anodic current pulses (metal dissolution). A constantly repeating sequence of cathodic and anodic pulses with the corresponding pulse pauses (timeout = interruption of the externally supplied current causes the desorption of impurities and the diffusion of active species to the workpiece surface) represents the so-called pulse sequence.

Simple pulse sequences each consist of one type of cathodic and anodic pulses (reverse pulse plating). Such a method can be found for example in US 2002/033341 A.

In addition to the variation and combination of different individual pulses within a sequence, a base current, a direct current, to which the actual pulse sequence is applied, is frequently also used.

By pulse deposition, several material properties of the deposited metal can be selectively changed. Behind this is always a variation of the electrochemical conditions on the setting of the individual pulse parameters during the deposition. While in DC deposition, the process can be varied only by the amount of current used for deposition (via the average current density), the user has a considerable set of different parameters available in pulse or inverse pulse separation. In addition to the average current density, these are the cathodic and anodic pulse current density, the cathodic and anodic pulse duration, the length of the pulse pause and the pulse frequency. Derived quantities, such as the duty cycle (ratio of the sum of the pulse durations per sequence to the sum of the length of the pulse pauses per sequence) and the ratio of anodic to cathodic current quantity per sequence are further important factors influencing the pulse deposition process. However, many of these parameters can not be varied completely independently of each other because they partially influence each other. The maximum pulse rate affects the structure and properties of the deposited metal layer.

In particular, due to the increasing relevance of nanotechnology, the aim is to have a very finely crystalline metal precipitate with primary crystal sizes in the nanometer range. The maximum pulse frequency (and thus the minimum possible pulse duration) is determined by the charge for charging (and discharging) the elec- trolytic bilayer necessary time determined. If this limit time is undershot, marked distortions of the applied rectangular pulses occur at the electrode surface (the workpiece to be coated), and the pulse deposition becomes uncontrollable and difficult to reproduce. Therefore, the process and the pulse sequence must be defined such that the time in which the charge and discharge of the double layer takes place is shorter than the pulse duration or the break after the pulse. It must be carried out separately for each electrolyte system a determination of the charging and discharging times.

The limitation by the mass transport is based on the depletion of the cations in the diffusion layer at the electrode or workpiece surface. The pulse deposition can directly influence the structure and the thickness of the diffusion layers.

Thus, in the pulse current separation, a distinction can be made between two different diffusion layers. In the immediate vicinity of the cathode, the metal ion concentration fluctuates in the rhythm of the pulse frequency, this is called a pulsating diffusion layer. This is followed by another diffusion layer with a constant concentration gradient (stationary diffusion layer). The depletion of cations in the pulsating diffusion layer limits the pulse current density, the depletion in the outer diffusion layer limits the average current density. The practical current density can thus be slightly increased in comparison to direct current, a further increase in the mean current densities succeeds only when manipulating the current density distribution in the reverse pulse separation.

Another advantage of pulse current deposition is an improvement in precipitation properties that depends on the precipitation structure. The precipitation structure is determined on the one hand by the formation of the primary crystallites of the deposited metal, and on the other by the further growth of these crystallites. The ratio of crystallite formation to crystallite growth can be affected by pulse deposition (e.g., via pulse current density), pulse rate or duty cycle.

The classic and probably best-described application for pulse separation is printed circuit board production. The copper system is considered a model substance.

In the known art, each individual layer is deposited using one of the types of methods described above. However, this limits the material properties of the respective deposited layer. Furthermore, previously known only layer systems, which have a maximum of three individual layers.

It is therefore an object of the invention to provide a coating method of the type mentioned, which allows the deposition of single or a plurality of layers whose material properties can be varied within a wide range.

This object is achieved by a coating method of the type mentioned in that at least one Abscheidesequenz is provided which is repeated at least once, wherein at least two different individual sequences are provided within the at least one deposition sequence. By combining two different individual sequences into a periodically recurring deposition sequence, it is possible to obtain a wide variety of properties of the layer produced in this way. The individual sequences change each other and are repeated at certain intervals. The number of single pulses used, which are assigned to the individual sequences, goes into the hundreds. By this method, layer properties can be achieved that can not be achieved with DC deposits, chemical deposits or conventional pulse depositions. Thus, it is possible to fundamentally change the structure of the layer structure or to produce an additional surface structure during the deposition. Defined zones of a particular crystal structure can thus be created across the layer and alternated as needed. In parallel, the coating uniformity increases. In particular, the following results can be achieved by suitable combination of the individual sequences:

- increased layer uniformity, even in complex and poorly suited for electroplating geometries;

Increasing the deposition rate with the same uniformity and otherwise consistent coating properties;

Increasing the tribological stability of metal surfaces, in particular light metal surfaces, whereby for the first time their use in highly wear-loaded systems is made possible;

Tribological and hardness-related graded coating systems; Parallel installation of micro- or nanoparticles;

Ultra-dense metal layers, even at low layer thicknesses as barrier layers; Production of microstructured surfaces with simultaneously high layer uniformity and layer density;

Targeted control of the thermal expansion coefficient by multilayer coating systems;

- Targeted control of electrical surface and layer conductivity;

Production of vibration-damping layer systems with simultaneous high tribological stability;

Increasing the corrosion stability of surfaces while improving the uniformity of the coating and the tribological stability of the surfaces;

Increasing the thermal stability of materials via the application of the layers;

Preferably, each single sequence comprises at least one of the following deposition methods:

• DC

• purely cathodic pulses (Unipolar Pulse Plating)

• Combination of cathodic and anodic pulses (reverse pulse plating)

• Combination of cathodic and anodic pulses with up to 500 single pulses (Pulsed Pulse Plating)

• Ramps and / or Triangular Pulses (Spike Current Pulse Plating)

Each of the above methods in combination with a superimposed pulse plating

For electrochemical pulse plating deposition and pulse reverse plating deposition electrochemical multipulse can be used in particular.

The deposition sequences used in the multipulse deposition according to the invention can consist, for example, of the following building blocks:

(A)

• DC phase followed by a pulse pause with a repetition rate between 3 and 500 times, or

• DC phase followed by an anodic pulse with a repetition rate between 3 and 500 times, or • DC phase followed by a cathodic pulse with a repetition rate between 3 and 500 times; followed by a (B)

• Pulse phase (Phase 1) consisting of 2 - 500 either cathodic or anodic single pulses, each with the same or different pulse current density and pulse length, each followed by either

• a break or

• a DC phase or

• a cathodic base current between 1% and 75% of the pulse current density or

• an anodic base current between 1% and 75% of the inverse cathodic pulse current density or

A cathodic pulse which differs from the preceding pulse in one or more of the pulse parameter pulse current density, pulse length, pulse shape or pulse frequency or

An anodic pulse of any desired pulse current density, pulse length, pulse shape or pulse frequency followed by a (C)

• Pulse current phase (phase 2) consisting of 2 - 500 either cathodic or anodic single pulses each with the same or different pulse current density and pulse length but different current density or pulse length or pulse frequency to phase 1 respectively followed by either

• a break or

• a DC phase or a cathodic base current between 1% and 75% of the pulse current density or

An anodic pulse of any desired pulse current density, pulse length, pulse shape or pulse frequency; or (A ')

• DC phase followed by a

Pulse current phase consisting of 2 - 500 either cathodic or anodic single pulses, each with the same or different pulse current density and pulse length, each followed by (B ')

• a break or

• a DC phase or

• a cathodic base current between 1% and 75% of the pulse current density or

A cathodic pulse which differs from the preceding pulse in the pulse current density and pulse length, pulse shape or

An anodic pulse of any desired pulse current density, pulse length, pulse shape or pulse frequency; or

(A ")

A pulse phase consisting of one in the number of individual pulses within 2-500 arbitrary series of pulses each followed by either (B ")

• a break or

• a DC phase or

• a cathodic base current between 1% and 75% of the pulse current density or

Another pulse of the same polarization but with different pulse current density with either the same or different pulse length or pulse shape; or (A '')

• a cathodic or anodic single pulse followed by (B '")

A pulse phase of equal or opposite polarization consisting of one in the number of individual pulses within 2-500 arbitrary series of pulses each followed by either (C ")

• a break or

• a DC phase or

• a cathodic base current between 1% and 75% of the pulse current density or

Another pulse of the same polarization, but with different pulse current density with either the same or different pulse length or pulse shape.

The length of the individual pulses and phases is in each case between 0.1 and 10,000 ms. The current densities of the respective pulses or direct currents are between 0.01 A / dm2 and 100 A / dm2.

The individual phases can be applied with potential or current (density) in a controlled manner.

In order to allow a desorption of impurities and a diffusion of active species to the workpiece surface, a break is advantageously provided between at least two successive individual sequences and / or after the expiration of a deposition sequence. This pause is obtained by the interruption of the externally supplied current.

In one embodiment, the method according to the invention has a periodic sequence which has at least one DC phase followed by a pulse current phase.

Furthermore, it can be provided that the individual sequences or else the entire deposition sequence is superimposed with a base current, wherein the base current advantageously has between 1% and 75% of the current density. The method according to the invention allows in particular a specific adjustment and change of the material properties of the applied layer if the duration of a single sequence is between 1 and 3000 microseconds.

The deposition takes place here from a deposition bath containing at least one aqueous solution of at least one salt or mixtures of salts, at least one molten salt or at least one ionic liquid or mixtures thereof.

In a variant of the method, the deposition bath additionally contains solids for incorporation into the at least one deposited layer. These solids include, in particular, particles, fibers, flakes and / or nanotubes (microscopically small, in particular tubular, structures with a diameter smaller than 100 nanometers).

The object is furthermore achieved by the coating method according to the invention in that the coating has at least four layers. In this case, the layers can be applied by means of at least one of the following methods, wherein preferably at least two layers are applied with respectively different methods:

• DC

• purely cathodic pulses (Unipolar Pulse Plating)

• Combination of cathodic and anodic pulses (reverse pulse plating)

• Ramps and / or Triangular Pulses (Spike Current Pulse Plating)

Each of the above methods in combination with a superimposed pulse plating

From these blocks, the multilayers can be combined in any order. Due to the selected combination, the resulting properties of the entire layer system can be controlled in a targeted manner.

Preferably, the coating has four, five, six, seven, eight, nine, ten, eleven or twelve layers. Likewise it can be provided that only two or three layers are provided, wherein advantageously at least one of the layers is applied by means of the multipulse method according to the invention. In a preferred embodiment of the invention, a first primary layer applied to the workpiece is followed by at least one second layer, which has a greater layer thickness than the primary layer. The primary layer optionally allows better adhesion of the subsequent layer.

In a further embodiment of the invention, the second layer is followed by at least one third outer layer whose layer thickness is smaller than that of the second. In this case, the third layer acts as a barrier against environmental influences of a chemical and / or mechanical nature. In this case, it is particularly preferred that the second layer is produced by means of an electroless process, and the primary layer and / or the final layer is produced by means of the multipulse process according to the invention.

The coating method according to the invention has proven particularly suitable for the use for depositing at least one layer on a metallic or non-metallic workpiece with a metallic coating, in particular it is suitable for workpieces made of aluminum, magnesium or titanium. The application of layer systems with special material properties by the method according to the invention also allows the use of these materials in areas which in particular have high demands on the wear resistance of the workpieces.

The individual layer layers as components of a total layer system can consist in particular of the following materials: electrolytically deposited metals and their alloys: nickel (in particular also taking into account the nickel-phosphorus ratio), copper, tin, silver, platinum, gold, zinc, rhodium, antimony , Chromium, cadmium, iron, cobalt, indium, tungsten, rhenium, bismuth, manganese; chemically (without external power) deposited layers of the aforementioned metals and their alloys;

In addition, heat treatments and / or cleaning steps can be carried out between the individual layers.

In the following, the invention will be explained in more detail with reference to some embodiments.

FIG. 6 graphically depicts a deposition sequence P consisting of three individual sequences, namely a superimposed pulse plating sequence A, a unipolar pulse plating sequence B and a pulsed pulse plating sequence C. The individual sequences A, B, C are interrupted by pulse pauses D. whose length is for example 5 ms, whereby in this case the power supply is interrupted from the outside. This deposition sequence P is repeated up to 500 times in this embodiment of the coating process according to the invention.

Example 1:

The layer properties can be significantly influenced by the multipulse method. An example of nickel shows that the structure of the layer can be flipped into lamellar (Fig. 8) only by employing the columnar multipole method of the present invention (Fig. 7) made according to the prior art reverse-pulse technique , It is also possible according to the invention to produce mixed types (FIG. 9) between columnar and lamellar.

The experimental conditions were the same except for the pulses in the experiments: electrolyte composition: nickel sulfamate type, temperature 45 ° C.

Chemical components

amount

Nickel sulfamate 80-95g / l

Nickel bromide 3 - 20g / l

Boric acid 30 - 40g / l

Org. Hardness additive 20 - 30ml / l

Wetting agent 1 - 3ml / l

Example f. commercial bath: Enthone Lectronic 1003

Pulse parameter (Fiq.7 ¹ )

Current-tight pulse time

Number [A / dm ² ] [ms] cath 1 - 8 3.0 - 4.0 20 - 40 cath 1 - 8 4.0 - 6.0 10 - 15

Pulse parameter (Fiα .8):

Current-tight pulse time

Number [A / dm ² ] [ms] cath 1 - 5 1.0 - 2.0 200 - 300 cath 120 - 200 1.0 - 2.0 5 - 10 cath 120 - 200 2.0 - 4.0 1 - 5 anod 2 - 10 1.5 - 3.0 150 - 250 cath 2 - 10 1.0 - 2.0 10 - 30 cath 1 - 5 1.0 - 2.0 2000 - 3000 The respective layer types show different layer hardnesses; the hardness of the layers depends on the deposition method (all layers were deposited from the same bath):

Type Microhardness HV 0.1

Columnar 220 - 250

Mixed type 210 - 270 lamellar 420 - 460

The nickel layers produced in this experiment by means of the multipulse method according to the invention have by far the highest microhardness.

The general layer structure (columnar / fine-crystalline / lamellar) can also be changed according to the invention. Here too, the anodic portion plays an essential role in the deposition sequence. As the applied current is varied by, for example, pulses, the nature of the adsorbed species may change, and depending on the rate constant of the adsorption, the surface diffusion changes. This leads to different crystallization mechanisms and properties of the deposited precipitate.

The kinetics of concurrent reactions have a great influence on the relative rate of competing reactions, e.g. during alloying or hydrogen evolution. By influencing the deposition kinetics via the shape and sequence of the applied current pulses, alloy compositions and phases can be manipulated and side reactions suppressed. In the reduction of the resulting hydrogen and the pulse break plays an important role. During the pauses of the stream, adsorbed substances or gas bubbles can desorb, in particular with simultaneous good bath movement.

In the production of multiple layers may be single or multiple rinses in water adjusted purity between steps necessary.

All starting materials to be coated can be pretreated or activated in a manner known per se in preparation for a galvanic coating.

In the following application examples, the following electrolyte compositions were used: El:

Chemical components Menqe

Nickel sulfamate 70 - 90g / l

Nickel bromide 5 - 20g / l

Boric acid 30 - 40g / l

Org. Hardness additive 15 - 25ml / l

Wetting agent 1 - 3ml / l

Example f. commercial bath: Enthone Lectronic

E2a: chemical nickel bath with phosphorus content 2 - 4% E2b: chemical nickel bath with phosphorus content 4 - 9% E2c: chemical nickel bath with phosphorus content 9 - 12%

E4:

Chemical components Menqe

Nickel sulfate 230 - 300g / l

Nickel chloride 40 - 60g / l

Boric acid 30 - 40g / l

Wetting agent 2 - 3ml / l

Org. Additives 20 - 30ml / l

Example f. commercial bath: Enthone Elpelyt E1 OX

E5:

Chemical components Menqe

Nickel sulfate 230 - 300g / l

Nickel chloride 40 - 60g / l

Boric acid 30 - 40g / l

Wetting agent 2 - 3ml / l

Org. Shine additives 20 - 30ml / l

Example f. commercial bath: Enthone Elpelyt GS6

E6:

Chemical components quantity

Chromic acid 200 - 250g / l

Sulfuric acid 5 - 10g / l

Example f. commercial bath: metal chemistry sapphire

E7:

Chemical components Menqe

Chromic acid 280 - 300g / l

Sulfuric acid 3 - 6g / l

Wetting agent 5 - 10ml / l

Example f. commercial bath: Enthone Ankor 1120 E8:

Chemical components Menqe

Silver cyanide 100-200g / l

Potassium cyanide 50 - 150g / l

Org. Additives 5 - 10ml / l

Potassium hydroxide 4g / l

Potassium silver cyanide 40 - 60g / l

Example f. commercial bath: Enthone Silvrex

E9:

Chemical components Menqe

Nickel sulfate 230 - 300g / l

Nickel chloride 40 - 60g / l

Boric acid 30 - 40g / l

Wetting agent 2 - 3ml / l

Org. Additives 20 - 30ml / l

Example f. commercial bath: metal chemistry ORION 2100

ELO:

Chemical components Menqe

Copper sulphate 70 - 90g / l

Example f. commercial bath: metal chemistry Chelux

Application 1:

Purpose: Increased wear resistance, tested in test setup with in a simulated simulated engine run with a mean of 6,000 rpm

Status quo: Durability with DC method or only electroless with 4% phosphorus: 40 h, hardness of conventional layers between 250 - 800HV

Inventive method: Shelf life 250h, surface hardness approx. 600HV, coating hardness approx. 1000HV

Substrate: Aluminum alloy AISi20Fe5Ni2 Layer system:

10 shows an electron-spectroscopic image of the layer system obtained from left to right:

Substrate material aluminum alloy,

2μm sulfamate nickel layer,

• 13μm chemical nickel,

2μm sulfamate nickel layer,

• 13μm chemical nickel,

• 2μm nickel - cobalt alloy layer

Coating parameter: MP = Multipulse:

BP = bipolar pulse:

Application 2:

Purpose: Increased thermal resistance of aluminum materials Status Quo: No durability under continuous load> 100

Inventive Method: Shelf life over 250 hours at temperatures up to 200 ^° C.

Substrate: Aluminum alloy AISi20Fe5Ni2 Layer system:

Beschichtunqsparameter:

MP = Multipulse:

BP = bipolar pulse:

Application 3:

Purpose: for a uniform, wear-resistant coating with particle storage

Status Quo: Layer thickness distribution of up to 1: 5 when using DC methods and same deposition times / layer thicknesses

Inventive Method: Layer thickness distributions at 1: 1.2

Substrate: tool steel

Schichtsvstem:

Beschichtunqsparameter:

MP = Multipulse:

BP = bipolar pulse:

Application 4:

Purpose: Layer system with vibration-damping properties

Status Quo: No observable vibration damping effect when using DC or simple Pulse / Pulse reverse plating method.

Inventive Method: Significant vibration damping can be observed even with cyclic continuous loading.

Substrate: Aluminum Alloy Layer:

Fig. 11: from left to right:

Substrate material aluminum alloy,

2μm sulfamate nickel layer,

• 13μm chemical nickel,

2μm sulfamate nickel layer,

• 13μm chemical nickel, 2μm nickel - cobalt alloy layer

Beschichtunqsparameter:

MP = multipulse

BP = bipolar pulse:

Application 5:

Purpose: To produce corrosion-resistant and wear-resistant coatings Status Quo: Durability in the CASS test (DIN 50021) <24 hours

Inventive method: Shelf life of the coating system> 50 hours in the CASS test (DIN 50021) with a layer hardness of approx. 1.000HV

Substrate: Steel Layer:

Beschichtunqsparameter:

MP = Multipulse:

SRP = superimposed reverse pulse:

SP = superimposed pulse:

Application 6:

Purpose: To produce layers with high thermal tolerance

Status quo: Chipping, blistering or cracking of the DC / external electroless applied coating systems in the thermal shock test: three cycles annealing at 300 ⁰ C for 2 hours followed by quenching in liquid nitrogen (<200 ° C).

Inventive method: Shelf life of the layer system in the above-mentioned thermal shock test without occurrence of bubbles, flaking or cracking.

Substrate: Steel Layer:

Beschichtunqsparameter:

MP = Multipulse:

SRP = superimposed reverse pulse:

SP = superimposed pulse:

Application 7:

Purpose: To produce layers with high corrosion resistance of aluminum thixoglossal alloys

Status Quo: Resistance in CASS test (DIN 50021) of conventional DC or external power - nickel layers: 12h

Inventive method: Resistance in the CASS test: 24 h Substrate: Aluminum alloy AIMgSi7 Thixoguss Schichtsvstem:

Fig. 12: from bottom to top:

Substrate material aluminum alloy,

• 10μm sulfamate nickel layer,

• 25μm chemical nickel,

• 10 μm semi-bright nickel layer,

• 10 μm bright nickel layer,

• 2μm gloss chrome layer

Coating parameter: MP = Multipulse:

SRP = superimposed reverse pulse:

SP = superimposed pulse:

Application 8:

Purpose: To produce corrosion-resistant barrier layers with high layer uniformity

Status quo: Insufficient diffusion barrier effect or only poor layer uniformity when using DC methods or electroless methods

Inventive method: Excellent barrier effect even under continuous thermal stress at 60 ^° C. with a layer distribution of 1: 1.3

Substrate: Aluminum alloy Schichtsvstem:

Beschichtunqsparameter:

MP = Multipulse:

SPE = superimposed reverse pulse:

SP = superimposed pulse:

Application 9:

Inventive method: Excellent barrier effect even under continuous thermal stress at 60 ^° C. with a layer distribution of 1: 1.3 Substrate: Aluminum alloy

Schichtsvstem:

Beschichtunqsparameter:

MP = Multipulse:

SPE = superimposed reverse pulse:

SP = superimposed pulse:

Application 10:

Status quo: Insufficient diffusion barrier effect or only poor layer uniformity when using DC methods or electroless methods Inventive method: Excellent barrier effect even under continuous thermal stress at 60 ^° C. with a layer distribution of 1: 1.3

Substrate: Aluminum alloy coating system:

Beschichtunqsparameter:

MP = Multipulse:

SPE = superimposed reverse pulse:

SP = superimposed pulse:

Application 11:

Purpose: To produce layers with high corrosion resistance

Inventive method: Resistance in the CASS test (DIN 50021):> 24 h Substrate: Aluminum Alloy AIMgSi7 Layer System:

Beschichtunqsparameter:

MP = Multipulse:

BP = bipolar pulse:

SP = superimposed pulse:

Application 12:

Purpose: To produce layers with high corrosion resistance and pore coverage of the base substrate

Inventive method: Resistance in the CASS test (DIN 50021):> 24 h Substrate: Aluminum alloy AIMgSi7 Schichtsvstem:

Beschichtunqsparameter:

MP = Multipulse:

BP = bipolar pulse:

SP = superimposed pulse:

Application 13:

Purpose: To produce wear-resistant coatings on aluminum

Status Quo: Resistance of conventional external power or DC methods in the tribotest <100 hours

Inventive method: Resistance in tribo test> 200 hours Substrate: Aluminum alloys Schichtsvstem:

Beschichtunqsparameter:

BP = bipolar pulse:

Claims

PATENT CLAIMS

1. An electrochemical coating method for the deposition of at least one layer on at least one workpiece in a deposition bath, comprising at least one deposition sequence (P) which is repeated at least once, wherein within the at least one deposition sequence (P) at least two individual sequences (A, B, C), and each individual sequence (A, B, C) has a specific deposition method, characterized in that the at least two individual sequences (A, B, C) have different deposition methods within a deposition sequence (P).

2. Coating process according to claim 1, characterized in that each individual sequence (A, B, C) comprises at least one of the following deposition processes:

• DC

• purely cathodic pulses

• Combination of cathodic and anodic pulses

• Combination of cathodic and anodic pulses with up to 500 single pulses

• Ramp and / or triangle pulses

• each of the above methods in combination with a base current

3. Coating method according to claim 1 or 2, characterized in that between at least two successive individual sequences (A, B, C) and / or after the expiry of the at least one deposition sequence (P) an interruption (D) of the externally supplied current takes place.

4. Coating method according to one of claims 1 to 3, characterized in that a deposition sequence (P) has at least one DC deposition followed by a pulsed deposition.

5. Coating method according to one of claims 2 to 4, characterized in that the base current between 1% and 75% of the deposition current density has.

6. Coating method according to one of claims 1 to 5, characterized in that the duration of a single sequence (A, B, C) is between 1 and 3,000 ms.

7. Coating method according to one of claims 1 to 6, characterized in that the deposition bath contains at least one aqueous solution of at least one salt or mixture of salts, at least one molten salt or at least one ionic liquid or mixtures thereof.

8. Coating method according to one of claims 1 to 7, characterized in that the deposition bath additionally contains solids for incorporation into the at least one deposited layer.

9. Coating method according to claim 8, characterized in that the solids are in particular particles, fibers, flakes and / or nanotubes.

10. An electrochemical coating method for the deposition of a plurality of layers on at least one workpiece, characterized in that the coating has at least four layers.

11. Coating method according to claim 10, characterized in that the layers are applied by at least one of the following methods:

• DC

• purely cathodic pulses

• Combination of cathodic and anodic pulses

• Combination of cathodic and anodic pulses with up to 500 single pulses

• Ramp and / or triangle pulses

• each of the above methods in combination with a base current

12. Coating method according to claim 10 or 11, characterized in that at least two layers are applied by different methods.

13. An electrochemical coating method for the deposition of a plurality of layers on at least one workpiece, wherein at least two layers are applied by different methods, characterized in that at least one layer with an electrochemical method according to one of claims 1 to 9 is applied.

14. Coating method according to claim 13, characterized in that the coating has two to twelve layers.

15. Coating method according to claim 13 or 14, characterized in that a first, applied to the workpiece surface primary layer at least a second layer follows, which has a greater layer thickness than the primary layer.

16. Coating method according to claim 15, characterized in that the second layer is followed by at least one third end layer whose layer thickness is less than that of the second one.

17. Coating process according to claim 15 or 16, characterized in that the second layer is produced by means of an electroless process.

18. Coating method according to one of claims 15 to 17, characterized in that the primary layer and / or the final layer by means of the method according to one of claims 1 to 9 is prepared.

19. Coating method according to one of claims 10 to 18, characterized in that a thermal treatment takes place between the application of two layers.

20. Coating method according to one of claims 10 to 19, characterized in that at least one layer is applied by means of a plasma oxide process.

21. Use of the coating method according to any one of claims 1 to 20 for the deposition on a metallic workpiece or a non-metallic workpiece with a metallic coating.

22. Use according to claim 21, characterized in that the workpiece is made of aluminum, magnesium or titanium.

2009 10 21

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