• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to an electrolyte for the plasma-electrolytic oxidation of workpieces made of light metal and / or light metal alloys containing a salt solution, wherein at least one salt or a combination of two or more salts is selected from a group comprising metal salts, in particular borates, phosphates, nitrates, sulfates, Aluminates, silicates, manganates, Molybdate, tungstates, and / or salts of organic acids, in particular methanesulfonates and / or amidosulfonates, and / or metal complexes and combinations thereof, wherein inorganic non-metallic particles are dispersed in this salt solution, and a process for plasma electrolytic oxidation made of light metal and / or light metal alloys workpieces.
    公开号:AT516503A4
    申请号:T50467/2015
    申请日:2015-06-09
    公开日:2016-06-15
    发明作者:
    申请人:Happy Plating Gmbh；
    IPC主号:
    专利说明:

    The invention relates to an electrolyte for the plasma-electrolytic oxidation of workpieces made of light metal and / or light metal alloys comprising a salt solution, wherein at least one salt or a combination of two or more salts is selected from a group comprising metal salts, in particular borates, phosphates, nitrates, sulfates, Aluminates, silicates, manganates, Molybdate, tungstates, and / or salts of organic acids, in particular methanesulfonates and / or amidosulfonates, and / or metal complexes and combinations thereof, and a method thereof.
    Workpieces of light metals, in particular aluminum, magnesium and titanium, are used in the art because of their low weight, but also because of their property to form a dense, adherent oxide layer on their surface, versatile. Electrochemical processes for forming these oxidation layers have long been known, for decorative layers usually voltages up to 25 V, for harder and / or thicker layers up to about 100 V are used.
    Furthermore, high-energy deposition methods have become known in which under the name plasma electrolytic oxidation ("PEO") a coating of workpieces is carried out at high voltages, resulting in strong local arc discharges ("microarcs") to form a conductive plasma channel between the electrolyte and the workpiece , which in its interior has temperatures between 5,000 and 20,000 K within a few microseconds, comes. This led to the formation of a ceramic layer by means of plasma-chemical reaction, which has a high hardness and abrasion resistance and excellent adhesion.
    In WO 2012/107754 A2, such a plasma electrolytic method is described, in which by means of trapezoidal pulses, the oxidation of metallic substrates. A similar process is also described in WO 2008/120046 A1.
    An additional possibility for controlling the layer properties is the incorporation of particles which are dispersed in the electrolyte. The incorporation of unmodified oxides, carbides and nitrides using alternating current is described in the article by V.N. Malyshev, K.M. Zorin, "Features of microarc oxidation coatings formation technologies in slurry electrolytes", Appl. Surf. Be. 254 (2007), 1511-1516. A control of the superficial charge of the particles is possible in this method only on the pH of the electrolyte. Thus, the plasma electrolytic oxidation process is possible only in certain pH ranges, which represents a significant limitation in the selection of the candidate particles.
    It is the object of the invention to provide an electrolyte as well as a method to produce an improved layer by plasma electrolytic oxidation, the properties of which can be determined both by the particles dispersed in the electrolyte and by the electrical parameters of the deposition.
    This object is achieved in that inorganic non-metallic particles are suspended in this salt solution. In this case, the inorganic non-metallic particles are preferably selected from a group which contains insoluble oxides, hydroxides or silicates in the salt solution of the electrolyte.
    Here, the inorganic non-metallic particles have an average diameter of at least 10 nm, and are preferably surface-modified, so that their surface energy and / or zeta potential is increased or reduced in terms of their initial state. Such a surface modification causes the inorganic non-metallic particles to be uniformly suspended in the electrolyte, allowing uniform incorporation into the oxidation layer during the deposition process.
    The surfaces of oxides, silicates, glasses, many minerals, but also of oxidizable metals are coated with hydroxyl groups. These hydroxyl groups are chemically reactive and can react, for example, with siloxanes according to the reaction scheme X-OH + (EtO) 3 Si-R -> X-O-Si (OEt) 2-R (1). As a result, the chemical properties of the surface of the particles are changed such that the functional group of the siloxane determines the chemical surface properties.
    This modification can be carried out both in an organic medium, such as toluene, and in aqueous solution.
    In order to keep particles in the size range of microns to nanometers in a stable suspension, it is necessary that these particles have a surface electric charge, whereby they repel electrostatically in suspension, which prevents flocculation.
    This electrical surface charge (zeta potential) can also be used to electrophoretically attach the particles to an oppositely charged electrode surface. Together with the plasma electrolytic oxidation, it is thus possible to store siloxane-modified particles in a plasma-electrolytically produced layer. This can be used, for example, to create higher layer thicknesses or to transfer certain properties of the particles (e.g., chemical composition or structural features) to the layer.
    Depending on the pH of the electrolyte, a positive or negative surface charge should be sought. A positive charge is achieved, for example, by the use of siloxanes having amino groups, e.g. 3-aminopropyltrimethoxysilane achieved. The amino groups are protonated in an acidic medium, whereby the thus modified particle receives a positive surface charge. Alternatively, by using 3-mercaptopropyltrimethoxysiloxane and subsequent oxidation to sulfonic acid, a negative surface charge in the neutral and basic media can be achieved by the reaction equation R-SH + 3 H 2 O 2 - *. R-SO 3 H + 3H 2 O (2). The modification of the surface on the one hand causes a high surface charge of the particles in the electrolyte in question to prevent precipitation, on the other hand, the particles can be transported electrophoretically to the electrode surface in the course of the deposition process. In this way, the incorporation rate of the particles in the resulting oxide layer can be controlled via the electrical parameters.
    In this case, particular preference is given to surface modifications by means of reactive compounds which are selected from a group which contains silicon and / or germanium compounds, in particular germanium halides and / or siloxanes and / or halogenated silanes.
    In an alternative embodiment of the electrolyte according to the invention, the inorganic non-metallic particles are selected from a group comprising clay minerals, in particular bentonite, kaolinite and / or montmorillonite.
    These clay minerals naturally have a favorable surface energy or zeta potential, which leads to a stable electrolyte suspension.
    The invention furthermore relates to a process for the plasma-electrolytic oxidation of workpieces produced from light metal and / or light metal alloys with an electrolyte according to the invention described above.
    In a first variant of the method according to the invention, it is provided that the plasma-electrolytic oxidation takes place by means of direct current, in particular at a voltage of 250 V to 700 V. It is particularly preferred here that the current density is between 1 A / dm2 and 30 A / dm2. Oxidation layers produced in this way have a particularly compact, dense layer which has only a very low porosity. Such a low porosity is particularly desirable when a particularly high corrosion resistance of the workpiece is required.
    Alternatively, the plasma electrolytic oxidation is carried out by means of pulse methods, with anodic pulses preferably being applied at a voltage of 250 V to 700 V. In this case, it is particularly preferred that the current density be between 1 A / dm2 and 30 A / dm2 during the on fashionable pulses. The use of the pulse method has the advantage that the plasma-chemical reaction at the surface of the workpiece can be controlled by targeted control of the pulses. This makes it possible in particular to achieve a low surface roughness and a lower porosity of the oxidation layer on the workpiece. Investigations by the applicant have also shown that a higher pulse frequency has a positive effect on the corrosion resistance of the coated workpieces.
    In order to be able to vary the properties of the oxidation layer with regard to its porosity, its adhesive strength and / or abrasion resistance, in a further embodiment of the invention additional cathodic pulses are applied whose voltage is preferably between 30 V and 200 V.
    In this case, it is particularly preferred that the current pulses have a duration of at least 5 ps and are separated by pauses of at least 3 ps.
    Further possible variations result from the superposition of the anodic and / or cathodic current pulses with a constant base current.
    Finally, the thickness and / or duration of the anodic and / or cathodic current pulses can also be varied during the production of the oxidation layer on the workpiece.
    The invention is explained in more detail below with reference to non-limiting exemplary embodiments with associated figures. Show here
    1 is a scanning electron micrograph of the surface of a surface-modified SiO 2 particles produced PEO layer,
    FIG. 2 shows the EDX spectrum of the surface of FIG. 1, FIG.
    3 is a scanning electron micrograph of a cross section through the PEO layer of Fig. 1,
    4 shows the EDX spectrum of a cross section of the PEO layer from FIG. 3, FIG.
    5 shows a scanning electron micrograph of the surface of a bentonite-added PEO layer,
    FIG. 6 shows the EDX spectrum of the surface of FIG. 5, FIG.
    7 is a scanning electron micrograph of a cross section through the PEO layer of Fig. 5,
    Fig. 8 shows the EDX spectrum of a cross section of the PEO layer of Fig. 7 and
    9 shows an X-ray diffraction program of the PEO layer from FIG. 7.
    Example 1 Coating with Surface-modified Aerosil 200 a. ) Modification of the Aerosil Particles and Preparation of the Electrolyte 25 g of Aerosil 200 (a non-porous, amorphous silica having a specific surface area of 200 m 2 / g, Evonik Industries) were suspended in 1 l of n-butanol. Subsequently, a solution of 20 ml of 35% hydrochloric acid, 200 ml of 3-mercaptopropyltrimethoxysiloxane and 20 ml of water and a solution of 120 ml of 3-mercaptopropyltrimethoxysiloxane in 100 ml of n-butanol were added and the mixture was stirred at 40 ° C for 8 to 10 hours. Thereafter, a solution of 40 ml of 25% ammonia, 200 ml of 3-mercaptopropyltrimethoxysiloxane and 100 ml of n-butanol was added and the mixture was stirred overnight.
    After filtering off, washing and drying, the modified Aerosil was taken up in 2 l of 35% H 2 O 2 and stirred at 60 ° C. for 24 hours in order to oxidise the surface-bonded thiol groups to sulfonic acid.
    The surface-modified Aerosil thus obtained was added to an electrolyte consisting of a solution of 3 g / l KOH and 3 g / l K 2 SiO 3 in a concentration of 30 g / l. b. ) Implementation of the PEO process
    The substrate used was a 1 mm thick sheet of the industrially used 6082 aluminum alloy measuring 25 mm × 100 mm.
    A bipolar rectangular pulse was used to produce the layer, with the anodic and cathodic current density 10 A / dm2 and the respective pulse duration 500 [iS, which corresponds to a frequency of 1 kHz. The coating time was 30 minutes.
    The raster electronic recordings according to FIGS. 1 and 3 and the associated EDX spectra according to FIGS. 2 and 4 show the formation of a compact, dense layer by the presence of the surface-modified particles in the electrolyte, which, in contrast to the particle-free layers, has only a low porosity.
    Example 2: Layer with bentonite a. ) Preparation of the electrolyte
    To an electrolyte consisting of 3 g / l NaOH and 3 g / l Na 2 SiO 3, 30 g / l bentonite was added and stirred until a uniform suspension was obtained. b. ) Implementation of the PEO process
    The substrate used was a 1 mm thick sheet of the copper-containing aluminum alloy 2017 with the dimensions 25 mm x 100 mm. A bipolar rectangular pulse was used to make the layer, with the anodic and cathodic current densities 10 A / dm 2 and the respective pulse duration 500 ps, which corresponds to a frequency of 1 kHz. The coating time was 30 minutes.
    The addition of these particles also caused the formation of a relatively thick, compact and low-pore layer, in which case the layer structure of montmorillonite (main constituent of bentonite) is at least partially preserved, as evidenced by the X-ray diffractometric measurement of FIG.
    权利要求:
    Claims (15)
    [1]
    1. Electrolyte for the plasma-electrolytic oxidation of workpieces produced from light metal and / or light metal alloys containing a salt solution, wherein at least one salt or a combination of two or more salts is selected from a group comprising metal salts, in particular borates, phosphates, nitrates, sulfates, aluminates, Silicates, manganates, molybdate, tungstates, and / or salts of organic acids, in particular methanesulfonates and / or amidosulfonates, and / or metal complexes and combinations thereof, characterized in that inorganic non-metallic particles are suspended in this salt solution.
    [2]
    2. An electrolyte according to claim 1, characterized in that the inorganic non-metallic particles are selected from a group containing in the salt solution insoluble oxides, hydroxides or silicates.
    [3]
    3. Electrolyte according to claim 1 or 2, characterized in that the inorganic non-metallic particles have an average diameter of at least 10 nm, and are preferably surface-modified, so that their surface energy and / or zeta potential is increased or reduced in terms of their initial state.
    [4]
    4. An electrolyte according to claim 3, characterized in that the inorganic non-metallic particles are modified by means of reactive compounds which are selected from a group which contains silicon and / or germanium compounds, in particular germanium halides and / or siloxanes and / or halogenated silanes.
    [5]
    5. Electrolyte according to one of claims 1 to 4, characterized in that the inorganic non-metallic particles are selected from a group containing clay minerals, in particular bentonite, kaolinite and / or montmorillonite.
    [6]
    6. A method for the plasma electrolytic oxidation of workpieces made of light metal and / or light metal alloys, characterized by an electrolyte according to one of claims 1 to 5.
    [7]
    7. The method according to claim 6, characterized in that the plasma-electrolytic oxidation takes place by means of direct current, in particular at a voltage of 250 V to 700 V.
    [8]
    8. The method according to claim 7, characterized in that the current density between 1 A / dm2 and 30 A / dm2.
    [9]
    9. The method according to claim 6, characterized in that the plasma-electrolytic oxidation takes place by means of pulse method, wherein anodic pulses are preferably applied with a voltage of 250 V to 700 V.
    [10]
    10. The method according to claim 9, characterized in that the current density during the anodic pulses between 1 A / dm2 and 30 A / dm2.
    [11]
    11. The method according to claim 9 or 10, characterized in that additional cathodic pulses are applied, whose voltage is preferably between 30 V and 200 V.
    [12]
    12. The method according to any one of claims 9 to 11, characterized in that the current pulses have a duration of at least 5 ps and are separated by pauses of at least 3 ps.
    [13]
    13. The method according to any one of claims 9 to 12, characterized in that the anodic and / or cathodic current pulses are superimposed with a constant base current.
    [14]
    14. The method according to any one of claims 9 to 13, characterized in that during the production of the oxidation layer on the workpiece made of light metal or light alloy, the strength and / or duration of the anodic and / or cathodic current pulses are varied.
    [15]
    15. Use of the method according to any one of claims 6 to 14 for the plasma electrolytic oxidation of materials of light metals and their alloys, in particular of aluminum, magnesium, titanium, beryllium, tantalum or zirconium and their alloys. 2015 06 09 Ha
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    同族专利:
    公开号 | 公开日
    ES2739548T3|2020-01-31|
    EP3307925B1|2019-03-13|
    DK3307925T3|2019-06-24|
    WO2016197175A1|2016-12-15|
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    EP3307925A1|2018-04-18|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
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    DE102011007424B8|2011-04-14|2014-04-10|Helmholtz-Zentrum Geesthacht Zentrum für Material- und Küstenforschung GmbH|A method of forming a coating on the surface of a light metal based substrate by plasma electrolytic oxidation and coated substrate|EP3875636A1|2020-03-03|2021-09-08|RENA Technologies Austria GmbH|Method for the plasma electrolytic oxidation of a metal substrate|
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    法律状态:
    2017-05-15| HA| Change or addition of new inventor|Inventor name: VERONIKA GRMAN, AT Effective date: 20170320 Inventor name: SELMA HANSAL, AT Effective date: 20170320 Inventor name: WOLFGANG DR. HANSAL, AT Effective date: 20170320 Inventor name: RUDOLF MANN, AT Effective date: 20170320 |
    2017-05-15| HC| Change of the firm name or firm address|Owner name: HIRTENBERGER ENGINEERED SURFACES GMBH, AT Effective date: 20170320 |
    2021-06-15| PC| Change of the owner|Owner name: RENA TECHNOLOGIES AUSTRIA GMBH, AT Effective date: 20210416 |
    优先权:
    申请号 | 申请日 | 专利标题
    ATA50467/2015A|AT516503B1|2015-06-09|2015-06-09|ELECTROLYTIC FOR PLASMA ELECTROLYTIC OXIDATION|ATA50467/2015A| AT516503B1|2015-06-09|2015-06-09|ELECTROLYTIC FOR PLASMA ELECTROLYTIC OXIDATION|
    DK16732922.6T| DK3307925T3|2015-06-09|2016-06-09|Method for plasma electrolytic oxidation|
    PCT/AT2016/050188| WO2016197175A1|2015-06-09|2016-06-09|Electrolyte for plasma electrolytic oxidation|
    EP16732922.6A| EP3307925B1|2015-06-09|2016-06-09|Process for plasma electrolytic oxidation|
    ES16732922T| ES2739548T3|2015-06-09|2016-06-09|Procedure for plasma electrolytic oxidation|
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