Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D9/00—Electrolytic coating other than with metals
  • C25D9/04—Electrolytic coating other than with metals with inorganic materials
  • C25D9/06—Electrolytic coating other than with metals with inorganic materials by anodic processes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
  • Y10T428/263—Coating layer not in excess of 5 mils thick or equivalent
  • Y10T428/264—Up to 3 mils
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
  • Y10T428/263—Coating layer not in excess of 5 mils thick or equivalent
  • Y10T428/264—Up to 3 mils
  • Y10T428/265—1 mil or less

Definitions

• the invention relates to vacuum pump components without conversion layers that are made of valve metals and alloys thereof.
• DE 101 63 864 A1 relates to a process for the coating of objects made of valve metals or their alloys with a thin barrier layer consisting of the metal and an oxide ceramic layer provided thereon whose surface has been coated with fluoropolymers, characterized in that the fluoropolymers are introduced into the capillary system of the oxide ceramic layer in the form of a solution by vacuum impregnation, followed by removing the non-wetting portions of the solution and drying.
• the group of valve metals includes aluminum, magnesium, titanium, niobium or zirconium and their alloys.
• this specification also defines further components of vacuum pumps made of valve metals, such as rotors and stators of turbo-molecular pumps.
• aluminum and its alloys means ultrapure aluminum and the alloys AlMn; AlMnCu; AlMg 1 , AlMg 1.5 ; E-AlMgSi; AlMgSi 0.5 ; AlZnMgCu 0.5 ; AlZnMgCu 1.5 ; G-AlSi 1.2 ; G-AlSi 5 MG; G-AlSi 8 Cu 3 ; G-AlCu 4 Ti; G-AlCu 4 TiMg.
• the magnesium cast alloys with the ASTM designations AS41, AM60, AZ61, AZ63, AZ81; AZ91, HK31, QE22, ZE41, ZH62, ZK51, ZK61, EZ33, HZ32 and the wrought alloys AZ31, AZ61, AZ80, M1 ZK60, ZK40 are suitable for the purposes of the invention.
• pure titanium and also titanium alloys such as TiAl 6 V 4 , TiAl 5 Fe 2.5 and others may be employed.
• the oxide ceramic layer is essentially formed by a conversion layer of the surface of the component, so that in practice part of the substrate material is lost and converted to the oxidation barrier layer.
• the above mentioned coating methods enable true-contour layers to be formed.
• all these layer systems have specific disadvantages in vacuum- technological application.
• the anodization methods include more or less pronounced pore structures that limit the corrosion protection.
• the electroless nickel layers have so-called “pinholes”, which at least require a greater layer thickness in order to minimize the number and size of the pinholes.
• the tribological behavior of electroless nickel layers, especially under vacuum, is insufficient because such layers tend to cause cold welding during crashs.
• WO 03/029529 A1 describes the preparation of an object with a ceramic coating of titania and/or zirconia that is resistant to corrosion, heat and abrasion, applied to said object made of aluminum and/or titanium by direct-current or alternating-current anodization.
• the objects underlying this prior art method are not specified. Also, there is no information about chemical resistance, especially resistance to citric acid or hydrochloric and/or hydrofluoric acid vapors.
• the object of the present invention is to provide vacuum pump components without conversion layers, made of valve metals or their alloys, that, in addition to having corrosion, heat and abrasion resistance, include a coating without a conversion layer that is produced by electroplating and is additionally resistant to chemicals, especially resistant to citric acid or hydrochloric acid vapors. This is particularly important in the production of components of vacuum pumps that, especially in vacuum technologies, come into contact with aggressive gases, such as HCl and/or HF vapors/gases.
• the above object is achieved by vacuum pump components without conversion layers, made of valve metals or their alloys, characterized in that their surfaces have a coating of at least one oxide and/or oxyfluoride of an element of the group consisting of boron, germanium, aluminum, magnesium, titanium, niobium, hafnium and/or zirconium and mixtures thereof, produced by electroplating and having a layer thickness within a range of from 5 to 50 ⁇ m.
• the deposited layers may have a hardness of about 700 HV.
• the basic service life of the electrolyte can be set by analytical monitoring and optionally replenishing over significantly longer periods than those required with the previously known methods for the coating of components of vacuum pumps made of valve metals and their alloys.
• the electrolyte of KEPLA Coat® must be discarded depending on usage because of contaminations originating from the starting material. This similarly applies to electrolytes of anodization layers.
• Components of vacuum pumps made of valve metals and their alloys according to the invention include, in particular, rotors, stators, stator disk halves, helical stages, housings and bearing shells.
• valve metals herein includes metals of the group of aluminum, magnesium, titanium, niobium and/or zirconium and their alloys.
• the specific alloys of aluminum, magnesium and titanium as mentioned in the introductory part of the description are also particularly preferred according to the present invention.
• At least one oxide and/or oxyfluorides of the group consisting of aluminum, titanium and/or zirconium are best suitable for realizing the advantages of the present invention.
• the thickness of the surface coating is from 5 to 50 ⁇ m. It is particularly preferred according to the present invention that the thickness of the surface coating is from 15 to 30 ⁇ m. If the thickness of the surface coating is selected too thin, sufficient protection against corrosion, heat, abrasion and chemicals cannot be ensured. In contrast, if the thickness of the surface coating is selected too large, the corresponding coatings will tend to chip off. In addition, correspondingly thick coatings are economically inefficient.
• Another embodiment of the present invention relates to a process for preparing vacuum pump components without conversion layers, made of valve metals or their alloys, that are produced by electroplating, characterized by
• a sample sheet of AlMgSi 1 with dimensions of 100 ⁇ 50 ⁇ 1.5 mm was subjected to anodic coating at 400 volts for 5 minutes in an electrolyte as described in WO 03/029529 A1, WO 2006/047501 A2 and WO 2006/047526 A2 within 5 minutes.
• the determined layer thickness was about 10 ⁇ m.
• a sample sheet as described in Example 1 was coated in an analogous way within 10 minutes.
• the determined layer thickness was about 12 ⁇ m.
• the sample sheets coated according to Examples 1 and 2 were exposed to a hydrochloric acid atmosphere formed above a bath containing 15% by weight hydrochloric acid.
• the oxide ceramic layer on the sample sheets was examined for chipping off after test durations of 144 hours and 300 hours. The oxide ceramic layer on the sample sheets was still intact after this exposure time.
• the sample sheets coated according to Examples 1 and 2 were exposed to citric acid solutions having concentrations of 2%, 3.5% and 5%.
• the oxide ceramic layer on the sample sheets was examined for chipping off after a test duration of 90 hours.
• the oxide ceramic layer on the sample sheets was still intact after this exposure time.

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• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Other Surface Treatments For Metallic Materials (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Physical Vapour Deposition (AREA)

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• 2011
  • 2011-06-24 DE DE102011105455A patent/DE102011105455A1/de not_active Withdrawn
• 2012
  • 2012-06-06 TW TW101120284A patent/TWI560327B/zh active
  • 2012-06-15 US US14/126,715 patent/US20140154503A1/en not_active Abandoned
  • 2012-06-15 KR KR1020147001902A patent/KR20140043129A/ko not_active Ceased
  • 2012-06-15 WO PCT/EP2012/061491 patent/WO2012175429A1/de not_active Ceased
  • 2012-06-15 EP EP12728262.2A patent/EP2723923B1/de active Active
  • 2012-06-15 JP JP2014516291A patent/JP5957075B2/ja active Active
  • 2012-06-15 CN CN201280028749.6A patent/CN103620091A/zh active Pending

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