Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J49/00—Particle spectrometers or separator tubes
  • H01J49/44—Energy spectrometers, e.g. alpha-, beta-spectrometers
  • H01J49/46—Static spectrometers
  • H01J49/48—Static spectrometers using electrostatic analysers, e.g. cylindrical sector, Wien filter
  • H01J49/488—Static spectrometers using electrostatic analysers, e.g. cylindrical sector, Wien filter with retarding grids
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/0021—Reactive sputtering or evaporation
  • C23C14/0036—Reactive sputtering
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/02—Pretreatment of the material to be coated
  • C23C14/021—Cleaning or etching treatments
  • C23C14/022—Cleaning or etching treatments by means of bombardment with energetic particles or radiation
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
  • C23C14/14—Metallic material, boron or silicon
  • C23C14/16—Metallic material, boron or silicon on metallic substrates or on substrates of boron or silicon
  • C23C14/165—Metallic material, boron or silicon on metallic substrates or on substrates of boron or silicon by cathodic sputtering
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
  • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
  • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
  • C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
  • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
  • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
  • C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
  • C25B11/075—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound
  • C25B11/081—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound the element being a noble metal

Definitions

• ABSTRACT A process for depositing a precious metal or its oxide on a metallic support by first submitting the metallic support to ionic bombardment in a rare gas atmosphere, then without cooling below 300C. depositing the precious metal'by cathodic sputtering conducted first in a rare gas atmosphere and then in an atmosphere of mixed oxygen and rare gas.
• the present invention relates to the deposition of precious metals or their oxides onto a metallic support by cathodic sputtering so as to improve the properties of the support, such as its resistance to medium corrosion as well as electrochemical activity.
• the composite product which is obtained can be used successfully as an electrode in electrolysis cells having a diaphragm or a mercury cathode, in fuel cells, and in desalination equipment.
• the electrodes generally used as anodes are often made of graphite. Their use has always involved some drawbacks resulting from their wear which causes an increase of the voltage required for a good working of the electrolysis cell, because of the increase of the distance between the two electrodes and a contamination of the reaction medium.
• Cathodic sputtering a technique which has been known for a long time, has been found to give depositions having an excellent adhesion on the different supports which have been used, a good regularity, a good homogeneity, and purity of the deposited layer.
• the conditions under. which thistechnique is undertaken have an influence particularly on the electrochemical properties of the electrodes so made.
• An object of the present invention is to provide a process of deposition of a precious metalor its oxide on a metallic support by cathodic sputtering which comprises the steps of first submitting the metallic support to 'a bombardment with ions in a residual atmosphere at reduced pressure of pure rare gas then without waiting a dropin the high temperature which results therefrom, depositing thereon a precious metal or its oxide by ineans of cathodic sputtering which is achieved first in a residual'atm'osphere at reduced pressure of pure raregas. then in a mixed atmosphere of rare gas and oxygen.
• This technique of cathodic sputtering falls into the category of metallic depositions by electrical discharge in agas at low pressure.
• the apparatus required comprises a vacuum enclosure, a pumping system, a high voltage electrical supply, and an introduction system for gas.
• the vacuum enclosure contains the cathode made of precious metal and the anode made of the metallic support on which the deposition is accomplished.
• Cathodic sputtering consists in extraction of atoms from the cathode under the action of the bombardment by the ions which are accelerated by the fall of cathodic potential.
• the electrons which are emitted from the cathode which is under a high negative voltage are accelerated and produce ionization of the residual gaseous molecules which are in the space between the electrodes.
• the positive ion is accelerated again to the cathode and an electron goes to the anode.
• the impact of the positive ion on the cathode produces the ejection of atoms which depositon the anodic substrate.
• the advantage of such a technique is to give coatings of high purity because of the possibility of degassing the high vacuum enclosure and varying the composition of the gaseous plasma which takes part in the discharge and has an influence on the structure and the properties of the deposited layers.
• the metallic support before its introduction into the vacuum enclosure is subjected to sanding, so as to give the metal a large developed surface favorable to good electrochemical properties an-then to a scouring treatment so as to obtain the clean state required.
• This support is then introduced into the enclosure and the support and the precious metal to be sprayed are put in electrode positions.
• the metallic support is put in cathodic position by applying toit the negative high voltage.
• the metallic support acts for atime as a cathode and sputters. During this operation the precious metal is protected from support projections by a mask.
• the ionic bombardment of the support acts to degas and scour the surface which is to receive the deposition by eliminating oxide layers and traces of hydrocarbons, greases, etc.
• This ionic bombardment which takes place at atmospheric temperature, is accomplished with an increase of temperature which reaches 300 to 500C.
• Themetallic support is then rapidly disconnected from the high voltage supply and put in the position of an anode ready to receive the deposition resulting from the sputtering of the precious metal which is put in cathode position.
• The'latter is freed of 'its mask and 4 then connected to the high voltage supply.
• the cathodic sputtering onto the anode is undertaken immediately, while avoiding a sensible decrease of the anode temperature, being then in the region of 300C. This maintenance of the temperature is very important for the electrochemical properties of the future electrode.
• the first stage of the cathodic sputtering of the precious metal is done in a residual atmosphere of pure rare gas for 30 seconds to 5 minutes. This time is sufficient to give the future electrode good properties of resistance to corrosion because the attached layer so formed is very adherent on the metallic support with formation of a diffused microlayer.
• the presence of rare gas avoids the formation of a metal oxide layer on the support surface. So there is obtained a support very near the metallic state, having a surface without any contamination, coated with a hard and compact layer of precious metal.
• the second stage of the cathodic sputtering is accomplished in a residual atmosphere of rare gas and oxygen, the ratio of partial oxygen pressure in the mixture being between 0.l and 25 percent.
• the introduction of oxygen at this stage of the process is very significant because it leads to a deposition of precious metal or its oxide having a particular physical aspect.
• a composition of divided microcrystalline and porous form which does not need any further activating treatment in order to present good electrochemical properties. It should be pointed out that in the case of precious metal sputtering with a given'rate of oxygen in rare gas the metal was not oxidized.
• a porous precious metal was obtained, having a lower density than normally, this resulting from oxygen adsorption by the metal without oxide formation.
• a coating of precious metal or oxide in microcrystalline form is obtained, with a large specific surface, this last property being very important because the electrochemical activity is directly proportional to this surface.
• argon Although the use of argon will be specified in detail hereinunder, it should be understood that the argon can be replaced entirely or partly by any rare gas.
• a metal capable of forming a barrier layer in electrolysis solutions can be used, for example, tantalum, zirconium, niobium, titanium and their alloys.
• a corrodable support which is a good conductor of electricity, such as copper, steel, aluminum previously coated with a protecting layer of these metals suf ficient to form a barrier layer of film.
• the precious metals constituting thecathode and which are to be deposited on the anode are metals of the platinum group, that is, platinum, iridium, palladium, ruthenium, osmium, rhodium, or their alloys or oxides, employed alone or mixed.
• the ionic bombardment on the metallic support, when it is connected as a cathode must be done for a sufficient period so as to allow a good degassing and scouring of the surface. Generally to 30 minutes are enough to obtain the required result.
• the duration of cathodic sputtering of the precious metal in pure argon phase must be sufficient to obtain a microlayer of diffusion allowing a good protection of the metallic support. A period of from 30 seconds to 5 minutes generally gives the required result. The period of this phase could be increased, but this would have no particular practical advantage, because the precious metal layer would be increased; thus resulting in an ac: onomical disadvantage without contributing a particular technical advantage.
• the second phase of cathodic sputtering in mixed argon-oxygen atmosphere is conducted until the deposition ofa precious metal or its oxide in a divided and porous state of 0.1 to 1 micron thick is obtained.
• This thickness of the layer results in an electrode which has a suitable activity life. It is generally reached with a sputtering time of2 to 30 minutes in mixed atmosphere of argon-oxygen.
• the anode so obtained is allowed to cool down in the vacuum enclosure.
• the percentage of oxygen is important. A minimum of oxygen is required to produce an electrode with a good activity. However, it is not necessary to use too high a percentage of oxygen which does not improve the electrochemical activity of the electrode, but on the contrary has the tendency of decreasing the yield of sputtering of the precious metal or its oxide and to increase abnormally the period of sputtering.
• the cathodic sputtering which is only done in pure argon atmosphere can be used for depositing a metal which forms a barrier layer on a good electrical conductor support such as copper, iron, or aluminum.
• a good electrical conductor support such as copper, iron, or aluminum.
• the conductor metal shows a good passivation towards corrosion agents and can be used as a metallic support on which a deposition of precious metal or its oxide is done by cathodic sputtering according to the present invention.
• the cathode sputtering of the precious metal which is done directly in the mixed atmosphere of argonoxygen, leads to an electrode having no protective diffusion microlayer which comes from the deposition in pure argon atmosphere.
• the entire deposit has a microcrystalline and porous form.
• the electrode of this kind presents a correct polarization curve in an electrolysis bath but its activity life is reduced, its electrochemical activity decreases rapidly, due to the peeling tendency of the metal deposit.
• An electrode of the same kind is obtained if after the phase of ionic bombardment of the metallic support, the temperature is permitted to drop down to about 50C. before the cathodic sputtering of the precious metal.
• EXAMPLE '1 A titanium plate which is,30 millimeters by 50 millimeters and 3 millimeters thick was cleaned by sanding, brushed under running water, then scoured in trichloroethylene vapors. lt was then rinsed, with methanol and then introduced into a vacuum enclosure. The pressure in the enclosure was of 10 torr.
• the phase of ionic bombardment of this titanium plate was accomplished by connecting it to a current sourcejwith a voltage of 3,000 volts. After having introduced pure argon at a partial pressure of 40 X 10 torr, the ionic bombardment intended to clean the titanium was conducted for 30 minutes, under a sputtering power of 1.8 watt/cm". The temperature of the titanium plate was stabilized at 350C. at the end of the operation. During the preliminary phase the platinum cathode has been protected by a mask movable by sliding.
• the titanium plate was then disconnected from the high voltage which was applied to the platinum cathode. The process took place rapidly so as to avoid the temperature dropping which was at that time between 300 to 350C.
• the first phase of platinum deposition on the titanium plate was done in pure argon atmosphere for 2 minutes at a temperature about 300C.
• the deposited platinum had a high density and had no porosity.
• An oxygen stream was then introduced 50 as to form an argon-oxygen composition in the ratio of 80/20.
• the platinum deposition was then carried on until the platinum layer thickness of about 2,500 Angstroms was obtained. This thickness was measured with a profilometer on glass plate samples. The two phases of the platinum deposition were accomplished under a voltage of 3,000 volts and a power of 2 watts/cm". The electrode was taken out of the enclosure after having been cooled for thirty minutes.
• the second phase of the platinum deposition in mixed argon-oxygen atmosphere resulted in the platinum in its active form characterized by a lower density compared with that of solid platinum and by a large electrical resistivity, by a very developed specific surface, marked with respect to catalytic activity.
• the active platinum has a cubic structure with centered faces without oxide after analysis by X ray diffraction, by reflection and transmittance, by electronic diffraction, and by infrared spectrometry.
• the platinized titanium electrode which has been made with this plate was introduced into an electrolysis cell containing a 300 grams per liter solution of sodium chloride.
• the electrochemical characteristics were determined at 90C., from the polarization curve and from the specific consumption of platinum during a prolonged working under a current density of about 2 amperes/cm 1 The following were measured: I v
• EXAMPLE 2 The platinum deposition was done immediately, without cooling, but directly in a mixed argon-oxygen atmosphere having a ratio of 80/20. in such a way, no protective non-porous diffusion microlayer, of high density platinum formed, buta microlayer of active highly porous platinum was directlyobtained. This deposition was done under a voltage of 3,000 volts and power of2 watts/cm for '4 minutes and led to a coating thickness of 2,200 Angstroms.
• the electrochemical characteristics of the platinized titanium electrode measured under the conditions of example 1 were as follows:
• the platinized titanium electrode so made the following electrochemical characteristics measured under the same conditions as examples 1 and 2:
• EXAMPLE 4 The deposition of platinum was accomplished after cooling for 30 minutes, at a temperature of 30C., directly in a mixed argon-oxygen atmosphere (80/20) under the same'voltage and the same power as in examples l, 2 and 3.
• the deposited active platinum was 2,200 Angstroms thick after a 4 minutes sputtering.
• the platinized titanium electrode obtained had the following electrochemical characteristics, measured under the same conditions as examples 1, 2 and 3:
• This comparison shows the advantage of a platinized titanium electrode made by the process according to the invention, which is resistant to a prolonged working in an electrolysis cell, the amount of platinum consumed being very low.
• EXAMPLE 5 The platinum deposition on a tantalum plate which was 30 millimeters by 50 millimeters and 3 millimeters thick was done under the same conditions as in example l, the titanium being replacedby tantalum which is subjected in the first phase to an ionic bombardment under the same conditions. The totalthickness of the platinum deposited, platinum microlayer and porous platinum, was of 2,000 Angstroms. The useof this platinized tantalum'plate as an electrode under the conditions of example 1, led to the following characteristics:
• EXAMPLE 6 A titanium plate of the same type as in example 1, was subjected to an ionic bombardment under the same conditions, the temperature being 300C.
• a ruthenium cathode was used in order to achieve the cathodic sputtering on the titanium plate.
• the deposition was accomplished in a first phase in an argon atmosphere for 45 seconds under a partial pressure of 50 X 10 torr and a sputtering power of 2.1 watts/cm and then in a mixed argon-oxygen atmosphere in the ratio 99.8/0.2, for 5 minutes at the same partial pressure, with a sputtering power of 1.9 watts/cm".
• the deposited layer was 2,700 Angstroms thick.
• a process for coating a metallic substrate by cathodic sputtering of a precious metal which comprises the steps of first submitting the metallic substrate to an ionic bombardment in a residual atmosphere of a pure rare gas, then, while at an elevated temperature and without exposure to another atmosphere, cathodic sputtering on said metallic substrate the precious metal first in a residual atmosphere of said pure rare gas and then in a residual atmosphere of oxygen admixed with said rare gas.
• the metallic substrate is a metal selected from the group consisting of tantalum, zirconium, niobium, titanium and their alloys.
• the precious metal to be sputtered is selected from the group consisting of platinum, iridium, palladium, ruthenium, osmium, rhodium, and their alloys, alone and mixed.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Electrochemistry (AREA)
• Analytical Chemistry (AREA)
• Physical Vapour Deposition (AREA)
• Inert Electrodes (AREA)

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Cited By (11)

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• 1970
  • 1970-04-21 FR FR7014327A patent/FR2088659A5/fr not_active Expired
• 1971
  • 1971-03-15 CH CH372571A patent/CH524690A/fr not_active IP Right Cessation
  • 1971-03-16 SE SE03345/71A patent/SE366345B/xx unknown
  • 1971-04-05 US US00131497A patent/US3773639A/en not_active Expired - Lifetime
  • 1971-04-06 RO RO66501D patent/RO61059A/ro unknown
  • 1971-04-16 NL NL7105157A patent/NL7105157A/xx unknown
  • 1971-04-19 ES ES390345A patent/ES390345A1/es not_active Expired
  • 1971-04-19 JP JP2520271A patent/JPS5324914B1/ja active Pending
  • 1971-04-19 CA CA110757A patent/CA933881A/en not_active Expired
  • 1971-04-19 GB GB2665571*A patent/GB1307956A/en not_active Expired
  • 1971-04-19 PL PL1971147635A patent/PL83268B1/pl unknown
  • 1971-04-20 LU LU63024D patent/LU63024A1/xx unknown
  • 1971-04-20 DE DE19712119066 patent/DE2119066A1/de active Pending
  • 1971-04-20 BE BE766023A patent/BE766023A/xx unknown
  • 1971-04-20 IL IL36656A patent/IL36656A/xx unknown
  • 1971-04-21 AT AT342371A patent/AT304990B/de not_active IP Right Cessation
  • 1971-04-22 BR BR2391/71A patent/BR7102391D0/pt unknown

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