EP0048284B1 - Mit einer Raney-Legierung beschichtete Kathode für Chloralkali-Elektrolysezellen und Verfahren zu ihrer Herstellung - Google Patents

Mit einer Raney-Legierung beschichtete Kathode für Chloralkali-Elektrolysezellen und Verfahren zu ihrer Herstellung Download PDF

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EP0048284B1
EP0048284B1 EP80105141A EP80105141A EP0048284B1 EP 0048284 B1 EP0048284 B1 EP 0048284B1 EP 80105141 A EP80105141 A EP 80105141A EP 80105141 A EP80105141 A EP 80105141A EP 0048284 B1 EP0048284 B1 EP 0048284B1
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nickel
raney
aluminum
molybdenum
layer
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EP0048284A1 (de
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Thomas James Gray
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Olin Corp
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Olin Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • B22F3/11—Making porous workpieces or articles
    • B22F3/1121—Making porous workpieces or articles by using decomposable, meltable or sublimatable fillers
    • B22F3/1134—Inorganic fillers
    • 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
    • C25B11/055—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material
    • C25B11/057—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material consisting of a single element or compound
    • C25B11/061—Metal or alloy
    • 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
    • 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
    • C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds

Definitions

  • Raney nickel active, porous nickel can be produced by selectively dissolving a soluble component, such as aluminum or zinc, out of an alloy of nickel and the soluble component.
  • a porous nickel of this type and the alloy from which it is produced are generally called “Raney nickel” or “Raney alloy” after their inventor. See U.S. Patent Nos. 1,563,787 (1925), 1,628,191 (1927) and 1,915, 473 (1933). There are various methods for producing this Raney nickel, and various applications for this metal are known.
  • Raney nickel surfaces on cathodes for chlor-alkali cells.
  • U.S. Patent No. 4,116,804 filed November 17, 1976 and issued September 26, 1978 to C. Needes and assigned to DuPont de Nemours describes an electrode, hereafter "Needes electrode", for use as a hydrogen evolution cathode in electrolytic cells in which a cohesive surface layer of Raney nickel is in electrical contact with a conductive metal core having an outer layer of at least 15 percent nickel (see Table 4 thereof), characterized in that the surface layer of Raney nickel is thicker than 75 pm and has a mean porosity of at least 11 percent.
  • the catalytic surface layer consists predominantly of Ni 2 Al 3 grains from which at least 60 percent of aluminum has been leached out with an aqueous base.
  • An overvoltage of about 60 millivolts is alleged.
  • reductions of 315 to 345 millivolts in hydrogen overvoltage as compared with mild steel cathodes is alleged.
  • subsequent testing indicates much higher overvoltages and actual reductions of only 100-150 millivolts.
  • spalling or delamination of the coating has been observed upon additional testing.
  • the patent teaches that any Raney nickel which forms from the NiAl 3 phase is mechanically weak and does not adhere well and is generally lost during leaching.
  • Ni 2 Al 3 (Gamma phase) is the preferred intermetallic precursor and governs the activity of the coating and that the heat treatment should be such that the proportion of Ni 2 Al 3 is maximized.
  • This mechanical weakness of Raney nickel from NiA1 3 is unfortunate because it was previously known that Raney Ni and NiA1 3 (Beta phase) is more active for hydrogen desorption than is Raney Ni from Ni 2 Al 3 (Gamma phase). See for example A. A. Zavorin et al, Kinetika i Kataliz, Vol. 18, No. 4, pp.
  • NiA1 3 is the major phase produced during heat treatments for 1, 10 or 30 minutes at about 725°C and that no more than 10 minutes is required at 725°C for alloying. When heat treated at 725°C, the alloy was found to have the greatest activity for carbon monoxide conversion catalysis (see Figure 2 thereof).
  • NiA1 3 is described as believed to be the most active intermetallic phase "as shown by Petrov et al (1969)" and photomicrographs are provided to show the structure.
  • a "dual-frame" electrode made of Raney nickel which is prepared by mixing a powdered Raney alloy (e.g. of nickel and an alloying component, such as aluminum) with a frame metal consisting of pure metal powder (e.g. carbonyl-nickel), pressing, sintering, and then dissolving out the alloying component from which the Raney alloy is prepared.
  • the surface layer of such an electrode consists of a dispersion of active Raney nickel particles, which is embedded in a frame made of inactive solid nickel particles.
  • This electrode is used, among other things, as a hydrogen evolution cathode in a chlorine-alkali electrolysis diaphragm cell.
  • Double-frame electrodes produced by the methods of powder metallurgy have insufficient mechanical strength to be suitable for producing large mesh electrodes such as those which are desired for industrial scale electrolysis of sodium chloride solutions.
  • Raney nickel One process for producing flat material from Raney nickel consists of the fact that used particles of a Raney alloy precursor (e.g., an alloy of nickel and aluminum) are sprayed onto a metallic carrier, and the aluminum is then selectively dissolved out; see U.S. Patent No. 3,637,437.
  • This material is suggested as a material for catalytic cathodes of fuel cells. Cathodes produced according to this method, however, generally have surfaces of low porosity and have a tendency to break apart.
  • U.S. Patent No. 3,272,728 and German Offenle- gungsschrift No. 2,527,386 (based on U.S. Patent Application Serial No. 489,284) describe electrodes with Raney nickel surfaces which are produced by simultaneously electrodepositing nickel and zinc from an inorganic electrolyte bath on a metal carrier (such as steel) and then selectively dissolving zinc out of the Ni-Zn alloy thus produced. This electrode treatment is supposed to reduce hydrogen overvoltage of steel cathodes by up to 150 millivolts.
  • British Patent No. 1,289,751 describes a process for producing porous nickel electrodes for electrochemical cells or fuel cells by electrodeposition of aluminum from an electrolyte containing an organoaluminum complex on a support made of nickel or a nickel alloy, wherein some of the aluminum deposited diffuses into the nickel, forming an alloy, from which aluminum is then leached.
  • the diffusion is carried out over a period of 1 or 2 hours in an inert atmosphere at a temperature of less than 659°C, preferably between 350 and 650°C.
  • Very thin electrodeposited layers, 5-20 pm thick are described.
  • Example 5 of the patent describes how a 25 mm-diameter pipe with a 1 mm-thick electrodeposited nickel layer, on which a 0.5 mm-thick aluminum layer has been deposited by flame spraying, is subjected to 6 hours of diffusion heat treatment at 650°C, in order to produce a diffusion layer at least 0.05 mm thick.
  • the pipe is then activated by immersing for 8 hours in 25 percent aqueous sodium hydroxide solution.
  • the patent states that the surface displays a high degree of efficacy for the catalytic hydrogenation of cyclohexane.
  • U.S. Patent No. 3,407,231 describes a process for producing a negative electrode with an active porous nickel surface for use in alkaline batteries.
  • the electrode is produced by bringing aluminum into contact with the surface of a nickel-containing core at an elevated temperature, so that nickel and aluminum interdiffuse to form a layer of Gamma phase nickel aluminide (Ni 2 Al 3 ), after which the aluminum which has diffused in is dissolved out with alkali hydroxide and a layer of active nickel is obtained, which is metallurgically bonded to the core.
  • Ni 2 Al 3 Gamma phase nickel aluminide
  • the process is supposed to be carried out by placing a nickel sheet in a packet made of a mixture of about 58 percent A1 2 0 3 , 40 percent aluminum powder, and 2 percent NH 4 CI and heating the packet for 8 hours in a reducing atmosphere at 800°C, so that a 200 ⁇ m-thick layer of Ni 2 Al 3 forms on each side of the nickel sheet, after which the coated nickel core is immersed in 6 N sodium hydroxide for about 16 hours at 80°C, in order to dissolve out at least 85 percent of the aluminum.
  • Raney nickel surfaces of electrodes produced according to this special method have low porosity.
  • the patent suggests that the nickel sheet be rolled between two aluminum sheets in order to produce a metallic bond, and the sandwich be heated in a reducing atmosphere at 543°C. Although temperatures below 649°C are preferred in this particular embodiment, the patent also suggests temperatures of as high as 872°C. It has been found. however, that in the case of bonding by rolling the desired metallic bond does not form.
  • EP-9830-AI there is disclosed a process for producing metal sheets or strips having on their surface a catalytic structure comprising a sintered powder Raney nickel alloy coating, the alloying element being iron, nickel, cobalt, or silver.
  • a mixture of a powder Raney metal alloy and of a powder skeletal material, like iron, nickel, or cobalt, is cold rolled onto a metal base such as steel, the degree of deformation within one pass being within the range of 20 to 60%. After sintering in a reducing atmosphere the soluble component of the Raney alloy is leached out by treatment with a base or an acid.
  • the above-mentioned object is achieved by an improved low overvoltage electrode having a Raney metal surface layer derived from an outer portion of a Mo-modified NiAl 3 precursor and by a method for producing such an electrode.
  • the low overvoltage electrode according to the invention for use as a hydrogen evolution cathode in an electrolytic cell being of the type that has a Raney metal surface layer in electrical contact with a conductive metal core is characterized in that said conductive metal core is an alloy containing from 80 to 95 percent nickel and from 20 to 5 percent molybdenum and in that said Raney metal surface is derived from leaching out aluminum and intermetallics from an adherent ortho-rhombic beta phase crystal structure of NiAl 3 precursory outer portion of said metal core, the precursory outer portion comprising in said ordered structure from 5 to 20 weight percent and preferably from 12 to 18 weight percent molybdenum of the total amount of nickel and molybdenum in said precursory outer portion.
  • the method of producing such a low overvoltage electrode according to the invention for use as a hydrogen evolution cathode in an electrolytic cell comprises the steps of:
  • Figure 1 graphically shows the cathode polarization potentials using three different Raney-treated cathodes in a typical chlor-alkali cell environment.
  • Figure 1 shows that the Raney nickel cathode of the invention with 15 percent by weight molybdenum from a molybdenum enriched Beta phase (Ni x Mo 1-x Al 3 ) precursor (hereafter ⁇ -Raney Ni-15mo) exhibited about 80 to120 millivolts less cathode polarization potential and hence 80-120 mV less overvoltage than Raney nickel coating derived from an unmodified NiA1 3 precursor.
  • a molybdenum enriched Beta phase (Ni x Mo 1-x Al 3 ) precursor hereafter ⁇ -Raney Ni-15mo
  • ⁇ -Raney Ni-15mo exhibited about 80 to120 millivolts less cathode polarization potential and hence 80-120 mV less overvoltage than Raney nickel coating derived from an unmodified NiA1 3 precursor.
  • the ⁇ -Raney Ni-15Mo had a constant overvoltage of approximately 60 millivolts over the entire seven week period shown. This is in contrast to all the other coatings tested in Figure 1 which exhibited significant potential increases. As noted before, the ⁇ -Raney Ni-15Mo did not exhibit any iron-fouling and did not have any appreciable thinning. The constant low overvoltage level is believed to be a result of this surprisingly unexpected constant nature of the coating during actual performance. It is seen that the mild steel sample, which started at about 540 millivolts overvoltage (i.e. /(-0.94) ⁇ (-1.500)/ volts, actually decreased in overpotential and then started rising. The explanation is the overplating of iron which has been recently found by others to cause increased roughness and hence lower actual current density and therefore lower overvoltage. It is well known that overpotential generally decreases when current density decreases. (See Figures 2 and 4).
  • FIG. 1 further shows that a major problem exists with prior art Raney nickel prepared from a purely Gamma phase intermetallic structure (hereafter G-Raney Ni).
  • G-Raney Ni prepared from a purely Gamma phase intermetallic structure
  • the prior art G-Raney Ni cathode exhibited both significant spalling and iron pick-up.
  • Figures 2 and 3 show the overpotential curves versus current density and time, respectively, for two catalytically coated cathodes of the invention, all prepared from Beta phase precursor. Each has a different percent by weight of molybdenum (10% for Ni-10Mo, 15% for Ni-15Mo) and a different method (plasma spraying and dipping) of depositing the aluminum prior to identical heat treatment.
  • Dipping a Ni-15Mo substrate in molten aluminum was found to produce, upon subsequent Raney treatment, a ⁇ -Raney Ni-15Mo cathode having about 20-40 millivolts less cathode overvoltage than that exhibited by a ⁇ -Raney Ni-10Mo cathode with a Ni-10Mo substrate on which the aluminum had been plasma sprayed prior to Raney treatment.
  • the reason for this difference is not known, although the result was confirmed. It is believed that the difference in molybdenum content was primarily responsible.
  • Figure 4 is a polarization versus current density graph showing the relative overpotentials of ⁇ -Raney Ni cathodes of the invention and prior art G-Raney Ni cathodes showing that ⁇ -Raney Ni is initially about 60 millivolts lower in overpotential than G-Raney Ni. Referring to Figure 1, it is seen that this difference increases with time.
  • Figure 5 is a 700X magnification cross-sectional view of a ⁇ -Raney Ni-15Mo coating of the invention taken with a scanning electrode microscope (SEM) showing at the bottom the core or substrate of nickel alloy with 15% by weight molybdenum (Ni-15Mo); a 40 pm layer of the Gamma phase (from Ni 2 Al 3 precursor) Raney Ni-15Mo or "G-Raney Ni-15Mo", immediately above the core and a 120 pm layer of the Beta phase (from NiAI 3 precursor) Raney Ni-15Mo or " ⁇ -Raney Ni-l5Mo" atop the G-Raney Ni-15Mo layer.
  • SEM scanning electrode microscope
  • the ⁇ -Raney Ni-15Mo layer is three times as thick as the G-Raney Ni-15Mo layer and the ⁇ -Raney Ni-15Mo layer is the outer layer and thus will be the layer in contact with any electrolyte in which the coated core is placed.
  • the ⁇ -Raney Ni-15Mo controls the activity of the coating.
  • the ⁇ -Raney Ni-15Mo does not fall off in the leaching step. Since the P-Raney Ni-15Mo predominates this whole coating of Figure 5 is collectively called a ⁇ -Raney Ni-15Mo coating.
  • Figure 6 is a 700X magnification SEM photomicrograph substantially identical to Figure 5 except that it is taken after the coated core of Figure 5 was operated for over six weeks in a laboratory scale membrane cell under conditions simulating a typical commercial chlor-alkali diaphragm cell.
  • the ⁇ -Raney Ni-15Mo coating did not experience any appreciable thinning after six weeks in a diaphragm cell catholyte, thus demonstrating that the ⁇ -Raney Ni-15Mo does not fall off.
  • Figure 7 shows how the interdiffusion of nickel and aluminum proceeds at 610°C.
  • a given weight of Ni 2 Al 3 has about 50 percent less aluminum than the same weight of NiAl 3 .
  • an NiA1 3 layer forms adjacent the aluminum reservoir and an Ni 2 Al 3 underneath.
  • the aluminum is at the far left side of the microphotograph. while nickel is at the far right. This is seen to occur even at temperatures as low as 610°C ifthe treatment is long enough.
  • the NiA1 3 (Beta) layer is only 5-10 ⁇ m thick while the Ni 2 Al 3 (Gamma) layer is about 35 pm thick as is proven by the microprobe readout.
  • the solid white horizontal line on the photograph is the "scan" line along which the microprobe scanned and the white dots are the relative atomic percent nickel found at the corresponding location on the scan line.
  • the corresponding location on the scan line is that point on the scan line which is directly above the corresponding dot.
  • This preponderance of Gamma phase is similarly pronounced at higher temperatures and similar heat treatment times.
  • the Beta phase predominates. It is thus believed the molybdenum stabilizes the NiA1 3 phase so as to yield a constant surprisingly low overvoltage upon subsequent leaching.
  • the overvoltage reductions are based on operation of the electrode as the cathode in a brine electrolysis cell at a current density of 200 milliamps per square centimeter (i.e. 200 ma/cm 2 or 2 KA/m 2 ), which is typical of current densities found in conventional diaphragm chlor-alkali cells.
  • the electrode can be in the form of any conveniently shaped plate or screen.
  • expanded metal screens are preferred.
  • the electrode of the present invention may also bear an optional, very thin coating of nickel atop the porous nickel surface.
  • the very thin coating which is preferably 5 to 10 ⁇ m thick, improves the mechanical strength and surface stability of the porous nickel layer, without diminishing its electrochemical activity.
  • Electrodes of the invention are prepared preferably by the improved process described above wherein an interdiffused nickel-aluminum alloy layer is formed, from which aluminum is subsequently selectively leached.
  • the process includes the steps of (a) preparing a metallic core with a nickel-bearing outer layer, (b) aluminizing the surface of the core, (c) interdiffusing the aluminum and nickel, (d) selectively leaching aluminum from the interdiffused material, (e) optionally chemically treating to prevent potential pyrophoricity and (f) optionally coating with nickel to improve the mechanical properties of the finalsurface.
  • the metallic core comprises the starting material for the electrode.
  • core is used interchangeably herein with “substrate” itself serve as the nickel-bearing outer layer, since this helps eliminate or reduce spalling of the coating by eliminating or reducing the possibility of corrosion at the interface between the outer layer and core by making the interface much less abrupt.
  • Cores in the form of screens or plates, especially screens, are preferred, but cores made from foils, wires, tubes or expanded metal are also suitable.
  • the nickel-bearing surface of the core, prior to further processing, is thoroughly cleaned by conventional means, such as chemical cleaning and/or grit blasting, to improve the bond between the nickel-bearing surface of the core and subsequently applied layers.
  • aluminizing is meant that aluminum is brought into initmate contact with the nickel-bearing material at the surface of the core so that when heated during the interdiffusion step the desired nickel-aluminum alloy layer is formed.
  • the aluminizing can be accomplished by any of several known methods, such as flame spraying aluminum onto the surface of the core, dipping the core into an aluminum melt or by use of fused salt electrolysis. Dipping is preferred since it has been found to yield the lowest overvoltage coating upon subsequent Raney treatment.
  • an aluminum layer of at least 100 ⁇ m thickness is deposited on the nickel-bearing surface of the core.
  • the interdiffusion step which is usually the next step in the process, is carried out at a temperature of at least 660°C, i.e., above the normal melting point of aluminum. Higher temperatures, under 750°C are suitable, with temperatures within the range of from about 700°C to about 750°C and particularly from about 715° to about 735°C being most preferred.
  • the interdiffusion is carried out in an atmosphere of hydrogen, nitrogen or an inert gas. This interdiffusion treatment is continued for a time sufficient for the aluminum and nickel to interdiffuse and form a Mo-modified nickel-aluminum alloy layer of at least 40 pm and preferably at least 80 pm in thickness. lnterdiffused nickel-aluminum alloy layers of 100-400 pm in thickness are preferred, with best results being obtained when the thicknesses are between 150- and 300- ⁇ m.
  • NiAI 3 has a higher proportion of aluminum than Ni 2 Al 3 , it is believed that temperature should be high enough to allow relatively fast interdiffusion yet not so high that the supply of aluminum is used up completely, because once the supply of "reservoir" aluminum in the aluminum layer is used up, further diffusion merely encourages the diffused aluminum to diffuse or spread out more thinly and thus encourages formation of Ni 2 Al 3 or other less desirable intermetallics having a lower aluminum content than NiAl 3 .
  • the interdiffusion time should be long enough to build up an interdiffused nickel alloy layer of suitable thickness but not so long as to deplete the aluminum reservoir. An interdiffusion time within the range of from about 1 minute to about 30 minutes satisfies this need.
  • Figure 5 presents a photomicrograph of a cross section of the ⁇ -Raney Ni-15Mo cathode formed from an interdiffused nickel-aluminum Beta phase alloy layer that was formed by dipping a Ni-15Mo substrate into molten aluminum and interdiffusing the nickel and aluminum at about 725°C for about 10 minutes.
  • the photomicrogra- phy shows the Ni-15Mo core, upon which is a relatively thin layer of Raneyed NipAI 3 , atop of which is comparatively thick layer of Raneyed NiAl 3 .
  • the P-Raney Ni 15-Mo cathode that is formed by leaching is derived almost entirely from the Ni .85 Mo .15 Al 3 phase.
  • Nickel formed from the Ni .85 Mo .15 Al 3 phase is not lost from the active surface during the subsequent leaching step. It is found that the Raney surface layer derived from Ni .85 Mo .15 Al 3 is stabilized by the 15 percent by weight molybdenum. From about 5-20 percent by weight Mo is sufficient to stabilize the Beta phase intermetallic.
  • the size of the Ni 2 A1 3 grains and the rate at which the thickness of the Ni Z Al 3 -containing layer grows are highly dependent on whether the aluminum layer is depleted the length of heat treatment as well as on the temperature at which the aluminum and nickel are interdiffused. Larger grain size and much faster buildup of the Ni 2 Al 3 - containing layer accompany the use of temperatures of 750°C or more.
  • the aluminizing and. interdiffusion steps are carried out sequentially.
  • the steps can also be performed simultaneously by a pack-diffusion technique.
  • a mixture of aluminum and alumina powders and an activator can be packed around a Mo-Ni-alloy core and then heated in a hydrogen atmosphere at a temperature of 750°C for about 8 hours to form the desired nickel-aluminum alloy layer.
  • the formation of the desired nickel-aluminum alloy layer is followed by a selective leaching step, wherein sufficient aluminum is removed from the surface and the Mo-modified nickel-aluminum alloy layer to form an active nickel surface layer.
  • the average size of the active nickel agglomerates is generally less than 35 pm.
  • Such an active layer is shown in cross section in the scanning-electron micrographs of Figures 5 and 6.
  • a strong aqueous base such as NaOH, KOH or other strongly basic solution capable of dissolving aluminum, is used in the selective leaching step.
  • the selective leaching is carried out in aqueous caustic solutions containing about 1 to about 30 weight percent NaOH.
  • a selective leaching treatment of 20 hours in 10 percent NaOH at ambient conditions i.e., temperature is not controlled
  • a treatment of 14 hours in 10 percent NaOH at ambient temperatures followed by 6 hours in 30 percent NaOH at 100°C has been found satisfactory for producing porous nickel surfaces of the invention.
  • a preferred selective leaching procedure is carried out first for 2 hours in 1 percent NaOH, then for 20 hours in 10 percent NaOH, both of these substeps under conditions in which temperature is not controlled, and finally for 4 hours in 30 percent NaOH at 100°C.
  • the teaching procedure removes at least about 60 percent, and preferably between about 75 and about 95 percent, of the aluminum from the interdiffused alloy layer and provides a porous nickel surface of unusually high electrochemical activity. It is recognized that the leaching conditions can be varied from those mentioned above to achieve effective selective dissolution of the aluminum.
  • the active nickel coatings may exhibit a tendency to heat when exposed to air. This self-heating tendency could possibly lead to problems of pyrophoricity.
  • an optical step of chemically treating the porous nickel layer can be used to eliminate this potential problem.
  • Convenient methods for this chemical treatment include immersing the porous nickel for at least 1 hour and usually less than 4 hours in a dilute aqueous solution containing, for example, by weight (a) 3 percent NaNo 3 or (b) 3 percent K 2 Cr 2 O 7 or (c) 3 percent NaC10 3 and 10 percent NaOH. These treatments eliminate the self-heating tendency of the porous nickel or nickel-molybdenum surface without diminishing its electrochemical activity or mechanical properties.
  • the mechanical properties of the layer can be improved by optionally coating a very thin layer of nickel onto the porous surface.
  • This nickel layer which is preferably 5 to 10 ⁇ m thick and can be applied from conventional electroless nickel or nickel electroplating baths, enhances the mechanical strength of the porous nickel layer without diminishing its electrochemical activity.
  • Beta phase (NiA1 3 ) intermetallic.
  • the Beta phase formation is stabilized by the addition of molybdenum in the amount of about 5-20 percent by weight of the total weight of nickel and molybdenum.
  • This molybdenum is apparently captured in the ordered orthorhombic Beta phase crystal structure such that the Beta phase can be represented by the formula Ni x Mo 1-x Al 3 where x is the weight percent nickel in the total weight of nickel and molybdenum.
  • Beta phase is the intermetallic of choice, this is an important advantage of the Ni-Mo-AI ternary alloy over the Ni-AI binary alloy.
  • the preferred electrode is a monolithic structure of a Ni-Mo alloy of 5-20 percent and most preferably from about 12-18 percent by weight molybdenum and about 80-95 percent and most preferably 82-88 percent by weight nickel which has been given a Raney treatment by dipping in molten aluminum and heating for about 1-30 minutes in an inert atmosphere at a temperature of from about 660°C to about 855°C.
  • a temperature of about 700°C to about 750°C and a time of about 5-15 minutes are more preferred because this gives sufficient time for enough aluminum to interdiffuse into the nickel to provide maximum perponderance of NiAI 3 or Beta phase over Gamma phase (Ni 2 Al 3 ) but does not allow enough time for the diffusion to result in the preponderance of Gamma phase (Ni 2 Al 3 ) as was specifically called for in U.S. Patent No. 4,116,804, noted above.
  • the electrodes of the invention can be made of the electrodes of the invention, especially as hydrogen- evolution cathodes of cells intended for the electrolysis of brine, water or the like.
  • the electrodes are particularly preferred for use in brine electrolysis cells, wherein the high electrochemical activity of the (3-Raney nickel or nickel-molybdenum surface remains constant for long periods of extended continuous use.
  • the diaphragm can be applied directly to the porous nickel surface of the electrode.
  • a tubular screen electrode of the invention with suction established through the inside of the tube, can be immersed in an aqueous dispersion of polytetrafluoroethylene fibers and asbestos fibers.
  • the fibers are sucked onto the outer surface of the screen until a diaphragm of the desired thickness is formed.
  • water is removed from the assembly, as for example, by heating at 95°C for 5 hours.
  • the assembly is then heated at 350°C for about one-half hour in an inert atmosphere, to complete the diaphragm fabrication.
  • the satisfactory operating lifetime of such diaphragms is not nearly as long as that of the cathodes of the brine electrolysis cells. Economics dictates that the diaphragms must be changed several times during the operating life of the cathode.
  • the diaphragms can be readily stripped from the porous nickel surface and replaced many times with insignificant detriment to the electrochemical activity or mechanical properties of the electrode. Similarly satisfactory results are also obtained with other diaphragm materials and with membrane materials (such as cationic exchange membranes of hydrophilic phosphonated, sulfonate or carboxylated fluorocarbontelomers blended with inert fibers such as asbestos, glass, tetrafluoroethylene and polytetrafluoroethylene).
  • membrane materials such as cationic exchange membranes of hydrophilic phosphonated, sulfonate or carboxylated fluorocarbontelomers blended with inert fibers such as asbestos, glass, tetrafluoroethylene and polytetrafluoroethylene.
  • Scanning electron micrograph cross sections are prepared perpendicular to the surface of the electrode. Micrographs are taken of typical areas of the cross section. A convenient magnification, usually between 150 and 700X permits inclusion of the entire thickness of the porous nickel layer in ths photomicrograph. The thickness of the porous nickel layer is determined by measuring the layer thickness depicted in the photomicrograph and dividing by the magnification. At least five such measurements are made on at least three micrographs and then averaged to obtain the thickness of the porous nickel layer of the electrode. For electrodes of the invention, this provides thickness measurements having a coefficient of variation of generally less than 5 percent. Photomicrographs of the type that can be used to make these thickness measurements are given in Figures 5 and 6.
  • Scanning electroc micrographs are prepared of randomly selected areas of the surface of the porous nickel layer of the electrode.
  • the magnification is conveniently set between about 100 and 500X.
  • the micrograph is printed on photographic paper of uniform weight.
  • the individual agglomerates of the porous nickel of the electrodes of the invention (labelled "A") are readily identifiable; the dark areas between and within the agglomerates (labelled "B") depict the porous regions.
  • a magnification is selected so that at least five full agglomerates are displayed in the photomicrograph.
  • the surface porosity and the average agglomerate size can be measured from the micrographs as follows:
  • An alternative method for measuring the average agglomerate size, D is to (1) cut out at least five typical agglomerates from each of five micrographs taken at the same magnification, X, of the surface of the electrode; (2) determine the total weight, w, and number, n, of the cut-out agglomerates; (3) measure K, the weight per unit area of the micrograph paper; and (4) calculate the average agglomerate size from Nickel-aluminum alloy layer prior to leaching
  • the nickel-aluminum alloy layer is of Ni 2 Al 3 or NiA1 3
  • measurement of the size of the grains is facilitated by superimposing a grid on the photomicrograph of the layer.
  • Ten squares of the grid are randomly selected from the middle 80 percent of the NiAl 3 or Ni 2 Al 3 containing layer.
  • the total number of grains, Z, within the boundary of each square is counted.
  • the area of the grid on the photomicrograph divided by the square of the magnification is the actual area, A, of the layer under examination.
  • This formula holdsforthe layers that consist essentially of NiAl 3 or Ni 2 Al 3 grains.
  • the average NiA1 3 or Ni 2 Al 3 grain size for a given sample is then simply the average of the size of the grains for each of the 10 grids.
  • the cross sections to be subjected to the micrographic examinations described above are prepared as follows.
  • a sample is cut and sectioned by use of a diamond saw operating at low speed.
  • the specimen is then mounted in an epoxy resin.
  • Convenient dimensions for the cross section of the specimen are about 6 by 13 millimeters.
  • Primary polishing of the specimen is carried out on a polishing wheel equipped with silicon carbide papers of grades 240A, 400A and 600A. Fine polishing is then accomplished by use of (a) 1.0 ⁇ m levigated a-alumina on a felt-covered wheel and then (b) 0.05 pm levigated y-alumina on a micro- cloth-covered wheel.
  • Figure 8 shows the structure of a test cell used for measuring the cathode potentials of the various plate electrodes of the samples given below.
  • FIG. 8 A schematic diagram of an electrochemical test cell, used for measuring the cathode potentials of the various plate electrodes of the examples below, is given in Figure 8.
  • Test cell 1 made of tetrafluoroethylene (“TFE”), is divided by diaphragm 2 into two chambers, cathode chamber 10 and anode chamber 20.
  • the diaphragm which is placed between two TFE separators 3 and 4 sealed in place by caustic- resistant gaskets 5 and 6 is made of Nafion@ 227, which is a homogeneous film 0,1778 mm thick of 1200 equivalent weight perfluorosulfonic acid resin which has been chemically modified by ethylene diamine converting a depth of 0,0381 mm to the perfluorosulfonamide laminated by a "T-12" tetrafluoroethylene filament fabric marketed by du Pont.
  • TFE tetrafluoroethylene
  • a circular titanium anode 21 of two square centimeters are coated with a titanium oxide- ruthenium oxide mixed crystal is installed at the end of the anode in the anode chamber.
  • Test electrode 11 which becomes the cathode of the test cell, is installed at the end of the cathode chamber by means of flanges and gaskets (not shown).
  • Perforated tetrafluoroethylene separators 3 and 4 are placed between diaphragm 2 and anode 21 and cathode 11, respectively.
  • a circular area of one square centimeter of the porous nickel surface of the test electrode is exposed to the interior of the cathode compartment.
  • the cathode and anode are connected electrically to controllable voltage source by cathode current collector 12 and anode current collector 22.
  • An ammeter is connected in the line between the two electrodes.
  • the entire cell 1 is then immersed in a thermostated liquid bath so as to give a constant operating temperature (e.g., 85°C).
  • Catholyte consisting of an aqueous solution, containing 11 weight percent sodium hydroxide and 15 weight percent sodium chloride, is pumped through inlet 13 into the cathode compartment at a rate which establishes an overflow through outlet 14.
  • the catholyte is maintained at 85°C.
  • anolyte consisting of an aqueous solution of 1.5 pH containing 24-26 weight percent sodium chloride is pumped through inlet 23 into the anode compartment and overflowed through outlet 24.
  • the salt concentrations of the catholyte and anolyte are typical of that encountered in commercial brine electrolysis cells.
  • catholyte and anolyte feeds assures better control of the desired catholyte composition.
  • the catholyte and anolyte flows are controlled so that there is a small flow of solution from the anode to the cathode compartment, which flow is sufficient to assure ionic conductivity across the cell, but insufficient to significantly affect the catholyte composition.
  • Luggin tetrafluoroethylene capillary 25, installed in the anode chamber 20 and Luggin capillary 15 installed in the cathode chamber 10 and positioned 1/2 mm from the surface are each connected to a respective mercury-mercury oxide reference electrode or "S.H.E.” (not shown), which in turn is connected through voltmeter 6, to the other electrode of cell 1.
  • a Luggin capillary is a probe which, in making ionic or electrolytic contact between the anode or cathode and the reference electrode, minimizes the voltage drop due to solution resistance and permits direct measurement of the anode or cathode potential with respect to the reference electrode.
  • a voltage is impressed between the anode and test electrode (i.e., cathode), such that a current density of 200 ma/cm 2 is established at the cathode.
  • the current density is the current measured by the ammeter in milliamps divided by the area (i.e., 1 cm 2 ) of the porous nickel surface of the test electrode exposed to catholyte.
  • 200 ma would be applied to cathode 11 to achieve a current density of 200 ma/cm 2 .
  • Hydrogen gas, generated at the cathode is removed from the cathode compartment through catholyte outlet 14.
  • Chlorine gas, generated at the platinum anode is similarly removed through anolyte outlet 24. The cell is operated in this manner for at least 2 hours prior to reading the cathode potential directly from the voltmeter.
  • electrodes are prepared and tested as cathodes in brine electrolysis test cells. All characterizations are carried out in accordance with the test procedures described above. Unless stated otherwise, all compositions are given as weight percentages.
  • test electrodes Five groups of test electrodes are prepared as follows, coupons Nos. 1 to 4 being for comparison only and coupon No. 5 being an embodiment according to the invention.
  • a 1.6-mm thick nickel 200 sheet, assaying at least 99 percent nickel, is cut into a coupon measuring about one cm 2 .
  • the coupon which is to become the core of the electrode is thoroughly cleaned by degreasing with acetone, lightly etching with 10 percent HCI, rinsing with water and after drying, grit blasting with No. 24 grit A1 2 0 3 at a pressure of 3.4 kg/cm 2 (50 psi).
  • the cleaned nickel coupon is aluminized by flame-spraying a 305 ⁇ m-thick coating of aluminum on the surface of the nickel coupon.
  • a conventional plasma-arc spray gun operating at 13 to 16 kilowatts at a distance about 10 cm from the coupon is used with aluminum powder with a particle size of 44 to 74 pm.
  • the aluminized nickel coupon is heat treated at 760°C for 8 hours in a nitrogen atmosphere to interdiffuse the nickel and aluminum and form a layer which is predominantly Gamma phase (Ni Z Al 3 ) nickel aluminide. After heat treating, the coupon is allowed to cool in a current of nitrogen for about 2 hours. This produces a predominantly Ni z Al 3 interdiffused layer.
  • the remaining coupon is then subjected to a leaching treatment wherein the aluminum is selectively removed from the interdiffused layer to leave an active porous nickel surface on the coupon.
  • the leaching treatment consists of immersing the interdiffused coupon in 10 percent NaOH for 20 hours, without temperature control, followed by 4 hours in 30 percent NaOH at 100°C. The coupon is then rinsed with water for 30 minutes.
  • a 1.6-mm-thick nickel 200 sheet, assaying at least 99 percent nickel, is cut into a coupon measuring about one cm 2 .
  • the coupon which is to become the core of the electrode is thoroughly cleaned by degreasing with acetone, lightly etching with 10 percent HCI, rinsing with water and after drying, grit blasting with No. 24 grit Al 2 O 3 at a pressure of 3.4 kg/cm 2 (50 psi).
  • the cleaned nickel coupon is aluminized by flame-spraying a 305-pm- thick coating of aluminum on the surface of the nickel coupon.
  • a conventional plasma-arc spray gun operating at 13 to 16 kilowatts at a distance about 10 cm from the coupon is used with aluminum powder with a particle size of 44 to 74 pm.
  • the aluminized nickel coupon is heat treated at 725°C for 10 minutes in a nitrogen atmosphere to interdiffuse the nickel and aluminum and form a layer which is predominantly Beta phase (NiA1 3 ) nickel aluminide. After heat treating, the coupon is allowed to cool in a current of nitrogen for about 2 hours. This produces a predominantly NiAl 3 interdiffused layer.
  • the remaining coupon is then subjected to a leaching treatment wherein the aluminum is selectively removed from the interdiffused layer to leave an active porous nickel surface on the coupon.
  • the leaching treatment consists of immersing the interdiffused coupon in 10 percent NaOH for 20 hours, without temperature control, followed by 4 hours in 30 percent NaOH at 100°C. The coupon is then rinsed with water for 30 minutes.
  • the cleaned nickel coupon is aluminized by applying a commercial flux and then dipping in a pot of molten aluminum for a sufficient time to entirely coat the coupon with aluminum.
  • the aluminized nickel coupon is heat treated at 725°C for 10 minutes in a nitrogen atmosphere to interdiffuse the nickel and aluminum and form a layer which is predominantly Beta phase (NiA1 3 ) nickel aluminide. After heat treating, the coupon is allowed to cool in a current of nitrogen for about 2 hours. This produces a predominantly NiAl 3 interdiffused layer.
  • the remaining coupon is then subjected to a leaching treatment wherein the aluminum is selectively removed from the interdiffused layer to leave an active porous nickel surface on the coupon.
  • the leaching treatment consists of immersing the interdiffused coupon in 10 percent NaOH for 20 hours, without temperature control, followed by 4 hours in 30 percent NaOH at 100°C. The coupon is then rinsed with water for 30 minutes.
  • a 1.6-mm-thick sheet of an alloy assaying at least 84 percent nickel and 15.0 ⁇ 0.1 percent Mo (Ni-15Mo) is cut into a circular coupon measuring about one cm 2.
  • the coupon which is to become the core of the electrode is thoroughly cleaned by degreasing with acetone, lightly etching with 10 percent HCI, rinsing with water and after drying, grit blasting with No. 24 grit Al 2 O 3 at a pressure of 3.4 kg/cm z (50 psi).
  • the cleaned nickel-molybdenum coupon is aluminized by applying a commercial flux and then dipping in a pot of molten aluminum for a sufficient time to entirely coat the coupon with aluminum.
  • the aluminized nickel-molybdenum coupon is heat treated at 725°C for 10 minutes in a nitrogen atmosphere to interdiffuse the nickel and aluminum and form a layer which is predominantly Beta phase nickel molybdenum aluminide ((Ni-15Mo)AI 3 ). After heat treating, the coupon is allowed to cool in a current of nitrogen for about 2 hours. This produces a predominantly Ni-15MoA1 3 interdiffused layer.
  • the remaining coupon is then subjected to a leaching treatment wherein the aluminum is selectively removed from the interdiffused layer to leave an active porous nickel-molybdenum surface on the coupon.
  • the leaching treatment consists of immersing the interdiffused coupon in 10 percent NaOH for 20 hours, without temperature control, followed by 4 hours in 30 percent NaOH at 100°C. The coupon is then rinsed with water for 30 minutes.
  • the cathode potentials are monitored 'for 45 days to determine if the potential experiences a steady increase or instead levels out at some value.
  • a ⁇ -Raney Ni-15Mo coupon of the invention is prepared by the same procedure as for coupon 5 of Example 1.
  • a second coupon of the invention is prepared by the same procedure as for coupon 2 of Example 1 except that instead of a 99 percent- +nickel sheet a Ni .90 ⁇ Mo .10 sheet is used instead, so as to produce a (3-Raney Ni-10Mo (plasma sprayed).
  • cathode polarization potential (IR Free) versus current density.
  • ⁇ -Raney Ni-15Mo has 20-40 millivolts less polarization, i.e., less overvoltage.
  • the cathodic potential is about 0.97 volts for P-Raney Ni-10Mo (plasma sprayed) and about -0.93 volts for ⁇ -Raney Ni-15Mo (dipped).
  • a typical IR Free cathodic potential for the mild steel electrode of Example 1 was -1.28 volts (see Figure 4).
  • Example 2 The coupons of Example 2 are tested for 45 days at 200 ma/cm 2 current density in the standard catholyte (15 percent NaCI, 11 percant NaOH, 0.1 percent NaCl0 3 , 73.9 percent H 2 0 at 85°C) and measured against a mercury, mercury oxide ("Standard Hydrogen Electrode" or "S.H.E.") by the electrochemical measurement technique noted above.
  • Two coupons of ⁇ -Raney Ni-15Mo (dipped) and one coupon of ⁇ -Raney Ni-10Mo (plasma sprayed) are used.
  • the ⁇ -Raney Ni-15Mo (dipped) coupons each have a constant cathodic potential of -1.03 volts (90 millivolts overpotential) while the P-Raney Ni-10Mo (plasma sprayed) has a slowly fluctuating cathodic potential of -1.04 to -1.140 volts versus the S.H.E.
  • the potential P-Raney Ni-10Mo (plasma sprayed) levels out after about 4 weeks and remains steady at -1.08 volts (140 millivolts) overpotential.
  • the coupons Nos. 1 to 3 prepared as follows are used for comparison against the electrode described in example 2.
  • a first coupon is prepared according to the same procedure as prescribed for coupon 2 of Example 1 to yield a prior art G-Raney Ni coated Ni cathode.
  • a second coupon is prepared according to the same procedure as prescribed for coupon 3 of Example 1 to yield a P-Raney Ni coated Ni cathode.
  • a third coupon is prepared according to the method prescribed for coupon 1 of Example 1 to yield a mild steel cathode.
  • the IR Free polarization curves versus current density are determined by electrochemical measurements for the three coupons in a standard catholyte as described above.
  • the ⁇ -Raney Ni cathode has about 60 millivolts less polarization potential at 200 ma/cm 2 than the prior art G-Raney Ni cathode, the ⁇ -Raney Ni-15Mo (dipped) cathode of the invention has about 110 millivolts less overpotential at 200 ma/cm 3 and therefore provides an unexpected improvement (see fig. 4).

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Claims (6)

1. Eine Elektrode mit niedriger Überspannung zur Verwendung als eine Wasserstoff erzeugende Elektrode in einer Elektrolysezelle, wobei die Elektrode von dem Typ ist, welche eine Oberflächenschicht aus einem Raney-Metall in elektrischem Kontakt mit einem leitenden Metallkern aufweist, dadurch gekennzeichnet, daß besagter leitender Metallkern eine Legierung ist, welche 80 bis 95% Nickel und 20 bis 5% Molybdän enthält, und daß besagte Oberfläche aus einem Raneymetall erhalten worden ist durch Herauslösen von Aluminium und intermetallischen Verbindung aus einem aushaftenden äußeren Teil des besagten Metallkerns wobei der äußere Teil eine Vorläufersubstanz in Form einer orthorhombischen, β-Phasen-Kristallstruktur von NiAl3 umfaßt und dieser äußere Teil in besagter geordneter Struktur 5 bis 20 Gewichtsprozent Molybdän enthält, bezogen auf die Gesamtmenge an Nikkel und Molybdän in besagtem äußeren Teil der Vorläufersubstanz.
2. Eine Elektrode mit niedriger Überspannung wie in Anspruch 1 beansprucht, dadurch gekennzeichnet, daß besagter äußerer Teil der Vorläufersubstanz in der geordneten Struktur 12 bis 18 Gewichtsprozent Molybdän enthält, bezogen auf die Gesamtmenge an Nickel und Molybdän in besagtem äußeren Teil der Vorläufersubstanz.
3. Ein Verfahren zur Herstellung einer Elektrode mit niedriger Überspannung zur Verwendung als Wasserstoff erzeugende Elektrode in einer Elektrolysezelle, welches die folgenden Schritte umfaßt:
a) Überziehen der Oberfläche eines reinen, nicht-porösen leitenden Metallgrundgefüges aus einer Molybdän-Legierung mit einem Gehalt an Molybdän im Bereich von 5 bis 20 Gewichtprozent und einem Gehalt an Nickel im Bereich von 80 bis 95 Geweichtsprozent mit Aluminium;
b) Wärmebehandeln besagter überzogener Oberfläche, indem besagte Oberfläche während etwa 1 bis 30 Minuten auf einer Temperatur im Bereich von 660°C bis 855°C gehalten wird, so daß ein Anteil des besagten Aluminiums in die äußeren Teile des besagten Metallgrundgefüges eindiffundiert und in besagten äußeren Teilen eine integrale Schicht einer Nickel-Molybdän-Aluminium-Legierung bildet, welche zur Hauptsache aus NiAl3-Körnchen mit einer orthorhombischen, β-Phasen-Kristallstruktur besteht, in welche geordnete Struktur Molybdän eingelagert ist, wobei der eindiffundierte Anteil an Aluminium aber nicht ausreicht, um in besagtem äußeren Teil ein Übergewicht an Ni2Al3-Körnchen zu bilden; und
c) Herauslösen von Aluminum und intermetallischen Verbindungen aus der Legierungsschicht, bis sich eine mit besagtem Grundgefüge eine Einheit bildende (integrale) Schicht aus Raney-Nichek-Molybdän gebildet hat.
4. Das Verfahren nach Anspruch 3, in welchem besagte Temperatur während der Wärmebehandlung im Bereich von 700°C bis 750°C gehalten wird.
5. Das Verfahren nach Anspruch 4, in welchem besagte Temperatur im Bereich von 715 bis 735°C gehalten wird.
6. Das Verfahrens nach Anspruch 3, in welchem besagte Maßnahme des Überziehens durch Eintauchen besagter Grundstruktur in geschmolzenes Aluminium bei einer Temperatur im Bereich von 650°C bis 765°C während 1 bis 2 Minuten durchgeführt wird.
EP80105141A 1980-08-28 1980-08-28 Mit einer Raney-Legierung beschichtete Kathode für Chloralkali-Elektrolysezellen und Verfahren zu ihrer Herstellung Expired EP0048284B1 (de)

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DE8080105141T DE3071904D1 (en) 1980-08-28 1980-08-28 Improved raney alloy coated cathode for chlor-alkali cells and method for producing the same
EP80105141A EP0048284B1 (de) 1980-08-28 1980-08-28 Mit einer Raney-Legierung beschichtete Kathode für Chloralkali-Elektrolysezellen und Verfahren zu ihrer Herstellung

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3837352A1 (de) * 1988-11-03 1990-05-10 Werner Ziem Verfahren zur herstellung von elektroden fuer elektrolysezellen
US10106902B1 (en) 2016-03-22 2018-10-23 Plasma Processes, Llc Zirconium coating of a substrate

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1233834B (de) * 1958-03-05 1967-02-09 Siemens Ag Elektrode fuer Elektrolyseure und Brennstoff-elemente mit oberflaechlicher Doppelskelett-Katalysator-Struktur
US4024044A (en) * 1975-09-15 1977-05-17 Diamond Shamrock Corporation Electrolysis cathodes bearing a melt-sprayed and leached nickel or cobalt coating
US4170536A (en) * 1977-11-11 1979-10-09 Showa Denko K.K. Electrolytic cathode and method for its production
US4177129A (en) * 1978-04-03 1979-12-04 Olin Corporation Plated metallic cathode

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3837352A1 (de) * 1988-11-03 1990-05-10 Werner Ziem Verfahren zur herstellung von elektroden fuer elektrolysezellen
US10106902B1 (en) 2016-03-22 2018-10-23 Plasma Processes, Llc Zirconium coating of a substrate

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DE3071904D1 (en) 1987-03-12

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