Inert electrode material in nanocrystalline powder form

Abstract

The invention relates to an inert electrode material in powder form comprising particles having an average particle size of 0.11 to 100 μm and each formed of an agglomerate of grains of a ceramic material and grains of a metal or alloy with each grain of ceramic material comprising a nanocrystal of the ceramic material and each grain of metal or alloy comprising a nanocrystal of the metal or alloy. Alternatively, each particle can be formed of an agglomerate of grains with each grain comprising a nanocrystal of a single phase ceramic material, a metal or an alloy. The electrode material in powder form according to the invention is useful for the manufacture of inert electrodes having improved thermal shock and corrosion resistance properties.

1 . An inert electrode material in powder form comprising particles having an average particle size of 0.1 to 100 μm and each formed of an agglomerate of grains of a ceramic material and grains of a metal or alloy with each grain of ceramic material comprising a nanocrystal of said ceramic material and each grain of metal or alloy comprising a nanocrystal of said metal or alloy.  
     
     
         2 . An inert electrode material according to  claim 1 , wherein each said particle is formed of an agglomerate of said grains of ceramic material and said grains of metal.  
     
     
         3 . An inert electrode material according to  claim 2 , wherein said ceramic material comprises an oxide, nitride or carbide of a metal selected from the group consisting of transition metals, p-group metals, rare earth metals and alkaline earth metals.  
     
     
         4 . An inert electrode material according to  claim 3 , wherein said ceramic material comprises an oxide, nitride or carbide of a transition metal selected from the group consisting of Ag, Co, Cu, Cr, Fe, Ir, Mo, Mn, Nb, Ni, Ru, Ta, Ti, V, W, Y, Zn and Zr.  
     
     
         5 . An inert electrode material according to  claim 3 , wherein said ceramic material comprises an oxide, nitride or carbide of a p-group metal selected from the group consisting of Al, Ge, In, Pb, Sb, Si and Sn.  
     
     
         6 . An inert electrode material according to  claim 3 , wherein said ceramic material comprises an oxide, nitride or carbide of a rare earth metal selected from the group consisting of Ce, La and Th.  
     
     
         7 . An inert electrode material according to  claim 3 , wherein said ceramic material comprises an oxide, nitride or carbide of an alkaline earth metal selected from the group consisting of Ca, Mg and Sr.  
     
     
         8 . An inert electrode material according to  claim 2 , wherein said metal is selected from the group consisting of chromium, cobalt, copper, gold, iridium, iron, nickel, niobium, palladium, platinum, rubidium, ruthenium, silicon, silver, titanium, yttrium and zirconium.  
     
     
         9 . An inert electrode material according to  claim 1 , wherein each said particle is formed of an agglomerate of said grains of ceramic material and said grains of alloy.  
     
     
         10 . An inert electrode material according to  claim 9 , wherein said ceramic material comprises an oxide, nitride or carbide of a metal selected from the group consisting of transition metals, p-group metals, rare earth metals and alkaline earth metals.  
     
     
         11 . An inert electrode material according to  claim 10 , wherein said ceramic material comprises an oxide, nitride or carbide of a transition metal selected from the group consisting of Ag, Co, Cu, Cr, Fe, Ir, Mo, Mn, Nb, Ni, Ru, Ta, Ti, V, W, Y, Zn and Zr.  
     
     
         12 . An inert electrode material according to  claim 10 , wherein said ceramic material comprises an oxide, nitride or carbide of a p-group metal selected from the group consisting of Al, Ge, In, Pb, Sb, Si and Sn.  
     
     
         13 . An inert electrode material according to  claim 10 , wherein said ceramic material comprises an oxide, nitride or carbide of a rare earth metal selected from the group consisting of Ce, La and Th.  
     
     
         14 . An inert electrode material according to  claim 10 , wherein said ceramic material comprises an oxide, nitride or carbide of an alkaline earth metal selected from the group consisting of Ca, Mg and Sr.  
     
     
         15 . An inert electrode material according to  claim 9 , wherein said alloy is selected from the group consisting of Cu—Ag, Cu—Ag—Ni, Cu—Ni, Cu—Ni—Fe, Cu—Pd, Cu—Pt and Ni—Fe alloys.  
     
     
         16 . An inert electrode material according to  claim 15 , wherein said alloy is a Cu—Ag alloy.  
     
     
         17 . An inert electrode material according to  claim 16 , wherein said ceramic material comprises a NiFe 2 O 4  spinel.  
     
     
         18 . An inert electrode material in powder form comprising particles having an average particle size of 0.1 to 100 μm and each formed of an agglomerate of grains with each grain comprising a nanocrystal of a single phase ceramic material.  
     
     
         19 . An inert electrode material according to  claim 18 , wherein said ceramic material comprises an oxide, nitride or carbide of a metal selected from the group consisting of transition metals, p-group metals, rare earth metals and alkaline earth metals.  
     
     
         20 . An inert electrode material according to  claim 19 , wherein said ceramic material comprises an oxide, nitride or carbide of a transition metal selected from the group consisting of Ag, Co, Cu, Cr, Fe, Ir, Mo, Mn, Nb, Ni, Ru, Ta, Ti, V, W, Y, Zn and Zr.  
     
     
         21 . An inert electrode material according to  claim 19 , wherein said ceramic material comprises an oxide, nitride or carbide of a p-group metal selected from the group consisting of Al, Ge, In, Pb, Sb, Si and Sn.  
     
     
         22 . An inert electrode material according to  claim 19 , wherein said ceramic material comprises an oxide, nitride or carbide of a rare earth metal selected from the group consisting of Ce, La and Th.  
     
     
         23 . An inert electrode material according to  claim 19 , wherein said ceramic material comprises an oxide, nitride or carbide of an alkaline earth metal selected from the group consisting of Ca, Mg and Sr.  
     
     
         24 . An inert electrode material according to  claim 19 , wherein said ceramic material is zinc oxide.  
     
     
         25 . An inert electrode material according to  claim 19 , wherein said ceramic material includes at least one dopant comprising an element selected from the group consisting of Al, Co, Cr, Cu, Fe, Mo, Nb, Ni, Sb, Si, Sn, Ti, V, W, Y, Zn and Zr.  
     
     
         26 . An inert electrode material according to  claim 25 , wherein said dopant is present in an amount of about 0.002 to about 1 wt. %.  
     
     
         27 . An inert electrode material according to  claim 26 , wherein the amount of dopant ranges from about 0.005 to about 0.05 wt. %.  
     
     
         28 . An inert electrode material according to  claim 27 , wherein the amount of dopant is about 0.008 wt. %.  
     
     
         29 . An inert electrode material according to  claim 25 , wherein said ceramic material comprises zinc oxide doped with aluminum oxide.  
     
     
         30 . An inert electrode material according to  claim 29 , wherein the aluminum oxide is present in an amount of about 0.008 wt. %.  
     
     
         31 . An inert electrode material in powder form comprising particles having an average particle size of 0.1 to 100 μm and each formed of an agglomerate of grains with each grain comprising a nanocrystal of a metal.  
     
     
         32 . An inert electrode material according to  claim 31 , wherein said metal is selected from the group consisting of chromium, cobalt, copper, gold, iridium, iron, nickel, niobium, palladium, platinum, rubidium, ruthenium, silicon, silver, titanium, yttrium and zirconium.  
     
     
         33 . An inert electrode material according to  claim 32 , wherein said metal is copper.  
     
     
         34 . An inert electrode material in powder form comprising particles having an average particle size of 0.1 to 100 μm and each formed of an agglomerate of grains with each grain comprising a nanocrystal of an alloy.  
     
     
         35 . An inert electrode material according to  claim 34 , wherein said alloy is selected from the group consisting of Cu—Ag, Cu—Ag—Ni, Cu—Ni, Cu—Ni—Fe, Cu—Pd, Cu—Pt and Ni—Fe alloys.  
     
     
         36 . An inert electrode material according to  claim 35 , wherein said alloy is a Cu—Ni alloy.  
     
     
         37 . An inert electrode material according to  claim 1 ,  9 ,  18 ,  31  or  34 , wherein said average particle size ranges from 1 to 10 μm.  
     
     
         38 . A process for producing an inert electrode material in powder form as defined in  claim 2 , which comprises the steps of: 
 a) subjecting at least one metal oxide, nitride or carbide to high-energy ball milling to form a first powder comprising particles having an average particle size of 0.1 to 100 μm and each formed of an agglomerate of grains of a ceramic material;    b) subjecting a metal to high-energy ball milling to form a second powder comprising particles having an average particle size of 0.1 to 100 μm and each formed of an agglomerate of grains with each nanocrystal of said metal;    c) mixing said first and second powders to form a powder mixture; and    d) subjecting the powder mixture obtained in step (c) to high-energy ball milling to form a nanocrystalline powder comprising particles having an average particle size of 0.1 to 100 μm and each formed of an agglomerate of grains of said ceramic material and grains of said metal, wherein each grain of ceramic material comprises a nanocrystal of said ceramic material and each grain of metal comprises a nanocrystal of said metal.    
     
     
         39 . A process according to  claim 38 , wherein said metal oxide, nitride or carbide is an oxide, nitride or carbide of a metal selected from the group consisting of transition metals, p-group metals, rare earth metals and alkaline earth metals.  
     
     
         40 . A process according to  claim 39 , wherein said metal oxide, nitride or carbide is an oxide, nitride or carbide of a transition metal selected from the group consisting of Ag, Co, Cu, Cr, Fe, Ir, Mo, Mn, Nb, Ni, Ru, Ta, Ti, V, W, Y, Zn and Zr.  
     
     
         41 . A process according to  claim 39 , wherein said metal oxide, nitride or carbide is an oxide, nitride or carbide of a p-group metal selected from the group consisting of Al, Ge, In, Pb, Sb, Si and Sn.  
     
     
         42 . A process according to  claim 39 , wherein said metal oxide, nitride or carbide is an oxide, nitride or carbide of a rare earth metal selected from the group consisting of Ce, La and Th.  
     
     
         43 . A process according to  claim 39 , wherein said metal oxide, nitride or carbide is an oxide, nitride or carbide of an alkaline earth metal selected from the group consisting of Ca, Mg and Sr.  
     
     
         44 . A process according to  claim 38 , wherein said metal is selected from the group consisting of chromium, cobalt, copper, gold, iridium, iron, nickel, niobium, palladium, platinum, rubidium, ruthenium, silicon, silver, titanium, yttrium and zirconium.  
     
     
         45 . A process according to  claim 38 , wherein steps (a), (b) and (d) are carried out in a vibratory ball mill operated at a frequency of 5 to 40 Hz.  
     
     
         46 . A process according to  claim 45 , wherein said vibratory ball mill is operated at a frequency of about 17 Hz.  
     
     
         47 . A process according to  claim 38 , wherein steps (a), (b) and (d) are carried out in a rotary ball mill operated at a speed of 100 to 2000 r.p.m.  
     
     
         48 . A process according to  claim 47 , wherein said rotary ball mill is operated. at a speed of about 1200 r.p.m.  
     
     
         49 . A process according to  claim 38 , wherein steps (a) and (b) are carried out under an inert gas atmosphere.  
     
     
         50 . A process according to  claim 49 , wherein said inert gas atmosphere comprises argon.  
     
     
         51 . A process according to  claim 38 , wherein steps (a) and (b) are carried out for a period of time of about 5 to 10 hours.  
     
     
         52 . A process for producing an inert electrode material in powder form as defined in  claim 9 , which comprises the steps of: 
 a). subjecting at least one metal oxide, nitride or carbide to high-energy ball milling to form a first powder comprising particles having an average particle size of 0.1 to 100 μm and each formed of an agglomerate of grains of a ceramic material;    b) subjecting at least two metals to high-energy ball milling to form a second powder comprising particles having an average particle size of 0.1 to 100 μm and each formed of an agglomerate of grains with each grain comprising a nanocrystal of an alloy of said metals;    c) mixing said first and second powders to form a powder mixture; and    d) subjecting the powder mixture obtained in step (c) to high-energy ball milling to form a nanocrystalline powder comprising particles having an average particle size of 0.1 to 100 μm and each formed of an agglomerate of grains of said ceramic material and grains of said alloy, wherein each grain of ceramic material comprises a nanocrystal of said ceramic material and each grain of alloy comprises a nanocrystal of said alloy.    
     
     
         53 . A process according to  claim 52 , wherein said metal oxide, nitride or carbide is an oxide, nitride or carbide of a metal selected from the group consisting of transition metals, p-group metals, rare earth metals and alkaline earth metals.  
     
     
         54 . A process according to  claim 53 , wherein said metal oxide, nitride or carbide is an oxide, nitride or carbide of a transition metal selected from the group consisting of Ag, Co, Cu, Cr, Fe, Ir, Mo, Mn, Nb, Ni, Ru, Ta, Ti, V, W, Y, Zn and Zr.  
     
     
         55 . A process according to  claim 53 , wherein said metal oxide, nitride or carbide is an oxide, nitride or carbide of a p-group metal selected from the group consisting of Al, Ge, In, Pb, Sb, Si and Sn.  
     
     
         56 . A process according to  claim 53 , wherein said metal oxide, nitride or carbide is an oxide, nitride or carbide of a rare earth metal selected from the group consisting of Ce, La and Th.  
     
     
         57 . A process according to  claim 53 , wherein said metal oxide, nitride or carbide is an oxide, nitride or carbide of an alkaline earth metal selected from the group consisting of Ca, Mg and Sr.  
     
     
         58 . A process according to  claim 52 , wherein said metals are selected from the group consisting of chromium, cobalt, copper, gold, iridium, iron, nickel, niobium, palladium, platinum, rubidium, ruthenium, silicon, silver, titanium, yttrium and zirconium.  
     
     
         59 . A process according to  claim 52 , wherein ferric oxide and nickel oxide are subjected to said high-energy ball milling in step (a), whereby said first powder comprises particles having an average particle size of 0.1 to 100 μm and each formed of an agglomerate of grains of a NiFe 2 O 4  spinel.  
     
     
         60 . A process according to  claim 59 , wherein copper and silver are subjected to said high-energy ball milling in step (b), whereby said second powder comprises particles having an average particle size of 0.1 to 100 μm and each formed of an agglomerate of grains with each grain comprising a nanocrystal of a Cu—Ag alloy.  
     
     
         61 . A process according to  claim 52 , wherein steps (a), (b) and (d) are carried out in a vibratory ball mill operated at a frequency of 5 to 40 Hz.  
     
     
         62 . A process according to  claim 61 , wherein said vibratory ball mill is operated at a frequency of about 17 Hz.  
     
     
         63 . A process according to  claim 52 , wherein steps (a), (b) and (d) are carried out in a rotary ball mill operated at a speed of 100 to 2000 r.p.m.  
     
     
         64 . A process according to  claim 63 , wherein said rotary ball mill is operated at a speed of about 1200 r.p.m.  
     
     
         65 . A process according to  claim 52 , wherein steps (a) and (b) are carried out under an inert gas atmosphere.  
     
     
         66 . A process according to  claim 65 , wherein said inert gas atmosphere comprises argon.  
     
     
         67 . A process according to  claim 52 , wherein steps (a) and (b) are carried out for a period of time of about 5 to 10 hours.  
     
     
         68 . A process according to  claim 52 , wherein step (b) is carried out in the presence of a lubricant.  
     
     
         69 . A process according to  claim 68 , wherein said lubricant is stearic acid.  
     
     
         70 . A process for producing an inert electrode material in powder form as defined in  claim 18 , which comprises subjecting a metal oxide, nitride or carbide to high-energy ball milling to form a nanocrystalline powder comprising particles having an average particle size of 0.1 to 100 μm and each formed of an agglomerate of grains with each grain comprising a nanocrystal of a single phase ceramic material.  
     
     
         71 . A process according to  claim 70 , wherein said metal oxide, nitride or carbide is an oxide, nitride or carbide of a metal selected from the group consisting of transition metals, p-group metals, rare earth metals and alkaline earth metals.  
     
     
         72 . A process according to  claim 71 , wherein said metal oxide, nitride or carbide is an oxide, nitride or carbide of a transition metal selected from the group consisting of Ag, Co, Cu, Cr, Fe, Ir, Mo, Mn, Nb, Ni, Ru, Ta, Ti, V, W, Y, Zn and Zr.  
     
     
         73 . A process according to  claim 71 , wherein said metal oxide, nitride or carbide is an oxide, nitride or carbide of a p-group metal selected from the group consisting of Al, Ge, In, Pb, Sb, Si and Sn.  
     
     
         74 . A process according to  claim 71 , wherein said metal oxide, nitride or carbide is an oxide, nitride or carbide of a rare earth metal selected from the group consisting of Ce, La and Th.  
     
     
         75 . A process according to  claim 71 , wherein said metal oxide, nitride or carbide is an oxide, nitride or carbide of an alkaline earth metal selected from the group consisting of Ca, Mg and Sr.  
     
     
         76 . A process according to  claim 70 , wherein zinc oxide is subjected to said high-energy ball milling.  
     
     
         77 . A process according to  claim 70 , wherein at least one dopant comprising an element selected from the group consisting of Al, Co, Cr, Cu, Fe, Mo, Nb, Ni, Sb, Si, Sn, Ti, V, W, Y, Zn and Zr is admixed with said metal oxide, nitride or carbide prior to ball milling.  
     
     
         78 . A process according to  claim 77 , wherein said dopant is used in an amount of about 0.002 to about 1 wt. %.  
     
     
         79 . A process according to  claim 78 , wherein the amount of dopant ranges from about 0.005 to about 0.05 wt. %.  
     
     
         80 . A process according to  claim 77 , wherein said metal oxide is zinc oxide and said dopant is aluminum oxide.  
     
     
         81 . A process according to  claim 80 , wherein said dopant is used in an amount of about 0.008 wt. %.  
     
     
         82 . A process according to  claim 70 , wherein said high-energy ball milling is carried in a vibratory ball mill operated at a frequency of 5 to 40 Hz.  
     
     
         83 . A process according to  claim 82 , wherein said vibratory ball mill is operated at a frequency of about 17 Hz.  
     
     
         84 . A process according to  claim 70 , wherein said high-energy ball milling is carried out in a rotary ball mill operated at a speed of 100 to 2000 r.p.m.  
     
     
         85 . A process according to  claim 84 , wherein said rotary ball mill is operated at a speed of about 1200 r.p.m.  
     
     
         86 . A process according to  claim 70 , wherein said high-energy ball milling is carried out under an inert gas atmosphere.  
     
     
         87 . A process according to  claim 86 , wherein said inert gas atmosphere comprises argon.  
     
     
         88 . A process for producing an invert electrode material in powder form as defined in  claim 31 , which comprises subjecting a metal to high-energy ball milling to form a nanocrystalline powder comprising particles having an average particle size of 0.1 to 100 μm and each formed of an agglomerate of grains with each grain comprising a nanocrystal of said metal.  
     
     
         89 . A process according to  claim 88 , wherein said metal is selected from the group consisting of chromium, cobalt, copper, gold, iridium, iron, nickel, niobium, palladium, platinum, rubidium, ruthenium, silicon, silver, titanium, yttrium and zirconium.  
     
     
         90 . A process according to  claim 89 , wherein said metal is copper.  
     
     
         91 . A process according to  claim 88 , wherein said high-energy ball milling is carried in a vibratory ball mill operated at a frequency of 5 to 40 Hz.  
     
     
         92 . A process according to  claim 91 , wherein said vibratory ball mill is operated at a frequency of about 17 Hz.  
     
     
         93 . A process according to  claim 88 , wherein said high-energy ball milling is carried out in a rotary ball mill operated at a speed of 100 to 2000 r.p.m.  
     
     
         94 . A process according to  claim 93 , wherein said rotary ball mill is operated at a speed of about 1200 r.p.m.  
     
     
         95 . A process according to  claim 88 , wherein said high-energy ball milling is carried out under an inert gas atmosphere.  
     
     
         96 . A process according to  claim 95 , wherein said inert gas atmosphere comprises argon.  
     
     
         97 . A process for producing an inert electrode material in powder form as defined in  claim 34 , which comprises subjecting at least two metals to high-energy ball milling to form a nanocrystalline powder comprising particles having an average particle of 0.1 to 100 μm and each formed of an agglomerate of grains with each grain comprising a nanocrystal of an alloy of the metals.  
     
     
         98 . A process according to  claim 97 , wherein said metals are selected from the group consisting of chromium, cobalt, copper, gold, iridium, iron, nickel, niobium, palladium, platinum, rubidium, ruthenium, silicon, silver, titanium, yttrium and zirconium.  
     
     
         99 . A process according to  claim 98 , wherein copper and nickel are subjected to said high-energy ball milling, whereby said nanocrystalline powder comprises particles having an average particle size of 0.1 to 100 μm and each formed of an agglomerate of grains with each grain comprising a nanocrystal of a Cu—Ni alloy.  
     
     
         100 . A process according to  claim 97 , wherein said high-energy ball milling is carried in a vibratory ball mill operated at a frequency of 5 to 40 Hz.  
     
     
         101 . A process according to  claim 100 , wherein said vibratory ball mill is operated at a frequency of about 17 Hz.  
     
     
         102 . A process according to  claim 97 , wherein said high-energy ball milling is carried out in a rotary ball mill operated at a speed of 100 to 2000 r.p.m.  
     
     
         103 . A process according to  claim 102 , wherein said rotary ball mill is operated at a speed of about 1200 r.p.m.  
     
     
         104 . A process according to  claim 97 , wherein said high-energy ball milling is carried out under an inert gas atmosphere.  
     
     
         105 . A process according to  claim 104 , wherein said inert gas atmosphere comprises argon.