Abstract: The present invention is an electroconductive particle for forming an electrode including a precious metal particle including Pt or a Pt alloy and having an average particle diameter of 50 to 150 nm, a first ceramic particle including Al2O3 or ZrO2 dispersed in the precious metal particle and having an average particle diameter of 5 to 50 nm, and a second ceramic particle including Al2O3 or ZrO2 bonded to an outer periphery of the precious metal particle and having an average particle diameter of 5 to 50 nm. The sum of the volume of the first ceramic particle and the volume of the second ceramic particle is preferably 2 to 40 vol % based on the whole electroconductive particle. A metal paste containing the electroconductive particle according to the invention is one from which an electrode film of low resistance and excellent durability can be manufactured and further excellent in adherence and conformability to a substrate.

Abstract: An object of the present invention is to provide a conductive fine particle for producing a metal paste that can produce an electrode film having a low resistance, and a metal paste utilizing the conductive fine particle. The present invention is a conductive particle for electrode formation having a core/shell structure, and the conductive particle comprises a core particle made of Pt or a Pt alloy and having a particle diameter of 10 to 200 nm, and a shell made of a ceramic containing Al2O3 or ZrO2 and covers at least a part of the core particle, wherein the ceramic constituting the shell is added in an amount of 0.5 to 15% by weight based on the core particle to cover the core. The core particle is preferably Pt or a Pt alloy alloyed with Pd, Au, Ag, or Rh.

Abstract: The present invention is a metallic wire rod comprising iridium or an iridium-containing alloy and, the wire rod has in the cross section thereof biaxial crystal orientation of 50% or more of abundance proportion of textures in which crystallographic orientation has preferred orientation to <100> direction. In the present invention, crystal orientation in the outer periphery from semicircle of the cross section which is the periphery of the wire rod is important, and in this zone, abundance proportion of textures in which crystallographic orientation has preferred orientation to <100> direction is preferably not less than 50%.

Abstract: An object of the present invention is to provide a conductive fine particle for producing a metal paste that can produce an electrode film having a low resistance, and a metal paste utilizing the conductive fine particle. The present invention is a conductive particle for electrode formation having a core/shell structure, and the conductive particle comprises a core particle made of Pt or a Pt alloy and having a particle diameter of 10 to 200 nm, and a shell made of a ceramic containing Al2O3 or ZrO2 and covers at least a part of the core particle, wherein the ceramic constituting the shell is added in an amount of 0.5 to 15% by weight based on the core particle to cover the core. The core particle is preferably Pt or a Pt alloy alloyed with Pd, Au, Ag, or Rh.

Abstract: An object of the present invention is to provide a material for a precious metal tip of a spark plug, which has more excellent durability, particularly oxidation wear resistance than a conventional one. The precious metal alloy for the spark plug according to the present invention contains 0.2 to 6.0 wt. % Cr as an essential component, further at least any one of Fe or Ni, and the balance being Ir. Here, the amount of Fe and Ni to be added is preferably 2.0 to 12.0 wt. % in total. According to the present invention, the surface may be oxidized to form an oxide layer made from a Cr—Fe oxide, a Cr—Ni oxide or a Cr—Fe—Ni oxide. The oxide layer is formed by a diffusion treatment by heating the precious metal alloy at 300 to 900° C. in an oxidative atmosphere, and preferably has a thickness of 5 to 100 ?m.

Abstract: An object of the present invention is to provide a material for a precious metal tip of a spark plug, which has more excellent durability, particularly oxidation wear resistance than a conventional one. The precious metal alloy for the spark plug according to the present invention contains 0.2 to 6.0 wt. % Cr as an essential component, further at least any one of Fe or Ni, and the balance being Ir. Here, the amount of Fe and Ni to be added is preferably 2.0 to 12.0 wt. % in total. According to the present invention, the surface may be oxidized to form an oxide layer made from a Cr—Fe oxide, a Cr—Ni oxide or a Cr—Fe—Ni oxide. The oxide layer is formed by a diffusion treatment by heating the precious metal alloy at 300 to 900° C. in an oxidative atmosphere, and preferably has a thickness of 5 to 100 ?m.

Abstract: Disclosed an electrode for a polymer electrolyte electrochemical cell which comprises catalyst supports carrying catalyst particles, a first solid polymer electrolyte layer insoluble in water and an organic solvent formed on the particles and a second solid polymer electrolyte layer insoluble or soluble in the organic solvent formed on part of the surface of the first solid polymer electrolyte layer and a process of preparing same.

Abstract: Disclosed is an electrode structure for fuel cell having a carbon support of which an apparent density is between 0.05 g/cm.sup.3 and 1.2 g/cm.sup.3.In this electrode structure, the sufficient diffusion of gases can be secured because the sufficient cavities are securely formed in the catalyst electrode layer by the carbon support having a smaller apparent density or a larger porosity even if the thickness of the catalyst electrode layer increases.

Abstract: Disclosed herein is a process of preparing a solid polymer electrolyte type fuel cell formed by combining a cathode current collector, a cathode containing cathode particles, an ion exchange membrane, an anode containing anode particles and an anode current collector characterized by comprising reducing a catalyst metal salt in an organic solution with the solid polymer electrolyte, depositing the reduced catalyst metal in the solid polymer electrolyte to form the cathode and/or the anode, interposing the cathode and/or the anode between the respective current collectors and the ion exchange membrane and pressing for assembling the fuel cell.Also disclosed is the same process as above except that the support is present in the solid polymer electrolyte.In the fuel cells prepared in accordance with the present invention, the catalyst metal always exists in the solid polymer electrolyte, and even if a cavity is formed in the solid polymer electrolyte, the catalyst metal is not exposed to the cavity.