TRANSITION METAL NITRIDE, FUEL CELL SEPARATOR, METHOD FOR PRODUCING TRANSITION METAL NITRIDE, METHOD FOR PRODUCING FUEL CELL SEPARATOR, FUEL CELL STACK AND FUEL CELL VEHICLE
First Claim
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1. A transition metal nitride comprising:
- a first layer formed of a nitride of a stainless steel containing at least Fe and Cr; and
a second layer formed on the first layer and having an exposed surface, the second layer being formed of another nitride having contents of components that differ from those in the first layer;
wherein the transition metal nitride has a composition distribution in which a Cr concentration is continuously changed from the first layer to the second layer in a thickness direction of these layers.
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Abstract
A transition metal nitride comprises a first layer formed of a nitride of a steel containing at least Fe ad Cr and second layer formed on a first layer and having an exposed surface. The transition metal nitride has a composition distribution in which Cr concentration is continuously changed from the first layer to the second layer in a thickness direction of these layers. A fuel separator comprises a base layer formed of a stainless steel containing at least Fe and Cr and a nitride layer formed of a transition metal nitride as described. Methods of forming transition metal nitrides and fuel cell separators are also included, as is a fuel cell vehicle including a fuel cell stack.
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19 Claims
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1. A transition metal nitride comprising:
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a first layer formed of a nitride of a stainless steel containing at least Fe and Cr; and
a second layer formed on the first layer and having an exposed surface, the second layer being formed of another nitride having contents of components that differ from those in the first layer;
wherein the transition metal nitride has a composition distribution in which a Cr concentration is continuously changed from the first layer to the second layer in a thickness direction of these layers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 18, 19)
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14. A method comprising:
carrying out a plasma nitriding on a surface of a base material formed of a stainless steel containing at least Fe and Cr while holding the surface at a temperature of lower than 425°
C., thereby forming a first layer and a second layer formed on and continuously connected to the first layer, the first layer having a M4N type crystal structure where a nitrogen atom is located in an octahedral gap at a center of an unit cell of a face-centered cubic lattice formed of one transition metal atom selected from the group consisting of Fe, Cr, Ni and Mo, which are contained as components of stainless steel, and the second layer having a nitride compound including a MN type crystal structure;
wherein M represents at least one transition metal element selected from the group consisting of Cr, Fe, Ni and Mo, and N represents nitrogen.- View Dependent Claims (15, 16, 17)
Specification