Glass-ceramic coatings and sealing arrangements and their use in fuel cells
AssigneeAlstom UK Limited
InventorsChristopher Thompson, Anthony Wood, Stephen Pyke
Life of this patent
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Abstract
To provide effective seals between the separator plates of fuel cells, particularly planar solid oxide fuel cells (SOFC's), a method of applying a glass-ceramic coating to such a separator plate comprises providing a laminar body incorporating a glass powder, e.g., a tape-cast sheet, forming a bond between the laminar body and the separator plate to form. an assembly comprising the separator plate and the laminar body, and heat-treating the assembly to convert the glass powder to a glass-ceramic.
Claims26
A high-performance seal between confronting faces of adjacent separator plates in a planar, solid oxide fuel cell stack, comprising:
- at least one glass-ceramic layer on at least one of the confronting faces of one of the separator plates, and at least one glass seal layer interposed between the at least one glass-ceramic layer and an adjacent separator plate, the at least one glass-ceramic layer being a duplex layer which comprises a first glass-ceramic layer for bonding the seal to the one separator plate, and a second glass-ceramic layer superimposed on the first glass-ceramic layer, the at least one glass seal layer being interposed between the second glass-ceramic layer and the adjacent separator plate, the second glass-ceramic layer being substantially thicker than the first glass-ceramic layer, the first and second layers being of different compositions to bond the seal to a surface of the separator plate in the first layer, while also matching a thermal expansion coefficient of the second layer with respect to a thermal expansion coefficient of the separator plate to which it is attached.
A method of forming a glass-ceramic coating on a substrate comprising a separator plate of a solid oxide fuel cell, the method comprising the steps of:
- a) applying to the substrate a bonding layer incorporating a glass powder and a binder;
- b) providing a laminar body incorporating a glass powder and a binder;
- c) applying a further layer on top of the bonding layer by bonding the laminar body to the bonding layer while both are in a green condition to form an assembly comprising the substrate, the bonding layer and the laminar body, the glass powder of the bonding layer having a different composition to that of the glass powder of the laminar body, the glass powder in the bonding layer having a composition selected to bond with the substrate;
- and
- d) heat-treating the assembly to convert the glass powder layers to glass-ceramic material.
A high-performance seal between confronting faces of adjacent separator plates in a planar, solid oxide fuel cell stack, comprising:
- duplex glass-ceramic layers bonded to both confronting faces of adjacent separator plates, and at least one glass seal layer interposed therebetween, each duplex layer comprising a first glass-ceramic layer for bonding the seal to the separator plate, and a second glass-ceramic layer superimposed on the first glass-ceramic layer.
A method of providing a glass-ceramic coating-having improved bonding to a substrate in a fuel cell, comprising the steps of:
- depositing a first, bonding layer of a glass powder mixed with a binder directly onto the substrate;
- adhering a laminar body comprising a glass powder mixed with a binder to the first layer to form a second layer which is substantially thicker than the first layer, the glass powder in the first layer having a different composition to that of the glass powder in the second layer, the glass powder in the first layer having a composition selected to bond with the substrate;
- the glass powder in both layers, being of a composition such as to form a glass-ceramic on heat treatment;
- and heat-treating a resultant green coating on the substrate to drive off the binder and convert the glass powder in both layers to glass-ceramic layers.
A glass-ceramic coating bonded to a substrate in a fuel cell, comprising:
- a first, bonding layer of a glass powder mixed with a binder deposited directly onto the substrate;
- a laminar body comprising a glass powder mixed with a binder adhered to the first layer to form a second layer which is substantially thicker than the first layer;
- the glass powder in the first layer having a different composition to that of the glass powder in the second layer, the glass powder in the first layer having a composition selected to bond with the substrate;
- the glass powder in both layers having been converted to glass-ceramic material by a heat-treatment.
Dependencies are inferred from the claim text.