Ceramic Electrolyte Porosity Reduction via Chemical Infiltration

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Solution Overview

Problem

Ceramic electrolyte layers in solid oxide fuel cells suffer from porosity and microcracks, leading to reduced performance and potential delamination due to high processing temperatures and thermal cycling, which increases oxygen partial pressures and causes oxidation.

Innovation Solution

A method involving infiltrating microcracks in ceramic layers with a liquid precursor containing oxidizable metal ions and exposing them to a base with a pH value of at least 9 to chemically convert the ions into oxides, reducing porosity and permeability at lower temperatures and minimizing thermal cycling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If high processing temperatures are used to decrease porosity and improve density of ceramic electrolyte layers, then the manufacturing precision and reliability improve, but the ceramic layer becomes susceptible to oxidation and thermal cycling damage, causing delamination and reducing overall reliability

Engineering Contradiction:

Improvedensity of ceramic electrolyte layerVSAvoidstability of ceramic layer

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The invention changes the processing temperature parameter from high temperature to low temperature (below 500°C) and uses chemical parameters (base solution with pH≥9) to achieve densification instead of thermal parameters, thereby avoiding oxidation and thermal cycling damage while still decreasing porosity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention replaces the thermal-mechanical sintering process with a chemical process involving base solution treatment. The base solution chemically reacts with metal ions in the ceramic layer to form metal hydroxides that fill pores and microcracks, achieving densification through chemical reactions rather than thermal-mechanical compression

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If conventional thermal spray processes are used to fabricate ceramic electrolyte layers, then large-area coating and low manufacturing cost are achieved, but the resulting layers contain pores and microcracks that increase permeability and reduce fuel cell performance

Engineering Contradiction:

Improvemanufacturing cost and area coverageVSAvoidpermeability of ceramic layer

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention performs preliminary action by applying a coating with acceptable porosity first, then subsequently treating it with base solution to fill the pores and microcracks. This two-stage approach allows easy manufacturing of the initial coating while achieving low permeability through the follow-up chemical treatment

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention introduces metal hydroxides as an intermediary substance that fills the pores and microcracks in the ceramic layer. The base solution delivers metal ions that convert to hydroxides in situ, acting as a filler material that blocks permeation paths without requiring complete elimination of the original porous structure

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach effectively decreases the porosity and permeability of ceramic layers, enhancing their performance and stability, while avoiding the issues associated with high-temperature processing, such as delamination and oxidation.

Implementation Method 1

infiltrating at least some of the microcracks with a liquid precursor

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

exposing the ceramic layer to a base having a pH value of at least about 9, so as to chemically convert the oxidizable metal ion into an oxide

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS8337939B2Method of processing a ceramic layer and related articles

Publication Date: 2012.12.25 GE VERNOVA INFRASTRUCTURE TECHNOLOGY LLC

AI summary

A method of processing a ceramic layer is provided. The method comprises the steps of providing a ceramic layer comprising a plurality of microcracks; infiltrating at least some of the plurality of microcracks with a liquid precursor comprising at least one oxidizable metal ion; and exposing the ceramic layer to a base having a pH value of at least about 9, so as to chemically convert the oxidizable metal ion into an oxide, thereby decreasing the porosity of the ceramic layer. A solid oxide fuel cell is provided. The solid oxide fuel cell comprises an anode; a cathode; and a ceramic electrolyte disposed between the anode and the cathode. The ceramic electrolyte is processed by the method comprising the steps of providing a ceramic electrolyte comprising a plurality of microcracks; infiltrating at least some of the plurality of microcracks with a liquid precursor comprising at least one oxidizable metal ion; and exposing the ceramic electrolyte to a base having a pH value of at least about 9, so as to chemically convert the oxidizable metal ion into an oxide, thereby decreasing the porosity of the ceramic electrolyte.