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Title: A New Technique for Joining Ceramic and Metal Components in High Temperature Electrochemical Devices

Abstract

Coal is a potentially a very inexpensive source of clean hydrogen fuel for use in fuel cells, turbines, and various process applications. To realize its potential however, efficient, low-cost gas separation systems are needed to provide high purity oxygen to enhance the coal gasification reaction and to extract hydrogen from the resulting gas product stream. Several types of inorganic membranes are being developed for hydrogen or oxygen separation, including porous alumina, transition metal oxide perovskites, and zirconia. One of the key challenges in developing solid-state membrane based gas separation systems is in hermetically joining the membrane to the metallic body of the separation device. In an effort to begin addressing this issue, a new brazing concept has been developed, referred to as reactive air brazing. This paper discusses the details of this joining technique and illustrates its use in bonding a wide variety of materials, including alumina, lanthanum strontium cobalt ferrite, and yttria stabilized zirconia.

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
920967
Report Number(s):
PNNL-SA-39894
AA1510100
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Advanced Materials, (Special Edition No. 2):84-94
Country of Publication:
United States
Language:
English
Subject:
air braze, electrochemical devices

Citation Formats

Weil, K. Scott, Hardy, John S., and Kim, Jin Yong Y.. A New Technique for Joining Ceramic and Metal Components in High Temperature Electrochemical Devices. United States: N. p., 2007. Web.
Weil, K. Scott, Hardy, John S., & Kim, Jin Yong Y.. A New Technique for Joining Ceramic and Metal Components in High Temperature Electrochemical Devices. United States.
Weil, K. Scott, Hardy, John S., and Kim, Jin Yong Y.. Mon . "A New Technique for Joining Ceramic and Metal Components in High Temperature Electrochemical Devices". United States. doi:.
@article{osti_920967,
title = {A New Technique for Joining Ceramic and Metal Components in High Temperature Electrochemical Devices},
author = {Weil, K. Scott and Hardy, John S. and Kim, Jin Yong Y.},
abstractNote = {Coal is a potentially a very inexpensive source of clean hydrogen fuel for use in fuel cells, turbines, and various process applications. To realize its potential however, efficient, low-cost gas separation systems are needed to provide high purity oxygen to enhance the coal gasification reaction and to extract hydrogen from the resulting gas product stream. Several types of inorganic membranes are being developed for hydrogen or oxygen separation, including porous alumina, transition metal oxide perovskites, and zirconia. One of the key challenges in developing solid-state membrane based gas separation systems is in hermetically joining the membrane to the metallic body of the separation device. In an effort to begin addressing this issue, a new brazing concept has been developed, referred to as reactive air brazing. This paper discusses the details of this joining technique and illustrates its use in bonding a wide variety of materials, including alumina, lanthanum strontium cobalt ferrite, and yttria stabilized zirconia.},
doi = {},
journal = {Journal of Advanced Materials, (Special Edition No. 2):84-94},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • Coal is a potentially very inexpensive source of clean hydrogen fuel for use in fuel cells, turbines, and various process applications. To realize its potential however, efficient, low-cost gas separation systems are needed to provide high purity oxygen to enhance the coal gasification reaction and to extract hydrogen from the resulting gas product stream. Several types of inorganic membranes are being developed for hydrogen or oxygen separation, including porous alumina, transition metal oxide perovskites, and zirconia. One of the key challenges in developing solid-state membrane based gas separation systems is in hermetically joining the membrane to the metallic body ofmore » the separation device. In an effort to begin addressing this issue, a new brazing concept has been developed, referred to as reactive air brazing. This paper discusses the details of this joining technique and illustrates its use in bonding a wide variety of materials, including alumina, lanthanum, strontium cobalt ferrite, and yttria stabilized zirconia.« less
  • One of the challenges in manufacturing solid-state electrochemical devices, such as planar solid oxide fuel cells (pSOFC) and oxygen generators, is in hermetically sealing the ceramic and metallic components such that the resulting joint remains rugged and stable under continuous high temperature operation in an oxidizing atmosphere. A well proven method of joining dissimilar materials is by brazing. Unfortunately many of the commercially available ceramic-to-metal braze alloys exhibit oxidation properties which are unacceptable for use in these applications. This paper outlines an alternative brazing technique that is being developed specifically for use in an oxidizing environment.
  • One of the challenges in manufacturing solid-state electrochemical devices, such as planar solid oxide fuel cells (pSOFC), is in joining the ceramic and metallic components such that the resulting joint is rugged and stable under continuous high temperature operation in an oxidizing atmosphere. A well proven method of joining dissimilar materials is by brazing. Unfortunately many of the commercially available ceramic-to-metal braze alloys exhibit oxidation behavior which is unacceptable for potential use in a pSOFC application. As a result, glass sealing is currently favored for stack assembly. However, the maximum operating temperature that a glass joint may be exposed tomore » is limited by the softening point of the glass. In addition, high temperature glasses with appropriately matching coefficients of thermal expansion typically display signs of devitrification within the first few hours of exposure at operating temperature. As they crystallize, the carefully engineered expansion properties of these seal materials change significantly, ultimately limiting the number of thermal cycles and the rate of cycling at which the joints are capable of surviving. Recently, we have developed an alternative braze composition which designed specifically for use in air. The results of this study to date will be discussed.« less
  • One of the challenges in manufacturing solid-state electrochemical devices, such as planar solid oxide fuel cells (pSOFC) and oxygen generators, is in hermetically sealing the ceramic and metallic components such that the resulting joint remains rugged and stable under continuous high temperature operation in an oxidizing atmosphere. A well proven method of joining dissimilar materials is by brazing. Unfortunately many of the commercially available ceramic-to-metal braze alloys exhibit oxidation properties which are unacceptable for use in these applications. This paper outlines an alternative brazing technique, reactive air brazing (RAB), that is being developed specifically for use in an oxidizing environment.
  • With the development of new ceramic materials, including those for structural applications, there is an increasing demand to join, ceramic components to metal structures. One of the major problems of joining ceramic to metal is the thermal expansion mismatch between them. Generally, the ceramic materials have lower thermal expansion coefficients than the metallic materials. A list of the thermal expansion coefficients of several structural ceramics and common metals is given. The active metal brazing process of the ceramic to the metal is examined in detail. Influences of all process variable, including joining materials, engineering joint design, and brazing procedures, aremore » evaluanted to obtain reliable joints between ceramic and metal with the active filler metal.« less