title: Fabrication and properties of thin-walled SOFC electrolyte tubes

authors: Hatchwell, Charles Edward

abstract: The object of this thesis was to fabricate tubular solid oxide fuel cell (SOFC) systems operating with both high and medium temperature electrolytes, and then to study their electrical behaviour using various current collection methods. The research has demonstrated that yttria-stabilised zirconia (YSZ) and Ce₀.₈Gd₀.₂O₁.₉ tubular electrolytes can be used as a basis for fabricating excellent high thermal shock resistant, rapid start up SOFC systems. The feasibility of using current collection materials with the Ce₀.₈Gd₀.₂O₁.₉ electrolyte system at operational and co-firing temperatures has also been established via chemical compatibility studies. 

Three methods of cathode current collection were investigated. These included silver coatings applied as strips along the cathode, Nimonic 90 alloy wires, and grooved metal Cr5Fe1Y₂O₃ plates. 

Conductive coatings were applied to the surface of the Nimonic 90 wires and Cr5Fe1Y₂O₃ plates. The effect these coatings had on cell performance was studied. For example, an 8 mol % YSZ tubular based SOFC was used in combination with an Ag-La₀.₈Sr₀.₂CrO₃ coated Cr5Fe1Y₂O₃ metal plate. At 900°C and 0.7 V, using H₂ bubbled through H₂O at 25 cm³ min⁻¹, a current density of 40 mA cm⁻² was achieved for the coated Cr5Fe1Y₂O₃ as compared to 16 mA cm⁻² for the non-coated. 

Dense (98% relative to theoretical), gas-tight, Ce₀.₈Gd₀.₂O₁.₉ electrolyte tubes were successfully fabricated using an extrusion process. Processing parameters, such as the modification of the Ce₀.₈Gd₀.₂O₁.₉ particle size by heat-treatment and addition of the correct proportions of organic extrusion aids, were shown to determine the quality of the final sintered tube. Electrodes were added to the electrolyte tube and the cell tested. At 600°C, using H₂ bubbled through H₂O at 25 cm³ min⁻¹, an open circuit voltage of 0.911 V was achieved. 

The chemical compatibility of the Ce₀.₈Gd₀.₂O₂ electrolyte with perovskite current collect coatings and Cr₂O₃ (the scale formed on the surface of Cr-based metal interconnects) was studied. The Cr₂O₃ and phase pure (La,Sr)CrO₃ perovskite were shown to be chemically compatible with the electrolyte at typical operating temperatures, and at co-firing temperatures. Second phases associated with the perovskite coatings were, however, shown to react with Ce₀.₈Gd₀.₂O₁.₉ at co-firing temperatures, digesting and reacting with the electrolyte. The reaction products formed were considered to be Cr based perovskite phases.

This thesis concludes with recommendations for future study.

text: Fabrication and properties of thin-walled SOFC electrolyte tubes The object of this thesis was to fabricate tubular solid oxide fuel cell (SOFC) systems operating with both high and medium temperature electrolytes, and then to study their electrical behaviour using various current collection methods. The research has demonstrated that yttria-stabilised zirconia (YSZ) and Ce₀.₈Gd₀.₂O₁.₉ tubular electrolytes can be used as a basis for fabricating excellent high thermal shock resistant, rapid start up SOFC systems. The feasibility of using current collection materials with the Ce₀.₈Gd₀.₂O₁.₉ electrolyte system at operational and co-firing temperatures has also been established via chemical compatibility studies. 

Three methods of cathode current collection were investigated. These included silver coatings applied as strips along the cathode, Nimonic 90 alloy wires, and grooved metal Cr5Fe1Y₂O₃ plates. 

Conductive coatings were applied to the surface of the Nimonic 90 wires and Cr5Fe1Y₂O₃ plates. The effect these coatings had on cell performance was studied. For example, an 8 mol % YSZ tubular based SOFC was used in combination with an Ag-La₀.₈Sr₀.₂CrO₃ coated Cr5Fe1Y₂O₃ metal plate. At 900°C and 0.7 V, using H₂ bubbled through H₂O at 25 cm³ min⁻¹, a current density of 40 mA cm⁻² was achieved for the coated Cr5Fe1Y₂O₃ as compared to 16 mA cm⁻² for the non-coated. 

Dense (98% relative to theoretical), gas-tight, Ce₀.₈Gd₀.₂O₁.₉ electrolyte tubes were successfully fabricated using an extrusion process. Processing parameters, such as the modification of the Ce₀.₈Gd₀.₂O₁.₉ particle size by heat-treatment and addition of the correct proportions of organic extrusion aids, were shown to determine the quality of the final sintered tube. Electrodes were added to the electrolyte tube and the cell tested. At 600°C, using H₂ bubbled through H₂O at 25 cm³ min⁻¹, an open circuit voltage of 0.911 V was achieved. 

The chemical compatibility of the Ce₀.₈Gd₀.₂O₂ electrolyte with perovskite current collect coatings and Cr₂O₃ (the scale formed on the surface of Cr-based metal interconnects) was studied. The Cr₂O₃ and phase pure (La,Sr)CrO₃ perovskite were shown to be chemically compatible with the electrolyte at typical operating temperatures, and at co-firing temperatures. Second phases associated with the perovskite coatings were, however, shown to react with Ce₀.₈Gd₀.₂O₁.₉ at co-firing temperatures, digesting and reacting with the electrolyte. The reaction products formed were considered to be Cr based perovskite phases.

This thesis concludes with recommendations for future study.

year: 1999

title: Which journal rankings best explain academic salaries? Evidence from the University of California

authors: Gibson, John

subjects: Journal rankings

abstract: The ranking of an academic journal is important to authors, universities, journal publishers and research funders. Rankings are gaining prominence as countries adopt regular research assessment exercises that especially reward publication in high impact journals. Yet even within a rankings-oriented discipline like economics there is no agreement on how aggressively lower ranked journals are down-weighted and in how wide is the universe of journals considered. Moreover, since it is typically less costly for authors to cite superfluous references, whether of their own volition or prompted by editors, than it is to ignore relevant ones, rankings based on citations may be easily manipulated. In contrast, when the merits of publication in one journal or another are debated during hiring, promotion and salary decisions, the evaluators are choosing over actions with costly consequences. We therefore look to the academic labor market, using data on economists in the University of California system to relate their lifetime publications in 700 different academic journals to salary. We test amongst various sets of journal rankings, and publication discount rates, to see which are most congruent with the returns implied by the academic labor market.

text: Which journal rankings best explain academic salaries? Evidence from the University of California The ranking of an academic journal is important to authors, universities, journal publishers and research funders. Rankings are gaining prominence as countries adopt regular research assessment exercises that especially reward publication in high impact journals. Yet even within a rankings-oriented discipline like economics there is no agreement on how aggressively lower ranked journals are down-weighted and in how wide is the universe of journals considered. Moreover, since it is typically less costly for authors to cite superfluous references, whether of their own volition or prompted by editors, than it is to ignore relevant ones, rankings based on citations may be easily manipulated. In contrast, when the merits of publication in one journal or another are debated during hiring, promotion and salary decisions, the evaluators are choosing over actions with costly consequences. We therefore look to the academic labor market, using data on economists in the University of California system to relate their lifetime publications in 700 different academic journals to salary. We test amongst various sets of journal rankings, and publication discount rates, to see which are most congruent with the returns implied by the academic labor market.

year: 2012-08

title: A Communitarian Approach to Accountability for the Common Good: A Case Study of Community Participation in Planning and Policy Making for Lake Taupo

authors: Arunachalam, Murugesh

subjects: accountability

abstract: This thesis seeks to gain a theoretical and empirical understanding of the meaning of a communitarian approach to accountability for the common good (CAACG). The hermeneutic analysis adopted in this study starts by explaining the researcher's pre-understandings which includes contemporary ideas on accountability, communitarianism and sustainability. A theoretical communitarian model was designed by synthesising these ideas. Using the theoretical model the researcher attempted to advance the meaning of CAACG in multiple contexts which include: the global context on sustainability; the New Zealand context on local governance; and more specifically in the context of planning and policy making for the sustainable development of the Taupo District. The use of such multiple contexts is crucial for this study. This is because communitarian ideology in New Zealand has historical roots in Local Government which, in recent years has been influenced by the global discourse on sustainable development. The adoption of multiple contexts is aimed at providing a holistic and historical understanding of planning and policy making processes in the Taupo District and the manifestation of CAACG in the processes.

In this interpretive study the term  text  is defined as the empirical data which consists of public documents, website material, minutes of community meetings, field notes and transcriptions of interviews. The empirical data is about processes and outcomes of collaboration between the community groups, public authorities and private entities in formulating strategies and policies for sustainable development of the Taupo District. Interpretation of the empirical data involved understanding the  text  from the vantage point of the pre-understandings of the interpreter. The interpretation of the  text  is is aimed at explaining the manifestation of CAACG in the Taupo District. The methodological orientations of the thesis are predominantly consistent with the hermeneutic tradition of Gadamer (1975). However, although the interpreter started with the intention of strictly confining to the subjectivist approach of Gadamer (1975), at times the hermeneutic methodology adopted by the researcher encroached into the methodological orientations of objectivist hermeneutics. The use of objectivist hermeneutic was inevitable as it was necessary to understand the authorial intention in the text before the interpreter understands the text from the perspective of his pre-understandings. Hence, the researcher rejects the assumption of objective-subjective dichotomy and subscribes more to the philosophical arguments advanced by contemporary scholars (such as Boland Jr, 1989 and Ricoeur, 1981) who find both the subjective and objective philosophies as necessary for interpreting texts. 

The hermeneutic analysis undertaken in this study suggests that the meaning of CAACG appears in the context of communal processes (including planning and policy making processes) and the strategies and policies formulated by the Taupo community. The meaning of CAACG may not be obvious to any reader of the  text . It arises from the interpretation of the  text  from the perspective of the interpreter's pre-understandings on a communitarian approach to accountability. The interpretation suggests the existence of a community of interests, community values and concerns, and communal processes in the Taupo District.  Community values and concerns are associated with Lake Taupo. The primary concern of the community is the pollution of Lake Taupo caused by animal farming in the land surrounding the lake and the impact the pollution has on the environmental, economic and cultural values of the community. The communal processes involved collaboration between the community and public authorities in planning and policy making for the protection of Lake Taupo. The interpretation also indicates the manifestation of several dimensions of accountability in the communal processes; joint accountability or 360 degree accountability in the Taupo District; and the holistic meaning of environmental and social accounting.

In the Taupo District the operation of the CAACG can be affected by several factors. Symmetry of power can be affected in terms of the preferential treatment given to the indigenous community and its segregation from the rest of the community. The strong influence of local authorities in the planning and decision making processes makes the community appear helpless without the local authorities. Communitarian processes intended to empower the community may actually strengthen the position of local authorities. Power has actually shifted from Central Government to local authorities and may not necessarily have shifted to communities. However, the endeavours to engage the community in the Taupo District can be seen as attempts to build the capacity of the community to participate in the processes and time will tell how effective the CAACG will prove to be.

This thesis is the pioneer in advancing the theorization of the CAACG and has added a substantial contribution to accountability literature. It suggests a new way of looking at environmental and social accounting in which the emphasis is on community involvement through reporting and deliberation (dialectical dimension of accountability) on the impacts of human activities on the natural environment. The CAACG is premised on the centrality of community and the assumption of a 360 degree accountability in which everyone in the community has mutual responsibility to protect the common good and can be subject to critical enquiry for the adverse impacts of their activities on the common good. The CAACG does not accord private corporations the privilege status of  reporting entities  but considers environmental and social accounting as the agenda of the community. 

The concept of CAACG is not utopian as it may sound to some readers of this thesis. There are ample evidence of communities throughout the world demanding a voice in statutory planning and decision making for sustainable development. The increasing focus on environmental sustainability and community participation in the planning and decision making processes arises from greater awareness of the detrimental impacts of environmental pollution and the realisation that the decision on the common good cannot be left to free market forces and private corporations. The natural environment belongs to a community of interests which wants to participate in joint responsibility and collective planning and decision making. No individual or group has the right to make decisions about the natural environment without consulting the community.

text: A Communitarian Approach to Accountability for the Common Good: A Case Study of Community Participation in Planning and Policy Making for Lake Taupo This thesis seeks to gain a theoretical and empirical understanding of the meaning of a communitarian approach to accountability for the common good (CAACG). The hermeneutic analysis adopted in this study starts by explaining the researcher's pre-understandings which includes contemporary ideas on accountability, communitarianism and sustainability. A theoretical communitarian model was designed by synthesising these ideas. Using the theoretical model the researcher attempted to advance the meaning of CAACG in multiple contexts which include: the global context on sustainability; the New Zealand context on local governance; and more specifically in the context of planning and policy making for the sustainable development of the Taupo District. The use of such multiple contexts is crucial for this study. This is because communitarian ideology in New Zealand has historical roots in Local Government which, in recent years has been influenced by the global discourse on sustainable development. The adoption of multiple contexts is aimed at providing a holistic and historical understanding of planning and policy making processes in the Taupo District and the manifestation of CAACG in the processes.

In this interpretive study the term  text  is defined as the empirical data which consists of public documents, website material, minutes of community meetings, field notes and transcriptions of interviews. The empirical data is about processes and outcomes of collaboration between the community groups, public authorities and private entities in formulating strategies and policies for sustainable development of the Taupo District. Interpretation of the empirical data involved understanding the  text  from the vantage point of the pre-understandings of the interpreter. The interpretation of the  text  is is aimed at explaining the manifestation of CAACG in the Taupo District. The methodological orientations of the thesis are predominantly consistent with the hermeneutic tradition of Gadamer (1975). However, although the interpreter started with the intention of strictly confining to the subjectivist approach of Gadamer (1975), at times the hermeneutic methodology adopted by the researcher encroached into the methodological orientations of objectivist hermeneutics. The use of objectivist hermeneutic was inevitable as it was necessary to understand the authorial intention in the text before the interpreter understands the text from the perspective of his pre-understandings. Hence, the researcher rejects the assumption of objective-subjective dichotomy and subscribes more to the philosophical arguments advanced by contemporary scholars (such as Boland Jr, 1989 and Ricoeur, 1981) who find both the subjective and objective philosophies as necessary for interpreting texts. 

The hermeneutic analysis undertaken in this study suggests that the meaning of CAACG appears in the context of communal processes (including planning and policy making processes) and the strategies and policies formulated by the Taupo community. The meaning of CAACG may not be obvious to any reader of the  text . It arises from the interpretation of the  text  from the perspective of the interpreter's pre-understandings on a communitarian approach to accountability. The interpretation suggests the existence of a community of interests, community values and concerns, and communal processes in the Taupo District.  Community values and concerns are associated with Lake Taupo. The primary concern of the community is the pollution of Lake Taupo caused by animal farming in the land surrounding the lake and the impact the pollution has on the environmental, economic and cultural values of the community. The communal processes involved collaboration between the community and public authorities in planning and policy making for the protection of Lake Taupo. The interpretation also indicates the manifestation of several dimensions of accountability in the communal processes; joint accountability or 360 degree accountability in the Taupo District; and the holistic meaning of environmental and social accounting.

In the Taupo District the operation of the CAACG can be affected by several factors. Symmetry of power can be affected in terms of the preferential treatment given to the indigenous community and its segregation from the rest of the community. The strong influence of local authorities in the planning and decision making processes makes the community appear helpless without the local authorities. Communitarian processes intended to empower the community may actually strengthen the position of local authorities. Power has actually shifted from Central Government to local authorities and may not necessarily have shifted to communities. However, the endeavours to engage the community in the Taupo District can be seen as attempts to build the capacity of the community to participate in the processes and time will tell how effective the CAACG will prove to be.

This thesis is the pioneer in advancing the theorization of the CAACG and has added a substantial contribution to accountability literature. It suggests a new way of looking at environmental and social accounting in which the emphasis is on community involvement through reporting and deliberation (dialectical dimension of accountability) on the impacts of human activities on the natural environment. The CAACG is premised on the centrality of community and the assumption of a 360 degree accountability in which everyone in the community has mutual responsibility to protect the common good and can be subject to critical enquiry for the adverse impacts of their activities on the common good. The CAACG does not accord private corporations the privilege status of  reporting entities  but considers environmental and social accounting as the agenda of the community. 

The concept of CAACG is not utopian as it may sound to some readers of this thesis. There are ample evidence of communities throughout the world demanding a voice in statutory planning and decision making for sustainable development. The increasing focus on environmental sustainability and community participation in the planning and decision making processes arises from greater awareness of the detrimental impacts of environmental pollution and the realisation that the decision on the common good cannot be left to free market forces and private corporations. The natural environment belongs to a community of interests which wants to participate in joint responsibility and collective planning and decision making. No individual or group has the right to make decisions about the natural environment without consulting the community.

year: 2010