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A continuing study of electrically conducting ceramics. Final report, August 9, 1978 - March 31, 1979

Technical Report:

Abstract

A series of 36 perovskite ceramics based on SrZrO/sub 3/ has been prepared and investigated as potential materials for electrodes for MHD systems using hydrogen as a fuel. All ceramics prepared were found to be relatively dark in color, indicating optical absorptions associated with the existence of conduction electrons. Many were found to be soft and crumbly after firing at 1400/sup 0/ or 1500/sup 0/C, but became hard and often quite shiny when fired at 1650/sup 0/C using a special graphite induction furnace. In most cases, this increase in hardness was also accompanied by a significant density increase. Most ceramics were found to be composed of second perovskite structures, i.e. manganates of Ba, Ca, Sr or La, in addition to the zirconate phase. Their room temperature electrical resistivity was determined by the van der Paaw method. Results show that resistivity falls below 100 ohm-cm (the value acceptable for MHD electrodes) for certain ceramics of the types tested. The resistivity value was found to vary significantly with firing temperature; this can be correlated with the crystal structures and number of phases within the ceramic. Weight loss measurements done at 1440/sup 0/C have enabled three ceramics to be identified as potential materials  More>>
Authors:
Publication Date:
Jan 01, 1979
Product Type:
Technical Report
Report Number:
NSTC-1979; CE-02213
Reference Number:
CANM-88-004267; ERA-14-011439; EDB-89-020959
Subject:
36 MATERIALS SCIENCE; 30 DIRECT ENERGY CONVERSION; MHD GENERATORS; ELECTRODES; PEROVSKITES; TEMPERATURE EFFECTS; BENCH-SCALE EXPERIMENTS; DENSITY; REVIEWS; VERY HIGH TEMPERATURE; DIRECT ENERGY CONVERTERS; DOCUMENT TYPES; PHYSICAL PROPERTIES; 360601* - Other Materials- Preparation & Manufacture; 300103 - MHD Generators- Materials, Components, & Auxiliaries
OSTI ID:
6822507
Research Organizations:
Nova Scotia Technical Coll., Halifax (Canada). Dept. of Chemical Engineering
Country of Origin:
Canada
Language:
English
Availability:
CANMET/TID, Energy, Mines and Resources Canada, 555 Booth St., Ottawa, Ont., Canada K1A 0G1; $0.34CAN per page, $3.40 CAN minimum.
Submitting Site:
CANM
Size:
Pages: 57
Announcement Date:

Technical Report:

Citation Formats

Not Available. A continuing study of electrically conducting ceramics. Final report, August 9, 1978 - March 31, 1979. Canada: N. p., 1979. Web.
Not Available. A continuing study of electrically conducting ceramics. Final report, August 9, 1978 - March 31, 1979. Canada.
Not Available. 1979. "A continuing study of electrically conducting ceramics. Final report, August 9, 1978 - March 31, 1979." Canada.
@misc{etde_6822507,
title = {A continuing study of electrically conducting ceramics. Final report, August 9, 1978 - March 31, 1979}
author = {Not Available}
abstractNote = {A series of 36 perovskite ceramics based on SrZrO/sub 3/ has been prepared and investigated as potential materials for electrodes for MHD systems using hydrogen as a fuel. All ceramics prepared were found to be relatively dark in color, indicating optical absorptions associated with the existence of conduction electrons. Many were found to be soft and crumbly after firing at 1400/sup 0/ or 1500/sup 0/C, but became hard and often quite shiny when fired at 1650/sup 0/C using a special graphite induction furnace. In most cases, this increase in hardness was also accompanied by a significant density increase. Most ceramics were found to be composed of second perovskite structures, i.e. manganates of Ba, Ca, Sr or La, in addition to the zirconate phase. Their room temperature electrical resistivity was determined by the van der Paaw method. Results show that resistivity falls below 100 ohm-cm (the value acceptable for MHD electrodes) for certain ceramics of the types tested. The resistivity value was found to vary significantly with firing temperature; this can be correlated with the crystal structures and number of phases within the ceramic. Weight loss measurements done at 1440/sup 0/C have enabled three ceramics to be identified as potential materials for thermoelectric converters requiring high temperature structural and chemical stability in oxidizing atmospheres. An appendix reviews the current status of the basis for development of perovskite ceramics and specific materials are discussed on the basis of relevant thermoelectric properties. Also included is a review of semiconductor thermocouples and of materials selection for insulators and electrodes for use in MHD systems. 91 refs., 3 figs., 10 tabs.}
place = {Canada}
year = {1979}
month = {Jan}
}