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Title: Restart of the chemical preparation process for the fabrication of ZnO varistors for ferroelectric neutron generator power supplies.

Abstract

To date, all varistors used in ferroelectric neutron generators have been supplied from a single, proprietary source, General Electric Corporate Research and Development (GE CR&D). To protect against the vulnerability of a single source, Sandia initiated a program in the early 1980's to develop a second source for this material. A chemical preparation process for making homogeneous, high purity ZnO-based varistor powder was generated, scaled to production quantities, and transferred to external suppliers. In 1992, the chem-prep varistor program was suspended when it appeared there was sufficient inventory of GE CR&D material to supply ferroelectric neutron generator production for many years. In 1999, neutron generator production schedules increased substantially, resulting in a predicted exhaustion of the existing supply of varistor material within five years. The chem-prep program was restarted in January, 2000. The goals of the program were to (1) duplicate the chem-prep powder synthesis process that had been qualified for WR production, (2) demonstrate sintered billets from the chem-prep powder met requirements, (3) develop a process for rod fabrication and demonstrate that all component specifications could be met, and (4) optimize the process from powder synthesis through component fabrication for full-scale production. The first three of these goals havemore » been met and are discussed in this report. A facility for the fabrication of production quantities of chem-prep powder has been established. All batches since the restart have met compositional requirements, but differences in sintering behavior between the original process and the restarted process were noted. Investigation into the equipment, precipitant stoichiometry, and powder processing procedures were not able to resolve the discrepancies. It was determined that the restarted process, which incorporated Na doping for electrical stability (a process that was not introduced until the end of the initial program and had not been investigated for processing effects), was responsible for the differences. Rod components fabricated since the restart have met requirements and have performed at a level comparable to chem-prep rods from the original program and GE CR&D rods currently in production.« less

Authors:
Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
USDOE
OSTI Identifier:
922090
Report Number(s):
SAND2005-0763
TRN: US0802139
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; SEMICONDUCTOR RESISTORS; NEUTRON GENERATORS; ZINC OXIDES; SYNTHESIS; POWER SUPPLIES; SINTERING; Neutron generators.; Ferroelectric materials.; Ferroelectric devices.

Citation Formats

Lockwood, Steven John. Restart of the chemical preparation process for the fabrication of ZnO varistors for ferroelectric neutron generator power supplies.. United States: N. p., 2005. Web. doi:10.2172/922090.
Lockwood, Steven John. Restart of the chemical preparation process for the fabrication of ZnO varistors for ferroelectric neutron generator power supplies.. United States. https://doi.org/10.2172/922090
Lockwood, Steven John. Tue . "Restart of the chemical preparation process for the fabrication of ZnO varistors for ferroelectric neutron generator power supplies.". United States. https://doi.org/10.2172/922090. https://www.osti.gov/servlets/purl/922090.
@article{osti_922090,
title = {Restart of the chemical preparation process for the fabrication of ZnO varistors for ferroelectric neutron generator power supplies.},
author = {Lockwood, Steven John},
abstractNote = {To date, all varistors used in ferroelectric neutron generators have been supplied from a single, proprietary source, General Electric Corporate Research and Development (GE CR&D). To protect against the vulnerability of a single source, Sandia initiated a program in the early 1980's to develop a second source for this material. A chemical preparation process for making homogeneous, high purity ZnO-based varistor powder was generated, scaled to production quantities, and transferred to external suppliers. In 1992, the chem-prep varistor program was suspended when it appeared there was sufficient inventory of GE CR&D material to supply ferroelectric neutron generator production for many years. In 1999, neutron generator production schedules increased substantially, resulting in a predicted exhaustion of the existing supply of varistor material within five years. The chem-prep program was restarted in January, 2000. The goals of the program were to (1) duplicate the chem-prep powder synthesis process that had been qualified for WR production, (2) demonstrate sintered billets from the chem-prep powder met requirements, (3) develop a process for rod fabrication and demonstrate that all component specifications could be met, and (4) optimize the process from powder synthesis through component fabrication for full-scale production. The first three of these goals have been met and are discussed in this report. A facility for the fabrication of production quantities of chem-prep powder has been established. All batches since the restart have met compositional requirements, but differences in sintering behavior between the original process and the restarted process were noted. Investigation into the equipment, precipitant stoichiometry, and powder processing procedures were not able to resolve the discrepancies. It was determined that the restarted process, which incorporated Na doping for electrical stability (a process that was not introduced until the end of the initial program and had not been investigated for processing effects), was responsible for the differences. Rod components fabricated since the restart have met requirements and have performed at a level comparable to chem-prep rods from the original program and GE CR&D rods currently in production.},
doi = {10.2172/922090},
url = {https://www.osti.gov/biblio/922090}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2005},
month = {3}
}