Improvement of the stability of the process for synthesizing chemically prepared varistor powder

Technical Report · Sun Aug 01 00:00:00 EDT 1993

DOI:https://doi.org/10.2172/10187174· OSTI ID:10187174

Lockwood, S J; Thomas, E V

Varistor material is currently supplied by a single commercial source. The chem-prep varistor process was developed as a backup/replacement. With the transfer of the process to the production facility, studies were made to verify that the process is stable in manufacturing. Process variables are the precursors oxalic acid, NaOH, and ZnCl{sub 2}. Process stability was determined by comparing assay uncertainty region with precipitant/ZnCl{sub 2} compositional region meeting electrical and physical property specifications. Assay variability was assessed by conducting a round robin; standard deviations of repeated assays of the same sample was 0.1 wt% by the same labs; 0.1-0.4 wt% among laboratories. A mixture experiment was then conducted to assess the effects of the precipitants/ZnCl{sub 2} on breakdown field, nonlinearity coefficient, and bulk density. Results indicate that the chem-prep process can be stable; however the nominal target composition was on the edge of the composition region, and it was moved to the center of the large region with acceptable electrical and physical properties. Tests of unpotted component rods made from the new composition met all specifications. 8 refs, 10 figs, 10 tabs.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 10187174
• Report Number(s): SAND-92-1986; ON: DE94000345
• Resource Relation: Other Information: PBD: Aug 1993
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
07 ISOTOPES AND RADIATION SOURCES
SEMICONDUCTOR RESISTORS
PRODUCTION
PRECURSOR
ZINC CHLORIDES
SODIUM HYDROXIDES
OXALIC ACID
ELECTRICAL PROPERTIES
DENSITY
POROSITY
BREAKDOWN
PROCESS CONTROL
STABILITY
POWDERS
CHEMICAL COMPOSITION
VARIATIONS
CHEMICAL ANALYSIS
COMPARATIVE EVALUATIONS
ERRORS
INTERLABORATORY COMPARISONS
426000
070201
COMPONENTS
ELECTRON DEVICES AND CIRCUITS
DESIGN, FABRICATION, AND OPERATION