Wittmer, Dale E.

"Nonoxide ceramic materials could substitute for high-temperature alloy steels containing imported critical and strategic materials such as cobalt, chromium, and nickel if their high-temperature properties can be improved. An important result of this substitution would be a reduction of the nation's need for imports of critical and strategic materials. In this Bureau of Mines investigation, the primary objective was to produce high-purity ultrafine (particles < 5 um equivalent spherical diameter (esd)) alpha-silicon carbide (alpha-SiC) powders with improved high-temperature properties using the Bureau's patented turbomilling process. A secondary objective was to determine the feasibility of using polymer mill construction materials as a means of eliminating metal contamination from the turbomill. Ultrafine alpha-SiC powders with Brunauer-Emmett-Teller surface areas from 30 to 35 m2/g ( 0.06 microm particle esd) were produced in an all-polymer turbomill. These high-purity powders (with 1-pct B and 1-pct C additions) hot-pressed to greater than 99 pct of their optimal density and exhibited properties commensurate with those of commercially available alpha-SiC. The most promising of the construction materials tested for the major wear surfaces of the turbomill was ultra-high-molecular-weight polyethylene, a polymer thermoplastic." - NIOSHTIC-2

NIOSH no. 10003358

National Institute for Occupational Safety and Health