Effects of powder characteristics, additives and atmosphere on the sintering of sulfate-derived BeO

Abstract

The factors affecting densification during sintering of sulfate-derived BeO to obtain high-purity, high-density nuclear hardware have been studied and correlated. The studies included the effects of crystallite size, residual SO 3 content, the nature of furnace atmosphere, the presence of impurities and additives, as well as the influence of processing variables such as time and temperature of sintering and the amounts and nature of binders and lubricants. Factors tending to inhibit sintering are large crystallite size (> 1200Å), high residual SO 3 content (> 1 % SO 3), presence of water vapour from any source, and presence of organic additives. The main factor promoting densification during sintering is the presence of additives which increase diffusion rates. Fe 2O 3 is most effective in this regard but MgO, CaO, and ZnO also produce noticeable effects, particularly at the lower sintering temperatures (< 1525° C). A1 2O 3 and UO 2 aid densification at higher temperatures.