Effect of Refractory on the Thermal Stability of SF6

The thermal decomposition of SF/sub 6/ is known to be oxygen-independent. Nevertheless, because of its high stability, the use of SF/sub 6/ as a conservative surrogate in incinerator performance valuation has been advocated and researched. This paper shows that refractory decreases markedly the stability of SF/sub 6/. The resulting increase in SF/sub 6/ decomposition was from 0 percent to 95 percent at 900/degree/C, and the temperatures at which 90-99 percent decomposition occurred were lowered by 300-150/degree/C. Refractory also decreased the stability of CCl/sub 4/ and C/sub 2/Cl/sub 4/, but to a lesser extent. The difference between the decompositions of C/sub 2/Cl/sub 4/ and SF/sub 6/ was reduced from several orders of magnitude to a factor of 2-4. Such a drastic and adverse change in relative stability could render SF/sub 6/ unsuitable as a conservative surrogate. The requirements for a conservative surrogate and the need for caution in its use are discussed, and further research areas are indicated.