DENSIFICATION OF LMH-2.
Abstract
Feasibilty was demonstrated for the hydrostatic compaction-fusion method of crystallizing BeH2. During the exploratory phase critical process variables were defined; then the process was partially developed through scale-up and production of 10 lbs of crystalline BeH2. Two process alternatives, namely dry encapsulation and slurry processes, were tested successfully. Because of its wider range of operating conditions, the dry encapsulation process was investigated more thoroughly. Process parameter studies yielded a good phase diagram for the region 120-250 C and 40-140 kpsi. A pressure of at least 40 kpsi (at 200 C) and a temperature of at least 130 C (with pressure above 90 kpsi) appears necessary for crystallization. Experimental evidence indicates the more thermally stable polymorph Phase 378-295 has a higher density (0.77-0.78) than does Phase 338-208 (0.73-0.74). Temperature quench rate had no effect on extent of crystallization or preferred polymorph. With the slurry process, hydrocarbon-wet BeH2 was crystallized at pressures of 70-140 kpsi and 205-230 C. However, concentrations of Phase 378-295 in the product were much lower than obtained by the dry process under similar operating conditions. An effective technique was developed for pre-compacting and encapsulating dry BeH2 feed prior to hydrostatic compaction-crystallization. It employs seamless aluminum capsules and steel plug closures fitted with Viton O-rings to seal against leakage of hydraulic fluid into the capsules. The finely divided BeH2 feed is easily pre-compacted within the capsule by means of a piston-mold unit operated at the moderate pressure of 7,000 psi. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1967
- Accession Number
- AD0389313
Entities
People
- E. M. Marlett
- G. J. Brendel