June_AMP_Digital

FEATURE

A D V A N C E D

M A T E R I A L S

P R O C E S S E S | J U N E

2 0 1 5

4 3

Fig. 11 —

Linear scale plot of residual gas analysis results in

graphite and all-metal (molybdenum) hot zones held at a tem-

perature of 2200

F. Water and air measurements are higher in the

graphite hot zone.

Fig. 12 —

Titaniumbulkhead forgings successfully processed in a

graphite insulated vacuum furnace to meet final stringent surface

contamination requirements.

Fig. 10 —

Residual gas trends as a function of vacuum and temperature in molybdenum hot zone (a) and graphite hot zone (b).

(a)

(b)

CONCLUSIONS

Water vapor is the dominant gas remaining in the vacu-

um systemat ambient temperature. Roughly 20% less water

vapor occurs in a molybdenum hot zone compared with a

graphite zone in ambient air. Carbonmonoxide begins to ex-

ceedwater vapor as the dominant gas above 1500°F. There is

50% less carbon monoxide in a molybdenum hot zone com-

pared to a graphite zone, with sources including H

0 reaction