The Continuous-flow aging system
The aging experiments on the Ag0Z in different types
of gases for long times up to 6 months (10 minutes - 6 months) were
performed to determine the impact of off-gas streams on the
Ag0Z. The experiments were done with the experimental
system shown in Figure 1. The Ag0Z was loaded into
column sets, which are connected with stainless steel gas tubing in two
ovens, and each column consisted of 5 sections. Each column was
connected with gas-stream lines of dry-air and humid-air (d.p. -40oC, -15 oC, and +15oC), respectively. Thermocouples were placed at each
stainless steel line in both ovens to monitor the gas temperature. The
Ag0Z loaded into column sets dried in a
N2 stream at 150 oC for 1 hour before
starting the aging experiment to remove moisture and dust which may have
existed in or on the Ag0Z. Each gas was passed into
each column through the gas lines for the designed periods at 150oC; flow rates were controlled by mass flow
controllers at 500 ml/min. Water vapor was generated by a water vapor
generator (Easidew, Michell Instruments) by controlling a dew point
hygrometer which can be controlled by flow rates of the dry air stream.
Each of the aged Ag0Z samples were obtained after
completion of aging at each desired aging time.