Apparatus - Hydrothermal Technology - page 82

Table 3.5 Materials Used as Reactor Linings

Material Temperature

( C)

Solutions Remarks

Titanium 550 Chlorides, hydroxides,

sulfates, sulfides

Corrosion in NaOH solution . 25%
in NH 4 Cl solution . 10%
(at 400 C)

Armco iron 450 Hydroxides Gradual oxidation producing

magnetite

Silver 600 Hydroxides

embrittlement

Gradual recrystallization and
partial dissolution

Platinum 700 Hydroxides, chlorides,

sulfates

Blackening in chlorides in the
presence of sulfur ions; partial
dissolution in hydroxides

Teflon 300 Chlorides, hydroxides Poor thermal conduction

Tantalum 500 Chlorides Begin to corrode in NH 4 Cl

solution 78%

Pyrex 300 Chlorides

Copper 450 Hydroxides Corrosion reduced in the presence

of fluoride ions and organic
compounds

Graphite 450 Sulfates Pyrolytic graphite most

suitable for linings

Nickel 300 Hydroxides

Quartz 300 Chlorides

Gold 700 Hydroxides, sulfates Partial dissolution in hydroxides

Figure 3.1 Sealed glass tube used by De Senarmont [9] .