Titanium Metals Corporation
Corrosion Resistance of Titanium
ALKALINE MEDIA

Titanium is generally very resistant to alkaline media including solutions of sodium hydroxide, potassium hydroxide, calcium hydroxide and ammonium hydroxide. In concentrations of up to approximately 70%, for example, titanium exhibits corrosion rates of less than or equal to 5 mpy [(0.127 mm/yr) Table 18.] Near nil corrosion rates are exhibited in boiling calcium hydroxide, magnesium hydroxide, and ammonium hydroxide solutions up to saturation.

Despite low corrosion rates in alkaline solutions, hydrogen pickup and possible embrittlement of titanium can occur at temperatures above 170 degrees F (77 degrees C) when solution pH is greater than or equal to 12. Successful application can be achieved where this guideline is observed.

INORGANIC SALT SOLUTIONS
Titanium is highly resistant to corrosion by inorganic salt solutions. Corrosion rates are generally very low at all temperatures to the boiling point. The resistance of titanium to chloride solutions is excellent (Table 3). However, crevice corrosion is a concern as illustrated in Figures 2, 3 and 4. Other acidic salt solutions, particularly those formed from reducing acids, may also cause crevice corrosion of unalloyed titanium at elevated temperatures. For instance, a boiling solution of 10 percent sodium sulfate, pH 2.0, causes crevice corrosion on TIMETAL 50A (Table 4). The TIMETAL Code-12 and 50A Pd alloys, on the other hand, are resistant to this environment.

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