The Oxide Film—A Protective Barrier

Tantalum occupies a position toward the electropositive end of the electromotive force table. Therefore, when in contact with most other metals, tantalum becomes cathodic. In galvanic couples in which tantalum is the cathode, nascent (or atomic) hydrogen forms and is absorbed by the tantalum, thereby causing hydrogen embrittlement. In chemical equipment, caution must be taken to electrically isolate tantalum from other metals or otherwise protect it from becoming cathodic. Cathodic protection is discussed later in this chapter. 

Amino acids Digesting proteins in hydrochloric acid Bayonet heaters, condaisers  

Ammonium chloride, pure Concentration before cr5 taUizing Heat exchangers High pressure 

Aqua regia Ore dissolving, pickling Bayonet heaters, pickling tank coils  

Bromine, pure Purification from chlorine and organics Boilers, condensers  

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