Tantalum Cleaning and Degreasing

Cleaning and degreasing of tantalum parts must be done after metalworking and machining in order to remove adherent greases and scales. It presents no special problems, and conventional methods and materials maybe used. However, owing to hydrogen embrittlement and corrosion by alkaline solutions, hot caustics (e.g., NaOH and KOH) must be avoided. 

Cleaning. Then the workpieces are immersed in hot hydrochloric acid in order to remove the particles of steel grit embedded in the metal. Owing to the complete inertness of tantalum metal versus hydrochloric acid, the acid can be used concentrated and hot. The parts should then be thoroughly rinsed with distilled or deionized water. Tap water, which often contains calcium cations that may be converted to insoluble sulfates in the subsequent cleaning process, must be avoided. 

Anodic electroetching. This can be performed using the tantalum workpiece as anode (+), while a large platinum cathode is used (-). The electrolytic bath consists of a solution of 

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