Tantalum is a bluish light gray metal with excellent corrosion resistance in most inorganic acids and has important applications in the chemical industry. Except for hydrofluoric acid, fluorine, fuming sulfuric acid and alkali, tantalum can withstand almost all chemical media (including hydrochloric acid at boiling point, nitric acid and sulfuric acid below 175°C).
Tantalum has excellent corrosion resistance to dilute sulfuric acid up to 75% and can be used at any temperature. The non-aerated concentrated sulfuric acid can be used for 160-170°C, and the aerated concentrated sulfuric acid can be used for 60°C. Tantalum can be used to replace stainless steel in the production of various inorganic acid equipment, the life of the stainless steel can be increased dozens of times. As a result, tantalum has been increasingly used in the chemical industry recently. However, as tantalum is a rare metal, its content in the earth's crust is 0.0002%, and its density is 16.6 g/cm 3, which makes tantalum much more expensive than other materials and limits the application of tantalum. Therefore, the main application forms are composite plates and linings. In order to reduce the cost, the thickness of tantalum layer is expected to be as thin as possible.
Domestic tantalum clad plate equipment research and development work is limited by a composite tantalum plate equipment manufacturing technology, tantalum composite panels and tantalum lining welding was very difficult, should be tantalum material and steel melting point difference (tantalum material melting point of 96 ° C , steel melting point is 1400 ° C), and the dog with Ta eutectic reaction at 1460 ° C, the Ta brittle intermetallic compound formation, under the influence of welding stress, it is easy to produce cracks and in the side of the joint interface tantalum will extend in the direction of tantalum weld molten pool, serious when produce perfoliate crack, At this time, the melted iron at the base will diffuse through the penetrating crack to the tantalum melting pool, and react with tantalum to produce Ta brittle compound, which will crack the welding seam, which is not conducive to the promotion and application of tantalum equipment in China and the development of the domestic chemical industry. Therefore, it is necessary to develop new manufacturing technology and structural form of tantalum composite plate and lining, which will play an important role in reducing equipment manufacturing cost and shortening equipment manufacturing cycle.
