Tantalum forms a stable anodic oxide film in an acidic electrolyte. Electrolytic capacitors made of tantalum have the advantages of large capacity, small size and good reliability. Capacitors are the most important use of tantalum. The amount of tantalum used in the late 1970s has been more than 2/3. Tantalum is also used to make electronic transmitting tubes and high-power electronic tube parts. Corrosion protection equipment made of tantalum is used in the production of strong acids, bromine, ammonia and other chemical industries. Tantalum can be used as a structural material for combustion chambers of aircraft engines. Tungsten tantalum, tungsten tantalum and hafnium alloys are used as heat-resistant and high-strength materials for rocket and jet engines, as well as parts for control and regulation equipment. Tantalum is easy to process and form, and can be used as accessories, heat insulation panels, heaters and heat sinks for high temperature vacuum furnaces. Tantalum can be used as a material in orthopedics and surgery. Tantalum carbide is used to manufacture cemented carbide at 250°C. Tantalum borides, silicates and nitrides and their alloys are used as exothermic elements and liquid metal coating materials in the atomic energy industry. Tantalum oxide is used in the manufacture of high-grade optical glasses and catalysts. In 1981, the proportion of tantalum consumption by various sectors in the United States was about: electronic components 73%, machinery industry 19%, transportation 6%, and other 2%.
The linear expansion coefficient of tantalum between 6.5 and 10℃ is 6×1-0K-100, the critical superconducting transition temperature is 4.38K, and the atomic thermal neutron absorption cross section is 21.3 Barn.
At temperatures below 150°C, tantalum is one of the most chemically stable metals. Only fluorine, hydrofluoric acid, acidic solutions containing fluoride ions and sulfur trioxide can react with tantalum. It reacts with concentrated alkali solution at room temperature and dissolves in molten alkali. Dense tantalum begins to oxidize slightly at 200°C and becomes significantly oxidized at 280°C. Tantalum has a variety of oxides, the most stable is tantalum pentoxide (Ta2O5).
Tantalum and hydrogen are identical to form brittle solid solutions and metal hydrides such as: Ta2H, TaH, TaH2, TaH3. At a vacuum of 800 to 1200°C, hydrogen precipitates from tantalum and restores its plasticity. Tantalum and nitrogen begin to react at about 300℃ to form solid solutions and nitrogen compounds. At temperatures above 2000°C and high vacuum, adsorbed nitrogen precipitates from tantalum. Tantalum and carbon exist in three phases of carbon-tantalum solid solution, low-priced carbide and high-priced carbide above 2800℃. Tantalum can react with fluorine at room temperature, and can react with other halogens to form halides above 250℃.
